How does our SOFC fuel cell work?
Our formula for sustainable power generation
In goes fuel, out comes electricity and heat. It sounds so simple, but there’s much more to the electrochemical process in a fuel cell. The energy generated is sustainable. And our solid oxide fuel cell (SOFC) can already run on fuels like natural gas and biomethane, which are converted to hydrogen in the fuel cell’s reformer. What’s important to know is that when it operates with natural gas or biomethane, carbon emissions are reduced by about two-thirds compared to power generation from coal. An example: 100 solid oxide fuel cell systems, each with an output of 10 kilowatts, achieve a total output of one megawatt. Compared to a coal-fired power plant with a one megawatt output, the SOFCs‘ carbon emissions are more than 4,000 tons less per year. What’s even more important is the fact that our SOFCs will also run on pure hydrogen in the future. The benefit of pure hydrogen as a fuel is that there are no carbon emissions – other than electricity and heat, it only produces water!
More than 85% overall efficiency
The SOFC’s output is impressive. Just when generating power, its efficiency at beginning of life is over 60 percent. When the generated heat is also put to productive use, the SOFC can even reach an overall efficiency of more than 85 percent.
What happens in the fuel cell?
To understand how natural gas, biomethane, and hydrogen are converted to electricity and heat, we need to examine the core of the fuel cell where reaction processes between cathodes and anodes (electrodes) convert chemical energy to electrical energy.
Inside the solid oxide fuel cell, the molecules of hydrogen and oxygen gas are split into their elements and then react to one another. This produces direct current (DC) that is converted to alternating current (AC) in an inverter. Heat and water are also generated. The heat can be transferred to a heating system as heat energy via an optional heat exchanger and can be used, for example, to heat the service water.
The electrochemical reaction takes place at temperatures between 500 and 700 degrees Celsius. The special thing about this method of power generation is that the production of nitrogen oxide and particulate matter is practically zero. When pure hydrogen is used as a fuel, not even carbon is generated, giving the fuel cell an edge over other power plants when it comes to sustainability.
What is the structure of the Bosch fuel cell?
The smallest element in a solid oxide fuel cell (SOFC) system is the cell itself. Several hundred cells form the fuel cell stack. Our partner for the development of fuel cell and stack technology is Ceres. What is unique about the Ceres SteelCell® is that the fuel cells are metal-supported and coated with ceramics.
The heart of the system is the SOFC stack where the electrochemical process takes place. The hotbox contains several stacks. The SOFC unit contains the hotbox, an air and gas supply system, an electronic control unit, and an exhaust system. Depending on requirements and the energy demand, multiple units can be connected to form power plants for decentralized power generation. This allows SOFC units to be scaled to create a decentralized energy supply system in the megawatt range.
The Bosch SOFC system is currently in the pilot phase. All technical specifications given are development objectives and refer to the beginning of life.