Fuel cells used to reduce cost of carbon capture

MIT Technology Review : Carbon-capture technology seeks to reduce power plants’ emission of CO ₂ by isolating and removing the gas from the plants’ exhaust and then storing it underground. Existing techniques double the cost of the electricity produced and reduce the plants’ efficiency by using some of the steam originally generated to drive their turbines. A new technique, developed by FuelCell Energy of Danbury, Connecticut, uses molten carbonate fuel cells to more easily isolate the carbon. As a bonus, the technique produces extra energy as well. Molten carbonate fuel cells absorb CO ₂ through one electrode, use the CO ₂ to create ions to drive a current, and then reemit the gas from the other electrode in a more concentrated form. When applied to exhaust gases that are 5% to 15% CO ₂, the fuel cells emit a mix of about 75% CO ₂ and 25% water vapor. The water vapor is easy to condense out, leaving just CO ₂ that can then be pressurized and stored. The technique has only been demonstrated in a lab, but the Department of Energy is providing funding for a larger test system to better determine how effective it could be in practice.