Fuel cell uses carbon dioxide to run, could clean fossil fuel emissions while creating energy

By James Maynard , May 30, 2013 07:32 PM EDT

Carbon capture technology may be able to remove carbon dioxide produced by power plants that burn fossil fuels. New molten carbonate fuel cells developed by FuelCell Energy that depend on carbon dioxide to run can capture the gas through electrochemical reactions as they produce electricity.

The carbon dioxide in emissions enter a negatively-charged electrode, and are converted into carbonate ions. These ions act as a bridge between the two electrodes in the fuel cell, allowing the flow of electricity. In the process, the carbonate atoms move to the positively-charged electrode and are converted back to carbon dioxide. This new gas, however, is concentrated, and can easily be removed for use in industrial applications or simply stored.

The devices could also be used at oil pumps, forcing carbon dioxide back into the well, which would then be capped, trapping the greenhouse gas underground. In so doing, the CO2 pumped into the well can push oil caught in fissures out of the well, making the operation more profitable.

Because the fuel cell produces electricity while storing the CO2, the energy generated could be sold by the power plant or oil rig, further lowering the cost of treating the carbon dioxide.

Traditional methods of scrubbing decrease the profit of running an energy-generating plant both through direct costs and a loss of power. Steam, that could have otherwise been used to power the turbine, is used to remove CO2 from the emissions. The process reduces electrical generation by one-third, according to industry estimates. By using that steam to create electricity and selling the energy created by the fuel cells, costs of cleaning carbon dioxide from fossil fuel emissions could plummet.

As fossil fuels grow faster than renewables for use in the production of electricity, fuel cells could be an answer to making the environmental choice the most profitable. Making fuel cells a practical solution to carbon dioxide storage has been a goal of environmental scientists for the last 20 years.

The new fuel cell system has only been tested in a laboratory setting so far, but the Department of Energy will be funding larger-scale tests. Current estimates by FuelCell Energy are that their new device would have an operating cost of between $20-30 per ton of CO2 removed. The next step is installing one of these devices in a full-size coal-burning power plant.

This may challenge the system, as the molten carbonate fuel cells work best with a cleaner emission, such as that from natural gas.

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