Is Clean Coal Finally a Reality?
Combustion is the main mechanism used to harness energy from coal. All existing coal burning processes consume oxygen to produce heat. The downside, however, is that it also produces a large amount of pollutants, such as nitrogen and sulfur oxides, which are difficult to contain and are harmful to the environment. OSU researchers found a way to harness the energy from coal through what they call Coal-Direct Chemical Looping (CDCL).
CDCL mixes tiny iron oxide beads to carry oxygen to spur the chemical reaction with coal, which is grounded into a fine powder. This mixture is then heated to high temperatures, where the materials react with each other. Carbon from the coal binds with the oxygen from the iron oxide to produce heat and almost pure carbon dioxide that rises to the top of the chamber where it is then captured. The excess heat harvested in this process produces water vapor to power steam-turbines to generate electricity. Researchers reported that each unit can produce about 25 thermal kilowatts. Pure carbon dioxide is separated and recycled, the iron beads are exposed to air inside the reactor becoming re-oxidized, allowing the beads to be re-generated almost indefinitely and the coal ash is removed and disposed of safely.
Coal-Direct Chemical Looping exceeds all the goals that the Department of Energy (DOE) has set in place for the development of clean energy from coal. Based on current tests the team at Ohio State University is confident that they will continue to exceed the requirements set by the DOE. OSU is preparing for their larger-scale pilot plant which is under construction at the U.S department of Energy's National Carbon Capture Center in Wilsonville, AL. Set to begin operations in late 2013, the plant will produce up to 250 kilowatts using CDCL.
The Department of Energy funded this research with private sector collaborating companies.
Heap of Coal image via Shutterstock