Final Report Summary - HYSOL (INNOVATIVE CONFIGURATION FOR A FULLY RENEWABLE HYBRID CSP PLANT)
Executive Summary:
The objective of this document is to provide a description of the HYSOL project, including the explication of the project context and objectives achieved, a description of the main results, the potential impact of the project and the main dissemination activities and exploitation of results.
Hysol project began in May 2013 as a European collaborative R&D and DEMO project on innovative solutions for a fully renewable hybrid concentrated solar power plant and has finished in July 2016.
The project is led by the Spanish EPC company COBRA (ACS Group) and includes a series of specialised SMEs, research centres and universities from different European countries. The eight partners participating in the project are: COBRA Instalaciones y Servicios (ACS-COBRA), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (PSA-CIEMAT), Agenzia Nazionale per le Nuove Tecnologie, l’Energia e lo Sviluppo Economico Sostenibile (ENEA), Investigación Desarrollo e Innovación Energética (IDIE), Air Industrie Thermique España (AITESA), Danmark Tekniske Universitet (DTU/MAN/SYS), Universidad Politécnica de Madrid (UPM), and Stichting Dienst Landbouwkundig Onderzoek (SDLO-PRI).
The milestones set at the beginning of the project have been achieved in the different periods. The first period has been focused on designing the heat recovery system and demonstrator plant, developing a static and dynamic simulation of the demonstrator plant, and defining the tests that would take place during the second phase of the project in the mock-up facility in ENEA and the demonstrator located in Manchasol (COBRA´s facility).
The second stage has been focused on the improvement of the simulations and its validation in the mock-up and demonstrator plants, final designs for a commercial Heat Recovery System, the construction works for the demonstrator, the experimental test campaign, the validation of the Heat Recovery System and the study of viability of the project in different locations (technically, economically and environmentally). By the end of the project, all the objectives have been fullfilled.
One of the initial objectives of the project was to achieve a 100% renewable electricity generation when using biogas. The research in the locations studied leads us to conclude that the locations where the current circumstances are optimal to construct a CSP plant, the biogas resource is not enough to supply fuel for Hysol. For this reason a commercial plant fueled with biogas is not viable in the regions where the CSP market has a high potential currently (MENA countries, South Africa, Chile, Mexico). However it is viable to obtain a 100% renewable plant in locations where a good combination of solar radiation, biomass supply and likelihood of commercial plant development occurs.
Project Context and Objectives:
Renewable energies have often problems in order to provide a stable and reliable power supply, as they often depend on meteorological circumstances that have a variable or stochastic component. This fact is often used by their detractors to favour the use of other alternatives such as fossil fuels. Concentrating Solar Power plants (CSP) are able to overcome this limitation by incorporating Thermal Energy Storage (TES) or by using residual heat from fossil fuels combustion processes in conventional heaters. These emerging technologies, although already in a commercial stage, remain still too expensive to compete against conventional non-renewable generation systems. Moreover, there is another inconvenient: gas performance in CSP is less efficient than in combined cycle plants. While a modern combined cycle plant can achieve an overall efficiency up to 55%, auxiliary heaters in a CSP plant convert gas to electricity at below 40%. Hence, the best natural gas performance takes place in a combined cycle plant. In spite of facing with the lower efficiency disadvantage, Integrated Solar Combined Cycles (ISCC) deal with this handicap by injecting steam obtained from the solar block into the fossil power cycle. However, these designs are limited up to 20% total solar enhancement. Without reliable, cost-effective energy storage or backup power, renewable sources will struggle to achieve a high inclusion into the electric grid. This project will provide the keys to develop a novel gas turbine / CSP with TES hybrid design that combines solar contribution with gas in a real integrated renewable hybrid plant.
The aim of HYSOL Project is to become the European reference in competition to this and other initiatives ongoing in the hybrid CSP/GT global market. The HYSOL Project focusses on overcoming the CSP technology limitations to increase its contribution in the global electric market, hybridising with a gas turbine to achieve 100 % stable and reliable power independently of meteorological circumstances. HYSOL plant is conceived to validate the use of 100% renewable energy sources (when using biomass derived gas fuel) for firm and dispatchable electricity production; this configuration will mean the highest contribution of solar energy in a hybrid plant up to date.
The main goal in the hybrid model design research is to achieve a flexible and stable energy production for the electrical system. Moreover, both economic costs and technology of the new elements developed and adapted to the needs of this hybrid technology were assessed from an operating profitability perspective and totally orientated to market feasibility (to optimize environmental performance).
Summarising, this new hybrid model will be capable of supplying electricity whenever is demanded by the Transmission and System Operator (TSO), thanks to the firm capacity achieved with the gas block and the new advanced automatic control and operation techniques applied. It will also have the capacity of working during a generation peak by operating with both turbines at the same time. With this innovative configuration it will not be necessary to have a high amount of energy as backup for the intermittent renewable sources (WIND, PV); it will reduce the requirements of Combined Cycle installations connected to the grid and substitute them with this technology.
The primary objective of HYSOL project was to develop a new hybrid technology capable of delivering firm and flexible energy to adapt the power output of the plant to any energy demand curve. The Hysol configuration comprises an aeroderivative gas turbine (AGT) with a heat recovery system (HRS) that will recover the heat from the exhaust gases into the storage system. The evaluation of biomass derived gas fuels (bio-gas and syngas) production and consumption in the hybrid CSP plant has been studied for the different locations, simulated and evaluated at a commercial scale.
Moreover, both economic and technological aspects of the new elements developed for this hybrid technology have been assessed from a construction and operating profitability perspective totally orientated to market feasibility.
HYSOL Project combined several R&D lines with the proprietary new technology demonstration. The project objectives were:
• Development of a new kind of hybrid system capable of transferring the energy from an AGT exhausts gases into molten salts.
• Optimization of the power conversion from gas turbine exhausts gases to molten salts.
• Assessment and optimisation of the technical feasibility, economics, energy efficiency and environmental performance of alternative strategies for the generation, upgrading, distribution and utilization of biomass derived gas fuels adapted to the needs of hybrid CSP-biogas plants.
• Quantification and minimising the environmental impact of electricity generation in hybrid-biomass CSP plants.
• Development of an integrated renewable process that supplies firm and flexible energy that adapts to the fluctuant demand through a base-load and peak-load generation.
• Achievement of a higher dispatchability (firm energy) due to the thermal storage and the energy recovered from the exhaust gases by the HRS that allows the CSP plant to store and produce energy not just during daytime.
• Stability in energy production, with independence of climate conditions and whenever the TSO demands.
• Development of a 100% renewable hybrid technology where there is enough biogas resource, that can be incorporated in the upcoming CSP technologies as well as retrofitting conventional ones through guaranteeing a 100% fully renewable source input at competitive prices.
• Obtaining a technology fit for any network: either isolated, with a large portion of intermittent resources or with a huge amount of interconnections.
• Cost reduction of the new plant configuration thanks to the synergy between technologies and, as a consequence, higher production rates that lead into a lower electricity price.
The project demonstration activity consisted in integrating the previous developments in the HYSOL power plant demonstrator, and that all possible technical solutions could be evaluated and cross-checked so that a successful integration was achieved. The demonstration work was not only technical, but also economic and environmental to get the optimum and most viable solution in the HYSOL power plant in every location.
Since CSP technology is already proved to be technically feasible, demonstrative projects like HYSOL are needed in order to reach the milestones that will help us to take the solar thermoelectric energy to the next level. In the estimated cost reduction scenarios for 2020, 20% of the savings will be produced by the increase in the size of the plants, 54% will be due to technological development, and the remaining 26% will be a consequence of the competitive market factor. Consequently, the most important impact on CSP industry will be cost reduction obtained through continuous technological development and higher production rates, such it is going to be undertaken in the HYSOL CSP/GT hybrid project.
The project was led by the Spanish EPC company COBRA (ACS Group) and includes a series of specialised SMEs, research centres and universities from different European countries (Spain, Italy, Denmark and the Netherlands). The eight partners participating in the project are:
Industrial partners:
• ACS-COBRA. Spain. Expertise in energy storage technologies, exploitation of 11 CSP plants with Parabolic Trough technology (48.9 MWe), and 2 projects with Tower technology (144 MWe), in Spain and USA.
• IDIE. Spain. RTD & engineering company, expertise in renewable energies, including thermo-solar plants and hybridization of renewable technologies.
• AITESA. Spain. Expertise and proprietary advanced technology aimed to provide solutions for the energy recovery of highly corrosive and/or dusty flue gases in industrial facilities.
Research partners:
• PSA-CIEMAT. Spain. It is the largest European public institute for research, development and testing of concentrating solar technologies.
• ENEA. Italy. Wide expertise in thermo-solar energy and gasification techniques, proprietary technology in molten salts.
• UPM. Spain. With expertise in biomass production, energy conversion technologies (including anaerobic digestion and biomass gasification) and environmental assessment of energy processes.
• DTU/MAN/SYS. Denmark. Specialised in energy systems analysis, socioeconomical analysis.
• SDLO-PRI. The Netherlands. Expertise in biomass and biogas production technologies, energy use and GHG emission estimation.
Project Results:
The activities to achieve the objectives of the project were distributed in seven different work packages. WP1 and WP7 were focused in the managerial and dissemination tasks respectively. The rest of the packages were aimed to carry out the technical, economic and environmental activities to validate the Hysol concept.
The results of the project can be classified according to the work package they were developed.
First of all, it is important to understand the basic configuration of HYSOL technology, so we recommend visiting the project webpage (www.hysolproject.eu) or watching HYSOL project video description in COBRA t&i Youtube channel: https://www.youtube.com/watch?v=i69s5zWkVzM.
The main objective of HYSOL project was to define a new kind of power plant that provides dispatchable and firm electricity production using full renewable sources: Concentrated Solar Power (CSP) and biogas. HYSOL uses similar principles as a Combined Cycle Gas Turbine (CCGT), which provides the highest gas-to-electricity performance of all the current commercial technologies. Therefore, HYSOL technology aims to reach similar performances as CCGT while being 100% renewable, dispatchable and firm; becoming the cornerstone of future energy systems with a high contribution of renewable energies.
WP2 PLANT ARQUITECTURE AND MODELLING:
In order to develop HYSOL project, there were several challenges to overcome: a new heat recovery system (HRS, developed in WP3), control systems (WP4), a proof of concept that the technology works (WP5), and the required economic analyses to assess the expected generation costs for this technology (WP6); among others.
All of these WPs had a close relationship with WP2, which was in charge of studying the plant as a whole, integrating the different elements involved (WP3, WP4, WP5) and providing cost and production evaluation for the economic analysis (WP6). As a consequence, WP2 answered the following questions which were key to the success of the project:
- How do HYSOL power plants work?
HYSOL technology presents a unique advantage compared to CCGT: it allows decoupling the operation point of the Steam Turbine (ST) and the Gas Turbine (GT). This means that both ST and GT can have different power outputs that are not dependent. This advantage is made possible thanks to the fact that there are two different energy sources and that part of the energy used in the GT can be stored in the Thermal Energy Storage (TES) system.
In order to clarify this point, a comparison with CCGT must be done. CCGT uses a GT to produce part of the electricity demand by burning gas as the primary source, and the GT exhaust gases are then used to produce steam to feed the ST that produces additional electricity. Therefore, the production of electricity in the ST depends on the amount of exhaust gases available, which is the same as depending on the amount of gas burned at a given instant. When CCGT power plants need to adjust their production to a given electricity demand instantaneously, the Gas Turbine (GT) and the Steam Turbine (ST) need to combine its production to meet that demand, usually maximizing the performance (which is the same as minimizing the fuel consumption). However, all the gas energy must be used in that instant, which means that both GT and ST need to work at partial loads, reducing its performance. This effect is especially negative when the energy to supply is very low, or the CCGT must be kept in line working at minimum loads to provide stability to the electric grid.
HYSOL power plants can use ST or GT at different points independently. The reason is that there is no need to use the exhaust gases energy instantaneously: it is stored in the Thermal Energy Storage (TES). In HYSOL, the thermal energy required to produce the steam is stored in molten salts tanks in the Thermal Energy Storage (TES) system. TES can be filled by normal operation of CSP plant and the GT exhaust gases energy. This allows maximizing the performance under partial loads, since the working turbine (ST or GT) can be operated with higher performances, saving thermal energy and reducing the consumption of gas. The problem is that this fact increases the freedom degrees in the power plant, and additional questions must be answered: which turbine should be operated? At what load? When should the ST/GT start/stop?
In order to understand HYSOL power plant operation, a model using Thermoflex (a software tool used to design power plants) was developed. Following process engineering methodologies, both Rankine Cycle (how the ST works) and Brayton Cycle (how the GT works) were calculated for nominal and partial loads. Brayton Cycle model was also adapted to define the demonstrator model and support the demonstrator engineering phase in collaboration with COBRA, AITESA and ENEA.
The criterion to optimize HYSOL power plants was defined by COBRA: they must produce the same electricity as a given electricity demand curve while minimizing the usage of auxiliary fuel. These criteria applied for WP2 (economic optimization was considered as part of WP6). The demand curves were defined as the national electricity demand (hourly) for a given country, scaled down so that the maximum demand value corresponds to the nominal value of HYSOL plant power output. In other words, the production of HYSOL plant should have the same “shape” as the national demand but adapted to its nominal power output.
Different operation strategies for power production were implemented by IDIE in the final model using control algorithms. IDIE and COBRA had regular meetings to define different operation strategies and evaluate the results according to three main parameters: solar energy production, fuel performance, and demand coverage ratio. The results showed that increasing the demand coverage ratio resulted in penalties in solar energy production and fossil fuel performance, and vice versa; so a compromise solution had to be identified.
An integral-predictive control algorithm was the final strategy selected. It leaded to similar values obtained for ISCC power plants in terms of fuel performance and demand coverage ratios, but with a significant solar energy contribution (and lower fuel consumption). A comparison with other hybrid solar technologies was performed for the case of Kingdom of Saudi Arabia (KSA) using these parameters. It was presented in SolarPACES 2015 and the scientific article is available at: http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4949185
As a conclusion, several conditions must be taken into account when operating HYSOL power plants: instantaneous production, future constraints, resource availability forecasts and demand and production expected. It has been solved within the project by using an integral-predictive control algorithm embedded in the power plant production models.
- What is the optimum configuration for HYSOL power plants?
Five case studies were developed in HYSOL project to assess different applications and conditions. The case studies were focused in Chile, KSA, Republic of South Africa (RSA), Mexico and Spain. The CSP technology selected for the case studies was a Solar Tower, since it provided higher performance values than Parabolic Trough. The configuration for the CSP was similar to Crescent Dunes project, since it is considered as the state-of-the-art of CSP Solar Tower plants.
The result of the analysis showed that a configuration using a 100MW Steam Turbine and 80MW Gas Turbine with a nominal power output of 130MW is a suitable solution for all the case studies. However, each case will have different optimum configurations depending on the criteria selected. In addition, the optimum configuration selection will also depend on the CSP configuration, which has not been optimized during the analysis of the case studies.
- What is HYSOL power production and fuel consumption?
Power plant models are used to estimate the electricity production of the power plant and with the installation, operation, and fuel costs the cost of the electricity produced can be calculated . The most common parameter used is Levelized Cost Of Energy (LCOE), that joins all these parameters and provides an estimation of costs. The LCOE of HYSOL configuration is provided as a result of WP6, while WP2 has provided the production results and the fuel consumption.
However, it is important to note that HYSOL plants are not defined to maximize electricity production, they are defined to supply a defined energy profile demand. In addition, HYSOL configurations are selected to maximize the usage of CSP energy, and minimize fuel consumption. The selected HYSOL configurations could increase its production, but always by increasing the fuel consumption.
As a consequence, power production and fuel consumption are not model outputs: they are the constraints considered as inputs to define HYSOL configurations. This is different from traditional fossil fuel plants, where the constraint is the nominal power output of the plant and the model results provide working hours, power production and fuel consumption values.
Due to this change of philosophy, two parameters were used instead of power production and fuel consumption during the project. Instead of power production, demand coverage ratio has been defined as the percentage of hours that HYSOL plant can provide the electricity demand. Instead of fuel consumption, electricity production due to gas rate has been defined as the share of electricity produced using fuel as primary source over the total HYSOL production is defined.
Going back to the cases studies analyzed, it has been found that a demand coverage above 95% can be met with electricity production due to gas lower than 50%. Of course, the value of the electricity production due to gas depends on the location (especially, solar resource available) and the demand curve selected, and some values of this indicator in the case analyses are lower than 30%.
- Can HYSOL technology be applied to existing power plants (retrofitting)?
An analysis was conducted during the last stages of the project, considering only the technical constraints in a power plant. This means that other issues, such as legal constrains (in Spain it would be impossible to retrofit any CSP power plant due to legislation), were not considered. The analysis evaluated if the retrofitted power plant would be economically feasible if the energy was paid at market prices, defined in the range of 40-50 USD/MWhe.
The study identified that there were three different technologies that could be retrofitted using HYSOL technology: CCGT, OCGT and CSP (parabolic trough and tower). OCGT power plants only have a Gas Turbine to produce electricity and they do not recover the energy from the exhaust gases, leading to gas-to-electricity performances around 35%. Despite its lower performance, this technology is still present in developing countries and regions were the gas cost is low.
CCGT analysis determined that using HYSOL in this power plants is a non-feasible solution, since they are usually optimized using different criteria (the ratio GT power/ST power is different than for HYSOL power plants) and CSP technology is too expensive to compensate the required investment in periods bellow 20 years.
OCGT retrofitting is economically viable if the total gas costs of the gas are higher than 10 USD/MMBTU during 20 years lifetime operation. This gas cost would not only include the market price of fuel but also other externalities, such as CO2 credits or similar. In this scenario, the high costs of CSP installation could be compensated thanks to savings in gas costs and the increase of gas-to-electricity efficiency.
CSP power plant retrofitting reduces the electricity cost production for CSP power plants, but they still need subsidies support since the final electricity cost is higher than the defined market prices region. However, a marginal analysis performed only to the components of the retrofitting (not considering the previous CSP installation) demonstrated that the electricity provided due to the GT+HRS installation, reached the market price value; and that they could contribute to the stability of the grid by providing dispatchable and firm energy.
WP3: GAS-MS HEAT RECOVERY SYSTEM
The main scientific and technological results obtained are:
The most appropriate metals for commercial heat exchangers have been selected, as a function of maximum temperature levels of the different types of solar power plants and temperature sections of the heat exchangers. Corrosion margins for each metal have also been defined. The heat exchangers will include a combination of stainless, alloy and carbon steel tubes, optimizing costs.
A list of basic design provisions to be taken into account during the basic design of the full-size commercial heat recovery system, mainly related to corrosion processes, gravitational drainage and anti-freezing protection, has been specified. Some of the main provisions adopted were:
• the heat exchanger should be designed with quasi-horizontal, 1% inclined tubes, for appropriate draining of molten salts
• bends of the tube bundles should be inserted within the flue gas passage
By means of steady-state regime CFD analysis, it was revealed how both heat transfer coefficients and pressure drop values obtained with conventional heat exchanger design tools were overestimated, due to the special design characteristics of the specified heat exchanger.
By means of transient regime CFD analysis, temperature gradients under all possible start-up conditions were calculated, so start-up procedures that avoid excessive thermal stresses in the tubes could be defined.
The MOSE facility of a small mock-up of the heat exchanger tube bundle was completed and experiments with natural gas and biogas to check molten salt heat transfer coefficients were accomplished. Results allowed to validate heat transfer correlations (for the molten salts and heating gas sides), showing the consistency of experimental data with the heat transfer correlations used for design. Also an analysis of the potential of alternative biomass derived gas fuels in locations compatible with HYSOL technology was conducted, serving as the basis to define the composition of the biogas employed in the mock-up tests conducted at the MOSE facility and also to determine the potential of alternative biomass resources and technologies for the generation of biogas fuels to be used in CSP plants based on HYSOL configuration.
Heat transfer elements of the reference full-size heat exchanger were optimized, in order to provide the specified effectiveness with minimum heat exchange surface and pressure drops. Gases pressure drop, quite significant for gas turbine performance is lower than 20 mbar. The performance functions of the reference full-size heat exchanger were obtained.
A basic design of a reference full-size heat recovery system was completed, adapting it to all the parameters of the reference industrial plant and taking into account all the specified provisions to work with molten salts inside heat exchange tubes.
A detail design of the reference full-size heat recovery system was prepared, including a detail arrangement of the molten salt heat exchanger and the water economizer and an overall arrangement of the whole heat recovery system. Additionally, a complete set of documents was elaborated, including equipment datasheets, lists and detail drawings.
An optimized and representative detailed design of a demonstrator heat recovery system was completed, with appropriate characteristics to, by means of testing experiences, validate and adjust the basic criteria and the simulation tools applied to the full-size heat recovery system, in order to minimize the risks of the next full-size commercial demonstration stage of the technology. Testing experiences have shown that:
• The heat exchanger can be filled with molten salt from the upper, inlet salt side, without significant differences of salt flow disequilibria between the columns, due to not evacuated gas bubbles, with respect to the safer and more complicated filling procedure from the bottom side.
• The tubes of the heat exchanger can be completely emptied of molten salt without problems and quite quickly.
• The slight inclination of the tubes (1% slope) has proved to be useful for the movement of salts and has not given any problem. Moreover, it has eliminated the specific vents and drain connections for the heat exchanger itself.
• Gases flow distribution, determined by pressure drop and temperature measurements along the tubes length at several points of gas path, was not fully optimized, but was considered sufficiently appropriate.
• Salt flow distribution, determined by salt temperature per tube, at the outlet of Demonstrator, showed some disequilibrium, easily fixable by means of a positive operating pressure.
• The impact of the inclusion of tube bends on the gas path and the wall effect was higher than foreseen by CFD analysis done, so special detail design provisions were required to avoid corresponding uncertainty.
The detail design of the reference full-size heat recovery system was finally revised, taking into account the results of the demonstrator testing. The revised design included some innovative solutions for the bundle of inclined tubes, allowing a great improvement of the performance with respect to the original design, reducing the required number of tubes (-23.7%) and the volume of the heat exchanger (-45.4%). The revised design of the full-size heat exchanger is considered totally validated, without constraints to be supplied as commercial equipment, with the usual performance guarantees. This revised detail design has served as reference for the cost estimation of commercial heat recovery systems, as a function of capacity and main design parameters.
WP4. DYNAMIC MODELLING AND ADVANCED REAL TIME OPERATION CONTROL
The main idea behind the control theory of dynamic systems is to achieve the following goals: to maintain the process stable at all times, to track the desired command input signal and to reject disturbance inputs. All these conditions must be maintained in spite of changes in the system dynamics due to operating conditions or environmental changes.
Modelling and simulation of dynamic processes are very important subjects in control system design. Control engineers must take advantage of the information provided by dynamic models in order to design and test control algorithms without performing experimental tests at real plants. Nevertheless, achieving accurate models that describe completely the real behaviour of dynamic systems is a hard task that requires the following steps: i) to understand and study the main physical phenomena, ii) to derive a mathematical formulation, iii) to translate the formulation into a modelling language, iv) to simulate the model, evaluate the obtained results and review the formulation taking into account the simulation results, v) to calibrate the model (tune unknown parameters or parameters with uncertainties) with experimental data and vi) to validate the models with experimental data in a wide range of operating conditions.
These three tasks, modelling, simulation and control, have been the main goals of this WP. During this project the objectives have been: i) to contribute to the dynamic modelling processes in order to obtain accurate and fast dynamic models for the HYSOL power plant configuration, ii) to perform dynamic simulations and, iii) to design, test and validate control strategies in order to improve the performance of the whole system.
From this point of view, the main scientific and technological results obtained within the HYSOL project are the following:
• Development of dynamic models of different components found at the HYSOL demonstrator plant and at the HYSOL commercial power plant configuration.
With the aim of studying the HYSOL power plant configuration, the development of each one of the main systems that compound the whole plant has been addressed. In this approach a model was developed for each physical subsystem, and the model of the total system was obtained by interconnecting the models of the subsytems by means of their interfaces. In our particular case, the subsystems are: a heat recovery system HRS (which is a heat exchanger with molten salt and exhaust gases from gas turbine), a molten salt storage tank, a gas turbine with a duct burner and a molten salt – thermal oil heat exchanger.
For those systems that a real physical component is available in order to model, calibrate and validate the dynamic models (the HRS, molten salt – thermal oil heat exchanger and the molten salt storage tanks in our case) physical principles like balance equations (typically based on the conservation of mass, momentum and energy) are used to define its behaviour. In contrast to this, for auxiliary equipment such as molten salt pumps and air heaters, black-box models in the form of transfer functions have been obtained based on input-output experimental data. In addition, typical dynamics collected from scientific literature have been coupled to steady state correlations (obtained within WP2) to define the main outputs of a gas turbine. In this case, a hybrid model (it combines continuous and discrete variables) has been developed in order to take into account the different equations that define each one of the operating modes that have been identified (stopped, starting, running and shutdown).
• Simulation executions to predict the response of the systems under different operating conditions.
As commented before, another important effort was spent at the simulation phase. It consisted in implementing the models into the chosen modelling language, proceed with the compilation of these models and performing simulations. Within the WP4, the Modelica language and MATLAB® tool have been used for the dynamic modelling of the power plant. The Modelica tool used was Dymola (Dassault Systemes, 2016), whereas the numerical integrator for Modelica dynamic simulations was DASSL (Petzold, 1983). The Modelica language has been designed to model conveniently complex physical systems because the language supports the object-oriented and equation-based paradigms.
The main components of the system have been identified and then have been modelled and developed in a reusable library for the HYSOL project. The one-dimensional case is assumed; therefore components have been discretized by the Finite Volume Method (FVM) in Control Volumes (CVs); the number of CVs can be configured by means of parameters.
During the HYSOL project, several stability and integrity simulation tests have been performed. A wide range of simulations have been carried on to define the appropriate number of CVs to obtain accurate results but at the same time reducing the computational time as much as possible. The dynamic model has been used to compare steady state values obtained within WP2 and WP3 and to estimate the dynamic behavior of the HYSOL demonstrator plant before commissioning the plant.
• Dynamic model validation using experimental data.
The success of the dynamic models developed under HYSOL project can be measured by the dynamic model validation using experimental data. This task has been carried on thanks to the availability of two facilities; the HYSOL demonstrator plant (located at Manchasol power plant) and the MOSA facility at Plataforma Solar de Almería (PSA).
The experimental campaign at HYSOL demonstrator plant has been essential to calibrate and validate the dynamic model of the main component of HYSOL project; the heat recovery system. After tuning heat transfer correlations, a good agreement between simulation results and experimental data was obtained, both in steady state conditions and for transitory responses in the complete operating range.
The remaining main components which compose the HYSOL power plant configuration (heat exchanger and molten salt tanks) have been validated by experimental campaigns at MOSA facility located at PSA. This molten salt test facility is a replica of a thermal energy two-tank storage system with molten salts as storage fluid. Being a reduced scale commercial two-tank molten salt storage system, everything related to this type of systems can be tested in this facility. The experimental campaigns in molten salt charge and discharge operating modes, covering the whole operating range, were used to adjust, calibrate and validate the transient response of the dynamic models, where very good results were obtained.
The dynamic model validations are the base of the success of the WP4, because future studies regarding to the commercial HYSOL power plant can be performed from solid conclusions reached during this project.
• Evaluation of proposed control loops.
The HYSOL demonstrator model has been the base for performing control simulations to validate the proposed control strategies, such strategies focused on maintaining desired operating conditions in the HRS, both for start-up stages, nominal conditions and partial loads before the demonstrator plant commissioning.
As in many processes in the industry, during the experimental campaign, a dead time was detected in the dynamic behaviour of the HRS. From a detailed study of the experimental data, the cause of this dead time is supposed to be produced by the accumulation of a large number of low-order system dynamics (molten salt pipe lines) with small passive zones which produce small dead times. This conclusion has a huge importance because it determines the approach to be followed by control engineers to design control strategies for commercial plants. Moreover, this dead time must be a variable that HRS design engineers must take into account to define appropriate constraints in the gas turbine exhaust mass flow rate gradients (which means in the gas turbine load gradients) to assure that the control system is able to maintain, first of all, safety conditions and, at the same time, the desired operating conditions at the HRS.
• Development of an operation training system for the HYSOL demonstrator plant.
As a consequence of the achievements obtained and previously explained, a complete simulation tool has been developed. It is an operation and training software tool for the HYSOL demonstrator built in Manchasol solar thermal power plant, which is the product obtained after the work performed in the whole WP4. This operation and training tool has three main parts:
i) Demonstrator dynamic model. It includes the different models and the global demonstrator model analyzed and designed during the HYSOL project. Since models were implemented using different modeling and simulation languages and tools, its integration was performed by using Functional Mock up Interface (FMI).
ii) Control scheme. The different control strategies considered for the demonstrator are included in this simulator. It is possible to change from manual control to automatic control choosing between different control strategies.
iii) Supervisory Control and Data Acquisition (SCADA) system. A SCADA system has been developed to interact with the control scheme, the demonstrator dynamic model and the real plant.
The simulator tool must represent as close as possible the HYSOL demonstrator located at Manchasol solar plant. Therefore, different operating modes and control strategies are included. Three operating modes have been considered: startup, running and shutdown. It allows defining and testing different turbine startup/shutdown curves, gas turbine partial loads and control algorithms.
This virtual tool is not only important to help understanding HYSOL demonstrator system behavior, but also to be used as reference to train operation staff to replace the real expensive equipment in a learning process.
• Optimisation studies for the HYSOL commercial plant operation.
For the commercial HYSOL case, the operating procedure can be studied and optimized for different operating modes using the complete power plant model developed under WP4.
An optimisation problem has been defined to calculate the best operating points for the new element included, the HRS, at different operating conditions. The goal is to minimize, for one part, the difference between the electric power demand and the obtained electric power and, for another part, the consumed gas in the gas turbine and duct burner. Promising results have been obtained in a preliminary study, but most of all, it gives an added value to the activities related with dynamic modelling and control strategies developed within this project.
WP5. PRE-INDUSTRIAL SCALE DEMONSTRATOR
The objectives of this work package were to develop and build the pre-industrial scale pilot plant, including electrical parts, instrumentation, a control system and all the equipment needed to carry out the experimental tests in order to validate the models developed in other work packages.
The design of the demonstration plant configuration was developed using the information generated in WP2 Plant Architecture and Modelling. The elements needed to carry out the tests were selected and the experiments and operational modes were designed. The demonstration plan configuration consists of an exhaust gas simulator which generates the gases at a similar temperature to the exhaust gases from a commercial gas turbine and different flow mass. Another key element is the Heat Recovery System that transfers the heat from the gases to the molten salts. The design of this component is one of the results of the project and the experimental tests have been essential to validate not only this design but also to improve the design for commercial purposes, also developed in this project. The rest of the facility comprises an auxiliary tank to store the molten salts, a pump to move the salts though the system, and an air-cooler to cool down the molten salts and close the cycle.
A key part of the minimum components selection was to choose the instrumentation and control system to measure and register the values of all the variables involved in the validation of the system.
As a result of the design, construction and operation of the plant the consortium has gathered the required information to analyse and evaluate the technology. The tests carried out in the plant were classified in three groups: steady-state, transients and off-design tests.
The steady-state tests consisted in studying how the system behaves at different gas turbine loads: nominal, 75%, 50% and technical minimum, warm stops and cold stop. The transients between steady and semi-steady states were studied to observe the inertia of the system and the times to obtain a steady state at a required load. At least, a group of off design tests were carried out in order to determine the behaviour of the heat recovery system under different combinations of values for the input variables (exhaust gases mass flow and inlet temperature in the HRS and molten salt inlet and outlet temperature). The results obtained after these experiments were analysed to validate the design of the heat recovery system and to obtain more precise control system parameters for a commercial plant.
WP6: ECONOMIC AND ENVIRONMENTAL ASSESSMENT
A) Economic assessment:
The following actions have been performed:
• The economic potential of HYSOL in comparison to competing technologies from a socio-economic and a corporate-economic perspective were studied, e.g. to compare HYSOL vs. Open/Combined Cycle Gas Turbine (OCGT and CCGT) for KSA, Mexico, RSA and Chile.
• A market assessment in the countries under analysis was carried out, highlighting the potential for the HYSOL project (by comparing, for example, the HYSOL with the generation costs relative to conventional power technologies).
The following results were obtained from the economic assessment:
• For the Republic of South Africa (RSA), HYSOL competes favourable relative to an Open Cycle Gas Turbine (OCGT) reference as can be seen from comparing results when base case data are assumed. This conclusion holds even without taking into account an assumed cost on CO2 emission. When compared to a Combined Cycle Gas Turbine (CCGT) reference plant the RSA HYSOL alternative is less favourable. However, introducing an assumed CO2 emission costs of 40 USD/tCO2eq emitted, narrows the Levelized Cost of Energy (LCOE) price difference considerable (down to a LCOE difference of less than 5 USD/MWh).
• For Chile, HYSOL is economically competitive when it is compared vs. OCGT and CCGT options, while it is not cost-effective in the Kingdom of Saudi Arabia (KSA) and in Mexico. The lack of competitiveness in these countries is due to the significantly low Natural Gas (NG) prices in comparison to Chile (The NG price in Chile is assumed to be about three times as much as in Mexico or KSA). Furthermore, the current NG price conditions discourage the economic attractiveness of HYSOL in these countries.
• In Mexico, the deployment of HYSOL could contribute to decrease gas and oil power plants in the mid-term.
B) Analysis of HYSOL concept fuel supply potentials:
Key parameters have been derived from the data of various agricultural residues types of the research conducted in period 1. These key parameters are used in the spatial analyses of biogas and digestate production in task 6.2.3.
The research has been described in a report with as title: “Biogas production and digestate utilisation from agricultural residues” which is included in deliverable 6.2.
Results are described focusing on the non-renewable energy use (NREU) and the greenhouse gas (GHG) emission from biogas production and utilization from animal manure and crop residues.
The preferred system for biogas production from agricultural residues involves local scale co-digestion with upgrading of biogas to biomethane by water scrubbing and injection into a gas grid for transport and storage. Electricity and heat needed for digestion and upgrading is internally produced using part of the biogas. Where no gas grid is available, different alternatives for transport exist. When much substrate is available on a short distance, the substrate can be transported to the location where the gas is used and biogas can be used without upgrading. Otherwise, compressed biomethane can be transported over longer distances to the nearest gas grid or to the location where the gas is used. Transport of liquefied biomethane can eventually be an alternative for very long distances. The digestate is assumed to be used as organic fertilizer at the location where alternatively the undigested residues would have been applied. Methane emission from digestate storage is captured and utilized, whereas no emission from manure storage in the biogas system was assumed. Agricultural residues, in this study: manures and crop residues, are variable in composition and digestibility and to cover a wide range of residues eight types have been distinguished: four types of manure (solid poultry manure, solid cattle manure, liquid cattle manure and liquid swine manure) and four types of crop residues (straw, stems and dead leaves, yellow leaves and green leaves), each with a composition and methane yield based on literature when possible and estimated when not available.
For the evaluation of the NREU and the GHG emission of the biogas production and utilisation a calculation model has been developed. In the model the NREU and GHG emission of biogas or biomethane produced from different substrates or mixtures of substrates and transported to a gas grid or the location where the gas is used are calculated and compared with reference values of using natural gas, assuming that the biomethane from digestion replaces natural gas. Model parameters were derived from literature and estimated when no information was available. According to EU legislation, a minimum reduction in GHG emission of 60% compared to the reference system is used to evaluate the results of the model. This standard is also applied for NREU reduction relative to the reference system and European marginal natural gas is used as reference energy source.
Results from the calculations for individual substrates show a low NREU for all substrates, complying with the chosen standard, if substrates are available within a certain distance of the digester. NREU increases with substrate transport distance and this increase depends on the gas yield per ton fresh substrate and is therefore especially high for liquid manures. Residues can be transported by truck from 70 km for liquid swine manure to approximately 600 km for stems, dead leaves and yellow leaves before the NREU reaches 40% of the NREU of the reference system. Also the GHG emission is low for all substrates and even negative for manures, especially liquid manures, due to the avoidance of methane emission from manure storage in the reference system where manure remains undigested. Liquid manures can be transported circa 400 km before the GHG emission reaches 40% of the GHG emission of the reference system. With this distance, however, the NREU reaches twice the NREU of the reference system, far above the chosen standard. For other residues acceptable substrate transport distances are shorter for the standard of GHG emission compared to the standard of NREU and range from almost 200 km (green leaves) to 400 km (solid poultry manure).
Although large uncertainties exist in both availability of substrates and parameter values and the calculations are made for ‘Best Available Practices’, the very low levels of NREU and GHG emission from biomethane production and use make it not likely that the GHG and NREU reduction standards will be exceeded under less favourable conditions. A sensitivity analysis showed that only with a 10% extra leakage of methane from the digester or digestate storage the reduction in GHG emission was smaller than the EU standard, which illustrates the importance to prevent methane losses from the digestion system. Results also showed that the avoided methane emission from manure storage in the reference system has a large ‘positive’ effect on the GHG reduction which is not directly achieved by the digestion system but is caused by the current imperfect storage systems of manure in the EU.
It is concluded that the production and transport of biomethane for use in HCSP plants is an acceptable renewable alternative for the use of natural gas according to the GHG emission reduction standard of the EU.
The research has been described in a report with as title: “Non-renewable energy use and GHG emissions of biogas production and utilisation” which is included in deliverable 6.2.
In the HYSOL project agricultural residues have been selected, namely animal manure and crop residues which are both by-products of food production, as source for biogas production because of their good environmental performance and ample availability throughout the world for use in future digesters. However, the use of agricultural residues in a digester may have negative consequences on soil organic matter and related crop production, as they are currently often used as soil amendments to maintain soil fertility. Biogas production based on agricultural residues needs to take possible limitations due to soil organic matter requirements into account to be regarded as a sustainable option for utilization in Hybrid (H) CSP plants.
We have analyzed the feasibility of producing and supplying sustainable biomethane to specified HCSP plants at selected locations in five different countries (Spain, Chile, Mexico, Saudi Arabia and South Africa). These countries are assumed promising target markets for the new technology that has been investigated in the HYSOL project.
The analysis is built on four distinct parts. First, the availability of manure and crop residues for digestion is spatially quantified by using detailed global maps of the density of the main livestock species and the occurrence of the main crop species in combination with a number of parameters to relate animal density to manure production and crop occurrence to crop residue production, both in principle available for digestion. Second, the potential gross methane productions are calculated from the various manure and crop residue types (assuming anaerobically digested at the farm-scale) and represented in maps with the same high resolution as the original input maps. Third, a new analysis has been developed and applied to assess the sustainable fraction of residue use, depending on local soil organic matter requirements, derived from combining various detailed maps of current soil organic matter, soil texture, terrain characteristics, average weather conditions, etc. The sustainable fraction of residue use, i.e. a value ranging from zero to one, is estimated for each grid cell of the map of each country and has been multiplied with the potential methane production to assess the sustainable methane production with respect to maintaining adequate soil organic matter levels for agriculture. Finally, aggregations are performed on the gridded potential and sustainable methane productions per country and in the surroundings of each HCSP plant location to assess the possibilities of supplying the amount of methane required by the HCSP plant.
In conclusion the following results have been obtained after the biomethane production assessment:
• Large reductions of acceptable agricultural residue use in the selected countries have been found ranging from minus 80% in Spain and South Africa to around minus 50% in Chile, Mexico and Saudi Arabia relative to unrestricted use.
• The calculated number of HSCP plants that could be supplied with net sustainably produced biomethane would be 26 for Mexico, 9 for Spain, 7 for Chile, 6 for South Africa and 4 for Saudi Arabia.
• Locating the digester near the available residues and transport compressed gas to the HCSP plant, rather than vice versa, seems better, because of the much lower energy costs of transporting compressed gas by truck.
• Agricultural residues in EU27 can in principle play an important role in the biogas demand of the coming decades (circa 30 Gm3 per year: calculated sustainable net biomethane production for EU27).
C) Energy systems analysis and Assessment of regulatory and policy framework regarding renewable energies:
The following actions have been performed:
• The effect on the energy system, when HYSOL is deployed, in terms of total system cost, direct CO2 emissions and energy mix under different scenarios in Africa, Western Europe and Mexico was examined.
• The ETSAP-TIAM model (energy optimization model) was used to carry out this task.
• Deliverable 6.1 has been completed, including both a socio-economic assessment and an energy system analysis.
• Country-specific RE policies and regulations, and assessment of the necessary economic incentives for economic viability of HYSOL was analysed by performing a feasibility study for the Kingdom of Saudi Arabia, Mexico, Chile and South Africa.
• Deliverable 6.4 has been completed, including both a private-economic assessment and an analysis of regulation and economic incentives.
The outcomes after the analysis show that, with the current values of the average power prices, a project is not profitable in the studied countries, meaning that it needs financial support. The high initial costs related with the investments were found to be the main cause for the non-profitability.
However, the highest profitability of the investment was found for RSA. Indeed, in a hypothetical case in which all the systems would have the same average power price (assumption considered in order to compare the four markets on the same base), RSA is the market where the HYSOL investment would perform the best, providing the highest Net present Value (NPV), the highest Internal Rate of Return (IRR) and a LCOE competitive with the market price. Mexico, Kingdom of Saudi Arabia and Chile then follow as promising markets for the investment in HYSOL
D) Environmental assessment:
The following technical targets were completed in the framework of this task:
• Completed Life Cycle Assessment (LCA) of different HYSOL configurations, including biogas production and upgrading to biomethane.
• Completed LCA of conventional Concentrated Solar Power (CSP) plants hybridized with different fuels for comparative purposes.
• Completed a comparative analysis of HYSOL with competing technologies including Combined Cycle Gas Turbine (CCGT), High Concentration Photovoltaic (HCPV), conventional CSP based on parabolic trough technology, conventional CSP based on solar tower technology, conventional CSP with different auxiliary fuel inputs.
• Completed analysis of the effect of location on the environmental performance of HYSOL plants including Spain, Chile, Kingdom of Saudi Arabia, South Africa and Mexico.
• Recommended design and operation strategy of HYSOL in order to minimize carbon footprint and optimize environmental performance.
• Evaluated socio-economic performance associated with the life cycle of HYSOL technology, as an expansion to the conventional environmental analysis.
• Full information about the technical results regarding all these targets was incorporated into Deliverable 6.3 Full Life Cycle Analysis of HYSOL Technology: "Environmental and socio-economic assessment".
The results from the environmental assessment are:
• Climate change category is relatively less affected than the toxicity categories.
• Biomethane is the main impact in climate change category in a HYSOL plant.
• E&M phase only 19.7% of climate change impact.
• Location is important: 35-43% impact variation.
• HYSOL performed the best when comparing with CCGT, and ISCC (<15%).
Potential Impact:
POTENTIAL IMPACT:
From a technical point of view the result of HYSOL project is an almost commercial technology for Solar Hybrid Combined Cycles (SHCC). To achieve this pre-commercial design the consortium has validated the performance of the demonstrator and viability of the project in different case studies, so financial institutions will consider the gap between the demonstrator and a commercial full size HRS as negligible and bankable. With this process the industry can minimize the risk that is involved in a bid of these features.
The operational experience of the demonstrator has helped to optimize and validate all the simulation tools (which are the base for future engineering purposes), the control system logics and the operation modes of future commercial plants.
Despite the initial objective was to achieve a 100% renewable electricity generation when using biogas, the research in the cases studied lead us to conclude that the locations where the current circumstances to install a CSP plant (meteorological and economical) are optimal there is not enough biogas resource to supply fuel for Hysol. However it is viable to obtain a 100% renewable plant in locations where a good combination of solar radiation, biomass supply and likelihood of commercial plant development occurs.
The project has demonstrated that a hybrid concept and the use of synergies between CSP and HYSOL technologies can change the renewable energy business. This kind of synergies would give a new vision of the renewable business taking as a hallmark the flexibility and the firmness of the electricity supply from a single energy pole.
In response to the expectations placed on this development, the expected target markets would be energy mixes with high penetration of gas and crude oil, energy mixes with renewable vocation and energy market with long sunny and rainy seasonal periods.
With these inputs the markets we have studied because we foresee a high potential are:
• Kingdom of Saudi Arabia (KSA), Egypt and similar: The energy strategy to follow in these countries is to adjust the demand curve in operating conditions. The developed energy pole could be adapting its electricity production to the demand curve of the country.
• Mexico, Republic of South Africa (RSA) and similar: The strategy for these countries is to use the GT in demand curve peaks and ST as base load.
• Chile and markets with similar solar radiation conditions: The strategy to follow in this country is base operating condition to produce stable energy during 8760 hours per year.
• Southern and Eastern Europe: Adapting production to electricity price and load curve.
• India and bordering regions: The study in this area is getting the feasibility without solar energy during periods of 2 to 4 months (monsoon).
In short, to take advantage of the possible synergy between electricity production technologies should give to this development the characteristic to offer the market the use of the resources available in each target area. In other words, each country or region, when thinking of its electrical system, should be aware that the best way to affront this challenge is to base their decision in the amount of sun, oil, biomass, gas or wind that the area have.
HYSOL is the initial step to give to the region the opportunity of management in a green-friendly way all the resources available, being a proposal economically viable and developing local works due to the high portion of the CSP technology involved in this development. At the end, the highest value of CAPEX of this proposal should be covered by renewable technology, specifically CSP, being recognized as one of the technologies that more contribute to local market development, with local industrial integrations of roughly 35% of CAPEX.
Short Term Market:
HYSOL is ready to be launched in the market, as key element of CSP hybrids solar plants as it is a combination of synchronous generation (CSP), dispatchable and firm energy production of a Gas Turbine and HYSOL (join to the thermal energy storage system), and grid stabilization capabilities (GES system).
According to this schedule, a market prospective has been made in order to select the best opportunities by that time, based on solar thermal energy roadmaps elaborated by countries/regions/associations. As a result of that study, the conclusions are that HYSOL consortium will prioritize five locations in order to commercialize new CSP hybrid plants: South Africa, Chile, Mexico, south of Europe and MENA countries.
• South Africa: is one of the countries with more CSP capacity (including announced and planned plants) around the world with a total of 1,415.73 MW, which 550 MW are using parabolic trough technology. The current data announces a forecast where South Africa is placed as one of the main potential markets, ranked in second position after USA (according to scorecard methodology of CSP Today Global Tracker). The forecast announces a meaningful increase of CSP capacity, especially using molten salts as heat transfer fluid, in forthcoming years according to the up-to-date data from CSP Today Global Tracker and insights and capacities.
• Italy: One of the main European countries which bet for CSP technology along with Spain. Despite Italy did not connect any CSP plants to the grid in 2014, many projects have entered the final authorization stage. The Italian government issued a decree on July 2016 to promote the development of 100MW of hybrid CSP and gas technologies. The target to be achieved is to build 600 MW of CSP by 2020 (Source: CSP Today Global Tracker).
HYSOL consortium is formed by European companies and not only aim to lead the sector by generating knowledge and building plants in non-European regions but also taking advantage of the potential in the south of Europe to deploy CSP technology. To do that, and considering the oil restrictions in energy generation facilities present in Italian tender requirements, HYSOL consortium targets Italy to build CSP hybrids plants (Parabolic Trough or/and Tower) using molten salts as HTF, overcoming both competitiveness and environmental issues in the country.
• MENA countries: MENA countries are formed by certain countries with high potential. Speaking about CSP capacity and plans which are already developing, special attention must be paid to Kuwait, Jordan, Saudi Arabia, UAE, Oman, Egypt and Morocco.
In short-term, they are designing strategies to increase the CSP technology share in generation mix, becoming this market into a target for CSP Utilities:
· Kuwait: One of the Kuwait energy targets is to provide 15% of the demand for energy from renewable sources. A multi-technology renewable energy park that will host 2,000MW installed capacity has been developed (SHAGAYA RENEWABLE ENERGY POWER PLANT). This park will be built with different technologies. It is expected that 57% Concentrated Solar Power (CSP) is with thermal energy storage, what is ideal for HYSOL technology.
· Jordan: Jordan is currently targeting 1,800 MW of wind and solar generation capacity by 2018 and a 10% renewable energy contribution to Jordan’s energy mix by 2020. To accomplish this target, Jordan has announced 250MW of CSP which is not part of the initial target.
· Saudi Arabia: KA-CARE (King Abdullah City for Atomic and Renewable Energy) aims to build a sustainable future for Saudi Arabia by developing a substantial alternative energy capacity fully supported by world-class local industries. KA-CARE’s renewable energy program will be the implementation of clean, cost-effective solar energy technologies by recommending generating a total of 41GW by 2032. By 2032, CSP will account for 25GW of electricity generated.
· Morocco: Currently the installed CSP capacity (2015) is 23 MW. Through MASEN2, Morocco is implementing projects under the Moroccan Solar Plan. The main points of Morocco’s energy policy goes through Sustainable development durable through the promotion of the renewable energies, for the strengthening of the competitiveness of the productive sectors of the country. It has been launched a Solar Program of 2000 MW by 2020 from solar PV/CSP.
• Isolated off-grid and small-scale electricity systems such as European Islands (Crete, Cyprus, Fuerteventura, etc.) are good areas in Europe for solar energy projects as they present high solar resource potential. Nevertheless, they present high electricity prices due to ancient energy generation technologies used and very polluting systems (diesel generators, fuel turbines, etc.). Besides, these places are very sensitive to the generation groups input/output due to their small size, so dispatchability and firmness is necessary.
Users’ needs and their economic benefit:
HYSOL adopters will be solar thermal energy plants owners: ENGIE, ENEL, E-ON, RWE, MASDAR, IBERDROLA, ENDESA, MAASEN, SAUDI ARAMCO, ACWA POWER, which are transnational thus their activities cover the whole geography depending on the tenders. As stated before, plant owners require other companies, EPC and O&M companies, to build their plants and afterwards to operate them.
Regarding user needs:
• Cost-competitiveness: A tender is a highly competitive process, so it is imperative to provide the best quote. Therefore, it is mandatory to obtain low values of LCOE in order to have more opportunities to win tenders. The results of the economic studies carried out in the different case studies (Chile, Mexico, South Europe, South Africa and Kingdom of Saudi Arabia) indicate that the Hysol technology entails a reduction of the LCOE compared to traditional CSP technologies. The highest profitability of the investment was found for South Africa. Moreover, in some regions (Chile, South Africa) Hysol can compete with traditional Open Cycle Gas Turbine even without taking into account an assumed cost on CO2 emission. According to our studies, Hysol is economically competitive even when it is compared to CCGT in some locations where the natural gas price is high (Chile).
• It is important to meet the requirements of the target tenders. In the case of the CSP tenders, it is important to take into account environmental aspects, such fluid requirements or oil restrictions, as in the case of Italian tenders or water requirements, as in the case of the MENA countries. Also, flexibility of the technology is another tender requirement to take into consideration in order to supply electricity in the most demanded hours. The results after studying the viability of Hysol in the five scenarios indicate that Hysol works as a base load or peaker, showing firmness comparable to fossil-fueled plants with high renewable content (the highest solar share of the existing hybrid technologies).
• Low technological risks: to deploy an innovative technology is crucial the control of technological risks and, in addition, ensure the right operation plant and O&M low cost. The detailed models developed and their validation during the project in the demonstration plant allowed us to test the feasibility of HYSOL with a wide range of operation modes, control strategies and electricity demands.
In summary HYSOL concept is a disruptive and technological reliable solution that aims to improve the current solutions for CSP hybrid plants on these key aspects: cost-competitiveness, flexibility and environmental sustainability.
In addition, it is expected that HYSOL solution adds an important leap to the CSP hybrid plants. That will encourage the bet for the technology, meaning an increase of tenders for CSP worldwide to cover the energy needs through renewable energies, above all in countries with good sun conditions. This must be taken into consideration since HYSOL introduces benefits in a double dimension as it will be economy profitable in short terms for plant owners through an increase of production, and in medium-long term, it will suppose the definitive blast-off of the technology experiencing a growth of CSP hybrid plants tenders.
MAIN DISSEMINATION ACTIVIES AND EXPLOITATION OF RESULTS:
Conferences: During the HYSOL project, the consortium has participated in a wide range of international conferences around the world in order to disseminate the knowledge related to the project. These include:
List of National Conferences:
1) XXXIV Jornadas de Automática, September 4-6, 2013, Barcelona, Spain
List of International Conferences:
1) E2KW, Energy and Environment Knowledge Week, Toledo, 20-22th of November 2013.
2) The 22nd European Biomass Conference and Exhibition, Copenhagen, 5-7th of June 2013
3) 13th European Control Conference, (ECC) June 24-27, 2014 Strasbourg, France.
4) SolarPaces 2014, Concentrating Solar Power and Chemical Energy Systems, September 16-19, 2014, Beijing, China.
5) 14th International Conference on Environmental Science and Technology, CEST2015, 3-5 September 2015, Rhodes, Greece.
6) SolarPaces 2015, Concentrating Solar Power and Chemical Energy Systems, October 13-16 2015, South Africa
7) 11th International Modellica Conference, 21-23 September 2015, France.
8) 1st Conference on Modelling, Identification and Control of Nonlinear Systems (MICNON), 24-26 June 2015, Saint Petersburg, Russia.
9) The 6th International Conference on Sustainable Energy Information Technology (SEIT 2016), Madrid, Spain.
10) The 24th Mediterranean Conference on Control and Automation (MED 2016). Athens, Greece.
Participation in influential organizations:
Members of the HYSOL project belong to the following key institutions relevant to the interest of HYSOL:
• EREC (European Renewable Energy Council),
• APPA (association of producers of renewable energy),
• EREF (European Renewable Energies Federation
• PROTERMOSOLAR (Spanish Association for Thermo-Solar Energy)
• SOLAR CONCENTRA.
• European Energy Research Alliance (EERAA) (http://www.eera-set.eu/)
• ESTELA SOLAR, Solar Power and Chemical Energy Systems (SolarPACES) of the International Energy Agency (IEA) (http://www.solarpaces.org)
• International Solar Energy Society (ISES) (http://www.ises.org/home/)
Academic members of the HYSOL project also have presence in educative and research platforms relative to the interests of HYSOL as follows:
• United Nations Environment Programme (UNEP);
• International Renewable Energy Agency (IRENA);
• Internantional Energy Agency (IEA);
• World Council for Rewable Energy,
• Global Reporting Initiative (GRI);
• Principles for responsible management education (PRME) (http://www.unprme.org/);
• Red Unirse (http://www.redunirse.org);
• United Nations Global Compact for Higher Education;
• Centro de Innovación en Tecnología para el desarrollo humano (idtUPM);
• Instituto Energía Solar UPM; Bioplat- plataforma tecnológica Española de la biomasa.
Diffusion meetings:
A series of meetings were carried out between partners of the HYSOL project and representative members of Influential organizations to discuss progress on the development of the hybrid technology and evaluate investment opportunities.
Hysol event: On 22nd June 2016, the project HYSOL was presented at the Manchasol concentrating solar power facilities that Cobra has in Alcazar de San Juan (Ciudad Real). In this event, aimed at celebrating and informing about the successful development of the project, the attendees, representatives from the main businesses in the energy sector, could see by themselves the actual reach that the developed prototype offers as well as the multiple technical and economic advances obtained thanks to the use of solar energy hybridization with fossil and renewable fuels managed by this innovative technology.
Press releases and publications: A total of 25 publications have been produced and 5 press notes have been released.
List of Websites:
Public web site:
www.hysolproject.eu
Contact details:
- Project Coordinator: Alberto R Rocha (arocha@acsindustria.com)
- Coordinator contact 1: Lucía González Cuadrado (luciagonzalez@grupocobra.com)
- Coordinator contact 2: Sara Muñoz Camacho (sara.munoz@acsindustrial.com)
The objective of this document is to provide a description of the HYSOL project, including the explication of the project context and objectives achieved, a description of the main results, the potential impact of the project and the main dissemination activities and exploitation of results.
Hysol project began in May 2013 as a European collaborative R&D and DEMO project on innovative solutions for a fully renewable hybrid concentrated solar power plant and has finished in July 2016.
The project is led by the Spanish EPC company COBRA (ACS Group) and includes a series of specialised SMEs, research centres and universities from different European countries. The eight partners participating in the project are: COBRA Instalaciones y Servicios (ACS-COBRA), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (PSA-CIEMAT), Agenzia Nazionale per le Nuove Tecnologie, l’Energia e lo Sviluppo Economico Sostenibile (ENEA), Investigación Desarrollo e Innovación Energética (IDIE), Air Industrie Thermique España (AITESA), Danmark Tekniske Universitet (DTU/MAN/SYS), Universidad Politécnica de Madrid (UPM), and Stichting Dienst Landbouwkundig Onderzoek (SDLO-PRI).
The milestones set at the beginning of the project have been achieved in the different periods. The first period has been focused on designing the heat recovery system and demonstrator plant, developing a static and dynamic simulation of the demonstrator plant, and defining the tests that would take place during the second phase of the project in the mock-up facility in ENEA and the demonstrator located in Manchasol (COBRA´s facility).
The second stage has been focused on the improvement of the simulations and its validation in the mock-up and demonstrator plants, final designs for a commercial Heat Recovery System, the construction works for the demonstrator, the experimental test campaign, the validation of the Heat Recovery System and the study of viability of the project in different locations (technically, economically and environmentally). By the end of the project, all the objectives have been fullfilled.
One of the initial objectives of the project was to achieve a 100% renewable electricity generation when using biogas. The research in the locations studied leads us to conclude that the locations where the current circumstances are optimal to construct a CSP plant, the biogas resource is not enough to supply fuel for Hysol. For this reason a commercial plant fueled with biogas is not viable in the regions where the CSP market has a high potential currently (MENA countries, South Africa, Chile, Mexico). However it is viable to obtain a 100% renewable plant in locations where a good combination of solar radiation, biomass supply and likelihood of commercial plant development occurs.
Project Context and Objectives:
Renewable energies have often problems in order to provide a stable and reliable power supply, as they often depend on meteorological circumstances that have a variable or stochastic component. This fact is often used by their detractors to favour the use of other alternatives such as fossil fuels. Concentrating Solar Power plants (CSP) are able to overcome this limitation by incorporating Thermal Energy Storage (TES) or by using residual heat from fossil fuels combustion processes in conventional heaters. These emerging technologies, although already in a commercial stage, remain still too expensive to compete against conventional non-renewable generation systems. Moreover, there is another inconvenient: gas performance in CSP is less efficient than in combined cycle plants. While a modern combined cycle plant can achieve an overall efficiency up to 55%, auxiliary heaters in a CSP plant convert gas to electricity at below 40%. Hence, the best natural gas performance takes place in a combined cycle plant. In spite of facing with the lower efficiency disadvantage, Integrated Solar Combined Cycles (ISCC) deal with this handicap by injecting steam obtained from the solar block into the fossil power cycle. However, these designs are limited up to 20% total solar enhancement. Without reliable, cost-effective energy storage or backup power, renewable sources will struggle to achieve a high inclusion into the electric grid. This project will provide the keys to develop a novel gas turbine / CSP with TES hybrid design that combines solar contribution with gas in a real integrated renewable hybrid plant.
The aim of HYSOL Project is to become the European reference in competition to this and other initiatives ongoing in the hybrid CSP/GT global market. The HYSOL Project focusses on overcoming the CSP technology limitations to increase its contribution in the global electric market, hybridising with a gas turbine to achieve 100 % stable and reliable power independently of meteorological circumstances. HYSOL plant is conceived to validate the use of 100% renewable energy sources (when using biomass derived gas fuel) for firm and dispatchable electricity production; this configuration will mean the highest contribution of solar energy in a hybrid plant up to date.
The main goal in the hybrid model design research is to achieve a flexible and stable energy production for the electrical system. Moreover, both economic costs and technology of the new elements developed and adapted to the needs of this hybrid technology were assessed from an operating profitability perspective and totally orientated to market feasibility (to optimize environmental performance).
Summarising, this new hybrid model will be capable of supplying electricity whenever is demanded by the Transmission and System Operator (TSO), thanks to the firm capacity achieved with the gas block and the new advanced automatic control and operation techniques applied. It will also have the capacity of working during a generation peak by operating with both turbines at the same time. With this innovative configuration it will not be necessary to have a high amount of energy as backup for the intermittent renewable sources (WIND, PV); it will reduce the requirements of Combined Cycle installations connected to the grid and substitute them with this technology.
The primary objective of HYSOL project was to develop a new hybrid technology capable of delivering firm and flexible energy to adapt the power output of the plant to any energy demand curve. The Hysol configuration comprises an aeroderivative gas turbine (AGT) with a heat recovery system (HRS) that will recover the heat from the exhaust gases into the storage system. The evaluation of biomass derived gas fuels (bio-gas and syngas) production and consumption in the hybrid CSP plant has been studied for the different locations, simulated and evaluated at a commercial scale.
Moreover, both economic and technological aspects of the new elements developed for this hybrid technology have been assessed from a construction and operating profitability perspective totally orientated to market feasibility.
HYSOL Project combined several R&D lines with the proprietary new technology demonstration. The project objectives were:
• Development of a new kind of hybrid system capable of transferring the energy from an AGT exhausts gases into molten salts.
• Optimization of the power conversion from gas turbine exhausts gases to molten salts.
• Assessment and optimisation of the technical feasibility, economics, energy efficiency and environmental performance of alternative strategies for the generation, upgrading, distribution and utilization of biomass derived gas fuels adapted to the needs of hybrid CSP-biogas plants.
• Quantification and minimising the environmental impact of electricity generation in hybrid-biomass CSP plants.
• Development of an integrated renewable process that supplies firm and flexible energy that adapts to the fluctuant demand through a base-load and peak-load generation.
• Achievement of a higher dispatchability (firm energy) due to the thermal storage and the energy recovered from the exhaust gases by the HRS that allows the CSP plant to store and produce energy not just during daytime.
• Stability in energy production, with independence of climate conditions and whenever the TSO demands.
• Development of a 100% renewable hybrid technology where there is enough biogas resource, that can be incorporated in the upcoming CSP technologies as well as retrofitting conventional ones through guaranteeing a 100% fully renewable source input at competitive prices.
• Obtaining a technology fit for any network: either isolated, with a large portion of intermittent resources or with a huge amount of interconnections.
• Cost reduction of the new plant configuration thanks to the synergy between technologies and, as a consequence, higher production rates that lead into a lower electricity price.
The project demonstration activity consisted in integrating the previous developments in the HYSOL power plant demonstrator, and that all possible technical solutions could be evaluated and cross-checked so that a successful integration was achieved. The demonstration work was not only technical, but also economic and environmental to get the optimum and most viable solution in the HYSOL power plant in every location.
Since CSP technology is already proved to be technically feasible, demonstrative projects like HYSOL are needed in order to reach the milestones that will help us to take the solar thermoelectric energy to the next level. In the estimated cost reduction scenarios for 2020, 20% of the savings will be produced by the increase in the size of the plants, 54% will be due to technological development, and the remaining 26% will be a consequence of the competitive market factor. Consequently, the most important impact on CSP industry will be cost reduction obtained through continuous technological development and higher production rates, such it is going to be undertaken in the HYSOL CSP/GT hybrid project.
The project was led by the Spanish EPC company COBRA (ACS Group) and includes a series of specialised SMEs, research centres and universities from different European countries (Spain, Italy, Denmark and the Netherlands). The eight partners participating in the project are:
Industrial partners:
• ACS-COBRA. Spain. Expertise in energy storage technologies, exploitation of 11 CSP plants with Parabolic Trough technology (48.9 MWe), and 2 projects with Tower technology (144 MWe), in Spain and USA.
• IDIE. Spain. RTD & engineering company, expertise in renewable energies, including thermo-solar plants and hybridization of renewable technologies.
• AITESA. Spain. Expertise and proprietary advanced technology aimed to provide solutions for the energy recovery of highly corrosive and/or dusty flue gases in industrial facilities.
Research partners:
• PSA-CIEMAT. Spain. It is the largest European public institute for research, development and testing of concentrating solar technologies.
• ENEA. Italy. Wide expertise in thermo-solar energy and gasification techniques, proprietary technology in molten salts.
• UPM. Spain. With expertise in biomass production, energy conversion technologies (including anaerobic digestion and biomass gasification) and environmental assessment of energy processes.
• DTU/MAN/SYS. Denmark. Specialised in energy systems analysis, socioeconomical analysis.
• SDLO-PRI. The Netherlands. Expertise in biomass and biogas production technologies, energy use and GHG emission estimation.
Project Results:
The activities to achieve the objectives of the project were distributed in seven different work packages. WP1 and WP7 were focused in the managerial and dissemination tasks respectively. The rest of the packages were aimed to carry out the technical, economic and environmental activities to validate the Hysol concept.
The results of the project can be classified according to the work package they were developed.
First of all, it is important to understand the basic configuration of HYSOL technology, so we recommend visiting the project webpage (www.hysolproject.eu) or watching HYSOL project video description in COBRA t&i Youtube channel: https://www.youtube.com/watch?v=i69s5zWkVzM.
The main objective of HYSOL project was to define a new kind of power plant that provides dispatchable and firm electricity production using full renewable sources: Concentrated Solar Power (CSP) and biogas. HYSOL uses similar principles as a Combined Cycle Gas Turbine (CCGT), which provides the highest gas-to-electricity performance of all the current commercial technologies. Therefore, HYSOL technology aims to reach similar performances as CCGT while being 100% renewable, dispatchable and firm; becoming the cornerstone of future energy systems with a high contribution of renewable energies.
WP2 PLANT ARQUITECTURE AND MODELLING:
In order to develop HYSOL project, there were several challenges to overcome: a new heat recovery system (HRS, developed in WP3), control systems (WP4), a proof of concept that the technology works (WP5), and the required economic analyses to assess the expected generation costs for this technology (WP6); among others.
All of these WPs had a close relationship with WP2, which was in charge of studying the plant as a whole, integrating the different elements involved (WP3, WP4, WP5) and providing cost and production evaluation for the economic analysis (WP6). As a consequence, WP2 answered the following questions which were key to the success of the project:
- How do HYSOL power plants work?
HYSOL technology presents a unique advantage compared to CCGT: it allows decoupling the operation point of the Steam Turbine (ST) and the Gas Turbine (GT). This means that both ST and GT can have different power outputs that are not dependent. This advantage is made possible thanks to the fact that there are two different energy sources and that part of the energy used in the GT can be stored in the Thermal Energy Storage (TES) system.
In order to clarify this point, a comparison with CCGT must be done. CCGT uses a GT to produce part of the electricity demand by burning gas as the primary source, and the GT exhaust gases are then used to produce steam to feed the ST that produces additional electricity. Therefore, the production of electricity in the ST depends on the amount of exhaust gases available, which is the same as depending on the amount of gas burned at a given instant. When CCGT power plants need to adjust their production to a given electricity demand instantaneously, the Gas Turbine (GT) and the Steam Turbine (ST) need to combine its production to meet that demand, usually maximizing the performance (which is the same as minimizing the fuel consumption). However, all the gas energy must be used in that instant, which means that both GT and ST need to work at partial loads, reducing its performance. This effect is especially negative when the energy to supply is very low, or the CCGT must be kept in line working at minimum loads to provide stability to the electric grid.
HYSOL power plants can use ST or GT at different points independently. The reason is that there is no need to use the exhaust gases energy instantaneously: it is stored in the Thermal Energy Storage (TES). In HYSOL, the thermal energy required to produce the steam is stored in molten salts tanks in the Thermal Energy Storage (TES) system. TES can be filled by normal operation of CSP plant and the GT exhaust gases energy. This allows maximizing the performance under partial loads, since the working turbine (ST or GT) can be operated with higher performances, saving thermal energy and reducing the consumption of gas. The problem is that this fact increases the freedom degrees in the power plant, and additional questions must be answered: which turbine should be operated? At what load? When should the ST/GT start/stop?
In order to understand HYSOL power plant operation, a model using Thermoflex (a software tool used to design power plants) was developed. Following process engineering methodologies, both Rankine Cycle (how the ST works) and Brayton Cycle (how the GT works) were calculated for nominal and partial loads. Brayton Cycle model was also adapted to define the demonstrator model and support the demonstrator engineering phase in collaboration with COBRA, AITESA and ENEA.
The criterion to optimize HYSOL power plants was defined by COBRA: they must produce the same electricity as a given electricity demand curve while minimizing the usage of auxiliary fuel. These criteria applied for WP2 (economic optimization was considered as part of WP6). The demand curves were defined as the national electricity demand (hourly) for a given country, scaled down so that the maximum demand value corresponds to the nominal value of HYSOL plant power output. In other words, the production of HYSOL plant should have the same “shape” as the national demand but adapted to its nominal power output.
Different operation strategies for power production were implemented by IDIE in the final model using control algorithms. IDIE and COBRA had regular meetings to define different operation strategies and evaluate the results according to three main parameters: solar energy production, fuel performance, and demand coverage ratio. The results showed that increasing the demand coverage ratio resulted in penalties in solar energy production and fossil fuel performance, and vice versa; so a compromise solution had to be identified.
An integral-predictive control algorithm was the final strategy selected. It leaded to similar values obtained for ISCC power plants in terms of fuel performance and demand coverage ratios, but with a significant solar energy contribution (and lower fuel consumption). A comparison with other hybrid solar technologies was performed for the case of Kingdom of Saudi Arabia (KSA) using these parameters. It was presented in SolarPACES 2015 and the scientific article is available at: http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4949185
As a conclusion, several conditions must be taken into account when operating HYSOL power plants: instantaneous production, future constraints, resource availability forecasts and demand and production expected. It has been solved within the project by using an integral-predictive control algorithm embedded in the power plant production models.
- What is the optimum configuration for HYSOL power plants?
Five case studies were developed in HYSOL project to assess different applications and conditions. The case studies were focused in Chile, KSA, Republic of South Africa (RSA), Mexico and Spain. The CSP technology selected for the case studies was a Solar Tower, since it provided higher performance values than Parabolic Trough. The configuration for the CSP was similar to Crescent Dunes project, since it is considered as the state-of-the-art of CSP Solar Tower plants.
The result of the analysis showed that a configuration using a 100MW Steam Turbine and 80MW Gas Turbine with a nominal power output of 130MW is a suitable solution for all the case studies. However, each case will have different optimum configurations depending on the criteria selected. In addition, the optimum configuration selection will also depend on the CSP configuration, which has not been optimized during the analysis of the case studies.
- What is HYSOL power production and fuel consumption?
Power plant models are used to estimate the electricity production of the power plant and with the installation, operation, and fuel costs the cost of the electricity produced can be calculated . The most common parameter used is Levelized Cost Of Energy (LCOE), that joins all these parameters and provides an estimation of costs. The LCOE of HYSOL configuration is provided as a result of WP6, while WP2 has provided the production results and the fuel consumption.
However, it is important to note that HYSOL plants are not defined to maximize electricity production, they are defined to supply a defined energy profile demand. In addition, HYSOL configurations are selected to maximize the usage of CSP energy, and minimize fuel consumption. The selected HYSOL configurations could increase its production, but always by increasing the fuel consumption.
As a consequence, power production and fuel consumption are not model outputs: they are the constraints considered as inputs to define HYSOL configurations. This is different from traditional fossil fuel plants, where the constraint is the nominal power output of the plant and the model results provide working hours, power production and fuel consumption values.
Due to this change of philosophy, two parameters were used instead of power production and fuel consumption during the project. Instead of power production, demand coverage ratio has been defined as the percentage of hours that HYSOL plant can provide the electricity demand. Instead of fuel consumption, electricity production due to gas rate has been defined as the share of electricity produced using fuel as primary source over the total HYSOL production is defined.
Going back to the cases studies analyzed, it has been found that a demand coverage above 95% can be met with electricity production due to gas lower than 50%. Of course, the value of the electricity production due to gas depends on the location (especially, solar resource available) and the demand curve selected, and some values of this indicator in the case analyses are lower than 30%.
- Can HYSOL technology be applied to existing power plants (retrofitting)?
An analysis was conducted during the last stages of the project, considering only the technical constraints in a power plant. This means that other issues, such as legal constrains (in Spain it would be impossible to retrofit any CSP power plant due to legislation), were not considered. The analysis evaluated if the retrofitted power plant would be economically feasible if the energy was paid at market prices, defined in the range of 40-50 USD/MWhe.
The study identified that there were three different technologies that could be retrofitted using HYSOL technology: CCGT, OCGT and CSP (parabolic trough and tower). OCGT power plants only have a Gas Turbine to produce electricity and they do not recover the energy from the exhaust gases, leading to gas-to-electricity performances around 35%. Despite its lower performance, this technology is still present in developing countries and regions were the gas cost is low.
CCGT analysis determined that using HYSOL in this power plants is a non-feasible solution, since they are usually optimized using different criteria (the ratio GT power/ST power is different than for HYSOL power plants) and CSP technology is too expensive to compensate the required investment in periods bellow 20 years.
OCGT retrofitting is economically viable if the total gas costs of the gas are higher than 10 USD/MMBTU during 20 years lifetime operation. This gas cost would not only include the market price of fuel but also other externalities, such as CO2 credits or similar. In this scenario, the high costs of CSP installation could be compensated thanks to savings in gas costs and the increase of gas-to-electricity efficiency.
CSP power plant retrofitting reduces the electricity cost production for CSP power plants, but they still need subsidies support since the final electricity cost is higher than the defined market prices region. However, a marginal analysis performed only to the components of the retrofitting (not considering the previous CSP installation) demonstrated that the electricity provided due to the GT+HRS installation, reached the market price value; and that they could contribute to the stability of the grid by providing dispatchable and firm energy.
WP3: GAS-MS HEAT RECOVERY SYSTEM
The main scientific and technological results obtained are:
The most appropriate metals for commercial heat exchangers have been selected, as a function of maximum temperature levels of the different types of solar power plants and temperature sections of the heat exchangers. Corrosion margins for each metal have also been defined. The heat exchangers will include a combination of stainless, alloy and carbon steel tubes, optimizing costs.
A list of basic design provisions to be taken into account during the basic design of the full-size commercial heat recovery system, mainly related to corrosion processes, gravitational drainage and anti-freezing protection, has been specified. Some of the main provisions adopted were:
• the heat exchanger should be designed with quasi-horizontal, 1% inclined tubes, for appropriate draining of molten salts
• bends of the tube bundles should be inserted within the flue gas passage
By means of steady-state regime CFD analysis, it was revealed how both heat transfer coefficients and pressure drop values obtained with conventional heat exchanger design tools were overestimated, due to the special design characteristics of the specified heat exchanger.
By means of transient regime CFD analysis, temperature gradients under all possible start-up conditions were calculated, so start-up procedures that avoid excessive thermal stresses in the tubes could be defined.
The MOSE facility of a small mock-up of the heat exchanger tube bundle was completed and experiments with natural gas and biogas to check molten salt heat transfer coefficients were accomplished. Results allowed to validate heat transfer correlations (for the molten salts and heating gas sides), showing the consistency of experimental data with the heat transfer correlations used for design. Also an analysis of the potential of alternative biomass derived gas fuels in locations compatible with HYSOL technology was conducted, serving as the basis to define the composition of the biogas employed in the mock-up tests conducted at the MOSE facility and also to determine the potential of alternative biomass resources and technologies for the generation of biogas fuels to be used in CSP plants based on HYSOL configuration.
Heat transfer elements of the reference full-size heat exchanger were optimized, in order to provide the specified effectiveness with minimum heat exchange surface and pressure drops. Gases pressure drop, quite significant for gas turbine performance is lower than 20 mbar. The performance functions of the reference full-size heat exchanger were obtained.
A basic design of a reference full-size heat recovery system was completed, adapting it to all the parameters of the reference industrial plant and taking into account all the specified provisions to work with molten salts inside heat exchange tubes.
A detail design of the reference full-size heat recovery system was prepared, including a detail arrangement of the molten salt heat exchanger and the water economizer and an overall arrangement of the whole heat recovery system. Additionally, a complete set of documents was elaborated, including equipment datasheets, lists and detail drawings.
An optimized and representative detailed design of a demonstrator heat recovery system was completed, with appropriate characteristics to, by means of testing experiences, validate and adjust the basic criteria and the simulation tools applied to the full-size heat recovery system, in order to minimize the risks of the next full-size commercial demonstration stage of the technology. Testing experiences have shown that:
• The heat exchanger can be filled with molten salt from the upper, inlet salt side, without significant differences of salt flow disequilibria between the columns, due to not evacuated gas bubbles, with respect to the safer and more complicated filling procedure from the bottom side.
• The tubes of the heat exchanger can be completely emptied of molten salt without problems and quite quickly.
• The slight inclination of the tubes (1% slope) has proved to be useful for the movement of salts and has not given any problem. Moreover, it has eliminated the specific vents and drain connections for the heat exchanger itself.
• Gases flow distribution, determined by pressure drop and temperature measurements along the tubes length at several points of gas path, was not fully optimized, but was considered sufficiently appropriate.
• Salt flow distribution, determined by salt temperature per tube, at the outlet of Demonstrator, showed some disequilibrium, easily fixable by means of a positive operating pressure.
• The impact of the inclusion of tube bends on the gas path and the wall effect was higher than foreseen by CFD analysis done, so special detail design provisions were required to avoid corresponding uncertainty.
The detail design of the reference full-size heat recovery system was finally revised, taking into account the results of the demonstrator testing. The revised design included some innovative solutions for the bundle of inclined tubes, allowing a great improvement of the performance with respect to the original design, reducing the required number of tubes (-23.7%) and the volume of the heat exchanger (-45.4%). The revised design of the full-size heat exchanger is considered totally validated, without constraints to be supplied as commercial equipment, with the usual performance guarantees. This revised detail design has served as reference for the cost estimation of commercial heat recovery systems, as a function of capacity and main design parameters.
WP4. DYNAMIC MODELLING AND ADVANCED REAL TIME OPERATION CONTROL
The main idea behind the control theory of dynamic systems is to achieve the following goals: to maintain the process stable at all times, to track the desired command input signal and to reject disturbance inputs. All these conditions must be maintained in spite of changes in the system dynamics due to operating conditions or environmental changes.
Modelling and simulation of dynamic processes are very important subjects in control system design. Control engineers must take advantage of the information provided by dynamic models in order to design and test control algorithms without performing experimental tests at real plants. Nevertheless, achieving accurate models that describe completely the real behaviour of dynamic systems is a hard task that requires the following steps: i) to understand and study the main physical phenomena, ii) to derive a mathematical formulation, iii) to translate the formulation into a modelling language, iv) to simulate the model, evaluate the obtained results and review the formulation taking into account the simulation results, v) to calibrate the model (tune unknown parameters or parameters with uncertainties) with experimental data and vi) to validate the models with experimental data in a wide range of operating conditions.
These three tasks, modelling, simulation and control, have been the main goals of this WP. During this project the objectives have been: i) to contribute to the dynamic modelling processes in order to obtain accurate and fast dynamic models for the HYSOL power plant configuration, ii) to perform dynamic simulations and, iii) to design, test and validate control strategies in order to improve the performance of the whole system.
From this point of view, the main scientific and technological results obtained within the HYSOL project are the following:
• Development of dynamic models of different components found at the HYSOL demonstrator plant and at the HYSOL commercial power plant configuration.
With the aim of studying the HYSOL power plant configuration, the development of each one of the main systems that compound the whole plant has been addressed. In this approach a model was developed for each physical subsystem, and the model of the total system was obtained by interconnecting the models of the subsytems by means of their interfaces. In our particular case, the subsystems are: a heat recovery system HRS (which is a heat exchanger with molten salt and exhaust gases from gas turbine), a molten salt storage tank, a gas turbine with a duct burner and a molten salt – thermal oil heat exchanger.
For those systems that a real physical component is available in order to model, calibrate and validate the dynamic models (the HRS, molten salt – thermal oil heat exchanger and the molten salt storage tanks in our case) physical principles like balance equations (typically based on the conservation of mass, momentum and energy) are used to define its behaviour. In contrast to this, for auxiliary equipment such as molten salt pumps and air heaters, black-box models in the form of transfer functions have been obtained based on input-output experimental data. In addition, typical dynamics collected from scientific literature have been coupled to steady state correlations (obtained within WP2) to define the main outputs of a gas turbine. In this case, a hybrid model (it combines continuous and discrete variables) has been developed in order to take into account the different equations that define each one of the operating modes that have been identified (stopped, starting, running and shutdown).
• Simulation executions to predict the response of the systems under different operating conditions.
As commented before, another important effort was spent at the simulation phase. It consisted in implementing the models into the chosen modelling language, proceed with the compilation of these models and performing simulations. Within the WP4, the Modelica language and MATLAB® tool have been used for the dynamic modelling of the power plant. The Modelica tool used was Dymola (Dassault Systemes, 2016), whereas the numerical integrator for Modelica dynamic simulations was DASSL (Petzold, 1983). The Modelica language has been designed to model conveniently complex physical systems because the language supports the object-oriented and equation-based paradigms.
The main components of the system have been identified and then have been modelled and developed in a reusable library for the HYSOL project. The one-dimensional case is assumed; therefore components have been discretized by the Finite Volume Method (FVM) in Control Volumes (CVs); the number of CVs can be configured by means of parameters.
During the HYSOL project, several stability and integrity simulation tests have been performed. A wide range of simulations have been carried on to define the appropriate number of CVs to obtain accurate results but at the same time reducing the computational time as much as possible. The dynamic model has been used to compare steady state values obtained within WP2 and WP3 and to estimate the dynamic behavior of the HYSOL demonstrator plant before commissioning the plant.
• Dynamic model validation using experimental data.
The success of the dynamic models developed under HYSOL project can be measured by the dynamic model validation using experimental data. This task has been carried on thanks to the availability of two facilities; the HYSOL demonstrator plant (located at Manchasol power plant) and the MOSA facility at Plataforma Solar de Almería (PSA).
The experimental campaign at HYSOL demonstrator plant has been essential to calibrate and validate the dynamic model of the main component of HYSOL project; the heat recovery system. After tuning heat transfer correlations, a good agreement between simulation results and experimental data was obtained, both in steady state conditions and for transitory responses in the complete operating range.
The remaining main components which compose the HYSOL power plant configuration (heat exchanger and molten salt tanks) have been validated by experimental campaigns at MOSA facility located at PSA. This molten salt test facility is a replica of a thermal energy two-tank storage system with molten salts as storage fluid. Being a reduced scale commercial two-tank molten salt storage system, everything related to this type of systems can be tested in this facility. The experimental campaigns in molten salt charge and discharge operating modes, covering the whole operating range, were used to adjust, calibrate and validate the transient response of the dynamic models, where very good results were obtained.
The dynamic model validations are the base of the success of the WP4, because future studies regarding to the commercial HYSOL power plant can be performed from solid conclusions reached during this project.
• Evaluation of proposed control loops.
The HYSOL demonstrator model has been the base for performing control simulations to validate the proposed control strategies, such strategies focused on maintaining desired operating conditions in the HRS, both for start-up stages, nominal conditions and partial loads before the demonstrator plant commissioning.
As in many processes in the industry, during the experimental campaign, a dead time was detected in the dynamic behaviour of the HRS. From a detailed study of the experimental data, the cause of this dead time is supposed to be produced by the accumulation of a large number of low-order system dynamics (molten salt pipe lines) with small passive zones which produce small dead times. This conclusion has a huge importance because it determines the approach to be followed by control engineers to design control strategies for commercial plants. Moreover, this dead time must be a variable that HRS design engineers must take into account to define appropriate constraints in the gas turbine exhaust mass flow rate gradients (which means in the gas turbine load gradients) to assure that the control system is able to maintain, first of all, safety conditions and, at the same time, the desired operating conditions at the HRS.
• Development of an operation training system for the HYSOL demonstrator plant.
As a consequence of the achievements obtained and previously explained, a complete simulation tool has been developed. It is an operation and training software tool for the HYSOL demonstrator built in Manchasol solar thermal power plant, which is the product obtained after the work performed in the whole WP4. This operation and training tool has three main parts:
i) Demonstrator dynamic model. It includes the different models and the global demonstrator model analyzed and designed during the HYSOL project. Since models were implemented using different modeling and simulation languages and tools, its integration was performed by using Functional Mock up Interface (FMI).
ii) Control scheme. The different control strategies considered for the demonstrator are included in this simulator. It is possible to change from manual control to automatic control choosing between different control strategies.
iii) Supervisory Control and Data Acquisition (SCADA) system. A SCADA system has been developed to interact with the control scheme, the demonstrator dynamic model and the real plant.
The simulator tool must represent as close as possible the HYSOL demonstrator located at Manchasol solar plant. Therefore, different operating modes and control strategies are included. Three operating modes have been considered: startup, running and shutdown. It allows defining and testing different turbine startup/shutdown curves, gas turbine partial loads and control algorithms.
This virtual tool is not only important to help understanding HYSOL demonstrator system behavior, but also to be used as reference to train operation staff to replace the real expensive equipment in a learning process.
• Optimisation studies for the HYSOL commercial plant operation.
For the commercial HYSOL case, the operating procedure can be studied and optimized for different operating modes using the complete power plant model developed under WP4.
An optimisation problem has been defined to calculate the best operating points for the new element included, the HRS, at different operating conditions. The goal is to minimize, for one part, the difference between the electric power demand and the obtained electric power and, for another part, the consumed gas in the gas turbine and duct burner. Promising results have been obtained in a preliminary study, but most of all, it gives an added value to the activities related with dynamic modelling and control strategies developed within this project.
WP5. PRE-INDUSTRIAL SCALE DEMONSTRATOR
The objectives of this work package were to develop and build the pre-industrial scale pilot plant, including electrical parts, instrumentation, a control system and all the equipment needed to carry out the experimental tests in order to validate the models developed in other work packages.
The design of the demonstration plant configuration was developed using the information generated in WP2 Plant Architecture and Modelling. The elements needed to carry out the tests were selected and the experiments and operational modes were designed. The demonstration plan configuration consists of an exhaust gas simulator which generates the gases at a similar temperature to the exhaust gases from a commercial gas turbine and different flow mass. Another key element is the Heat Recovery System that transfers the heat from the gases to the molten salts. The design of this component is one of the results of the project and the experimental tests have been essential to validate not only this design but also to improve the design for commercial purposes, also developed in this project. The rest of the facility comprises an auxiliary tank to store the molten salts, a pump to move the salts though the system, and an air-cooler to cool down the molten salts and close the cycle.
A key part of the minimum components selection was to choose the instrumentation and control system to measure and register the values of all the variables involved in the validation of the system.
As a result of the design, construction and operation of the plant the consortium has gathered the required information to analyse and evaluate the technology. The tests carried out in the plant were classified in three groups: steady-state, transients and off-design tests.
The steady-state tests consisted in studying how the system behaves at different gas turbine loads: nominal, 75%, 50% and technical minimum, warm stops and cold stop. The transients between steady and semi-steady states were studied to observe the inertia of the system and the times to obtain a steady state at a required load. At least, a group of off design tests were carried out in order to determine the behaviour of the heat recovery system under different combinations of values for the input variables (exhaust gases mass flow and inlet temperature in the HRS and molten salt inlet and outlet temperature). The results obtained after these experiments were analysed to validate the design of the heat recovery system and to obtain more precise control system parameters for a commercial plant.
WP6: ECONOMIC AND ENVIRONMENTAL ASSESSMENT
A) Economic assessment:
The following actions have been performed:
• The economic potential of HYSOL in comparison to competing technologies from a socio-economic and a corporate-economic perspective were studied, e.g. to compare HYSOL vs. Open/Combined Cycle Gas Turbine (OCGT and CCGT) for KSA, Mexico, RSA and Chile.
• A market assessment in the countries under analysis was carried out, highlighting the potential for the HYSOL project (by comparing, for example, the HYSOL with the generation costs relative to conventional power technologies).
The following results were obtained from the economic assessment:
• For the Republic of South Africa (RSA), HYSOL competes favourable relative to an Open Cycle Gas Turbine (OCGT) reference as can be seen from comparing results when base case data are assumed. This conclusion holds even without taking into account an assumed cost on CO2 emission. When compared to a Combined Cycle Gas Turbine (CCGT) reference plant the RSA HYSOL alternative is less favourable. However, introducing an assumed CO2 emission costs of 40 USD/tCO2eq emitted, narrows the Levelized Cost of Energy (LCOE) price difference considerable (down to a LCOE difference of less than 5 USD/MWh).
• For Chile, HYSOL is economically competitive when it is compared vs. OCGT and CCGT options, while it is not cost-effective in the Kingdom of Saudi Arabia (KSA) and in Mexico. The lack of competitiveness in these countries is due to the significantly low Natural Gas (NG) prices in comparison to Chile (The NG price in Chile is assumed to be about three times as much as in Mexico or KSA). Furthermore, the current NG price conditions discourage the economic attractiveness of HYSOL in these countries.
• In Mexico, the deployment of HYSOL could contribute to decrease gas and oil power plants in the mid-term.
B) Analysis of HYSOL concept fuel supply potentials:
Key parameters have been derived from the data of various agricultural residues types of the research conducted in period 1. These key parameters are used in the spatial analyses of biogas and digestate production in task 6.2.3.
The research has been described in a report with as title: “Biogas production and digestate utilisation from agricultural residues” which is included in deliverable 6.2.
Results are described focusing on the non-renewable energy use (NREU) and the greenhouse gas (GHG) emission from biogas production and utilization from animal manure and crop residues.
The preferred system for biogas production from agricultural residues involves local scale co-digestion with upgrading of biogas to biomethane by water scrubbing and injection into a gas grid for transport and storage. Electricity and heat needed for digestion and upgrading is internally produced using part of the biogas. Where no gas grid is available, different alternatives for transport exist. When much substrate is available on a short distance, the substrate can be transported to the location where the gas is used and biogas can be used without upgrading. Otherwise, compressed biomethane can be transported over longer distances to the nearest gas grid or to the location where the gas is used. Transport of liquefied biomethane can eventually be an alternative for very long distances. The digestate is assumed to be used as organic fertilizer at the location where alternatively the undigested residues would have been applied. Methane emission from digestate storage is captured and utilized, whereas no emission from manure storage in the biogas system was assumed. Agricultural residues, in this study: manures and crop residues, are variable in composition and digestibility and to cover a wide range of residues eight types have been distinguished: four types of manure (solid poultry manure, solid cattle manure, liquid cattle manure and liquid swine manure) and four types of crop residues (straw, stems and dead leaves, yellow leaves and green leaves), each with a composition and methane yield based on literature when possible and estimated when not available.
For the evaluation of the NREU and the GHG emission of the biogas production and utilisation a calculation model has been developed. In the model the NREU and GHG emission of biogas or biomethane produced from different substrates or mixtures of substrates and transported to a gas grid or the location where the gas is used are calculated and compared with reference values of using natural gas, assuming that the biomethane from digestion replaces natural gas. Model parameters were derived from literature and estimated when no information was available. According to EU legislation, a minimum reduction in GHG emission of 60% compared to the reference system is used to evaluate the results of the model. This standard is also applied for NREU reduction relative to the reference system and European marginal natural gas is used as reference energy source.
Results from the calculations for individual substrates show a low NREU for all substrates, complying with the chosen standard, if substrates are available within a certain distance of the digester. NREU increases with substrate transport distance and this increase depends on the gas yield per ton fresh substrate and is therefore especially high for liquid manures. Residues can be transported by truck from 70 km for liquid swine manure to approximately 600 km for stems, dead leaves and yellow leaves before the NREU reaches 40% of the NREU of the reference system. Also the GHG emission is low for all substrates and even negative for manures, especially liquid manures, due to the avoidance of methane emission from manure storage in the reference system where manure remains undigested. Liquid manures can be transported circa 400 km before the GHG emission reaches 40% of the GHG emission of the reference system. With this distance, however, the NREU reaches twice the NREU of the reference system, far above the chosen standard. For other residues acceptable substrate transport distances are shorter for the standard of GHG emission compared to the standard of NREU and range from almost 200 km (green leaves) to 400 km (solid poultry manure).
Although large uncertainties exist in both availability of substrates and parameter values and the calculations are made for ‘Best Available Practices’, the very low levels of NREU and GHG emission from biomethane production and use make it not likely that the GHG and NREU reduction standards will be exceeded under less favourable conditions. A sensitivity analysis showed that only with a 10% extra leakage of methane from the digester or digestate storage the reduction in GHG emission was smaller than the EU standard, which illustrates the importance to prevent methane losses from the digestion system. Results also showed that the avoided methane emission from manure storage in the reference system has a large ‘positive’ effect on the GHG reduction which is not directly achieved by the digestion system but is caused by the current imperfect storage systems of manure in the EU.
It is concluded that the production and transport of biomethane for use in HCSP plants is an acceptable renewable alternative for the use of natural gas according to the GHG emission reduction standard of the EU.
The research has been described in a report with as title: “Non-renewable energy use and GHG emissions of biogas production and utilisation” which is included in deliverable 6.2.
In the HYSOL project agricultural residues have been selected, namely animal manure and crop residues which are both by-products of food production, as source for biogas production because of their good environmental performance and ample availability throughout the world for use in future digesters. However, the use of agricultural residues in a digester may have negative consequences on soil organic matter and related crop production, as they are currently often used as soil amendments to maintain soil fertility. Biogas production based on agricultural residues needs to take possible limitations due to soil organic matter requirements into account to be regarded as a sustainable option for utilization in Hybrid (H) CSP plants.
We have analyzed the feasibility of producing and supplying sustainable biomethane to specified HCSP plants at selected locations in five different countries (Spain, Chile, Mexico, Saudi Arabia and South Africa). These countries are assumed promising target markets for the new technology that has been investigated in the HYSOL project.
The analysis is built on four distinct parts. First, the availability of manure and crop residues for digestion is spatially quantified by using detailed global maps of the density of the main livestock species and the occurrence of the main crop species in combination with a number of parameters to relate animal density to manure production and crop occurrence to crop residue production, both in principle available for digestion. Second, the potential gross methane productions are calculated from the various manure and crop residue types (assuming anaerobically digested at the farm-scale) and represented in maps with the same high resolution as the original input maps. Third, a new analysis has been developed and applied to assess the sustainable fraction of residue use, depending on local soil organic matter requirements, derived from combining various detailed maps of current soil organic matter, soil texture, terrain characteristics, average weather conditions, etc. The sustainable fraction of residue use, i.e. a value ranging from zero to one, is estimated for each grid cell of the map of each country and has been multiplied with the potential methane production to assess the sustainable methane production with respect to maintaining adequate soil organic matter levels for agriculture. Finally, aggregations are performed on the gridded potential and sustainable methane productions per country and in the surroundings of each HCSP plant location to assess the possibilities of supplying the amount of methane required by the HCSP plant.
In conclusion the following results have been obtained after the biomethane production assessment:
• Large reductions of acceptable agricultural residue use in the selected countries have been found ranging from minus 80% in Spain and South Africa to around minus 50% in Chile, Mexico and Saudi Arabia relative to unrestricted use.
• The calculated number of HSCP plants that could be supplied with net sustainably produced biomethane would be 26 for Mexico, 9 for Spain, 7 for Chile, 6 for South Africa and 4 for Saudi Arabia.
• Locating the digester near the available residues and transport compressed gas to the HCSP plant, rather than vice versa, seems better, because of the much lower energy costs of transporting compressed gas by truck.
• Agricultural residues in EU27 can in principle play an important role in the biogas demand of the coming decades (circa 30 Gm3 per year: calculated sustainable net biomethane production for EU27).
C) Energy systems analysis and Assessment of regulatory and policy framework regarding renewable energies:
The following actions have been performed:
• The effect on the energy system, when HYSOL is deployed, in terms of total system cost, direct CO2 emissions and energy mix under different scenarios in Africa, Western Europe and Mexico was examined.
• The ETSAP-TIAM model (energy optimization model) was used to carry out this task.
• Deliverable 6.1 has been completed, including both a socio-economic assessment and an energy system analysis.
• Country-specific RE policies and regulations, and assessment of the necessary economic incentives for economic viability of HYSOL was analysed by performing a feasibility study for the Kingdom of Saudi Arabia, Mexico, Chile and South Africa.
• Deliverable 6.4 has been completed, including both a private-economic assessment and an analysis of regulation and economic incentives.
The outcomes after the analysis show that, with the current values of the average power prices, a project is not profitable in the studied countries, meaning that it needs financial support. The high initial costs related with the investments were found to be the main cause for the non-profitability.
However, the highest profitability of the investment was found for RSA. Indeed, in a hypothetical case in which all the systems would have the same average power price (assumption considered in order to compare the four markets on the same base), RSA is the market where the HYSOL investment would perform the best, providing the highest Net present Value (NPV), the highest Internal Rate of Return (IRR) and a LCOE competitive with the market price. Mexico, Kingdom of Saudi Arabia and Chile then follow as promising markets for the investment in HYSOL
D) Environmental assessment:
The following technical targets were completed in the framework of this task:
• Completed Life Cycle Assessment (LCA) of different HYSOL configurations, including biogas production and upgrading to biomethane.
• Completed LCA of conventional Concentrated Solar Power (CSP) plants hybridized with different fuels for comparative purposes.
• Completed a comparative analysis of HYSOL with competing technologies including Combined Cycle Gas Turbine (CCGT), High Concentration Photovoltaic (HCPV), conventional CSP based on parabolic trough technology, conventional CSP based on solar tower technology, conventional CSP with different auxiliary fuel inputs.
• Completed analysis of the effect of location on the environmental performance of HYSOL plants including Spain, Chile, Kingdom of Saudi Arabia, South Africa and Mexico.
• Recommended design and operation strategy of HYSOL in order to minimize carbon footprint and optimize environmental performance.
• Evaluated socio-economic performance associated with the life cycle of HYSOL technology, as an expansion to the conventional environmental analysis.
• Full information about the technical results regarding all these targets was incorporated into Deliverable 6.3 Full Life Cycle Analysis of HYSOL Technology: "Environmental and socio-economic assessment".
The results from the environmental assessment are:
• Climate change category is relatively less affected than the toxicity categories.
• Biomethane is the main impact in climate change category in a HYSOL plant.
• E&M phase only 19.7% of climate change impact.
• Location is important: 35-43% impact variation.
• HYSOL performed the best when comparing with CCGT, and ISCC (<15%).
Potential Impact:
POTENTIAL IMPACT:
From a technical point of view the result of HYSOL project is an almost commercial technology for Solar Hybrid Combined Cycles (SHCC). To achieve this pre-commercial design the consortium has validated the performance of the demonstrator and viability of the project in different case studies, so financial institutions will consider the gap between the demonstrator and a commercial full size HRS as negligible and bankable. With this process the industry can minimize the risk that is involved in a bid of these features.
The operational experience of the demonstrator has helped to optimize and validate all the simulation tools (which are the base for future engineering purposes), the control system logics and the operation modes of future commercial plants.
Despite the initial objective was to achieve a 100% renewable electricity generation when using biogas, the research in the cases studied lead us to conclude that the locations where the current circumstances to install a CSP plant (meteorological and economical) are optimal there is not enough biogas resource to supply fuel for Hysol. However it is viable to obtain a 100% renewable plant in locations where a good combination of solar radiation, biomass supply and likelihood of commercial plant development occurs.
The project has demonstrated that a hybrid concept and the use of synergies between CSP and HYSOL technologies can change the renewable energy business. This kind of synergies would give a new vision of the renewable business taking as a hallmark the flexibility and the firmness of the electricity supply from a single energy pole.
In response to the expectations placed on this development, the expected target markets would be energy mixes with high penetration of gas and crude oil, energy mixes with renewable vocation and energy market with long sunny and rainy seasonal periods.
With these inputs the markets we have studied because we foresee a high potential are:
• Kingdom of Saudi Arabia (KSA), Egypt and similar: The energy strategy to follow in these countries is to adjust the demand curve in operating conditions. The developed energy pole could be adapting its electricity production to the demand curve of the country.
• Mexico, Republic of South Africa (RSA) and similar: The strategy for these countries is to use the GT in demand curve peaks and ST as base load.
• Chile and markets with similar solar radiation conditions: The strategy to follow in this country is base operating condition to produce stable energy during 8760 hours per year.
• Southern and Eastern Europe: Adapting production to electricity price and load curve.
• India and bordering regions: The study in this area is getting the feasibility without solar energy during periods of 2 to 4 months (monsoon).
In short, to take advantage of the possible synergy between electricity production technologies should give to this development the characteristic to offer the market the use of the resources available in each target area. In other words, each country or region, when thinking of its electrical system, should be aware that the best way to affront this challenge is to base their decision in the amount of sun, oil, biomass, gas or wind that the area have.
HYSOL is the initial step to give to the region the opportunity of management in a green-friendly way all the resources available, being a proposal economically viable and developing local works due to the high portion of the CSP technology involved in this development. At the end, the highest value of CAPEX of this proposal should be covered by renewable technology, specifically CSP, being recognized as one of the technologies that more contribute to local market development, with local industrial integrations of roughly 35% of CAPEX.
Short Term Market:
HYSOL is ready to be launched in the market, as key element of CSP hybrids solar plants as it is a combination of synchronous generation (CSP), dispatchable and firm energy production of a Gas Turbine and HYSOL (join to the thermal energy storage system), and grid stabilization capabilities (GES system).
According to this schedule, a market prospective has been made in order to select the best opportunities by that time, based on solar thermal energy roadmaps elaborated by countries/regions/associations. As a result of that study, the conclusions are that HYSOL consortium will prioritize five locations in order to commercialize new CSP hybrid plants: South Africa, Chile, Mexico, south of Europe and MENA countries.
• South Africa: is one of the countries with more CSP capacity (including announced and planned plants) around the world with a total of 1,415.73 MW, which 550 MW are using parabolic trough technology. The current data announces a forecast where South Africa is placed as one of the main potential markets, ranked in second position after USA (according to scorecard methodology of CSP Today Global Tracker). The forecast announces a meaningful increase of CSP capacity, especially using molten salts as heat transfer fluid, in forthcoming years according to the up-to-date data from CSP Today Global Tracker and insights and capacities.
• Italy: One of the main European countries which bet for CSP technology along with Spain. Despite Italy did not connect any CSP plants to the grid in 2014, many projects have entered the final authorization stage. The Italian government issued a decree on July 2016 to promote the development of 100MW of hybrid CSP and gas technologies. The target to be achieved is to build 600 MW of CSP by 2020 (Source: CSP Today Global Tracker).
HYSOL consortium is formed by European companies and not only aim to lead the sector by generating knowledge and building plants in non-European regions but also taking advantage of the potential in the south of Europe to deploy CSP technology. To do that, and considering the oil restrictions in energy generation facilities present in Italian tender requirements, HYSOL consortium targets Italy to build CSP hybrids plants (Parabolic Trough or/and Tower) using molten salts as HTF, overcoming both competitiveness and environmental issues in the country.
• MENA countries: MENA countries are formed by certain countries with high potential. Speaking about CSP capacity and plans which are already developing, special attention must be paid to Kuwait, Jordan, Saudi Arabia, UAE, Oman, Egypt and Morocco.
In short-term, they are designing strategies to increase the CSP technology share in generation mix, becoming this market into a target for CSP Utilities:
· Kuwait: One of the Kuwait energy targets is to provide 15% of the demand for energy from renewable sources. A multi-technology renewable energy park that will host 2,000MW installed capacity has been developed (SHAGAYA RENEWABLE ENERGY POWER PLANT). This park will be built with different technologies. It is expected that 57% Concentrated Solar Power (CSP) is with thermal energy storage, what is ideal for HYSOL technology.
· Jordan: Jordan is currently targeting 1,800 MW of wind and solar generation capacity by 2018 and a 10% renewable energy contribution to Jordan’s energy mix by 2020. To accomplish this target, Jordan has announced 250MW of CSP which is not part of the initial target.
· Saudi Arabia: KA-CARE (King Abdullah City for Atomic and Renewable Energy) aims to build a sustainable future for Saudi Arabia by developing a substantial alternative energy capacity fully supported by world-class local industries. KA-CARE’s renewable energy program will be the implementation of clean, cost-effective solar energy technologies by recommending generating a total of 41GW by 2032. By 2032, CSP will account for 25GW of electricity generated.
· Morocco: Currently the installed CSP capacity (2015) is 23 MW. Through MASEN2, Morocco is implementing projects under the Moroccan Solar Plan. The main points of Morocco’s energy policy goes through Sustainable development durable through the promotion of the renewable energies, for the strengthening of the competitiveness of the productive sectors of the country. It has been launched a Solar Program of 2000 MW by 2020 from solar PV/CSP.
• Isolated off-grid and small-scale electricity systems such as European Islands (Crete, Cyprus, Fuerteventura, etc.) are good areas in Europe for solar energy projects as they present high solar resource potential. Nevertheless, they present high electricity prices due to ancient energy generation technologies used and very polluting systems (diesel generators, fuel turbines, etc.). Besides, these places are very sensitive to the generation groups input/output due to their small size, so dispatchability and firmness is necessary.
Users’ needs and their economic benefit:
HYSOL adopters will be solar thermal energy plants owners: ENGIE, ENEL, E-ON, RWE, MASDAR, IBERDROLA, ENDESA, MAASEN, SAUDI ARAMCO, ACWA POWER, which are transnational thus their activities cover the whole geography depending on the tenders. As stated before, plant owners require other companies, EPC and O&M companies, to build their plants and afterwards to operate them.
Regarding user needs:
• Cost-competitiveness: A tender is a highly competitive process, so it is imperative to provide the best quote. Therefore, it is mandatory to obtain low values of LCOE in order to have more opportunities to win tenders. The results of the economic studies carried out in the different case studies (Chile, Mexico, South Europe, South Africa and Kingdom of Saudi Arabia) indicate that the Hysol technology entails a reduction of the LCOE compared to traditional CSP technologies. The highest profitability of the investment was found for South Africa. Moreover, in some regions (Chile, South Africa) Hysol can compete with traditional Open Cycle Gas Turbine even without taking into account an assumed cost on CO2 emission. According to our studies, Hysol is economically competitive even when it is compared to CCGT in some locations where the natural gas price is high (Chile).
• It is important to meet the requirements of the target tenders. In the case of the CSP tenders, it is important to take into account environmental aspects, such fluid requirements or oil restrictions, as in the case of Italian tenders or water requirements, as in the case of the MENA countries. Also, flexibility of the technology is another tender requirement to take into consideration in order to supply electricity in the most demanded hours. The results after studying the viability of Hysol in the five scenarios indicate that Hysol works as a base load or peaker, showing firmness comparable to fossil-fueled plants with high renewable content (the highest solar share of the existing hybrid technologies).
• Low technological risks: to deploy an innovative technology is crucial the control of technological risks and, in addition, ensure the right operation plant and O&M low cost. The detailed models developed and their validation during the project in the demonstration plant allowed us to test the feasibility of HYSOL with a wide range of operation modes, control strategies and electricity demands.
In summary HYSOL concept is a disruptive and technological reliable solution that aims to improve the current solutions for CSP hybrid plants on these key aspects: cost-competitiveness, flexibility and environmental sustainability.
In addition, it is expected that HYSOL solution adds an important leap to the CSP hybrid plants. That will encourage the bet for the technology, meaning an increase of tenders for CSP worldwide to cover the energy needs through renewable energies, above all in countries with good sun conditions. This must be taken into consideration since HYSOL introduces benefits in a double dimension as it will be economy profitable in short terms for plant owners through an increase of production, and in medium-long term, it will suppose the definitive blast-off of the technology experiencing a growth of CSP hybrid plants tenders.
MAIN DISSEMINATION ACTIVIES AND EXPLOITATION OF RESULTS:
Conferences: During the HYSOL project, the consortium has participated in a wide range of international conferences around the world in order to disseminate the knowledge related to the project. These include:
List of National Conferences:
1) XXXIV Jornadas de Automática, September 4-6, 2013, Barcelona, Spain
List of International Conferences:
1) E2KW, Energy and Environment Knowledge Week, Toledo, 20-22th of November 2013.
2) The 22nd European Biomass Conference and Exhibition, Copenhagen, 5-7th of June 2013
3) 13th European Control Conference, (ECC) June 24-27, 2014 Strasbourg, France.
4) SolarPaces 2014, Concentrating Solar Power and Chemical Energy Systems, September 16-19, 2014, Beijing, China.
5) 14th International Conference on Environmental Science and Technology, CEST2015, 3-5 September 2015, Rhodes, Greece.
6) SolarPaces 2015, Concentrating Solar Power and Chemical Energy Systems, October 13-16 2015, South Africa
7) 11th International Modellica Conference, 21-23 September 2015, France.
8) 1st Conference on Modelling, Identification and Control of Nonlinear Systems (MICNON), 24-26 June 2015, Saint Petersburg, Russia.
9) The 6th International Conference on Sustainable Energy Information Technology (SEIT 2016), Madrid, Spain.
10) The 24th Mediterranean Conference on Control and Automation (MED 2016). Athens, Greece.
Participation in influential organizations:
Members of the HYSOL project belong to the following key institutions relevant to the interest of HYSOL:
• EREC (European Renewable Energy Council),
• APPA (association of producers of renewable energy),
• EREF (European Renewable Energies Federation
• PROTERMOSOLAR (Spanish Association for Thermo-Solar Energy)
• SOLAR CONCENTRA.
• European Energy Research Alliance (EERAA) (http://www.eera-set.eu/)
• ESTELA SOLAR, Solar Power and Chemical Energy Systems (SolarPACES) of the International Energy Agency (IEA) (http://www.solarpaces.org)
• International Solar Energy Society (ISES) (http://www.ises.org/home/)
Academic members of the HYSOL project also have presence in educative and research platforms relative to the interests of HYSOL as follows:
• United Nations Environment Programme (UNEP);
• International Renewable Energy Agency (IRENA);
• Internantional Energy Agency (IEA);
• World Council for Rewable Energy,
• Global Reporting Initiative (GRI);
• Principles for responsible management education (PRME) (http://www.unprme.org/);
• Red Unirse (http://www.redunirse.org);
• United Nations Global Compact for Higher Education;
• Centro de Innovación en Tecnología para el desarrollo humano (idtUPM);
• Instituto Energía Solar UPM; Bioplat- plataforma tecnológica Española de la biomasa.
Diffusion meetings:
A series of meetings were carried out between partners of the HYSOL project and representative members of Influential organizations to discuss progress on the development of the hybrid technology and evaluate investment opportunities.
Hysol event: On 22nd June 2016, the project HYSOL was presented at the Manchasol concentrating solar power facilities that Cobra has in Alcazar de San Juan (Ciudad Real). In this event, aimed at celebrating and informing about the successful development of the project, the attendees, representatives from the main businesses in the energy sector, could see by themselves the actual reach that the developed prototype offers as well as the multiple technical and economic advances obtained thanks to the use of solar energy hybridization with fossil and renewable fuels managed by this innovative technology.
Press releases and publications: A total of 25 publications have been produced and 5 press notes have been released.
List of Websites:
Public web site:
www.hysolproject.eu
Contact details:
- Project Coordinator: Alberto R Rocha (arocha@acsindustria.com)
- Coordinator contact 1: Lucía González Cuadrado (luciagonzalez@grupocobra.com)
- Coordinator contact 2: Sara Muñoz Camacho (sara.munoz@acsindustrial.com)