Published on March 24th, 2013 | by James Ayre74
“Clean Coal” In The Near Future? Technology Reaches New Milestone
March 24th, 2013 by James Ayre
A commercially viable way to burn coal while capturing the CO2 emissions is moving closer to reality. Researchers at the American Chemical Society (ACS) recently reported the achievement of a new milestone on the path to commercial use, a successful 200-hour test on a sub-pilot scale version of the technology while using two of the most highly polluting forms of coal.
The test was recently detailed in a study published in the ACS journal Energy & Fuels.
While a clean and rapid break away from coal use within the next few years would be the ideal, it is very likely that coal will continue to be used in some capacity into the near future. So perhaps this technology has a place, potentially helping to reduce carbon emissions, and limit the speed and extent at which future climate change will occur.
The technology works by separating and collecting the carbon dioxide before it is released from the smokestacks. The research team has been working for more than 10 years on their two versions of carbon capture, dubbed Syngas Chemical Looping (SCL) and Coal-Direct Chemical Looping (CDCL). The ACS release says:
“They involve oxidizing coal, syngas or natural gas in a sealed chamber in the absence of the atmospheric oxygen involved in conventional burning. Metal compounds containing oxygen are in the chamber. They provide the oxygen for oxidation, take up coal’s energy, release it as heat in a second chamber and circulate back for another run in the first chamber.”
This new 200-hour test is, to date, the “longest continuous operation of the CDCL test system. It operated successfully for 200 hours without an involuntary shutdown. The system used sub-bituminous and lignite coals, which are the main source of carbon dioxide emissions at U.S. coal-fired power plants. Carbon dioxide captured during operation had a purity of 99.5 percent.”
99.5% isn’t bad. The economics of the technology aren’t entirely clear yet though, and it’s hard to imagine an expensive add-on to coal burning gaining much traction, even if it does reduce greenhouse gas emissions.