The FuelCell Energy Direct FuelCell® (DFC®) is based on carbonate fuel cell technology. The fuel cell electrochemical reactions are supported by an electrolyte layer in which carbonate ions serve as the ion bridge that completes the electrical circuit. A side effect of this basic aspect of the technology is that carbon dioxide (CO2) introduced at the air electrode is converted to carbonate ions and transferred through the electrolyte layer to the fuel electrode, where it is converted back to CO2.
The result is that a DFC stack can be used as a carbon purification membrane – transferring CO2 from a dilute air stream to a more concentrated fuel exhaust stream. The concentrated CO2 can then be captured and used for industrial purposes, oil and gas extraction, or sequestered. This has the potential to solve a problem that the US Department of Energy (and other agencies around the world) has been struggling with for years, which is to develop and deploy an efficient and cost effective solution to concentrate and capture the CO2 in the exhaust of large coal or natural gas powerplants to avoid the harmful greenhouse effects caused by these emissions.
Conventional technologies that are being considered for carbon capture are expensive and have high power need, consuming a significant amount of the power output of the fossil fueled power plant they are trying to clean. FCE is developing a carbon capture system which uses DFC stacks as carbon concentration systems. Exhaust streams from fossil power or thermal systems are sent to the air intake of a DFC stack, which transfers the CO2 to the fuel stream, where it is much more concentrated and can be easily removed for sequestration or industrial use. Instead of consuming power like existing carbon capture systems, the DFC Carbon Capture system produces additional power and in an environmentally friendly manner that is virtually absent of pollutants. The production, rather than use of power, is critical to reducing the cost of the carbon capture process.
This concept has been studied analytically and in small cell tests utilizing FuelCell Energy resources and support from the U.S. Environmental Protection Agency (EPA). FCE is currently being funded by the U.S. Department of Energy to conduct detailed system cost and performance studies, as well as bench scale stack tests to demonstrate the concept. The next step is a demonstration fuel cell power plant configured for carbon capture to be located at an operating coal-fired power plant.