Huffington Magazine Issue 66 | Page 64

PAUL MAROTTA/GETTY IMAGES THE CARBON QUANDARY For the most part, American coalfired facilities, like those in most of the rest of the world, rely on comparatively simple, decades-old pulverized coal technology that is highly polluting and inefficient. Further, only the very newest natural gas-fired plant designs could conceivably meet any meaningful greenhouse gas emissions standard for newly built power plants. Most older coal and gas plants — and even those using the most advanced super- and ultra-supercritical coal technologies — would fall well short. For these, the only options in a carbon-constrained world would be to shut down or endeavor to capture and then either use or store — or “sequester” as some definitions of CCS have it — CO₂ emissions. Capturing the stuff isn’t much of technological feat. Three primary methods are used: Pre-combustion, post-combustion, and “oxyfuel.” Post-combustion, the most mature of the carbon-capture methods, simply scrubs the CO₂ out of the exhaust stream after the fuel is burned — typically by injecting a chemical into the waste that absorbs carbon dioxide. This technique is well-developed and can be retrofitted onto most of the HUFFINGTON 09.15.13 standard coal-fired power plants operating around the world today. Pre-combustion — meaning the CO₂ is stripped out before the coal is burned — is a newer technique. But because it requires the fuel to be converted to a gas first, it’s really only an option for that tiny percentage of newer, high-efficiency, synthetic-gas coal plants, and perhaps natural gas plants as well. Like the postcombustion method, a so-called “oxyfuel” system strips out the CO₂ after the fuel is burned, but it attempts to simplify the extraction by burning the coal in a pure oxygen environment, leaving behind only carbon dioxide and water vapor. Condensing out the In his 2009 book, Our Choice, Al Gore argues that CCS technology remains a pipe dream.