Solid Oxide Fuel Cells (SOFCs) are high temperature energy conversion devices similar to batteries which are able to convert gaseous and liquid fuels into electrical and heat energy with considerably greater efficiencies than conventional combustion devices such as boilers or engines. Unlike other types of fuel cells, they are able to run on a wide range of fuels including those which are already practical, such as natural gas, as well as renewably derived fuels such as biogas. SOFCs are therefore a highly desirable technology with the potential to reduce fuel consumption, decrease greenhouse gas emissions and enable the efficient utilisation of fuels from waste and renewable resources. While the high operating temperatures of SOFCs (600°C – 1000°C) makes them most suited to stationary applications where both electrical and heat energy are required, how will they be used in future? A handful of new SOFC systems are shown below which give an indication. More information can be accessed by clicking on the relevant picture.
Images from: (1) Bloom Energy, (2) Redox Power Systems, (3) Mitsubishi Heavy Industries, (4) Ceres power, (5) AIST.
There are a range of large scale, domestic scale, CHP (Combined Heat and Power) and CCHP (Combined Cooling, Heating and Power) SOFC systems currently available or in development. SOFC systems for large scale power generation include Bloom Energy’s 200 kW Energy Server range (1), which can each produce enough electricity to meet the ‘baseload requirements of up to 160 homes’. Smaller scale SOFC systems include the intriguing ‘dishwasher-sized’ 25 kW Cube in development by Redox Power Systems (2). The CHP potential of SOFCs has been demonstrated on a large scale by Mitsubishi Heavy Industries’ 200 kW Combined-Cycle SOFC hybrid system (3), which feeds the hot SOFC exhaust gases into a Micro Gas Turbine to cogenerate more electrical power. SOFC technology is also making its way into homes, with Ceres Power’s 1 kW Wall-Mountable Micro-CHP SOFC System (4) designed to provide heat and electrical power in place of conventional household boilers.
It is crucial these systems are designed to run on natural gas; it is highly unlikely any would be even close to commercialisation if they weren’t able to run on such a cheap and widely available fuel. In addition, a big selling point for many SOFC systems is their modular format, which allows multiple units to be combined in order to meet greater power demands. It is features such as these which have firmly established SOFCs in the stationary fuel cell market, with further growth expected through increasing residential micro-CHP and megawatt installations.
However, it may possibly be a little narrow-minded to think that SOFCs will only be used in stationary applications. The National Institute of Advanced Industrial Science and Technology in Japan have developed a portable hand-held SOFC system (5) intended to provide power to disaster areas and emergency situations. This system is able to run on liquid fuels such as LPG and has a lower operating temperature (600°C) so that it has fast start-up times, essential for portability. Such examples of new SOFC technology indicate the possibility of SOFC growth in niche portable markets.
Research Fellow and Lecturer in Materials Chemistry
Sustainable Environment Research Centre
University of South Wales