Annex 32: Solid Oxide Fuel Cells
Presented by by Jari Kiviaho, VTT Fuel Cells, Finland
Solid Oxide Cells (SOCs) are unique, flexible, and highly efficient energy converters. The underlying work principle is based on electrochemical and catalytic reactions – similar to battery technology – but with the advantage of having, the energy stored in a fuel or a gas outside the actual SOC. This separation of the energy conversion unit from the stored energy allows for cost competitive and large-scale storage and transportation of energy with minimal losses even over large distances. For SOCs, low cost materials are used and the storage capacity is only limited by the size of the storage tanks or gas pipes.
Due to the flexible operation in different modes and the usability of carbon containing gases or fuels, SOCs provide solutions to numerous energy challenges under many different local, geographic, and political conditions. They help to integrate a high degree of energy production from renewable sources such as wind and solar into energy systems, to reduce CO2 emissions, and to reduce the carbon footprint of energy production towards carbon neutral concepts.
Although the local scenarios differ in the regions and countries, the overall trend goes to more energy production from renewable sources, worldwide. Basing energy systems on those fluctuating and only to limited extend predictable sources, requires technologies for balancing, substitution, and storage – in all those segments, SOC technologies can play key roles.
Hydrogen is in a number of countries (such as France, Great Britain, Japan) considered as a major energy carrier of the future and the main solution towards decarbonizing the society and has achieved strong political attention. SOCs can produce hydrogen with unmatched high efficiencies in an electrolysis process. In addition to other electrolysis technologies, only SOCs are able to be operated in both ways, as hydrogen production unit and as electricity producer using hydrogen, in the same cell and stack. This ability provides unique balancing and storing opportunities in combination with wind or solar.
Other concepts involve electricity production through SOFCs using natural gas or biogas, where some regions and countries put a special emphasis on e.g. Netherlands, Japan, Finland, and Denmark. In that way, SOFC can bridge the transition from fossil to fossil-free energy systems. Biogas is a renewable energy source and for example produced in wastewater treatment plants or in landfill locations. Both, in Europe and Asian countries, such biogas sources are vast and not exploited currently. The composition often makes it difficult to employ conventional power production. SOFCs are able to produce electricity with high efficiencies exceeding 60%. While the use of biogas as fuel is still in the development phase, stationary units using natural gas fuel are sold on commercial basis, with a certain governmental support.
The exploitation of the SOC technology for balancing electricity production from renewable sources, to provide means of electricity storage, and to deliver fuels for the transport and chemicals to the industry has gained increasing attention worldwide. While Germany has progressed in many SOC concepts, this power-to-X has probably attracted the most focus from the political side.
European support of SOC research and development under the umbrella of the Fuel Cells and Hydrogen Joint Undertaking has contributed to the advancement of SOC technologies towards the market. The process was significantly supported from the private side with each Euro funded by HORIZON2020 being balanced by three Euro from the industry.