New process allows fuel cells to run on coal
Lately we're hearing a lot about the green energy potential of fuel cells, particularly hydrogen fuel cells. Unfortunately, although various methods of hydrogen production are being developed, it still isn't as inexpensive or easily obtainable as fossil fuels such as coal. Scientists from the Georgia Institute of Technology, however, have recently taken a step towards combining the eco-friendliness of fuel cell technology with the practicality of fossil fuels - they've created a fuel cell that runs on coal gas.
For some time now, it has been possible to operate solid oxide fuel cells using hydrocarbons. Those cells typically conk out in as little as half an hour, however, because carbon deposits have formed on their anodes in a clogging process known as "coking."
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The Georgia Tech researchers have devised a vapor-deposition technique for growing nanostructures from barium oxide nanoparticles on those anodes. By absorbing moisture, the structures start a water-based chemical reaction, that oxidizes carbon deposits as they form. Using this approach, the team have been able to run coal gas-powered fuel cells for up to 100 hours, with no signs of carbon deposits.
Unlike hydrogen fuel cells, these ones do create carbon dioxide in the course of operation. Part of that CO2 is reused, however, for gasifying the coal. The rest is in a much more pure form than that produced simply by the burning of coal in a power plant, so extensive separation and purification wouldn't be required for sequestration.
The fuel cells are also said to capture about half of the energy in the coal gas, as opposed to the third captured by burning. Propane gas has also been shown to work in the cells, offering performance similar to that of coal.
Because solid oxide fuel cells have traditionally operated best at temperatures above 850°C (1,562°F), they have had to be made from relatively expensive heat-resistant materials. When treated with barium oxide and running on coal gas, however, they can operate at temperatures as low as 750°C (1,382°F). While this still sounds pretty hot, it would reportedly allow for the use of less expensive materials, thus lowering the cost of the cells and making them more accessible. That said, the treatment could be easily applied to the anodes of traditional fuel cells, so no separate production processes or facilities would be required.
The Georgia Tech scientists are now looking into the long-term durability of the fuel cells, along with the possible effects that contaminants might have on them.
The research was recently published in the journal Nature Communications.