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Small-Scale Solar Thermal Combined Cycle

Periodic Reporting for period 1 - POLYPHEM (Small-Scale Solar Thermal Combined Cycle)

Reporting period: 2018-04-01 to 2019-09-30

The main objective of POLYPHEM is to improve the performance of small-scale Concentrated Solar Power (CSP) plants and their flexibility to generate power on demand. A new technology is proposed: a solar-driven combined cycle with integrated thermal energy storage. The outcomes of the project will allow in the short term to reinforce the competitiveness of this new low carbon energy technology, to favour its integration in the medium term in the European energy mix and to contribute to the mitigation of climate change.
The power block considered in POLYPHEM is a combined cycle in the range 40 kW to 2000 kW. The purpose is to meet the variable demand of energy of a mini-grid. The baseline technology consists of an air Brayton cycle as top cycle and an Organic Rankine Cycle (ORC) as bottom cycle.
POLYPHEM broadens this technology by driving the top cycle with solar energy through the development of an advanced pressurized air solar receiver and by including an innovative thermal energy storage unit between both cycles. Besides electricity generation, other applications will be considered for future developments, such as heating/cooling of multi-family buildings or water desalination for small communities.
The POLYPHEM project will implement a prototype system and will validate this innovative configuration for power generation in a relevant environment, will assess its technical, economic and environmental performances and will establish the guidelines for the commercial deployment of this technology in the long term.
WP1- Selection of materials for the solar receiver: 12 candidate metallic materials have been benchmarked. Nickel-based alloy Haynes 230 and Inconel 600 are qualified for mechanical testing. The optical characterization of a coating proposed by ARRAELA is ongoing. The solar receiver has been designed by CEA and CNRS.
WP2- The generator suited for the application is delivered. The gas-turbine is defined. The design is tailor-made and optimized for the project. The engine is made of commercially available and robust components. The combustion chamber is replaced by a flameless catalytic combustor developed by KAEFER. The recovery heat exchanger has been designed by AALBORG CSP. The programmable logic controller is designed, with a high level of safety integrity. The modular design allows the installation of components distributed at various locations and linked by an Ethernet network. The software is developed by KAEFER. The Organic Rankine Cycle system has been adapted to the project from a solution developed by ORCAN ENERGY. The new design has been validated with simulation considering the expected operating conditions.
WP3- Jarytherm DBT has been chosen as HTF in the storage loop. Various grades of technical concrete materials developed by ARRAELA have been benchmarked and their compatibility with HTF has been experimentally assessed with a long-term ageing protocol. The storage tank is designed. It is a cylinder 2.6 m in diameter, 3.2 m in height. From the experience shared by the participants on thermocline modelling, CIEMAT has specified the entire thermal storage system.
WP4-The plant layout is defined. The operation modes and strategies are defined. The specifications of the sub-components serve as inputs for the static simulation at design operating conditions. The piping and instrumentation diagram is done. The controller is under development by KAEFER. The core of the controller is shaped for the gas-turbine. A frequency converter connects the generator to the electric grid or to a load bank via a DC bus according to the operation mode.
WP7- Fraunhofer ISE started the dynamic system modelling for off-design simulation with the optical simulation model of THEMIS heliostat field coupled to a simple model of solar receiver. Compressor and expander charts have been integrated to the model, allowing the simulation of the top cycle for short periods and for annual assessment.
WP9- Euronovia created the POLYPHEM website, brochure, and a LinkedIn account. Several partners have participated to international Conferences (SolarPACES, CSP plaza, JNES), to general public events (ESOF, Sustainable places) and run joint actions with other H2020 CSP projects such as newsletters and Twitter account.
Technology Impact objectives:
• propose a new design for the next generation of small-scale CSP plants
• feature a reduced water requirement compared to steam Rankine cycle.
• provide an optical efficiency of small solar tower system higher than that of any other solar field
• offer an extended range of designs by varying the size of the components, each design being optimized for a specific need (power generation, cogeneration, heating/cooling, water desalination).
Economic Impact: The levelized cost of electricity estimated for the POLYPHEM technology developed at the end of the project (2020-2025) is 21 c€/kWh in sunny regions (2600 kWh/m2/y). When commercial technology will be ready in 2030-2040, the LCOE is expected to drop down to 16.5 c€/kWh which will be competitive with the cost of electricity generation in remote areas in Africa, Middle-East or India.
European competitiveness: The project will strengthen competitiveness and growth of European companies already engaged in CSP related activities. The new capacities acquired by the POLYPHEM partners from the private sector in the design and construction of components and products of high technology will allow to address existing markets with elevated added value and to increase their competitiveness. The project will also actively support the business activity of SMEs by opening a new field in which the early movers will have a decisive competitive advantage over potential competitors. The outcomes of the project will create new business opportunities for industries developing products like technical concrete, organic Rankine cycles, high temperature and high performance heat exchangers, insulating materials and thermal processes that compose the innovative POLYPHEM cycle.
Environmental Impact: The POLYPHEM project develops a solar technology for clean power and process heat generation. The main strategic targets of POLYPHEM addressing environmental issues are the following:
• To increase electricity generation based on Concentrated Solar Power (CSP).
• To develop Thermal Energy Storage (TES) systems.
• To supply Green technologies.
• To develop integrated energy solutions.
• To use desalination in order to increase water availability.
• To contribute to sustainable agricultural and food production.
• To allow environmental savings by reducing CO2 emissions.
Social Impact: The deployment of the POLYPHEM technology in the regions of interest is expected to contribute to the supply of electricity on-demand through mini-grids and to water supply when co-generation is implemented. Local communities who live in isolated and arid regions will therefore benefit from this technology. Employment in Europe and in the regions of interest is also expected to be favoured. The construction of future POLYPHEM plants can create about 1000 jobs which will benefit to SMEs, half of them being located in EU and the rest will be created in the regions of implementation.
Thermal storage material: Technical concrete HEATEK-RV, selected for tank wall and filler
Design of recovery heat exchanger
Design of micro gas-turbine, tailor-made for the project
Process Flow Diagram
Design of solar receiver