Final Report Summary - FCPOWEREDRBS (Demonstration Project for Power Supply to Telecom Stations through FC technology)
Executive Summary:
The main objective of the project FCpoweredRBS has been to carry out a set of field trials to demonstrate the industrial readiness and market appeal of power generation systems for off-grid Radio Base Station based on Fuel Cell technology. The trials have involved 13 live Radio stations in Italy, configured to simulate off-grid conditions and 2 fully operating Lab test environments in the research centres of the University of Rome Tor Vergata (UniRoma2) and JRC. The scope has been to assess the market readiness of FC based system for the integration of renewable sources (PV in this case), and the related H2 infrastructure for theTelecommunication market. A further challenge has been to demonstrate that fuel cell technologies could be a real alternative to standard power sources (batteries and diesel generators) for Telecom applications and also to highlight the advantages in using this technology to potential customers in different industrial sectors.
The proposed solution aimed at demonstrating to the TelCo operators possible advantages in terms of Total Cost of Ownership to power off-grid Radio Base Stations, replacing the Diesel generator with a new system combining renewable and PEM Fuel Cell energy fuelled with pure hydrogen (either locally produced and stored or transported) or with Methanol. Furthermore with respect to the market readiness of the proposed solutions, the objectives of the project for the RBS power units using fuel cells have to match with the TelCo demanding requirements as reliability greater than 95% and durability of more than 2 years (under real-time conditions). The Project consortium integrated different EU FC and H2 related technology manufacturers with a market leader for Telecom Systems and with R&D institutions. This peculiar opportunity has also been key to pursue a bottom-up approach which it allows to modify the energy requirements and the load profile of the energy utilization to fit in an optimum way the performances expected for the Fuel Cell system.
Results obtained, both in the labs through benchmark testing, and in the field trials, allowed for stating that this technology is mature from the technical standpoint, although system integration still plays a major role, especially in a peculiar application that is the TelCO market. Results obtained in terms of TCO demonstrated also the financial advantages obtainable, due to the higher efficiency of the fuel cells if compared to Diesel gensets, to savings in logistics, and to the better characteristics of load scalability which are typical of fuel cell based systems.
Project Context and Objectives:
Remotely located RBS for Telecom application are becoming more and more important with the increasing penetration of mobile services in rural areas.
As for many of these stations the connection to the electricity grid is not an option, specific off-grid power generation solutions are required which are quite often based on diesel fuel generators.
Recently, the GSM Association has developed an interest for developing renewable based generation systems which are supposed to be “the best way for mobile operators to extend their networks off-grid while minimising energy costs and their impact on the environment” according to the Senior Programme Manager of their Green Power for Mobile (GPM) initiative. PV and small wind generation are the standard generation system although their inherent unpredictable characteristics presents critical issues requiring either the use of large battery sets or the back-up use of diesel generators.
Fuel cells are one promising technology, but it is necessary to prove that the technology does indeed offer an attractive alternative or complementary capacity.
During the last few years, off-grid power generation systems based on fuel cell technology have experienced a significant interest, due to the fact that they can offer economic advantages to potential users, as well as technical and environmental benefits.
These potential benefits of fuel cell technology may be briefly summarised as follows:
• longer lifetimes than batteries. When properly designed to cover peak power requirement, fuel cells can meet a longer lifetime with the present status of the technology with respect to batteries;
• lower maintenance than conventional technologies, especially with respect to diesel generators; This is due to the inherent nature of hydrogen fuel cells, which have not mechanical moving parts other than fans;
• environmentally friendly. Fuel cells using hydrogen produce only water vapour. In these off-grid power-type applications, they present a clear advantage over diesel generators which generate pollutants and significant CO2 emissions
• better scalability than diesel generators. The fuel cells can easily be designed to match the given power requirement and thereby ensure high efficiency even at low power requirements. In the off-grid power-type applications the power requirements are often low and the diesel generator suffers from low efficiency and thereby high fuel costs whereas the fuel cell can be operated at its best performance.
Several studies have also pointed out the economic benefits of fuel cells over these other alternatives. Lifecycle cost analyses reveal that fuel cells provide a more economic alternative over both batteries and diesel generators over their lifetime. Primarily this is due to the replacement schedule of batteries and the significant maintenance needs of diesel generators, adding up to significant O&M costs that overcome the larger initial capital investment in fuel cells. With these factors in mind, it is clear to see where the increasing interest in fuel cell-based solutions comes from. While there are several specific markets that fuel cells can enter, the telecommunications industry is perhaps one of the most attractive, due to their use patterns and overall increase in size worldwide.
Today (2017) in the world, the off-grid and bad-grid (or unreliable grid) sites are globally about 1.1 million and more than 90% of these are powered though diesel genset. Recent studies have estimated that the off-grid and bad-grid sites can reach a total of approximately 1.2 million by 2020, with around 400.000 off-grid sites and 800.000 bad-grid sites.
These figures may provide an interesting potential market for Hybrid Renewable Energy Systems in mobile telecommunication networks.
In this scenario, the FCpoweredRBS Project is based on the following targets:
• a significant demonstration of the off-grid power generation solution in Telecom applications. This implies a concerted effort with a greater number of units at the same time being tested at several sites, which provides a level of reliability in data across test sites not found otherwise;
• a statistically significant number of units undergoing field trials meeting commercialisation criteria
• a benchmark protocol for the FC technology for the reference application field to be added in parallel to the available benchmark protocols. In the Project this procedure has been developed and implemented by independent parties (the R&D centres participating the project and the JRC which is a reference lab to this aim), providing further reliability and a point of reference for final users, who now know how their units perform in relation to the benchmark data.
• significant dissemination efforts to inform potential users of the high level of technical performance achieved. These efforts are aimed to overcome the lack of awareness about this technology in Telecom applications. Dissemination of information and exploitation of the project results about hydrogen fuel cell technology in the reference industries is a key factor because it allows potential buyers to know the good results of FCpoweredRBS project. This can lead to a greater penetration and diffusion of such systems by developing a European network of applications.
The project FCpoweredRBS Project (Acronym for “Demonstration Project for Power Supply to Telecom Stations through FC technology”) has been focused on an EU-wide set of field trials aimed to demonstrate the industrial readiness and market appeal of power generation systems for off-grid Radio Base Station based on fuel cell technology.
This demonstration project, aiming to test FC and H2 on a complete field test – based on 13 really operating Radio stations representing off-grid conditions and other 2 really operating in research test environment –constitutes the largest such undertaking of its kind in Europe and contributes to assess the market readiness of FC and the relative H2 infrastructure for this early market putting the participating companies at the forefront of fuel cell technology worldwide for these applications. One of the main goals is to increase the visibility of fuel cells as a real alternative to standard power sources (batteries and diesel generators) for Telecom applications and also prove to potential customers in different industrial sectors their advantages. Furthermore, with respect to this specific but already promising early market the project allows the EU manufacturer to fill a competitive gap with respect to their USA competitors which are extremely active in this sector.
The technological start point for the project is represented by a renewable based power generation configuration for off-grid RBS which today uses locally generated electricity as an integration to Diesel Gensets. Besides environmental concerns this configuration in the case of off-grid remote sites has important Operational Expenditures which are due to both energy consumption and to Genset maintenance and fuel logistic. The FCpoweredRBS Project solution has to demonstrate the advantage of innovative power generation solution substituting the diesel generator with a PEM Fuel Cell generator fuelled with pure hydrogen (either locally produced and stored or transported) or with Methanol.
From an energy point of view this solution allows:
• an effective match with local Renewable Energy generation (mainly PV);
• a different match with batteries which could either increase their life or reduce their dimension;
• a more efficient energy production with zero local emissions.
Furthermore with respect to the market readiness of the proposed solutions, the objectives of the project for the RBS power units using fuel cell are the following:
• Reliability greater than 95%
• Durability of more than 2 years (under real-time conditions)
The final objective is to demonstrate the industrial application readiness and market appeal of hydrogen and fuel cells for powering stand alone off-grid stations.
According to the call, the Consortium has set the following scientific and technical objectives:
1. Demonstrate the advantages of hydrogen and fuel cells with the supporting hydrogen refuelling infrastructure for delivering the expected power supply service, compared to the solutions used today. FC based solution may both increase the hours of unattended operation due to the higher efficiency and to the storage potential of H2 or Methanol.
2. a significant scale demonstration which allows a complete assessment of the technology Telecom applications. The significant amount of sites on-field tested (13 sites) represents high maturity levels of Fuel Cell technology
3. Show a commercial customer value proposition. The customer value proposition is an intrinsic part of the project, being the final users an active part of the test.
4. Moving forward the standards developments in order to support the commercial development of this application. The FCpoweredRBS Project tests have been executed in real sites and this has required the development of a clear certification procedure. The integration of the FC and H2 technologies with other existing technologies in the Telecom world has required the development of a common certification level which will be instrumental for the commercial development of this application
5. Demonstrate a viable hydrogen supply solution for this application
Although the H2 supply would not represent a major issue in this project, a real set of supply solution have been developed for some of the system configurations tested.
6. Dissemination of results. Dissemination of information and exploitation of the project results about hydrogen fuel cell technology in the reference industries is a key factor because it allows potential buyers to know the good results of FCpoweredRBS project. Additionally, dissemination activities may increase the profitability of this technology and open up the market for other applications as well.
Conferences, workshops and seminars are dissemination channels.
The purpose of those events is to present the project results, as well as exchange market interests, promote best practices, inform about the technologies available. Exploitation issues have to be studied regarding the identification of non-technical barriers to deployment of this technology.
7. Certification procedures & RCS The relevant Regulations, Codes and Standards (RCS) currently in place and under development have been the basis for the institution of harmonised certification procedures to facilitate public acceptance and legal approval by authorities
8. Life cycle assessment. A separate task has to deal exclusively with the economic aspects of the technology. The aim is to calculate life cycle costs for fuel cell technologies using the results of the project and conduct an assessment of the economic payback periods required for fuel cell technology as compared to conventional solutions already available in the marketplace. Environmental considerations have to be taken into account, to estimate reductions of greenhouse gas emissions from this technology.
Project Results:
The project aims to an on field analysis of hydrogen and fuel cell potential as energy sources of Radio Base Systems in the telecommunication field. To this aim one of the main activity of the project is the integration of a fuel cell system as programmable energy production source in the design of a fully working Hybrid Renewable Energy Systems integrating renewable energy sources (Photovoltaic) and electric batteries. The system has proved to be a potential competitive solution to the standard diesel based generation due to different features: high conversion efficiency and, related to this efficiency, extended intervals of unattended operation (low fuel consumption); cheap maintenance costs; low noise and fast/easy starting-up features and heat management high potential at low temperature ambient conditions; very low CO2 emissions.
The optimum integration of the fuel cell based system has proved to be a function of specific system requirements. To this aim, a bottom up approach was used to analyze the technical features considered relevant for the integration for each component and for the whole system. The collaboration of all the project partners allowed the study and successful implementation of the most effective solutions for this specific application ensuring a correct interoperability among all equipment. For each equipment, a set of relevant technical specifications was identified requiring, in most of the cases, specific changes and customization.
System design, with specific reference to component and subsystems sizing, has demonstrated to be one of the most important aspects for the development of generation systems with required performances and expected lifetime. The main performance parameters identified is the HRES global efficiency, may also be defined as the ratio between the energy requested from the load, ELoad, and the sum of the PV energy input, EPV-in = ERES, and the H2 (MH2) consumed from the 200 bar bottles, which is supposed to be produced from fossil sources (EFES):
A size Index has been in fact introduced as the ratio between ELoad and the ERES and could be evaluated a priori, to classify different systems (for example depending on different PV and RBS power sizings, based on the non-dimensional RES availability over a year:
• if the size Index (Isize) is lesser than 1, the HRES may be considered to be a stand-alone system, and the FES requirement over the year could theoretically be equal to zero. In such cases ηsys could be considered in the order of the theoretically achievable energy conversion efficiency from RES, ηRES* which, in the case of a PV powerplant, is in the order of 15%. The obtainment of lower values is indicative of poor performance of the HPS in terms of RES exploitation.
• if the size Index (Isize) is greater than 1, the micro-grid mainly relies on FES and their minimum requirements over the year is the mere difference between the load requirement and the renewable energy available after the conversion and assuming a “perfect” conversion of the primary source into electricity.
The system efficiency can be developed as a function of the average PV panel efficiency and average fuel cell efficiency. Also a reference reforming efficiency is introduced to take into account the primary energy (FES) consumption.
Based on the system efficiency the CO2 savings can be calculated for each solution proposed in the project.
The TCO (Total Cost of Ownership) is used as a reference element to compare the FC based solution with the standard Diesel one and is a function of CAPEX (Capital Expenses) and OPEX (Operational Expenses). With regard to the OPEX contribution, the H2 mass consumption represents the main input parameter. With regard to a given time horizon (for example a year), it may be calculated as the ratio between the energy consumed and the Low Heating Value of Hydrogen. Having a specific formula would allow to compare the H2 costs of different systems having same size index, and may be used to have an annual projection of the H2 mass consumed.
With respect to the on field tests, the design activities have been performed also based on other constraints:
• the power request of the RBS used in this application was considered to be in the range of 1 kWe.
• to simplify the authorization process, the volumetric capacity of the hydrogen tanks was limited to 0.75 m³ as this allow to avoid the request for a specific Fire Prevention Certificate according to Italian regulation (law: DPR 151/2001);
• another constraint considered was the available area for the photovoltaic system. Considering the usual dimensions of a radio sites, a good compromise was to consider 30-35 m2 as maximum dimension possible. It means a limitation of 5kw power of the PV system.
Based on the above inputs and constraints, UNIROMA2 and ERICSSON have worked out the simulation and the modeling of the overall system necessary for development of the specifications.
The RBS power system has been modeled through MATLAB/Simulink routines and code developed by UNIROMA2, including the different modeled sub-systems (PV modules, batteries, Fuel Cell and electrolyzer).
One year simulations have been performed with different configurations:
• DANTHERM and MES SA fuel cells
• with and without electrolyser
• 1 to 2 kW power requirements, assumed constant over time
• 4 kWp, 5 kWp,6 kWp – 10 kWp PV modules
• different sizes for H2 storage
• different geographic locations: northern Italy, central Italy and southern Italy
• different battery pack sizes (160 Ah, 320 Ah, 480 Ah and 640 Ah).
• ideal radiation profiles, i.e. no cloud (shade) effects are taken into account.
System control strategies have been defined assuming priority order basis (RBC, Rule Based Control), to have maximum exploitation of the renewable source (through the PV panels), and using the H2 only when strictly needed as it is the most expensive resource available on site. Assumptions can thus be synthesized as follows:
• order of priority: PV->Batteries->H2
• only component losses have been considered
• batteries are charged by PV panels
• no transient phenomena have been taken into account
• minimum power requirements for electrolysers has been assumed equal to 25% of rated power
Further simulation outputs have been calculated to evaluate system performances as functions of:
• number of H2 refills
• minimum autonomy [days]
• maximum autonomy [months]
• number of FC working hours
The number of FC starts and stops per day has also been evaluated to understand the system behavior under variable and average weather conditions.
A sensitivity analysis has been performed to evaluate the impact of the battery pack sizing and the site location on the system performances.
Effect of battery sizing: the first set of simulations has been performed to understand the impact of battery sizing on system performance, by also varying location (northern, central and southern Italy). The baseline 5kWp have been selected to that aim. From the simulations, it was evident that beyond 320Ah a saturation behavior is presented by increasing the battery pack size, in terms of all the reported parameters. Saturation is more evident for northern sites, where the lower energy from radiation reduces the benefits of larger battery size. Same trends have been obtained with both the technology under test: Dantherm and MES in the system configuration without electrolyzer. Results obtained with the electrolyzer, by keeping the 5kWp PV panel, clearly indicate a negligible advantage in terms of efficiency, that is due to the minimum benefit given by the extra power available during the summer that is counter-balanced by the power requirement of the electrolyzer. A larger size (e.g. 10 kWp) is thus required to have an advantage with the electrolyzer system configuration.
Effect of PV panel sizing: simulation results, clearly indicate that the saturation effect observed for the 5 kWp panel, is less evident for larger PV sizing, especially for southern Italy sites, where a more favorable matching can be obtained between the energy required by the RBS load and the PV panel power production.
Effect of RBS load average power: the effect of RBS load power has also been studied by keeping the PV panel size equal to 5 kWp. A more evident saturation can be observed due to the mismatch between the energy available from radiation and energy required from the load. This effect causes a much higher number of FC working hours, and then a RBS efficiency much closer to the FC efficiency, that in turn significantly affects the number of H2 refills per year.
Effect of variable weather: finally the effect of variable weather has been observed over the year, to have an idea about the impact on the number of starts/stops per day, that is increased especially during the winter/fall. A highlight of the worst week can be observed in the figure (April/May), where it is evident that under repeated fall/spring cloudy days the FC may be turned on repeatedly during the day. This requires a deeper analysis of control system strategy under similar circumstances. FC turn on during summer repeated cloudy days may be partially mitigated by increasing the battery size pack: this is one of the reasons why a 640 Ah battery capacity has been finally selected.
The conclusions of the simulation activities can be summarized as follows:
• 640 Ah battery package is enough to optimize system efficiency (larger sizing does not provide further advantage), also giving some advantages under real weather conditions.
• 5 kWp PV power is not enough to assure the self-sustainability of the configured system (H2 produced by the electrolyser). 10 kWp PV are instead enough to produce some extra power during highly sunned days in summer time, to be provided to the electrolyser.
• Number of refills can vary from about 1 per month in Southern Italy to up to 2 per month in Northern Italy (minimum autonomy in the range 10-15 days) with 5 kWp PV
• FC working hours, affecting the FC lifetime, is in the range of 2000-4000h/year.
• Increasing the power consumption from 1 kW to 2 kW the system efficiency drops about 15 percentage points, number of refills dramatically increase 4-5 times and minimum autonomy drops to 4-5 days. Also number of FC working hours is more than doubled. Such results shows that 2 kW power consumption can hardly be handled with 5 kWp PV
Following the conclusions of the simulation activities, the system architecture initial proposal was modified to integrate the hydrogen production and storage components with the RES system: in the initial phase of the project two photovoltaic strings of the same power were included in the system and supposed to work independently.
During normal daytime operation and with a suitable solar radiation, the first string, connected to the Energy Box (EB) was only dedicated to fulfill the power needs of the Radio Base Station. The other, instead connected to a MPPT Battery Charger (BC), was dedicated, to charge the batteries and to compensate an eventual lack of the energy coming from the photovoltaic system. At night as the discharge of the batteries up to a default value was expected, the system had to properly manage the energy contribution of the fuel cells (FC). With the aim to isolate the batteries bank and the related Battery Charger while the FC was running, the scheme had to be complicated by the introduction of a series of switches.
In order to make the system more compliant to the project objectives and to the telecom requirements, additional design efforts were needed to achieve improvements on efficiency and robustness. A reduction of potential sources of energy inefficiency and on the other side a reduction of potential sources of instability as redundant component and switches has led to a simplification of system design which is based on a unique photovoltaic system directly connected to the Energy Box. For this component an upgrade in hardware and firmware was required increasing the power output apparatus to 5Kw, implementing the functionality of Battery Charger and finally introducing the functionality of the 'BUS iDC (Intelligent DC BUS).
These changes allowed us to connect in parallel all the sources of energy, getting all the energy coming from the PV constantly available and injected in the system. As second step, a specific priority was assigned to each energy sources, in order PV, batteries and finally FC, which was activated only if, in a low solar radiation condition, the batteries reach a specific level of discharge.
All the energy fluxes have been managed by the output voltage of the individual components connected in the bus (iDC-BUS) and following a specific algorithm implemented in the control unit. The idea, confirmed by the first lab test, was to let the load to use any of the Watts produced by RES, keeping all the other sources ready to compensate in case of need. This allowed us to get the maximum benefit of the use of the FC so improving the overall TCO of the system.
The energy management of the system was modified to introduce the electrolyzer. The hydrogen storage was divided in primary (produced locally) and secondary (manually refilled) and the control algorithm changed according to the electrolyzer characteristics. Being connected in parallel with the other components in the iDC-BUS, a specific algorithm has been implemented to determine accurately and timely the proper amount of production of hydrogen considering the available RES energy, without compromising the system stability and energy priorities. This is done by analyzing the measurements of: the voltage-current values to the batteries, the solar irradiation, the temperature of the photovoltaic panel and also the battery charge.
Natural Gas was also supposed to a test fuel for the FCpoweredRBS project. Unfortunately this technology was not considered mature from Telecom operators and has been withdrawn from the test plan.
The overall system management is controlled by the Control Board where all the algorithms have been implemented as well as all the data collected from the probes and the single elements connected. Three points of measurements (voltage and current) have been identified: current OUT of PV-BC & iDC-CS, current OUT and IN of battery bank and current OUT of Fuel Cells.
As already commented, the algorithm will give higher priority to the photovoltaic source and it is based on two main principles depending if the amount of renewable energy exceeds or not the power need of the load.
In the first case, the solar irradiation is enough to power the DC load, the PV-BC & iDC-CS will first inject energy to charge the batteries. If still additional energy will be available, the CB activates the Electrolyzer to the maximum level of H2 production possible.
However, when the photovoltaic energy is not enough for the load, the batteries will complete the energy supply. When the 50% of DoD is reached, the algorithm will activate the FC to provide the energy towards the load and minimize the charging of the batteries in this solar condition. First the H2 produced by the Electrolyzer at low pressure supplies the FC until it is available. Second the higher pressure backup H2 storage will provide the FC with the needed fuel.
The system peculiarity is that the injection of the energy from the different sources in the iDC-Bus is made only by changing the DC voltage level always giving the highest priority to the photovoltaic. The aim is to not use the H2 to charge the batteries but let the renewable energy to do that.
Additional improvements have been defined based on the results of the field testing. Beside the ordinary maintenance activity focused on giving continuity of the running systems, additional optimization activities have been implemented to catch, analyse inefficiencies, and correct the system behaviour by customizing the algorithm or modifying working parameters. In general, the tests confirmed that the intelligent algorithm implemented to handle the power coming from the different energy sources was properly designed to match the best system efficiency and the lowest TCO.
Important feedbacks from field data were:
- A critical issue is that the AGM batteries, implemented in the project, lose their effectiveness in a short time with 50% DoD, unless we set DoD at low values (below 40%). For this reason we might use a different storage technology (Lithium batteries), which nevertheless implies higher expenses.
- Regarding the FC Methanol (Idatech), its average power consumption in stand-by is very high (over 300 Watt with peak up to 700 Watt) due to the presence of the reformer, this explains how Fuel Cell has a low efficiency if the DC load is below 1000 Watt. Moreover, the FC Methanol shuts down when the power supply is below 300 Watt. Due to their high consumption in stand-by mode, the Methanol FC are not that efficient to be used in back-up environment, as in the tested radio site one; similarly, they’re best suited to be used with loads higher than 1400W, where they’re providing a higher efficiency; no tuning may be performed to improve the above intrinsic Methanol behaviors
Regarding the FC H2 (Dantherm), its power consumption in stand-by is around 50 Watt. In the case, where FC H2 might be requested to supply power below 100 Watt over a long period of time (over 1 hour) , the FC has shown to be vulnerable to faults that can also cause the stop of the FC. In order to solve the issue, on Dantherm recommendation, it has been configured a switch-off of the FC after a period of 30 minutes characterized by a continuous power supply below 100 Watt. When it has been integrated in the whole Hybrid System together with PV panel and Batteries Package. However, during the period of experimental activities in all the sites involved in the trial, the Hybrid System has shown acceptable reliability of its firmware and control logic.
- For DC load up to 1000 Watt, the experimentation has shown that the capacity of the Battery Package (640 Ah) and Photovoltaic System have been properly dimensioned. On the contrary, in the cases where the DC load is significantly high (over 1200 Watt), the experimentation has highlighted how the Fuel Cell H2 usually turns on at night, since a significant part of the energy produced by the Photovoltaic System during the day cannot be stored due to the limited capacity of the Battery Package (640Ah). This fact suggests increasing the capacity of the Battery Package and Photovoltaic System when the DC load is over 1200 Watt.
- The maximum efficiency of the Hybrid System (based on either FC Methanol or H2) can be achieved when the FC will be able to supply also low amount of power to the load (0-300 Watt) for extended periods (over six hours). Only in this way, the System can really benefit from the single contribution of all energy sources (PV, Batteries, and FC).
- The Methanol fuel cells have showed a better maturity, specifically in the electronic part that shall be further improved in the H2 fuel cells to provide the reliability required for the implementation in the telecommunication operator’s environment, where a high reliability is a must to be pursued.
Another key objective achieved by the project was the development of the test protocols for each system application to be valid as a benchmark protocol concerning basic requirements of the customers (end user), possible extreme values anticipated for normal system operation and possible risks.
The main purpose of these test protocols is to confirm that the FCpoweredRBS systems were capable to reach their objective that is to accurately estimate by testing and evaluation of the test results obtained in the laboratory tests conducted by UNIROMA2 and JRC during the first about 18 months of the project duration (laboratory trial tests) and, to confirm these results during the field tests.
- Regarding the durability, the trial has shown that both the configurations of Hybrid System based on FC H2 and FC ME have worked properly for a period of about 10.000 hours in the sites of Fiano Romano (based on FC H2) and Sonnino (based on FC ME); field tests have shown an acceptable level of stability without any major fault or decrease of performance.
For the laboratory test the main goal were:
• Test the system under operating conditions that are representative of real operation on site
• test all the devices that compose the system for good operation and effectiveness from the standpoint of system control issues and stable behavior
• evaluate the efficiency of the system under a pre-defined test protocol for the sake of comparison with similar systems at equal design parameters (for example Isize and others as commented above).
• obtain a TCO (total cost of owenership) value of the system combining laboratory and field test results
For the field tests additional main goals, if compared with the benchmark ones, were:
• Obtain realistic system start-ups and shut-downs and real environmental conditions (for example temperature, humidity, etc).
• Coupling the HRES to a real RBS load including the recoding of delivered PV power and of stored energy through the use of batteries and of the hydrogen produced by water electrolysis.
• Check the system reliability by recording any failure in particular out of the DC (direct current) bus voltage optimal range during testing
As far as the benchmark test protocol is concerned, the system control strategy has been implemented by input/output power profiles and SOC (state of charge) via dependence on latitude of PV power production, dependence on seasons and weather and RBS load requirements. The latitude considered for employing PV and FC powered RBS systems in Europe was chosen as 47° North by bi-normal distribution calculation radiation frequency versus latitude .In making this calculation idealised (smoothed) summer and winter radiation profiles were used based on averaged data recorded at the said latitude. Characteristic of seasons especially for spring and fall are oscillations in the radiation profiles at a time-scale of about one hour constituting the envelope of profiles considered at high radiation (summer) and low radiation (winter). The benchmark profile should test the system according to seasonal variations to have realistic data over longer periods, typically a whole year. Also, this profile should be representative of a whole year's operation for the PV component. First an equinox day duration (which is average over the year) is identified, and elaborated considering three options to account for different weather:
• High radiation day (in the summer), full radiation for the chosen latitude, representing a typical summer day.
• Fully cloudy day, radiation equal to 10% of a high radiation day, representing a typical winter day.
• Variable weather day, with a radiation profile regularly oscillating between good and bad weather conditions, representing typical spring and fall days alike
The benchmark radiation profile for the tests comprises a consecutive period of 72 hours, starting with the profile of the winter day at 6 am, that is a condition for sure characterized by zero SOC in the real field. The test start condition is that the batteries shall be at minimum SOC not to influence the evaluation of system performance.
This PV power profile derived from the radiation profiles depends on the efficiency of the PV panels (that takes into account the panels' orientation and tilt towards the sun), the solar radiation measured by the weather station and on the surface area of the panels
A constant RBS load being an average DC consumption was assumed as power demand (Pload) for the test. The DC loads are 1 kW for the Dantherm system, and 900 W for the MES system due to different nominal operating conditions. In both the cases the power is within the usual range of real world RBS applications, nevertheless.
The laboratory tests to be conducted on the systems are performance characterization tests, including Input and output test parameter, Performance characterization test and test procedure.
The three days of testing - Day 1 to Day 3 in the benchmark characterization test have been conducted consecutively.
Data analysis from on field demonstration tests
The FCpoweredRBS project aimed at proving the effectiveness of H2 and FC technology as main programmable power supply technology to feed off-grid RBS using Hybrid Renewable Energy Systems (HRES) configurations.
Different off-grid generation systems, including fuel cells and electrolyzers provided by different companies, have been demonstrated on a real scale test. Systems were provided by Dantherm Power (H2 fuel cells) and GreenHydrogen.DK (electrolyzer). Methanol was also tested as another potential fuel for FC using Ballard fuel cell systems.
Thirteen RBSs have been tested for a significant period (1 year) using HRES optimized systems. The results of this experimental test have been analyzed, dealing with the effects due to the use of real equipment, real radiation profile and real control system on the performance of the HRES and representing a complete demonstration test for the proposed technology.
The systems have been first tested in the laboratories both at the University of Rome Tor Vergata and at the JRC laboratories in Petten to define the benchmark performance. The HRES systems, mainly with two different design solutions (with and without electrolyzer), have been deployed in several locations in Italy (mainly in Lazio), powering telecom RBSs owned by Italian operators (TIM and H3G).
The systems have been characterized by the following characteristics/specifications of the sub-systems and include in general:
• A 2.5–5.5 kWp power output PV system based on the HareonSolar HR-200W module, having a STC efficiency equal to 15.7%.
• A 640 Ah at 48 V electrochemical storage system characterized
by 16 lead-acid Marathon M12V155FT batteries each providing 160A at h12 VDC.
• A rack mountable Fuel Cell based power system, composed by 3 Dantherm DBX 2000 hydrogen fueled PEM Fuel Cells with power output up to 3X1.7 kW at 47–57 VDC.
• A 2.5 kW Ballard methanol fueled PEM Fuel Cell system (in two sites) used in place of the hydrogen fueled system described above.
• A 5 kW alcalyne Green Hydrogen electrolyzer (in one site) composed by two 2.5 kW stacks. The electrolyzer operates with 48 VDC input, 30 bar compressed air and purified water input.
The solutions have been deployed by integrating the PV canopy, additional shelters for H2 or Methanol storage, and external cabinets for fuel cells, batteries and, where necessary, the electrolyzer cabinet.
The sites have been fully equipped with sensors and remote data gathering has been implemented with an acquisition data remote system. The controls on the functionality of the system as well as the fault management of the plant are operated by a Logic Control System Unit. All the measurements (from PV system, DC bus and single equipment) are collected and processed: a customized SW platform allows data post-processing in order to elaborate graphs and consolidated reports.
Moreover, the SW application provides in real time the details of power and consumption of any element and in addition gives the opportunity to start/stop and regulate the different components for tuning activities. Several levels of access permission are defined in order to have differentiated account for Operators (read-only), Front Office Operation&Maintenance people and upper levels of support (Ericsson and partners).
The main measured and stored parameters during the normal FCpoweredRBS operation are: current at all the different nodes of interest (PV output, battery connection, FC output, load), H2 bottle pressure and temperature.
The results described refer here mainly to six sites installed in Lazio (central Italy), among the total number of n.13 installed for the deployment phase of the project: Baschi(#1),Fiano Romano(#2),Colle Turchina(#3), Sasso(#4), Campoleone(#5), Sonnino(#6). Complete data have been collected for all the sites under test. The 6 sites have been considered the most significant from the statistic standpoint and enough to be representative of the different systems from the point of view of design parameters.
For the six sites analyzed, data are available over the whole 2015 (January to December), mainly in terms of energy consumed at the load, produced by the PV and the FC system and stored in the battery system if necessary. The energy consumptions of the six sites are the sum of the energy output of the PV system and the part provided by the Fuel cell.
As the power consumption at each site is rather different (higher for site #1–2 and lower for sites #3–6), H2 consumptions have been very different for the sites. It is thus useful to take into account the non-dimensional design parameter ISIZE (ISIZE=ELoad/ERES): this parameter is on average equal to about 0.15 (typical value of PV system efficiency) and describes, as said above, the ratio between the energy consumed at the load and available from radiation. The higher ISIZE the larger is the dependence of the given HRES design on external fossil sources (H2 in this case). The analysis of sites #1 and #2 (load about 1,3 kW) confirms that for these installations the use of the fuel cell during the colder months cannot be avoided. A significant dependence on programmable power sources may be also observed in the case of sites characterized by a rather low ISIZE value, even lower than a typical PV system efficiency (sites #5 and 6). In this case, however, the dependence is due to the lack of long term storage systems, which would be capable of shifting the extra power produced during the summer periods toward the winter periods. The use of the electrolyzer is a possible solution for seasonal storage. Nevertheless, losses included in the conversion chain for H2 production with the electrolyzer and its subsequent utilization in the fuel cell may require extra sizing of the PV system.
An in-depth analysis of the results obtained led to the following main conclusions:
• operation of the systems was demonstrated for six sites during a full year period (Jan-Dec 2015), proving that this solution is technologically mature to be compared with the current standard solution for off-grid RBS based on Diesel-genset;
• the design parameter ISIZE=ELoad/ERES is on average roughly equal to 0.15 for all the sites; however the performances of different systems (for example system efficiency ƞSYS) should be compared only at equal ISIZE. Thus, among sites characterized by greater ISIZE (#1 and #2), system #1 performs better as it has the same requirement of fossil sources EFES/ERES with a greater ISIZE than site #2. Among the sites with lowest values of ISIZE (#3–6), #4 performs better as it has the lowest overall consumption of fossil sources EFES/ERES;
• By comparing the fossil source requirements of all the sites with the same parameter calculated theoretically for Diesel genset based systems, it can be stated that the fuel cell based systems allow for obtaining noteworthy fuel savings during the year. Sites #1–2, for the more frequent use of programmable sources during the year, evidently show the higher difference between (EFES/ERES)FC-based and (EFES/ERES )Diesel-based and thus the greatest fuel saving potential;
• the behavior of current output and requirement of all the sub- systems over time during three representative days (worst average and good weather days respectively during the month) has been shown for the six sites during the month of September 2015. It is worth noting that the use of the fuel cell during the day may be useful especially during bad weather or in the case of systems characterized by high ISIZE. The satisfactory behavior of the control systems has been demonstrated, as the fuel cell is capable of fast providing current to the load or to the batteries (depending on the batteries state of charge) during sudden cloud shading events with no major issues.
To summarize, the results of on field tests show that the hybrid renewable energy solution may be competitive with the current standard solution based on Diesel generator in terms of energy efficiency and minimum consumption of fossil fuel. Proper sizing and control strategy optimization are key-factors to this aim. Moreover, despite the integration of FC with many different components, tests have shown an acceptable level of stability and reliability of the hybrid solution.
LCA analysis and TCO study
A full lifecycle analysis (LCA) of the fuel cell systems being operated as UPS or backup power sources has been carried out.
Life Cycle Analysis allows to assess the environmental impact of Hybrid Power System assemblies and their usage. The main results of the analysis can be summarized as follows:
• FC based HRESs are an environmentally friendly solution, especially in terms of use as the consumption of fuel primary sources that is much lesser, especially by taking advantage of the production of hydrogen on-site with the electrolyzer.
• According to a Total Cost of Ownership criteria, the hybrid system is very competitive: infact TCO are same of a Diesel genset after 2.5 years for the system without electrolyzer, while by adding the electrolyzer that period is increased by additional 2 years.
• Efforts should be done to reduce purchase cost: increasing manufacturing
efficiency by reducing the quantity of precious metals in FC stack, optimizing stack design and improving production process performance.
In detail, regarding TCO analysis, a specific tool has been developed in order to compare the different hybrid systems with the typical solution based on the use of diesel genset.
To define a proper commercial proposition for the hybrid FC-PV solutions for off-grid radio sites or sites of fixed networks in telecommunication sector, it is pivotal to take into account that the objective of fixed/mobile operators is usually to have a Return of Investment (RoI) of three years or less. It means that a proposal of hybrid energy system can be attractive for the operators only in case the hybrid FC-PV system has a breakeven time Vs diesel generator solution of maximum three years.
The lifetime of the main components of each solution (for instance the degradation of the stacks or of the batteries) and the related replacement have been considered to calculate the TCO as well as other input data necessarily related to the specific site of the trial and to the operational costs; some of these data (such as type of hybrid system installed, average load, number of H2 cylinders, energy produced by fuel cell, runtime of fuel cell, fuel consumption, etc.) may vary from site to site.
The Total Cost of Ownership analysis over 10 years upfront investments and operational costs is aimed to benchmark economically the FC hybrid systems vs off-grid radio sites today solution (i.e. turn-key service including diesel genset rental and refueling service). In the calculation, an annual inflation has been assumed at 2%.
All the costs related to battery replacement, operation & maintenance (parts and labor), stack replacement, annual H2 Cylinder rental fee, H2 or methanol delivery &connection fees, have been taken into account on yearly basis.
A diesel genset is usually the preferred solution to power telecommunication equipment and cooling system. For a typical BTS site with a load requirement in the range of 2 kW, a standard size 10 kW is typically chosen for reliability reasons. The turnkey service includes the rental of the diesel generator, fuel costs and logistics. Refueling is typically required every 250 hours.
The turnkey service, including the genset, the refueling and maintenance , is the most convenient solution from the economic point of view, especially if compared to the expensive purchase of the diesel genset and the additional operating costs for diesel consumption, refueling activities along with the expensive maintenance of rotating elements.
Systems analysed in the TCO are the following:
Type A1
• 3 Fuel Cells @ 1.7 kW “Dantherm”
• H2 stored in 200 bar pressure tanks
• Energy Box
• 5 kW PV Panels
Type A2
• 2 Fuel Cells @ 2.5 or 5 kW “IdaTechElectraGen™”, operating with H2
produced by a steam reforming system of c (named “HydroPlus”), stored in a specific tank allocated under the fuel cell box for a capacity of 225 lt.
• Energy Box
• 5 kW PV Panels
Type C1
• 3 Fuel Cells @ 1.7 kW “Dantherm”,
• H2 stored in 200 bar pressure tanks,
• “Green Hydrogen Electrolyser” to produce H2 locally stored in a 30 bar pressure buffer tank,
• Energy Box,
• 5 kW PV Panels.
The economic analysis, carried out using the Total Cost of Ownership criteria, have been done for three system types: H2 fuel cell based (A1), methanol fuel cell based (A2) and H2 fuel cell with electrolyzer based (C1).
All the different costs have been detailed, with a description of the main assumptions. A comparison of the cumulative TCO over 10 years operation, tells that the despite the greater investment at the beginning, the baseline (A1) system has equal costs of the Diesel genset after 2.5 years. This period meets the current expectations of the mobile operators market. When comparing the Methanol fed system (A2) with the baseline and the Diesel genset, it presents slightly greater costs than the H2 one); however it still gives similar advantages if compared to the Diesel genset (breakeven time of hybrid system based on FC ME Vs Diesel genset after 3.5 years).
A sensitivity analysis has also been done decreasing by 30% H2 costs (system A1) and doubling the methanol tank volume at 450 lt (system A2).
Similar effects have been observed on costs, with a reduction of the equal costs time down to around 2 years for system A1 (FC H2) and 3 years for system A2 (FC ME). Finally, the system with the electrolyzer has been studied, under the assumption of additional tanks for low pressure storage of H2, as the electrolyzer is theoretically capable of producing up to 21 kg H2 at 30 bar per year.
Since the costs of the system are higher due to the electrolyzer, the time of equal costs Vs Diesel genset is higher or equal to 4.5 years.
Life Cycle Analysis (LCA) of Fuel Cell powered Radio Base systems has been done to assess their environmental impact and usage.
Systems are characterized mainly by a fuel cell subsystem, a PV subsystem, a battery subsystem and an electrolyzer subsystem. The results obtained for the fuel cell system, show that the manufacturing of both Balance of Plant and Stack are very important with that regard. Within the Stack assembly, attention must be given to improve the efficiency of the production processes and raw material utilization for Bipolar Plates. The MEA (Membrane Electrode Assembly) has a great impact, mostly for the electrodes and gasket contribution, with a heavier role of the cathode that contains a greater amount of PGM (Platinum Group Metals).
For the PV subsystem, the most important contribution is given by the Si cells, inverter and conduits. The electrolyzer subsystem presents a completely different scenario from the Fuel Cell, mostly due to the use of Nickel as catalyst in place of PGM; thus the BOP (Balance of Plant) has the greater impact. For the battery subsystem, steel and electronic material exhibit the greater environmental impact for the system, while leadis by far the component most affecting the impact considering the analysis of the battery pack only.
Four system designs (scenarios) have been compared, characterized by different power ratios of the subsystems, as they were used in different telecom stations. The baseline (Baschi2) has been thus compared with a smaller system for the limited load requested (Campoleone), with a methanol fueled system characterized by the presence of a reformer (Sonnino), and with a system with an electrolyzer (Rome). It is noteworthy in the comparison that the methanol fuel cell system has slightly lesser impact due to the use of methanol tank in place of hydrogen bottles.
The system with electrolyzer has the greatest impact, also due to a greater power size PV subsystem. The comparison from the energy standpoint, tells that the system with the electrolyzer is the best one, while the worst performances are presented by the methanol fed system as energy consumption is affected by the energy required to sustain the operating temperature of the methanol reformer.
Uncertainty analysis has been carried out on the Pt content, with no major impact on life-cycle, and similar results have been obtained for Nafion usage. The impact of MEA manufacturing process has been also studied for the different scenarios, and it has been observed especially important toward the ozone layer depletion, photochemical oxidation and acidification.
The comparison with the Diesel genset, that is the mainstream technology to power off-grid RBS, showed a greater impact of the fuel cell based systems as far as the assemblies are concerned, and especially for systems with the electrolyzer. The difference is somehow mitigated by taking also into account, along with the assemblies, the use phases. The evaluation of use-phase alone, tells that the system with the electrolyzer has the lowest life cycle impact, as it has the lowest consumption of fuel resources and consumable materials; with this regard, the Diesel genset is quite remarkably penalized.
Potential Impact:
Potential impact
The integration of renewable energy sources such as Photovoltaic (PV) with electric batteries and hydrogen in a Hybrid Renewable Energy Systems (HRES) represents an effective energy generation solution for remote off-grid Radio Base Stations (RBS).
In fact, the experimental activities, performed in the labs and in the field as part of the FCpoweredRBS project, have shown that the HRES based on the usage of hydrogen storage and fuel cells together with a PV system and electrochemical batteries, are very attractive thanks to the following key-factors.
1) they may operate unattended for longer periods due to a high conversion efficiency (i.e. low fuel consumption);
2) they are characterized by cheap maintenance costs unlike conventional technologies, especially with respect to diesel-genset based technologies;
3) they are low noise and environmentally friendly since they may satisfy the RBS energy requirement with very low CO2 emissions, in line with existing and future greenhouse emission limits unlike diesel-gensets
4) they are characterized by better scalability than diesel-gensets; in fact, fuel cells can easily be designed to match the given power requirement and thereby ensure high efficiency even at low power requirements; in the off-grid power-type applications the power requirements are often low (P< 3 kWatt) and the diesel-genset suffers from low efficiency with consequent high fuel costs, whereas the fuel cells can be operated at its best performance
5) the analysis of the Total Cost of Ownership (TCO) over 10 years has shown that HRES based on fuel cells and H2 are more convenient if compared to diesel-genset based solutions; TCO analysis, based on data collected from the on-field experimental activities, considers all the mentioned costs over time, both through direct and indirect costs over the entire life-cycle of the given system (cost of fuel included); therefore TCO takes into account all the costs related to purchase and installation, operation and maintenance of the system.
The TCO analysis has shown that the hybrid system based on H2 fuel cells compared to the diesel genset has a breakeven time approximately of 2.5 years in case the genset is provided in a turn-key service (including rental of diesel genset and services of refueling and maintenance) and approximately less than 2 years in case of purchase of diesel genset with additional costs for diesel refueling and maintenance activities.
Moreover, the TCO analysis over 10 years has highlighted a significant increase of savings in comparison to diesel genset solution after the breakeven time.
In fact, after 10 years, the total cost of ownership of the hybrid system based on H2 fuel cells is lower than about 60% of diesel genset solution.
The research activities have shown slightly worse results in case of hybrid system based on fuel cells with methanol where the break-even is slightly greater than 3 years and in case of hybrid system based on fuel cells with H2 produced locally through an electrolyser where break-even against a genset based solution is of about 5 years, due to the high costs of the electrolyser.
Thanks to the above-mentioned key-factors, HRES using fuel cell technology and H2 together with electric energy storage may easily become an attractive and feasible alternative solution to guarantee reliable, efficient and clean energy production to remote RBS, if compared to the diesel-genset.
Telecom specifications on energy production quality are very demanding (24 h / 7 days’ continuous supply, high availability, long autonomy without attendance) and under these conditions HRES integrating electrochemical energy storage with local hydrogen production and storage represent an effective solution if compared to battery or hydrogen only systems. In fact, the integrated use of the electrochemical batteries for short term storage and hydrogen locally produced by electrolysis for medium term and potentially seasonal storage, allows for a more effective utilization of local renewable energy sources, not excessively penalizing the batteries life cycle.
The potential worldwide market of these HRES is very interesting in the telecommunication arena.
In fact A research study by the GSM Association (GSMA) indicates that future mobile subscriber growth, with related new RBS sites deployment, will be focused especially in the developing countries in Africa and Asia.
The major driver of the estimated growth in off-grid and bad-grid (or unreliable grid) RBS towers is the expected expansion of mobile networks into rural regions in Africa and Asia, large parts of which face limited availability of reliable electric grids.
Over the past ten years there has been a tremendous growth in the green power for mobile telecommunication networks and most of the green power solutions are solar or wind-powered. Despite this, the deployment of green power solutions is still relatively marginal, as it is estimated to be lesser then 10% on a worldwide basis. It is important thus to take into consideration that in some developing countries, where the cost of oil is low, the mainstream solution based on the diesel genset may still be very competitive in terms of TCO.
Today (as of 2017) the off-grid and bad-grid sites are globally about 1.1 million and more than 90% of these are powered though diesel genset. The off-grid and bad-grid sites worldwide are estimated to reach a total number of approximately 1.2 million by 2020, with about 400.000 off-grid sites and 800.000 bad-grid sites. In powering off-grid and bad-grid RBSs towers, environmental and social sustainability are becoming a key factor, in addition to economic aspects. Hence, energy systems using renewables coupled with sustainable energy storage solutions (e.g. Photovoltaic (PV) & wind, PV & diesel genset & battery, PV& wind & diesel, and PV & fuel cell systems) are going to receive more attention than before. The above figures, as well as the new attitude that would hopefully be taken into consideration, may provide an interesting potential market for HRES in mobile telecommunication networks, such the ones tested in our FCpoweredRBS project based on PV panels and FCs.
The operating phase of the Project has been very valuable for identifying some non-technical barriers to a massive deployment of the new technology, based on power generation systems using fuel cell technology and H2.
On the basis of the results obtained and issues met during the Project, the main non-technical obstacles may be summarized based on the following main areas. It is worth highlighting that such issues mainly refer to the Italian country, and thus cannot be easily applicable to other European countries exactly as they are listed:
1. Legal and permitting constraints related to H2 usage/storage may not provide a safe predictability of the success of the project
2. Natural barriers for the installation of the whole system (e.g. lack of space, not proper solar radiation, ...)
3. High risk perception about the usage of H2 as fuel, due to the poor knowledge of the H2 properties and behaviors
4. Limited or absence of Government incentives and promotional support
Regarding legal and permitting constraints related to H2 usage/storage we shall highlight that it usually takes long time and low predictability to obtain permit/building authorizations from local administrations for fuel cell and H2 storage implementation.
The Fire Prevention Certificate certifies compliance with the existing legal requirements, as well as the presence of the necessary fire safety requirements within the structure certified. There are three stages in the procedure to obtain the Fire Prevention Certificate that take usually several months (over 4 months): approval by the Provincial Fire Department of a fire prevention project for the company prepared by qualified experts; inspection by the Fire Department to verify the correct implementation of the approved project at the company premises; if the result is positive then the Provincial Fire Department will issue the Fire Prevention Certificate.
In order to speed up the operative process and avoid to request the authorization to the Provincial Fire Department, for the deployment of the FCpoweredRBS Project a decision has been made to stay within the legal limits related to the values of maximum geometric capacity for gas and liquid methanol tanks. In fact, according to the local law (Italian Legislative Decree n° 151/2001), it is not necessary the Fire Prevention Certificate in case of:
geometric capacity hydrogen tanks < 0.75 m³
geometric capacity methanol tanks < 0.3 m³
Moreover, according to the Italian regulation about risk evaluation (art. 293 of Italian Legislative Decree n° 81/2008), which derives from European occupational health and safety normative, an evaluation of explosion risk, named ATEX, must be taken into consideration. Risk evaluation has to be conducted by portioning the potential ATEX area into zones, based on the frequency and duration of the presence of flammable gases. The areas where explosive atmosphere may form are identified and protective measures are applied, besides providing an adequate warning for the danger zones.
It is evident that tanks positioning and hydrogen system allocation should be subject to careful design activities in order to avoid formation of explosive atmosphere, avoiding the occurrence of potential sources of ignition.
Regarding natural barriers for the installation of the whole hybrid system (fuel cell, H2 Storage and PV panel), it is important to take into consideration that often the off-grid radio sites may be located in rural areas such as deep valleys, impervious slopes, top of mountains, deserts, etc..
To provide sufficient energy the installation of 5kW photovoltaic panels requires a quite large free area (at least 35/40 square meters), without obstacles that may produce shadowing effects.
Moreover, an easy access to the site is necessary in order to guarantee the recurrent H2 refueling operations, especially using H2 cylinders that may require the transportation with heavy vehicles.
Regarding high risk perception about the usage of H2 as fuel, we can highlight that the presence of hydrogen sometimes may meet the opposition of the landowner to host storage of hydrogen and of the population living nearby the site, although hydrogen is substantially safer than conventional hydrocarbon fuels (such as gasoline) in the event of any accident.
The public perception on the risks and safety of hydrogen might be long-term negatively influenced by history of hydrogen related incidents.
The high risk perception is mainly due to a lack of educated knowledge about the usage of hydrogen as fuel. This lack of knowledge sometimes implies a higher perception of risk and, therefore, oversizing the safety measures, implying additional costs or even worst, stopping the project due to the amount of excessive misinterpreted barriers.
Main dissemination activities and exploitation results
As already highlighted in the previous section, it is of pivotal importance to begin raising awareness on the positive aspects and advantages of the adoption of H2 Fuel Cells technology in telecommunication applications.
For this reason, dissemination of information has been done via a regularly updated website, as well as publications and presentations at relevant conferences and specific meetings with potential buyers such as Network Mobile Operators.
Dissemination of information and exploitation of the project results about hydrogen fuel cell technology in the reference industries is a key factor because it allows potential buyers to understand better the good results obtained as outcomes of the FCpoweredRBS project. Moreover, dissemination activities may increase the profitability of this technology and open up the market for other applications as well.
A common webpage has been developed where the results and findings in the project have been described.
Moreover, the partners have participated in international conferences to present FCPoweredRBS to a wider audience, both in and outside of the hydrogen and fuel cell community.
Conferences, workshops and seminars have been used as a dissemination channel.
The purpose of those events has been to present the project results, as well as exchange market interests, promote best practices, inform about the technologies available.
Among all the dissemination activities it’s remarkable the appreciation received by the scientific community thanks to the two main publications about the project results:
• Paper published at the International Journal of Hydrogen Energy and entitled “Fuel cell based power systems to supply power to Telecom Stations”, vol. 39, Issue 36, 2014.
• Paper published at the International Journal of Hydrogen Energy and entitled “Fuel cell based Hybrid Renewable Energy Systems for off-grid telecom stations: Data analysis from on field demonstration tests”, published on Applied Energy in Volume 192, 2017,
One blocking point for the deployment of the energy systems using renewables coupled with sustainable energy storage solutions in Europe, is the strong electrification performed over the last years.
However, thanks to the great results achieved in the FCpoweredRBS project in terms of system performance and total cost of ownership, recently Ericsson has convinced Telecom Italia customer to purchase the hybrid system based on H2 fuel cells together with photovoltaic panels and electrochemical battery package. The hybrid system is used as power system in a 3kW central office in Altavilla Milicia in Sicily. Ericsson has shown how the storage of H2 in a specific cylinders bundle, is a solution convenient in terms of total cost of ownership and makes the power generator more resilient in terms of durability.
This hybrid system, implemented in 2017, has been working properly for over 3 months and can pave the way for future implementations in sites with power consumption up to 5 kWatt.
However, a stronger awareness and systematic will of the Governments is required to finally allow this kind of solutions to evolve from the current prototype scenario into a more commercial one.
List of Websites:
web site: www.fcpoweredrbs.eu
Partners conctacts:
Ericsson Telecomunicazioni: Giancarlo Tomarchio (giancarlo.tomarchio@ericsson.com)
University of Rome Tor Vergata: Stefano Cordiner (cordiner@uniroma2.it); Vincenzo Mulone (mulone@uniroma2.it)
Dantherm: Karlsen Morten (MLK@dantherm.com)
JRC: Alberto Pilenga (Alberto.PILENGA@ec.europa.eu)
Green Hydrogen: Jørgen Jensen (jkj@greenhydrogen.dk)
The main objective of the project FCpoweredRBS has been to carry out a set of field trials to demonstrate the industrial readiness and market appeal of power generation systems for off-grid Radio Base Station based on Fuel Cell technology. The trials have involved 13 live Radio stations in Italy, configured to simulate off-grid conditions and 2 fully operating Lab test environments in the research centres of the University of Rome Tor Vergata (UniRoma2) and JRC. The scope has been to assess the market readiness of FC based system for the integration of renewable sources (PV in this case), and the related H2 infrastructure for theTelecommunication market. A further challenge has been to demonstrate that fuel cell technologies could be a real alternative to standard power sources (batteries and diesel generators) for Telecom applications and also to highlight the advantages in using this technology to potential customers in different industrial sectors.
The proposed solution aimed at demonstrating to the TelCo operators possible advantages in terms of Total Cost of Ownership to power off-grid Radio Base Stations, replacing the Diesel generator with a new system combining renewable and PEM Fuel Cell energy fuelled with pure hydrogen (either locally produced and stored or transported) or with Methanol. Furthermore with respect to the market readiness of the proposed solutions, the objectives of the project for the RBS power units using fuel cells have to match with the TelCo demanding requirements as reliability greater than 95% and durability of more than 2 years (under real-time conditions). The Project consortium integrated different EU FC and H2 related technology manufacturers with a market leader for Telecom Systems and with R&D institutions. This peculiar opportunity has also been key to pursue a bottom-up approach which it allows to modify the energy requirements and the load profile of the energy utilization to fit in an optimum way the performances expected for the Fuel Cell system.
Results obtained, both in the labs through benchmark testing, and in the field trials, allowed for stating that this technology is mature from the technical standpoint, although system integration still plays a major role, especially in a peculiar application that is the TelCO market. Results obtained in terms of TCO demonstrated also the financial advantages obtainable, due to the higher efficiency of the fuel cells if compared to Diesel gensets, to savings in logistics, and to the better characteristics of load scalability which are typical of fuel cell based systems.
Project Context and Objectives:
Remotely located RBS for Telecom application are becoming more and more important with the increasing penetration of mobile services in rural areas.
As for many of these stations the connection to the electricity grid is not an option, specific off-grid power generation solutions are required which are quite often based on diesel fuel generators.
Recently, the GSM Association has developed an interest for developing renewable based generation systems which are supposed to be “the best way for mobile operators to extend their networks off-grid while minimising energy costs and their impact on the environment” according to the Senior Programme Manager of their Green Power for Mobile (GPM) initiative. PV and small wind generation are the standard generation system although their inherent unpredictable characteristics presents critical issues requiring either the use of large battery sets or the back-up use of diesel generators.
Fuel cells are one promising technology, but it is necessary to prove that the technology does indeed offer an attractive alternative or complementary capacity.
During the last few years, off-grid power generation systems based on fuel cell technology have experienced a significant interest, due to the fact that they can offer economic advantages to potential users, as well as technical and environmental benefits.
These potential benefits of fuel cell technology may be briefly summarised as follows:
• longer lifetimes than batteries. When properly designed to cover peak power requirement, fuel cells can meet a longer lifetime with the present status of the technology with respect to batteries;
• lower maintenance than conventional technologies, especially with respect to diesel generators; This is due to the inherent nature of hydrogen fuel cells, which have not mechanical moving parts other than fans;
• environmentally friendly. Fuel cells using hydrogen produce only water vapour. In these off-grid power-type applications, they present a clear advantage over diesel generators which generate pollutants and significant CO2 emissions
• better scalability than diesel generators. The fuel cells can easily be designed to match the given power requirement and thereby ensure high efficiency even at low power requirements. In the off-grid power-type applications the power requirements are often low and the diesel generator suffers from low efficiency and thereby high fuel costs whereas the fuel cell can be operated at its best performance.
Several studies have also pointed out the economic benefits of fuel cells over these other alternatives. Lifecycle cost analyses reveal that fuel cells provide a more economic alternative over both batteries and diesel generators over their lifetime. Primarily this is due to the replacement schedule of batteries and the significant maintenance needs of diesel generators, adding up to significant O&M costs that overcome the larger initial capital investment in fuel cells. With these factors in mind, it is clear to see where the increasing interest in fuel cell-based solutions comes from. While there are several specific markets that fuel cells can enter, the telecommunications industry is perhaps one of the most attractive, due to their use patterns and overall increase in size worldwide.
Today (2017) in the world, the off-grid and bad-grid (or unreliable grid) sites are globally about 1.1 million and more than 90% of these are powered though diesel genset. Recent studies have estimated that the off-grid and bad-grid sites can reach a total of approximately 1.2 million by 2020, with around 400.000 off-grid sites and 800.000 bad-grid sites.
These figures may provide an interesting potential market for Hybrid Renewable Energy Systems in mobile telecommunication networks.
In this scenario, the FCpoweredRBS Project is based on the following targets:
• a significant demonstration of the off-grid power generation solution in Telecom applications. This implies a concerted effort with a greater number of units at the same time being tested at several sites, which provides a level of reliability in data across test sites not found otherwise;
• a statistically significant number of units undergoing field trials meeting commercialisation criteria
• a benchmark protocol for the FC technology for the reference application field to be added in parallel to the available benchmark protocols. In the Project this procedure has been developed and implemented by independent parties (the R&D centres participating the project and the JRC which is a reference lab to this aim), providing further reliability and a point of reference for final users, who now know how their units perform in relation to the benchmark data.
• significant dissemination efforts to inform potential users of the high level of technical performance achieved. These efforts are aimed to overcome the lack of awareness about this technology in Telecom applications. Dissemination of information and exploitation of the project results about hydrogen fuel cell technology in the reference industries is a key factor because it allows potential buyers to know the good results of FCpoweredRBS project. This can lead to a greater penetration and diffusion of such systems by developing a European network of applications.
The project FCpoweredRBS Project (Acronym for “Demonstration Project for Power Supply to Telecom Stations through FC technology”) has been focused on an EU-wide set of field trials aimed to demonstrate the industrial readiness and market appeal of power generation systems for off-grid Radio Base Station based on fuel cell technology.
This demonstration project, aiming to test FC and H2 on a complete field test – based on 13 really operating Radio stations representing off-grid conditions and other 2 really operating in research test environment –constitutes the largest such undertaking of its kind in Europe and contributes to assess the market readiness of FC and the relative H2 infrastructure for this early market putting the participating companies at the forefront of fuel cell technology worldwide for these applications. One of the main goals is to increase the visibility of fuel cells as a real alternative to standard power sources (batteries and diesel generators) for Telecom applications and also prove to potential customers in different industrial sectors their advantages. Furthermore, with respect to this specific but already promising early market the project allows the EU manufacturer to fill a competitive gap with respect to their USA competitors which are extremely active in this sector.
The technological start point for the project is represented by a renewable based power generation configuration for off-grid RBS which today uses locally generated electricity as an integration to Diesel Gensets. Besides environmental concerns this configuration in the case of off-grid remote sites has important Operational Expenditures which are due to both energy consumption and to Genset maintenance and fuel logistic. The FCpoweredRBS Project solution has to demonstrate the advantage of innovative power generation solution substituting the diesel generator with a PEM Fuel Cell generator fuelled with pure hydrogen (either locally produced and stored or transported) or with Methanol.
From an energy point of view this solution allows:
• an effective match with local Renewable Energy generation (mainly PV);
• a different match with batteries which could either increase their life or reduce their dimension;
• a more efficient energy production with zero local emissions.
Furthermore with respect to the market readiness of the proposed solutions, the objectives of the project for the RBS power units using fuel cell are the following:
• Reliability greater than 95%
• Durability of more than 2 years (under real-time conditions)
The final objective is to demonstrate the industrial application readiness and market appeal of hydrogen and fuel cells for powering stand alone off-grid stations.
According to the call, the Consortium has set the following scientific and technical objectives:
1. Demonstrate the advantages of hydrogen and fuel cells with the supporting hydrogen refuelling infrastructure for delivering the expected power supply service, compared to the solutions used today. FC based solution may both increase the hours of unattended operation due to the higher efficiency and to the storage potential of H2 or Methanol.
2. a significant scale demonstration which allows a complete assessment of the technology Telecom applications. The significant amount of sites on-field tested (13 sites) represents high maturity levels of Fuel Cell technology
3. Show a commercial customer value proposition. The customer value proposition is an intrinsic part of the project, being the final users an active part of the test.
4. Moving forward the standards developments in order to support the commercial development of this application. The FCpoweredRBS Project tests have been executed in real sites and this has required the development of a clear certification procedure. The integration of the FC and H2 technologies with other existing technologies in the Telecom world has required the development of a common certification level which will be instrumental for the commercial development of this application
5. Demonstrate a viable hydrogen supply solution for this application
Although the H2 supply would not represent a major issue in this project, a real set of supply solution have been developed for some of the system configurations tested.
6. Dissemination of results. Dissemination of information and exploitation of the project results about hydrogen fuel cell technology in the reference industries is a key factor because it allows potential buyers to know the good results of FCpoweredRBS project. Additionally, dissemination activities may increase the profitability of this technology and open up the market for other applications as well.
Conferences, workshops and seminars are dissemination channels.
The purpose of those events is to present the project results, as well as exchange market interests, promote best practices, inform about the technologies available. Exploitation issues have to be studied regarding the identification of non-technical barriers to deployment of this technology.
7. Certification procedures & RCS The relevant Regulations, Codes and Standards (RCS) currently in place and under development have been the basis for the institution of harmonised certification procedures to facilitate public acceptance and legal approval by authorities
8. Life cycle assessment. A separate task has to deal exclusively with the economic aspects of the technology. The aim is to calculate life cycle costs for fuel cell technologies using the results of the project and conduct an assessment of the economic payback periods required for fuel cell technology as compared to conventional solutions already available in the marketplace. Environmental considerations have to be taken into account, to estimate reductions of greenhouse gas emissions from this technology.
Project Results:
The project aims to an on field analysis of hydrogen and fuel cell potential as energy sources of Radio Base Systems in the telecommunication field. To this aim one of the main activity of the project is the integration of a fuel cell system as programmable energy production source in the design of a fully working Hybrid Renewable Energy Systems integrating renewable energy sources (Photovoltaic) and electric batteries. The system has proved to be a potential competitive solution to the standard diesel based generation due to different features: high conversion efficiency and, related to this efficiency, extended intervals of unattended operation (low fuel consumption); cheap maintenance costs; low noise and fast/easy starting-up features and heat management high potential at low temperature ambient conditions; very low CO2 emissions.
The optimum integration of the fuel cell based system has proved to be a function of specific system requirements. To this aim, a bottom up approach was used to analyze the technical features considered relevant for the integration for each component and for the whole system. The collaboration of all the project partners allowed the study and successful implementation of the most effective solutions for this specific application ensuring a correct interoperability among all equipment. For each equipment, a set of relevant technical specifications was identified requiring, in most of the cases, specific changes and customization.
System design, with specific reference to component and subsystems sizing, has demonstrated to be one of the most important aspects for the development of generation systems with required performances and expected lifetime. The main performance parameters identified is the HRES global efficiency, may also be defined as the ratio between the energy requested from the load, ELoad, and the sum of the PV energy input, EPV-in = ERES, and the H2 (MH2) consumed from the 200 bar bottles, which is supposed to be produced from fossil sources (EFES):
A size Index has been in fact introduced as the ratio between ELoad and the ERES and could be evaluated a priori, to classify different systems (for example depending on different PV and RBS power sizings, based on the non-dimensional RES availability over a year:
• if the size Index (Isize) is lesser than 1, the HRES may be considered to be a stand-alone system, and the FES requirement over the year could theoretically be equal to zero. In such cases ηsys could be considered in the order of the theoretically achievable energy conversion efficiency from RES, ηRES* which, in the case of a PV powerplant, is in the order of 15%. The obtainment of lower values is indicative of poor performance of the HPS in terms of RES exploitation.
• if the size Index (Isize) is greater than 1, the micro-grid mainly relies on FES and their minimum requirements over the year is the mere difference between the load requirement and the renewable energy available after the conversion and assuming a “perfect” conversion of the primary source into electricity.
The system efficiency can be developed as a function of the average PV panel efficiency and average fuel cell efficiency. Also a reference reforming efficiency is introduced to take into account the primary energy (FES) consumption.
Based on the system efficiency the CO2 savings can be calculated for each solution proposed in the project.
The TCO (Total Cost of Ownership) is used as a reference element to compare the FC based solution with the standard Diesel one and is a function of CAPEX (Capital Expenses) and OPEX (Operational Expenses). With regard to the OPEX contribution, the H2 mass consumption represents the main input parameter. With regard to a given time horizon (for example a year), it may be calculated as the ratio between the energy consumed and the Low Heating Value of Hydrogen. Having a specific formula would allow to compare the H2 costs of different systems having same size index, and may be used to have an annual projection of the H2 mass consumed.
With respect to the on field tests, the design activities have been performed also based on other constraints:
• the power request of the RBS used in this application was considered to be in the range of 1 kWe.
• to simplify the authorization process, the volumetric capacity of the hydrogen tanks was limited to 0.75 m³ as this allow to avoid the request for a specific Fire Prevention Certificate according to Italian regulation (law: DPR 151/2001);
• another constraint considered was the available area for the photovoltaic system. Considering the usual dimensions of a radio sites, a good compromise was to consider 30-35 m2 as maximum dimension possible. It means a limitation of 5kw power of the PV system.
Based on the above inputs and constraints, UNIROMA2 and ERICSSON have worked out the simulation and the modeling of the overall system necessary for development of the specifications.
The RBS power system has been modeled through MATLAB/Simulink routines and code developed by UNIROMA2, including the different modeled sub-systems (PV modules, batteries, Fuel Cell and electrolyzer).
One year simulations have been performed with different configurations:
• DANTHERM and MES SA fuel cells
• with and without electrolyser
• 1 to 2 kW power requirements, assumed constant over time
• 4 kWp, 5 kWp,6 kWp – 10 kWp PV modules
• different sizes for H2 storage
• different geographic locations: northern Italy, central Italy and southern Italy
• different battery pack sizes (160 Ah, 320 Ah, 480 Ah and 640 Ah).
• ideal radiation profiles, i.e. no cloud (shade) effects are taken into account.
System control strategies have been defined assuming priority order basis (RBC, Rule Based Control), to have maximum exploitation of the renewable source (through the PV panels), and using the H2 only when strictly needed as it is the most expensive resource available on site. Assumptions can thus be synthesized as follows:
• order of priority: PV->Batteries->H2
• only component losses have been considered
• batteries are charged by PV panels
• no transient phenomena have been taken into account
• minimum power requirements for electrolysers has been assumed equal to 25% of rated power
Further simulation outputs have been calculated to evaluate system performances as functions of:
• number of H2 refills
• minimum autonomy [days]
• maximum autonomy [months]
• number of FC working hours
The number of FC starts and stops per day has also been evaluated to understand the system behavior under variable and average weather conditions.
A sensitivity analysis has been performed to evaluate the impact of the battery pack sizing and the site location on the system performances.
Effect of battery sizing: the first set of simulations has been performed to understand the impact of battery sizing on system performance, by also varying location (northern, central and southern Italy). The baseline 5kWp have been selected to that aim. From the simulations, it was evident that beyond 320Ah a saturation behavior is presented by increasing the battery pack size, in terms of all the reported parameters. Saturation is more evident for northern sites, where the lower energy from radiation reduces the benefits of larger battery size. Same trends have been obtained with both the technology under test: Dantherm and MES in the system configuration without electrolyzer. Results obtained with the electrolyzer, by keeping the 5kWp PV panel, clearly indicate a negligible advantage in terms of efficiency, that is due to the minimum benefit given by the extra power available during the summer that is counter-balanced by the power requirement of the electrolyzer. A larger size (e.g. 10 kWp) is thus required to have an advantage with the electrolyzer system configuration.
Effect of PV panel sizing: simulation results, clearly indicate that the saturation effect observed for the 5 kWp panel, is less evident for larger PV sizing, especially for southern Italy sites, where a more favorable matching can be obtained between the energy required by the RBS load and the PV panel power production.
Effect of RBS load average power: the effect of RBS load power has also been studied by keeping the PV panel size equal to 5 kWp. A more evident saturation can be observed due to the mismatch between the energy available from radiation and energy required from the load. This effect causes a much higher number of FC working hours, and then a RBS efficiency much closer to the FC efficiency, that in turn significantly affects the number of H2 refills per year.
Effect of variable weather: finally the effect of variable weather has been observed over the year, to have an idea about the impact on the number of starts/stops per day, that is increased especially during the winter/fall. A highlight of the worst week can be observed in the figure (April/May), where it is evident that under repeated fall/spring cloudy days the FC may be turned on repeatedly during the day. This requires a deeper analysis of control system strategy under similar circumstances. FC turn on during summer repeated cloudy days may be partially mitigated by increasing the battery size pack: this is one of the reasons why a 640 Ah battery capacity has been finally selected.
The conclusions of the simulation activities can be summarized as follows:
• 640 Ah battery package is enough to optimize system efficiency (larger sizing does not provide further advantage), also giving some advantages under real weather conditions.
• 5 kWp PV power is not enough to assure the self-sustainability of the configured system (H2 produced by the electrolyser). 10 kWp PV are instead enough to produce some extra power during highly sunned days in summer time, to be provided to the electrolyser.
• Number of refills can vary from about 1 per month in Southern Italy to up to 2 per month in Northern Italy (minimum autonomy in the range 10-15 days) with 5 kWp PV
• FC working hours, affecting the FC lifetime, is in the range of 2000-4000h/year.
• Increasing the power consumption from 1 kW to 2 kW the system efficiency drops about 15 percentage points, number of refills dramatically increase 4-5 times and minimum autonomy drops to 4-5 days. Also number of FC working hours is more than doubled. Such results shows that 2 kW power consumption can hardly be handled with 5 kWp PV
Following the conclusions of the simulation activities, the system architecture initial proposal was modified to integrate the hydrogen production and storage components with the RES system: in the initial phase of the project two photovoltaic strings of the same power were included in the system and supposed to work independently.
During normal daytime operation and with a suitable solar radiation, the first string, connected to the Energy Box (EB) was only dedicated to fulfill the power needs of the Radio Base Station. The other, instead connected to a MPPT Battery Charger (BC), was dedicated, to charge the batteries and to compensate an eventual lack of the energy coming from the photovoltaic system. At night as the discharge of the batteries up to a default value was expected, the system had to properly manage the energy contribution of the fuel cells (FC). With the aim to isolate the batteries bank and the related Battery Charger while the FC was running, the scheme had to be complicated by the introduction of a series of switches.
In order to make the system more compliant to the project objectives and to the telecom requirements, additional design efforts were needed to achieve improvements on efficiency and robustness. A reduction of potential sources of energy inefficiency and on the other side a reduction of potential sources of instability as redundant component and switches has led to a simplification of system design which is based on a unique photovoltaic system directly connected to the Energy Box. For this component an upgrade in hardware and firmware was required increasing the power output apparatus to 5Kw, implementing the functionality of Battery Charger and finally introducing the functionality of the 'BUS iDC (Intelligent DC BUS).
These changes allowed us to connect in parallel all the sources of energy, getting all the energy coming from the PV constantly available and injected in the system. As second step, a specific priority was assigned to each energy sources, in order PV, batteries and finally FC, which was activated only if, in a low solar radiation condition, the batteries reach a specific level of discharge.
All the energy fluxes have been managed by the output voltage of the individual components connected in the bus (iDC-BUS) and following a specific algorithm implemented in the control unit. The idea, confirmed by the first lab test, was to let the load to use any of the Watts produced by RES, keeping all the other sources ready to compensate in case of need. This allowed us to get the maximum benefit of the use of the FC so improving the overall TCO of the system.
The energy management of the system was modified to introduce the electrolyzer. The hydrogen storage was divided in primary (produced locally) and secondary (manually refilled) and the control algorithm changed according to the electrolyzer characteristics. Being connected in parallel with the other components in the iDC-BUS, a specific algorithm has been implemented to determine accurately and timely the proper amount of production of hydrogen considering the available RES energy, without compromising the system stability and energy priorities. This is done by analyzing the measurements of: the voltage-current values to the batteries, the solar irradiation, the temperature of the photovoltaic panel and also the battery charge.
Natural Gas was also supposed to a test fuel for the FCpoweredRBS project. Unfortunately this technology was not considered mature from Telecom operators and has been withdrawn from the test plan.
The overall system management is controlled by the Control Board where all the algorithms have been implemented as well as all the data collected from the probes and the single elements connected. Three points of measurements (voltage and current) have been identified: current OUT of PV-BC & iDC-CS, current OUT and IN of battery bank and current OUT of Fuel Cells.
As already commented, the algorithm will give higher priority to the photovoltaic source and it is based on two main principles depending if the amount of renewable energy exceeds or not the power need of the load.
In the first case, the solar irradiation is enough to power the DC load, the PV-BC & iDC-CS will first inject energy to charge the batteries. If still additional energy will be available, the CB activates the Electrolyzer to the maximum level of H2 production possible.
However, when the photovoltaic energy is not enough for the load, the batteries will complete the energy supply. When the 50% of DoD is reached, the algorithm will activate the FC to provide the energy towards the load and minimize the charging of the batteries in this solar condition. First the H2 produced by the Electrolyzer at low pressure supplies the FC until it is available. Second the higher pressure backup H2 storage will provide the FC with the needed fuel.
The system peculiarity is that the injection of the energy from the different sources in the iDC-Bus is made only by changing the DC voltage level always giving the highest priority to the photovoltaic. The aim is to not use the H2 to charge the batteries but let the renewable energy to do that.
Additional improvements have been defined based on the results of the field testing. Beside the ordinary maintenance activity focused on giving continuity of the running systems, additional optimization activities have been implemented to catch, analyse inefficiencies, and correct the system behaviour by customizing the algorithm or modifying working parameters. In general, the tests confirmed that the intelligent algorithm implemented to handle the power coming from the different energy sources was properly designed to match the best system efficiency and the lowest TCO.
Important feedbacks from field data were:
- A critical issue is that the AGM batteries, implemented in the project, lose their effectiveness in a short time with 50% DoD, unless we set DoD at low values (below 40%). For this reason we might use a different storage technology (Lithium batteries), which nevertheless implies higher expenses.
- Regarding the FC Methanol (Idatech), its average power consumption in stand-by is very high (over 300 Watt with peak up to 700 Watt) due to the presence of the reformer, this explains how Fuel Cell has a low efficiency if the DC load is below 1000 Watt. Moreover, the FC Methanol shuts down when the power supply is below 300 Watt. Due to their high consumption in stand-by mode, the Methanol FC are not that efficient to be used in back-up environment, as in the tested radio site one; similarly, they’re best suited to be used with loads higher than 1400W, where they’re providing a higher efficiency; no tuning may be performed to improve the above intrinsic Methanol behaviors
Regarding the FC H2 (Dantherm), its power consumption in stand-by is around 50 Watt. In the case, where FC H2 might be requested to supply power below 100 Watt over a long period of time (over 1 hour) , the FC has shown to be vulnerable to faults that can also cause the stop of the FC. In order to solve the issue, on Dantherm recommendation, it has been configured a switch-off of the FC after a period of 30 minutes characterized by a continuous power supply below 100 Watt. When it has been integrated in the whole Hybrid System together with PV panel and Batteries Package. However, during the period of experimental activities in all the sites involved in the trial, the Hybrid System has shown acceptable reliability of its firmware and control logic.
- For DC load up to 1000 Watt, the experimentation has shown that the capacity of the Battery Package (640 Ah) and Photovoltaic System have been properly dimensioned. On the contrary, in the cases where the DC load is significantly high (over 1200 Watt), the experimentation has highlighted how the Fuel Cell H2 usually turns on at night, since a significant part of the energy produced by the Photovoltaic System during the day cannot be stored due to the limited capacity of the Battery Package (640Ah). This fact suggests increasing the capacity of the Battery Package and Photovoltaic System when the DC load is over 1200 Watt.
- The maximum efficiency of the Hybrid System (based on either FC Methanol or H2) can be achieved when the FC will be able to supply also low amount of power to the load (0-300 Watt) for extended periods (over six hours). Only in this way, the System can really benefit from the single contribution of all energy sources (PV, Batteries, and FC).
- The Methanol fuel cells have showed a better maturity, specifically in the electronic part that shall be further improved in the H2 fuel cells to provide the reliability required for the implementation in the telecommunication operator’s environment, where a high reliability is a must to be pursued.
Another key objective achieved by the project was the development of the test protocols for each system application to be valid as a benchmark protocol concerning basic requirements of the customers (end user), possible extreme values anticipated for normal system operation and possible risks.
The main purpose of these test protocols is to confirm that the FCpoweredRBS systems were capable to reach their objective that is to accurately estimate by testing and evaluation of the test results obtained in the laboratory tests conducted by UNIROMA2 and JRC during the first about 18 months of the project duration (laboratory trial tests) and, to confirm these results during the field tests.
- Regarding the durability, the trial has shown that both the configurations of Hybrid System based on FC H2 and FC ME have worked properly for a period of about 10.000 hours in the sites of Fiano Romano (based on FC H2) and Sonnino (based on FC ME); field tests have shown an acceptable level of stability without any major fault or decrease of performance.
For the laboratory test the main goal were:
• Test the system under operating conditions that are representative of real operation on site
• test all the devices that compose the system for good operation and effectiveness from the standpoint of system control issues and stable behavior
• evaluate the efficiency of the system under a pre-defined test protocol for the sake of comparison with similar systems at equal design parameters (for example Isize and others as commented above).
• obtain a TCO (total cost of owenership) value of the system combining laboratory and field test results
For the field tests additional main goals, if compared with the benchmark ones, were:
• Obtain realistic system start-ups and shut-downs and real environmental conditions (for example temperature, humidity, etc).
• Coupling the HRES to a real RBS load including the recoding of delivered PV power and of stored energy through the use of batteries and of the hydrogen produced by water electrolysis.
• Check the system reliability by recording any failure in particular out of the DC (direct current) bus voltage optimal range during testing
As far as the benchmark test protocol is concerned, the system control strategy has been implemented by input/output power profiles and SOC (state of charge) via dependence on latitude of PV power production, dependence on seasons and weather and RBS load requirements. The latitude considered for employing PV and FC powered RBS systems in Europe was chosen as 47° North by bi-normal distribution calculation radiation frequency versus latitude .In making this calculation idealised (smoothed) summer and winter radiation profiles were used based on averaged data recorded at the said latitude. Characteristic of seasons especially for spring and fall are oscillations in the radiation profiles at a time-scale of about one hour constituting the envelope of profiles considered at high radiation (summer) and low radiation (winter). The benchmark profile should test the system according to seasonal variations to have realistic data over longer periods, typically a whole year. Also, this profile should be representative of a whole year's operation for the PV component. First an equinox day duration (which is average over the year) is identified, and elaborated considering three options to account for different weather:
• High radiation day (in the summer), full radiation for the chosen latitude, representing a typical summer day.
• Fully cloudy day, radiation equal to 10% of a high radiation day, representing a typical winter day.
• Variable weather day, with a radiation profile regularly oscillating between good and bad weather conditions, representing typical spring and fall days alike
The benchmark radiation profile for the tests comprises a consecutive period of 72 hours, starting with the profile of the winter day at 6 am, that is a condition for sure characterized by zero SOC in the real field. The test start condition is that the batteries shall be at minimum SOC not to influence the evaluation of system performance.
This PV power profile derived from the radiation profiles depends on the efficiency of the PV panels (that takes into account the panels' orientation and tilt towards the sun), the solar radiation measured by the weather station and on the surface area of the panels
A constant RBS load being an average DC consumption was assumed as power demand (Pload) for the test. The DC loads are 1 kW for the Dantherm system, and 900 W for the MES system due to different nominal operating conditions. In both the cases the power is within the usual range of real world RBS applications, nevertheless.
The laboratory tests to be conducted on the systems are performance characterization tests, including Input and output test parameter, Performance characterization test and test procedure.
The three days of testing - Day 1 to Day 3 in the benchmark characterization test have been conducted consecutively.
Data analysis from on field demonstration tests
The FCpoweredRBS project aimed at proving the effectiveness of H2 and FC technology as main programmable power supply technology to feed off-grid RBS using Hybrid Renewable Energy Systems (HRES) configurations.
Different off-grid generation systems, including fuel cells and electrolyzers provided by different companies, have been demonstrated on a real scale test. Systems were provided by Dantherm Power (H2 fuel cells) and GreenHydrogen.DK (electrolyzer). Methanol was also tested as another potential fuel for FC using Ballard fuel cell systems.
Thirteen RBSs have been tested for a significant period (1 year) using HRES optimized systems. The results of this experimental test have been analyzed, dealing with the effects due to the use of real equipment, real radiation profile and real control system on the performance of the HRES and representing a complete demonstration test for the proposed technology.
The systems have been first tested in the laboratories both at the University of Rome Tor Vergata and at the JRC laboratories in Petten to define the benchmark performance. The HRES systems, mainly with two different design solutions (with and without electrolyzer), have been deployed in several locations in Italy (mainly in Lazio), powering telecom RBSs owned by Italian operators (TIM and H3G).
The systems have been characterized by the following characteristics/specifications of the sub-systems and include in general:
• A 2.5–5.5 kWp power output PV system based on the HareonSolar HR-200W module, having a STC efficiency equal to 15.7%.
• A 640 Ah at 48 V electrochemical storage system characterized
by 16 lead-acid Marathon M12V155FT batteries each providing 160A at h12 VDC.
• A rack mountable Fuel Cell based power system, composed by 3 Dantherm DBX 2000 hydrogen fueled PEM Fuel Cells with power output up to 3X1.7 kW at 47–57 VDC.
• A 2.5 kW Ballard methanol fueled PEM Fuel Cell system (in two sites) used in place of the hydrogen fueled system described above.
• A 5 kW alcalyne Green Hydrogen electrolyzer (in one site) composed by two 2.5 kW stacks. The electrolyzer operates with 48 VDC input, 30 bar compressed air and purified water input.
The solutions have been deployed by integrating the PV canopy, additional shelters for H2 or Methanol storage, and external cabinets for fuel cells, batteries and, where necessary, the electrolyzer cabinet.
The sites have been fully equipped with sensors and remote data gathering has been implemented with an acquisition data remote system. The controls on the functionality of the system as well as the fault management of the plant are operated by a Logic Control System Unit. All the measurements (from PV system, DC bus and single equipment) are collected and processed: a customized SW platform allows data post-processing in order to elaborate graphs and consolidated reports.
Moreover, the SW application provides in real time the details of power and consumption of any element and in addition gives the opportunity to start/stop and regulate the different components for tuning activities. Several levels of access permission are defined in order to have differentiated account for Operators (read-only), Front Office Operation&Maintenance people and upper levels of support (Ericsson and partners).
The main measured and stored parameters during the normal FCpoweredRBS operation are: current at all the different nodes of interest (PV output, battery connection, FC output, load), H2 bottle pressure and temperature.
The results described refer here mainly to six sites installed in Lazio (central Italy), among the total number of n.13 installed for the deployment phase of the project: Baschi(#1),Fiano Romano(#2),Colle Turchina(#3), Sasso(#4), Campoleone(#5), Sonnino(#6). Complete data have been collected for all the sites under test. The 6 sites have been considered the most significant from the statistic standpoint and enough to be representative of the different systems from the point of view of design parameters.
For the six sites analyzed, data are available over the whole 2015 (January to December), mainly in terms of energy consumed at the load, produced by the PV and the FC system and stored in the battery system if necessary. The energy consumptions of the six sites are the sum of the energy output of the PV system and the part provided by the Fuel cell.
As the power consumption at each site is rather different (higher for site #1–2 and lower for sites #3–6), H2 consumptions have been very different for the sites. It is thus useful to take into account the non-dimensional design parameter ISIZE (ISIZE=ELoad/ERES): this parameter is on average equal to about 0.15 (typical value of PV system efficiency) and describes, as said above, the ratio between the energy consumed at the load and available from radiation. The higher ISIZE the larger is the dependence of the given HRES design on external fossil sources (H2 in this case). The analysis of sites #1 and #2 (load about 1,3 kW) confirms that for these installations the use of the fuel cell during the colder months cannot be avoided. A significant dependence on programmable power sources may be also observed in the case of sites characterized by a rather low ISIZE value, even lower than a typical PV system efficiency (sites #5 and 6). In this case, however, the dependence is due to the lack of long term storage systems, which would be capable of shifting the extra power produced during the summer periods toward the winter periods. The use of the electrolyzer is a possible solution for seasonal storage. Nevertheless, losses included in the conversion chain for H2 production with the electrolyzer and its subsequent utilization in the fuel cell may require extra sizing of the PV system.
An in-depth analysis of the results obtained led to the following main conclusions:
• operation of the systems was demonstrated for six sites during a full year period (Jan-Dec 2015), proving that this solution is technologically mature to be compared with the current standard solution for off-grid RBS based on Diesel-genset;
• the design parameter ISIZE=ELoad/ERES is on average roughly equal to 0.15 for all the sites; however the performances of different systems (for example system efficiency ƞSYS) should be compared only at equal ISIZE. Thus, among sites characterized by greater ISIZE (#1 and #2), system #1 performs better as it has the same requirement of fossil sources EFES/ERES with a greater ISIZE than site #2. Among the sites with lowest values of ISIZE (#3–6), #4 performs better as it has the lowest overall consumption of fossil sources EFES/ERES;
• By comparing the fossil source requirements of all the sites with the same parameter calculated theoretically for Diesel genset based systems, it can be stated that the fuel cell based systems allow for obtaining noteworthy fuel savings during the year. Sites #1–2, for the more frequent use of programmable sources during the year, evidently show the higher difference between (EFES/ERES)FC-based and (EFES/ERES )Diesel-based and thus the greatest fuel saving potential;
• the behavior of current output and requirement of all the sub- systems over time during three representative days (worst average and good weather days respectively during the month) has been shown for the six sites during the month of September 2015. It is worth noting that the use of the fuel cell during the day may be useful especially during bad weather or in the case of systems characterized by high ISIZE. The satisfactory behavior of the control systems has been demonstrated, as the fuel cell is capable of fast providing current to the load or to the batteries (depending on the batteries state of charge) during sudden cloud shading events with no major issues.
To summarize, the results of on field tests show that the hybrid renewable energy solution may be competitive with the current standard solution based on Diesel generator in terms of energy efficiency and minimum consumption of fossil fuel. Proper sizing and control strategy optimization are key-factors to this aim. Moreover, despite the integration of FC with many different components, tests have shown an acceptable level of stability and reliability of the hybrid solution.
LCA analysis and TCO study
A full lifecycle analysis (LCA) of the fuel cell systems being operated as UPS or backup power sources has been carried out.
Life Cycle Analysis allows to assess the environmental impact of Hybrid Power System assemblies and their usage. The main results of the analysis can be summarized as follows:
• FC based HRESs are an environmentally friendly solution, especially in terms of use as the consumption of fuel primary sources that is much lesser, especially by taking advantage of the production of hydrogen on-site with the electrolyzer.
• According to a Total Cost of Ownership criteria, the hybrid system is very competitive: infact TCO are same of a Diesel genset after 2.5 years for the system without electrolyzer, while by adding the electrolyzer that period is increased by additional 2 years.
• Efforts should be done to reduce purchase cost: increasing manufacturing
efficiency by reducing the quantity of precious metals in FC stack, optimizing stack design and improving production process performance.
In detail, regarding TCO analysis, a specific tool has been developed in order to compare the different hybrid systems with the typical solution based on the use of diesel genset.
To define a proper commercial proposition for the hybrid FC-PV solutions for off-grid radio sites or sites of fixed networks in telecommunication sector, it is pivotal to take into account that the objective of fixed/mobile operators is usually to have a Return of Investment (RoI) of three years or less. It means that a proposal of hybrid energy system can be attractive for the operators only in case the hybrid FC-PV system has a breakeven time Vs diesel generator solution of maximum three years.
The lifetime of the main components of each solution (for instance the degradation of the stacks or of the batteries) and the related replacement have been considered to calculate the TCO as well as other input data necessarily related to the specific site of the trial and to the operational costs; some of these data (such as type of hybrid system installed, average load, number of H2 cylinders, energy produced by fuel cell, runtime of fuel cell, fuel consumption, etc.) may vary from site to site.
The Total Cost of Ownership analysis over 10 years upfront investments and operational costs is aimed to benchmark economically the FC hybrid systems vs off-grid radio sites today solution (i.e. turn-key service including diesel genset rental and refueling service). In the calculation, an annual inflation has been assumed at 2%.
All the costs related to battery replacement, operation & maintenance (parts and labor), stack replacement, annual H2 Cylinder rental fee, H2 or methanol delivery &connection fees, have been taken into account on yearly basis.
A diesel genset is usually the preferred solution to power telecommunication equipment and cooling system. For a typical BTS site with a load requirement in the range of 2 kW, a standard size 10 kW is typically chosen for reliability reasons. The turnkey service includes the rental of the diesel generator, fuel costs and logistics. Refueling is typically required every 250 hours.
The turnkey service, including the genset, the refueling and maintenance , is the most convenient solution from the economic point of view, especially if compared to the expensive purchase of the diesel genset and the additional operating costs for diesel consumption, refueling activities along with the expensive maintenance of rotating elements.
Systems analysed in the TCO are the following:
Type A1
• 3 Fuel Cells @ 1.7 kW “Dantherm”
• H2 stored in 200 bar pressure tanks
• Energy Box
• 5 kW PV Panels
Type A2
• 2 Fuel Cells @ 2.5 or 5 kW “IdaTechElectraGen™”, operating with H2
produced by a steam reforming system of c (named “HydroPlus”), stored in a specific tank allocated under the fuel cell box for a capacity of 225 lt.
• Energy Box
• 5 kW PV Panels
Type C1
• 3 Fuel Cells @ 1.7 kW “Dantherm”,
• H2 stored in 200 bar pressure tanks,
• “Green Hydrogen Electrolyser” to produce H2 locally stored in a 30 bar pressure buffer tank,
• Energy Box,
• 5 kW PV Panels.
The economic analysis, carried out using the Total Cost of Ownership criteria, have been done for three system types: H2 fuel cell based (A1), methanol fuel cell based (A2) and H2 fuel cell with electrolyzer based (C1).
All the different costs have been detailed, with a description of the main assumptions. A comparison of the cumulative TCO over 10 years operation, tells that the despite the greater investment at the beginning, the baseline (A1) system has equal costs of the Diesel genset after 2.5 years. This period meets the current expectations of the mobile operators market. When comparing the Methanol fed system (A2) with the baseline and the Diesel genset, it presents slightly greater costs than the H2 one); however it still gives similar advantages if compared to the Diesel genset (breakeven time of hybrid system based on FC ME Vs Diesel genset after 3.5 years).
A sensitivity analysis has also been done decreasing by 30% H2 costs (system A1) and doubling the methanol tank volume at 450 lt (system A2).
Similar effects have been observed on costs, with a reduction of the equal costs time down to around 2 years for system A1 (FC H2) and 3 years for system A2 (FC ME). Finally, the system with the electrolyzer has been studied, under the assumption of additional tanks for low pressure storage of H2, as the electrolyzer is theoretically capable of producing up to 21 kg H2 at 30 bar per year.
Since the costs of the system are higher due to the electrolyzer, the time of equal costs Vs Diesel genset is higher or equal to 4.5 years.
Life Cycle Analysis (LCA) of Fuel Cell powered Radio Base systems has been done to assess their environmental impact and usage.
Systems are characterized mainly by a fuel cell subsystem, a PV subsystem, a battery subsystem and an electrolyzer subsystem. The results obtained for the fuel cell system, show that the manufacturing of both Balance of Plant and Stack are very important with that regard. Within the Stack assembly, attention must be given to improve the efficiency of the production processes and raw material utilization for Bipolar Plates. The MEA (Membrane Electrode Assembly) has a great impact, mostly for the electrodes and gasket contribution, with a heavier role of the cathode that contains a greater amount of PGM (Platinum Group Metals).
For the PV subsystem, the most important contribution is given by the Si cells, inverter and conduits. The electrolyzer subsystem presents a completely different scenario from the Fuel Cell, mostly due to the use of Nickel as catalyst in place of PGM; thus the BOP (Balance of Plant) has the greater impact. For the battery subsystem, steel and electronic material exhibit the greater environmental impact for the system, while leadis by far the component most affecting the impact considering the analysis of the battery pack only.
Four system designs (scenarios) have been compared, characterized by different power ratios of the subsystems, as they were used in different telecom stations. The baseline (Baschi2) has been thus compared with a smaller system for the limited load requested (Campoleone), with a methanol fueled system characterized by the presence of a reformer (Sonnino), and with a system with an electrolyzer (Rome). It is noteworthy in the comparison that the methanol fuel cell system has slightly lesser impact due to the use of methanol tank in place of hydrogen bottles.
The system with electrolyzer has the greatest impact, also due to a greater power size PV subsystem. The comparison from the energy standpoint, tells that the system with the electrolyzer is the best one, while the worst performances are presented by the methanol fed system as energy consumption is affected by the energy required to sustain the operating temperature of the methanol reformer.
Uncertainty analysis has been carried out on the Pt content, with no major impact on life-cycle, and similar results have been obtained for Nafion usage. The impact of MEA manufacturing process has been also studied for the different scenarios, and it has been observed especially important toward the ozone layer depletion, photochemical oxidation and acidification.
The comparison with the Diesel genset, that is the mainstream technology to power off-grid RBS, showed a greater impact of the fuel cell based systems as far as the assemblies are concerned, and especially for systems with the electrolyzer. The difference is somehow mitigated by taking also into account, along with the assemblies, the use phases. The evaluation of use-phase alone, tells that the system with the electrolyzer has the lowest life cycle impact, as it has the lowest consumption of fuel resources and consumable materials; with this regard, the Diesel genset is quite remarkably penalized.
Potential Impact:
Potential impact
The integration of renewable energy sources such as Photovoltaic (PV) with electric batteries and hydrogen in a Hybrid Renewable Energy Systems (HRES) represents an effective energy generation solution for remote off-grid Radio Base Stations (RBS).
In fact, the experimental activities, performed in the labs and in the field as part of the FCpoweredRBS project, have shown that the HRES based on the usage of hydrogen storage and fuel cells together with a PV system and electrochemical batteries, are very attractive thanks to the following key-factors.
1) they may operate unattended for longer periods due to a high conversion efficiency (i.e. low fuel consumption);
2) they are characterized by cheap maintenance costs unlike conventional technologies, especially with respect to diesel-genset based technologies;
3) they are low noise and environmentally friendly since they may satisfy the RBS energy requirement with very low CO2 emissions, in line with existing and future greenhouse emission limits unlike diesel-gensets
4) they are characterized by better scalability than diesel-gensets; in fact, fuel cells can easily be designed to match the given power requirement and thereby ensure high efficiency even at low power requirements; in the off-grid power-type applications the power requirements are often low (P< 3 kWatt) and the diesel-genset suffers from low efficiency with consequent high fuel costs, whereas the fuel cells can be operated at its best performance
5) the analysis of the Total Cost of Ownership (TCO) over 10 years has shown that HRES based on fuel cells and H2 are more convenient if compared to diesel-genset based solutions; TCO analysis, based on data collected from the on-field experimental activities, considers all the mentioned costs over time, both through direct and indirect costs over the entire life-cycle of the given system (cost of fuel included); therefore TCO takes into account all the costs related to purchase and installation, operation and maintenance of the system.
The TCO analysis has shown that the hybrid system based on H2 fuel cells compared to the diesel genset has a breakeven time approximately of 2.5 years in case the genset is provided in a turn-key service (including rental of diesel genset and services of refueling and maintenance) and approximately less than 2 years in case of purchase of diesel genset with additional costs for diesel refueling and maintenance activities.
Moreover, the TCO analysis over 10 years has highlighted a significant increase of savings in comparison to diesel genset solution after the breakeven time.
In fact, after 10 years, the total cost of ownership of the hybrid system based on H2 fuel cells is lower than about 60% of diesel genset solution.
The research activities have shown slightly worse results in case of hybrid system based on fuel cells with methanol where the break-even is slightly greater than 3 years and in case of hybrid system based on fuel cells with H2 produced locally through an electrolyser where break-even against a genset based solution is of about 5 years, due to the high costs of the electrolyser.
Thanks to the above-mentioned key-factors, HRES using fuel cell technology and H2 together with electric energy storage may easily become an attractive and feasible alternative solution to guarantee reliable, efficient and clean energy production to remote RBS, if compared to the diesel-genset.
Telecom specifications on energy production quality are very demanding (24 h / 7 days’ continuous supply, high availability, long autonomy without attendance) and under these conditions HRES integrating electrochemical energy storage with local hydrogen production and storage represent an effective solution if compared to battery or hydrogen only systems. In fact, the integrated use of the electrochemical batteries for short term storage and hydrogen locally produced by electrolysis for medium term and potentially seasonal storage, allows for a more effective utilization of local renewable energy sources, not excessively penalizing the batteries life cycle.
The potential worldwide market of these HRES is very interesting in the telecommunication arena.
In fact A research study by the GSM Association (GSMA) indicates that future mobile subscriber growth, with related new RBS sites deployment, will be focused especially in the developing countries in Africa and Asia.
The major driver of the estimated growth in off-grid and bad-grid (or unreliable grid) RBS towers is the expected expansion of mobile networks into rural regions in Africa and Asia, large parts of which face limited availability of reliable electric grids.
Over the past ten years there has been a tremendous growth in the green power for mobile telecommunication networks and most of the green power solutions are solar or wind-powered. Despite this, the deployment of green power solutions is still relatively marginal, as it is estimated to be lesser then 10% on a worldwide basis. It is important thus to take into consideration that in some developing countries, where the cost of oil is low, the mainstream solution based on the diesel genset may still be very competitive in terms of TCO.
Today (as of 2017) the off-grid and bad-grid sites are globally about 1.1 million and more than 90% of these are powered though diesel genset. The off-grid and bad-grid sites worldwide are estimated to reach a total number of approximately 1.2 million by 2020, with about 400.000 off-grid sites and 800.000 bad-grid sites. In powering off-grid and bad-grid RBSs towers, environmental and social sustainability are becoming a key factor, in addition to economic aspects. Hence, energy systems using renewables coupled with sustainable energy storage solutions (e.g. Photovoltaic (PV) & wind, PV & diesel genset & battery, PV& wind & diesel, and PV & fuel cell systems) are going to receive more attention than before. The above figures, as well as the new attitude that would hopefully be taken into consideration, may provide an interesting potential market for HRES in mobile telecommunication networks, such the ones tested in our FCpoweredRBS project based on PV panels and FCs.
The operating phase of the Project has been very valuable for identifying some non-technical barriers to a massive deployment of the new technology, based on power generation systems using fuel cell technology and H2.
On the basis of the results obtained and issues met during the Project, the main non-technical obstacles may be summarized based on the following main areas. It is worth highlighting that such issues mainly refer to the Italian country, and thus cannot be easily applicable to other European countries exactly as they are listed:
1. Legal and permitting constraints related to H2 usage/storage may not provide a safe predictability of the success of the project
2. Natural barriers for the installation of the whole system (e.g. lack of space, not proper solar radiation, ...)
3. High risk perception about the usage of H2 as fuel, due to the poor knowledge of the H2 properties and behaviors
4. Limited or absence of Government incentives and promotional support
Regarding legal and permitting constraints related to H2 usage/storage we shall highlight that it usually takes long time and low predictability to obtain permit/building authorizations from local administrations for fuel cell and H2 storage implementation.
The Fire Prevention Certificate certifies compliance with the existing legal requirements, as well as the presence of the necessary fire safety requirements within the structure certified. There are three stages in the procedure to obtain the Fire Prevention Certificate that take usually several months (over 4 months): approval by the Provincial Fire Department of a fire prevention project for the company prepared by qualified experts; inspection by the Fire Department to verify the correct implementation of the approved project at the company premises; if the result is positive then the Provincial Fire Department will issue the Fire Prevention Certificate.
In order to speed up the operative process and avoid to request the authorization to the Provincial Fire Department, for the deployment of the FCpoweredRBS Project a decision has been made to stay within the legal limits related to the values of maximum geometric capacity for gas and liquid methanol tanks. In fact, according to the local law (Italian Legislative Decree n° 151/2001), it is not necessary the Fire Prevention Certificate in case of:
geometric capacity hydrogen tanks < 0.75 m³
geometric capacity methanol tanks < 0.3 m³
Moreover, according to the Italian regulation about risk evaluation (art. 293 of Italian Legislative Decree n° 81/2008), which derives from European occupational health and safety normative, an evaluation of explosion risk, named ATEX, must be taken into consideration. Risk evaluation has to be conducted by portioning the potential ATEX area into zones, based on the frequency and duration of the presence of flammable gases. The areas where explosive atmosphere may form are identified and protective measures are applied, besides providing an adequate warning for the danger zones.
It is evident that tanks positioning and hydrogen system allocation should be subject to careful design activities in order to avoid formation of explosive atmosphere, avoiding the occurrence of potential sources of ignition.
Regarding natural barriers for the installation of the whole hybrid system (fuel cell, H2 Storage and PV panel), it is important to take into consideration that often the off-grid radio sites may be located in rural areas such as deep valleys, impervious slopes, top of mountains, deserts, etc..
To provide sufficient energy the installation of 5kW photovoltaic panels requires a quite large free area (at least 35/40 square meters), without obstacles that may produce shadowing effects.
Moreover, an easy access to the site is necessary in order to guarantee the recurrent H2 refueling operations, especially using H2 cylinders that may require the transportation with heavy vehicles.
Regarding high risk perception about the usage of H2 as fuel, we can highlight that the presence of hydrogen sometimes may meet the opposition of the landowner to host storage of hydrogen and of the population living nearby the site, although hydrogen is substantially safer than conventional hydrocarbon fuels (such as gasoline) in the event of any accident.
The public perception on the risks and safety of hydrogen might be long-term negatively influenced by history of hydrogen related incidents.
The high risk perception is mainly due to a lack of educated knowledge about the usage of hydrogen as fuel. This lack of knowledge sometimes implies a higher perception of risk and, therefore, oversizing the safety measures, implying additional costs or even worst, stopping the project due to the amount of excessive misinterpreted barriers.
Main dissemination activities and exploitation results
As already highlighted in the previous section, it is of pivotal importance to begin raising awareness on the positive aspects and advantages of the adoption of H2 Fuel Cells technology in telecommunication applications.
For this reason, dissemination of information has been done via a regularly updated website, as well as publications and presentations at relevant conferences and specific meetings with potential buyers such as Network Mobile Operators.
Dissemination of information and exploitation of the project results about hydrogen fuel cell technology in the reference industries is a key factor because it allows potential buyers to understand better the good results obtained as outcomes of the FCpoweredRBS project. Moreover, dissemination activities may increase the profitability of this technology and open up the market for other applications as well.
A common webpage has been developed where the results and findings in the project have been described.
Moreover, the partners have participated in international conferences to present FCPoweredRBS to a wider audience, both in and outside of the hydrogen and fuel cell community.
Conferences, workshops and seminars have been used as a dissemination channel.
The purpose of those events has been to present the project results, as well as exchange market interests, promote best practices, inform about the technologies available.
Among all the dissemination activities it’s remarkable the appreciation received by the scientific community thanks to the two main publications about the project results:
• Paper published at the International Journal of Hydrogen Energy and entitled “Fuel cell based power systems to supply power to Telecom Stations”, vol. 39, Issue 36, 2014.
• Paper published at the International Journal of Hydrogen Energy and entitled “Fuel cell based Hybrid Renewable Energy Systems for off-grid telecom stations: Data analysis from on field demonstration tests”, published on Applied Energy in Volume 192, 2017,
One blocking point for the deployment of the energy systems using renewables coupled with sustainable energy storage solutions in Europe, is the strong electrification performed over the last years.
However, thanks to the great results achieved in the FCpoweredRBS project in terms of system performance and total cost of ownership, recently Ericsson has convinced Telecom Italia customer to purchase the hybrid system based on H2 fuel cells together with photovoltaic panels and electrochemical battery package. The hybrid system is used as power system in a 3kW central office in Altavilla Milicia in Sicily. Ericsson has shown how the storage of H2 in a specific cylinders bundle, is a solution convenient in terms of total cost of ownership and makes the power generator more resilient in terms of durability.
This hybrid system, implemented in 2017, has been working properly for over 3 months and can pave the way for future implementations in sites with power consumption up to 5 kWatt.
However, a stronger awareness and systematic will of the Governments is required to finally allow this kind of solutions to evolve from the current prototype scenario into a more commercial one.
List of Websites:
web site: www.fcpoweredrbs.eu
Partners conctacts:
Ericsson Telecomunicazioni: Giancarlo Tomarchio (giancarlo.tomarchio@ericsson.com)
University of Rome Tor Vergata: Stefano Cordiner (cordiner@uniroma2.it); Vincenzo Mulone (mulone@uniroma2.it)
Dantherm: Karlsen Morten (MLK@dantherm.com)
JRC: Alberto Pilenga (Alberto.PILENGA@ec.europa.eu)
Green Hydrogen: Jørgen Jensen (jkj@greenhydrogen.dk)