What we are doing
Fuel Cells are receiving considerable attention as clean, highly efficient devices for the production of both electricity and, for some applications, high-grade waste heat. A recent DTI study ‘A fuel cell vision for the UK (2003)’ predicted 5 million fuel cell vehicles and 10 GW of residential and commercial generation by 2020. However, considerable technical challenges remain for this scenario to be realised. Specifically, advances are needed in the areas of:
- Fuel cell integrity - particularly with regards to the thick-film ceramic electrolytes adopted in solid oxide fuel cells (SOFCs)
- Fuel cell durability
- Fuel cell power density
- Fuel flexibility - whether this be the ability to use renewable fuels such as bio-alcohols, or the ability to use logistic fuels such as diesel or kerosene
Furthermore, all of these issues need to be addressed in the context of the ultimate capital and operating cost of the fuel cell. This program aims to investigate and mitigate some of the key challenges facing fuel cell development.
Key Objectives
• To produce a thick-film SOFC with essentially ‘zero’ leakage or fuel and air across the electrolyte
• To significantly improve fuel cell durability by halving the present degradation rate.
• To substantially improve the power density of existing fuel cells;
i) High temperature polymer electrolyte fuel cells (HT-PEFCs) to match the performance of current low temperature PEFCs
ii) HT-SOFCs such that the performance at 750°C matches present performance at 850°C
iii) Intermediate temperature (IT)-SOFCs such that the performance at 500°C matches current performance at 550°C
• To enhance fuel flexibility to encompass both renewable and logistic fuels
• To establish a dissemination, outreach and training program in fuel cell science and engineering
Research Themes
The program is split into five work packages, four of which address key technical challenges facing fuel cell development (zero leakage, improved durability, improved performance and fuel flexibility) and one dealing with dissemination and training.
Interlacing these work packages are a number of investigation ‘themes’:
- PEFCs
- Fuels
- SOFC anodes cathodes and electrolytes
- Novel routes to powders and components
- Characterisation techniques
- Fuel cell modelling
- High temperature PEFCs
- High temperature SOFCs
- Metal supported IT-SOFCs
Future Plans
The program is in its early stages; however, a view of the scope of future work can be seen by closer inspection of each of the work packages:
Zero leakage Solid Oxide Fuel Cells - An improved understanding of electrolyte processing is necessary in order to formulate strategies for producing leak-free electrolytes. The strategy will be to study the fundamental processing steps involved in green layer deposition and sintering constrained by the substrate.
Significantly improved fuel cell durability - There are many factors which may combine to shorten the useful lifetime of a fuel cell. Stresses generated by thermal gradients, differential thermal expansion and changes in the chemistry of the materials under operating conditions can lead to fracture or delamination. Sophisticated finite element analysis techniques which couple with the flow and reaction rates are being developed to take account of stress generating and relieving mechanisms over the lifetime of the fuel cell, supported by a range of materials characterisation techniques.
Significantly improved fuel cell performance - This objective will be achieved by linking novel material and engineering developments with micro-scale modelling of electrodes. In terms of applications, there are essentially two temperature ranges for higher temperature PEFC operation:
- 110-130°C for automotive operation
- 150-200°C for automotive and stationary operation
MEAs for the two target temperature ranges are likely to be based around two different classes of membrane. For the lower temperature, these will probably be proton exchange polymers that rely on liquid H2O to assist proton conduction, while the higher temperature range will need polymers that conduct protons without liquid H2O.
The performance of SOFCs, is largely dominated by the performance of the cathode, in particular when our objective is to operate at lower temperatures.
Enhanced fuel flexibility - Fuel choice for fuel cells is a major issue. Although all fuel cells operate most effectively with hydrogen, the absence of significant volumes of truly clean hydrogen means that other fuels must be considered until the hydrogen economy is approached. Ideally, fuel cells for stationary applications should use natural gas or LPG, and those for transport and portable applications should use liquid fuels such as diesel, kerosene, methanol etc. These liquid fuels are of particular importance to the early commercialisation of fuel cells through defence, portable leisure and remote generation applications. There is also interest in operating on renewable fuels such as alcohols, or those derived from biomass and waste.
Dissemination, outreach and training - The Consortium aims to provide program partners, industry, policy and decision makers with information, advice and support to address technical issues in the development and successful exploitation of fuel cell technologies. Furthermore, the Consortium aims to provide a trained body of researchers to serve the emerging UK fuel cell industry.
Consortium Manager
Professor Nigel Brandon
Imperial College London
Contact
Dr Gregory Offer
Imperial College London
gregory.offer@imperial.ac.uk
Consortium Membership
Academic Partners
Heriot-Watt University
Imperial College London
University College London
University of Cambridge
University of Newcastle
University of St Andrews
Non-Academic Partners
Ceres Power Ltd.
Intelligent Energy
Johnson Matthey
Pictures 'Thermal Imaging Photo of Fuel Cell Pellet Cell'