December 3, 2007 4:00 AM PST
FAQ: All about coal--a necessary evil
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What about carbon capture?
Since coal can't disappear overnight, several start-ups and industrial giants have gravitated toward ideas for storing carbon dioxide and other pollutants that come from it. Powerspan is building a facility in Sugarland, Texas, that will capture the emissions equal to a 125-megawatt generator. The company has developed a process called Electro-Catalytic Oxidation that filters out nitric oxide, sulfur dioxide, mercury, and fine particles from smokestacks. The remaining carbon dioxide is captured by an ammonia-based solution, which is later recovered.
Then there is Skyonic, which has come up with an industrial process called SkyMine that captures 90 percent of the carbon dioxide coming out of smoke stacks and mixes it with sodium hydroxide to make sodium bicarbonate, or baking soda. The baking soda can then be used as a safe material for landfills or sold to industrial buyers.
"It is cleaner than food-grade (baking soda)," said Joe David Jones, Skyonic's CEO.
The big issue for these companies will be cost--capture systems like this will likely cost tens to hundreds of millions--and how difficult it will be to retrofit existing facilities to accommodate this stuff.
How good is carbon capture and sequestration?
No one knows. Ideas range from putting gases into empty, underground chambers and ringing it with warning sensors (plans are being sketched out for trials in North Africa) to pumping it into porous rock formations (where it will bind with rock) or saline aquifers.
The goal of the Southeast Regional Carbon Sequestration Partnership (SECARB), funded by the National Energy Technology Laboratory of the Department of Energy, is to study carbon-dioxide injection and storage capacity of the Tuscaloosa-Woodbine geologic system that stretches from Texas to Florida. The region has the potential to store more than 200 billion tons of the gas, which the department says is equal to about 33 years of emissions.
Beginning in the fall, SECARB scientists will start to inject a million tons of carbon dioxide a year into a brine reservoir near Natchez, Miss. The large scale of the projects raises questions, though. What about soil contamination, leakage, or earthquakes?
Meanwhile, the clock is ticking.
"We haven't invested in deep research or spent much money in testing out the scenarios. There are a lot of uncertainties," said Jiang Lin, a scientist with the China Sustainable Energy Program with Lawrence Berkeley Lab in a recent speech.
"Without carbon capture and sequestration, we are all toast," Lin added.
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