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Evaluating the Performance of Fuel Cells in European Energy Supply Grids

Periodic Report Summary 2 - FC-EUROGRID (Evaluating the Performance of Fuel Cells in European Energy Supply Grids)

Project Context and Objectives:
Introduction

Stationary fuel cells, other than mobile and vehicle applications that quasi ‘take their system environment with them’, operate under a variety of constraints which are defined by the energy supply grid they are integrated into and the application they serve. Generally, it will be said that stationary fuel cells offer the advantages of high efficiency operation with low emissions, low noise and modular design.
Nevertheless, a closer look at efficiency figures reveals that at the current status of technology practical efficiencies of fuel cell devices are often barely comparable with current power generating equipment. On the other hand, improvements in conventional generating plant are gradually rising to a level that some years ago was believed to be solely reserved to fuel cell systems. If we consider only emission balances and greenhouse gas (GHG) abatement, it must be acknowledged that the GHG savings from a fuel cell operated in the German grid will very much differ from those of a fuel cell producing electricity in France – simply due to the lower carbon footprint of the French electricity supply system.
An additional problem is introduced as different fuel cell types (PEFC, HT-PEFC, MCFC, SOFC) display different efficiencies in electricity production from natural gas, with the low temperature fuel cells generally operating at lower efficiencies due to the necessary gas processing whereas the high temperature fuel cells can utilise internal reforming of methane at considerably higher efficiencies. Still, the total efficiency of the low temperature variants may be higher due to the better use of exhaust heat and the latent heat in the water vapour produced.
As a result of this complex situation there is no simple means of predicting the advantages that a stationary fuel cell system would offer in any given energy supply environment. The task of setting minimum benchmark targets for projects to be awarded funding under the FCH JU scheme was therefore abandoned since there was no sensible way of setting general conditions that would apply independently to both technology and system integration across Europe.
The FC-EuroGrid project looked into the interdependencies of stationary fuel cell systems with electricity supply grids. The goal was to select and define benchmark indicators and measures that allow the assessment and comparison of fuel cells with conventional power generating technologies, but also amongst each other. Also, the project strove to identify optimal conditions under which fuel cells can offer a maximum of environmental and energy efficiency advantages.
The main objective of the project was to establish technical and economic targets and benchmarks that allow the assessment of fuel cells in stationary power generation. The fuel savings and CO2 emission reductions are a function of the electricity grid structure and the fuels employed.
Using these results it was possible to determine, whether a fuel cell installation effectively improves fuel use and improves the CO2 footprint, amongst other criteria.
From the point of view of the FCH JU, this insight can lead to a more focused allocation of research funding, identification of R&D gaps and objective comparison of fuel cell with competing technologies.


Methodology
Stationary fuel cells operate under a variety of constraints which are defined by the energy supply grid they are integrated into and the application they serve. Generally, stationary fuel cells offer the advantages of high efficiency operation with low emissions, low noise and modular design.
Nevertheless, it must be acknowledged that the GHG savings from a fuel cell operated on the German grid will very much differ from those of a fuel cell producing electricity in France – due to the difference in carbon footprint(1) of the French electricity supply system.
Different fuel cell types (PEFC, HT-PEFC, MCFC, SOFC) display different efficiencies in electricity production from natural gas.
As a result of this complex situation there is no simple means of predicting the advantages that a stationary fuel cell system would offer in any given energy supply environment. The task of setting minimum benchmark targets for projects to be awarded funding under the FCH JU scheme was therefore abandoned since there was no sensible way of setting general conditions that would apply independently of both technology and system integration across Europe.
The project will establish pertinent application categories (among them: µCHP, CHP, decentralised electricity production, etc.), establish benchmarks from the performance of competing power generating technology (in the different EU countries), identify the technical and economic targets for the key applications, and review the potential of the different fuel cell technologies to fulfil them. The goal is to collect all data necessary in evaluating the performance of stationary fuel cells in the European energy markets (predominately heat and electricity) and paving the way to objective criteria of best practice and minimum standards, as well as an appraisal of the type of applications that actually lead to reductions in gross energy consumption, emissions and depletion of fossil energy resources.

(1) The ‘carbon footprint’ denotes the figure of carbon dioxide emissions per kWh of electricity delivered to the end customer, as stated by electricity companies in their customer information. This is defined as the average specific GHG emissions of the utility’s electricity production derived from annual statistics.

Project Results:
The first phase of the project served to collect data, develop the methodology of analysis and generate some of the more involved background data. Information was collected on ’typical’ European electricity supply grids as represented by the countries Germany, Italy, France, Denmark, Finland, Poland, and UK. Data from utilities and EUROSTAT were used in the data collection into an ’Atlas of European electricity grids’. A set of ’indicators’ was established from these data, for instance in the form of CO2 emissions / kWh of electricity delivered to customers, shares of fuels used in the electricity generation system etc. Fuel cell systems were simulated in a variety of different installation environments in order to determine average efficiencies in specific operating regimes. Finally, data of competing technology was compiled in order to start establishing benchmarks and good practice criteria. This now leads to the implementation of the methodology and the establishment of assessment procedures in the second half of the project.
The second year was therefore dedicated to the (further) development of the models used to evaluate the performance of micro combined heat and power (μCHP) and distributed generation (DG) units and develop benchmarks and an analysis methodology. This process proved rather involved and took a long time to be concluded to the satisfaction of all partners. The models in WP3 had to be revised many times until they performed adequately and the different operating regimes (heat or electric load governed, or driven by economic considerations) had been evaluated and the best methodology identified. Of the three operating modes only the heat following mode proved to give transparent results that are useful for European grids with a feed-in modus.
The second year also saw the dissemination workshops run with the FCH JU and the industrial advisory committee.
Due to changes in the structure within Eon Ruhrgas, Eon New Build & Technology took over the responsibilities (’rights and obligations’) from Eon Ruhrgas as from 01 Oct 2012. At the same time the project was extended to 31 Dec 2012 to allow for the conclusion of all ongoing work. The final workshop, though, could only be organised 26 Feb. 2013, after the project had ended. The final amendment, arranging the transfer of rights and obligations from Eon Ruhrgas to Eon NBT was received in Dec. 2013.
The final presentation of the project results was delivered at the Project Review Days in Nov. 2013 in Brussels.
The findings of the project are available in the deliverables and the Executive Summary and can be used by FCH JU and the public to evaluate the environmental impact of fuel cell based μCHP and DG units.

The final results are summarised in the following section.
Potential Impact:
Results

The project used two main approaches to derive the results shown here:
- model calculations with a simulation programme for residential electricity and heat supply in different European countries
- a sensitivity analysis of various parameters defining a micro CHP (μCHP) and distributed generation (DG) unit and its operating environment

Results show that the CO2 savings for different μCHP and DG units running in heat following mode for different countries vary. Positive values, indicating savings, are achieved for countries where the carbon footprint of the (electricity) grid is high enough that a natural gas driven micro CHP unit can produce electricity with a lower carbon emission than emanating from grid electricity. This is the case for Germany, Poland, Italy and the UK. Negative values indicate additional emissions and are observed for the cases of Finland and France. It is obvious that the lower the carbon footprint of the exisiting electricity system is, the more negative the impact of the CHP unit. The best performing unit is the SOFC CHP with steam reforming. The PEFC CHP units and internal combustion engine unit have roughly the same savings in CO2 emissions, whereas the Stirling bases CHP units have a comparatively low or negative emissions balance. The latter is due to the fact that they only produce little electricity and their heat production only just compares to conventional heat; i.e. the emission reduction is very low or even more emissions generated in comparison.

The results become more clear if the total efficiency and electrical efficiency are plotted as a parameter. It is seen that the higher the electrical efficiency, the higher the emission reduction - as long as the grid CO2 footprint is high enough (essentially above that of burning natural gas, i.e. ~200 g CO2/kWh). Both electrical and total efficiency play a decisive role in establishing the emission reduction from micro CHP units.

The singular results of the simulation model were then further refined using sensitivity analysis. This method has the advantage that the tipping point between positive and negative impact can be immediately determined. The R factor is the ratio of electrical to thermal power delivered, Pel is the electrical power and the z-axis gives the CO2 reduction. Clearly, the higher the electrical efficiency (high R value), the higher the CO2 savings in grids with sufficiently high carbon footprint. The break-even plane in this case is around 200 gCO2/kWh, which is close to the emission factor of natural gas fuel. It is apparent that the electrical power rating only has a major impact at high electrical efficiency (high R value). This is based on increasing delivery to the grid substituting high carbon footprint electricity.

Outlook and Recommendations

From the results presented it is obvious that the CO2 savings that can be achieved by a residential fuel cell installation in Europe will widely vary with location and the carbon footprint of the respective grid. It can be argued that the strong integration between most European grids will not allow a discrimination of the local carbon footprint on a purely physical basis, since the electric power flow in the grid will not be traceable to a specific source. Nevertheless, grid operators have to declare their emission balances throughout the EU and it can be assumed that it is correct to allocate this balance to the point of use of the respective customer.
Having said this, it is clearly a different case of employing a distributed generation (DG) unit in a grid with a high carbon footprint (e.g. Poland, Germany, UK, Italy etc.) or one with a relatively low footprint (e.g. France, Finland etc.). This statement is based on the methodology of limiting our view to the point of use, looking into the case of a customer choosing their energy supply equipment. The statement will change, if the electricity substitution is not referenced to the average kWh replaced but the marginal kWh, or when scenaria of whole market segments being equipped with μCHP and DG units are considered. In which cases the comparison would not be made with the average grid carbon footprint but with the carbon emissions of the power generation unit that would deliver the next incremental kWh or with the footprint of the generation band competing with the μCHP/DG produced electricity.
Assuming that the market introduction phase of fuel cell based μCHP/DG units will be dominated by end user choice of equipment at least for the next ten years, this approach has been adopted throughout this project. This view was agreed with the FCh JU.
Therefore the following conclusions can be drawn:
- the main benefits of μCHP/DG units based on fuel cells compared with conventional technologies will be a reduction of primary energy use in the combined generation of electricity and provision of space heating and warm water, a reduction in overall greenhouse gas emissions (except in those countires with high share of low-carbon electricity sources), and a reduction of grid losses,
- although the reduction of greenhouse gas emissions will vary with the carbon footprint, the savings in primary energy are in general very pronounce, since the efficiency of the power supply to end customers does not vary as much across Europe as does the carbon footprint (of course, if a large share of primary energy comes from renewable resources and/or nuclear, the savings will be of little value – in this case the competition or complementarity between μCHP/DG and renewables and other low carbon electricity requires a closer analysis),
- therefore total efficiency of μCHP/DG units is essential in providing environmental benefits; this figure determines the overall primary energy savings even in grids with low carbon footprint,
- likewise the electrical efficiency is of high importance especially in the future with higher penetration of low and passive energy buildings, and should be as high as possible, although this hardly imporves the CO2 savings in grids with low carbon footprint,
- any other indicators (other emissions, indirect costs, etc.) will be directly coupled to the forementioned figures and show the same respective behaviour,
- in Northern Europe, heat following mode combined with a heat storage is the only operational mode that may lead to significant savings; trying to avoid feeding into the grid (by electricity load following) leads to sub-optimal performance with respect to emission reduction and primary energy savings; the case of coupling with cooling and air conditioning units was not inspected in this project,
- the investment cost reduction necessary in competing with today’s cost of energy provision is high but not as dramatic as often claimed; the cost of a 1 kW μCHP unit, including 10 kW backup boiler, could lie in the order of 10.000 EUR.
The following recommendations may be drawn based on the project results:
- residential fuel cell μCHP units should be developed to high standards of total energy efficiency close to 100% (LHV),
- residential fuel cell μCHP units should be developed to high standards of electrical efficiency above 55% (LHV),
- target costs for fully installed units should lie in the order of magnitude of current commercially available μCHP/DG units and can be marginally higher as the electrical efficiency increases.
List of Websites:
http://www.fc-eurogrid.eu/fc-eurogrid/EN/Home/home_node.html