LOS ANGELES, Feb. 21 (UPI) -- Burying the problem of carbon dioxide emissions from power plants is a particularly appealing response to climate change, but as with many a green energy idea, the concept of carbon sequestration still faces technical and financial hurdles before it becomes commonplace.
Carbon sequestration has all of the appeal of sweeping dust under the rug; carbon dioxide, a greenhouse gas, is captured as coal, and natural gas is burned to generate electricity. It is then pumped deep underground into geological formations that trap it if not forever at least for years.
"Carbon sequestration will play a key role in the United States' effort to mitigate climate change and holds the key to the continued environmentally responsible use of coal," Assistant Secretary of Energy Jeffrey Jarrett said last fall as he announced $450 million in assistance over the next 10 years for a slate of projects aimed at commercializing carbon sequestration.
Slashing the U.S. output of carbon dioxide is seen worldwide as critical if the buildup of greenhouse gases in the atmosphere is going to be halted, or at least slowed. Calculations by Massachusetts Institute of Technology peg the CO2 emissions from a large 1,000-megawatt U.S. power plant burning pulverized coal at between 6 and 8 metric tons per year; a natural gas plant emits about half that level.
The contentious debate will continue over whether or not climate change is a real enough threat to warrant risking a radical downshifting of the U.S. industrial economy; however, the political winds in Washington have shifted as the presidential campaign starts taking shape. Major U.S. industrial groups have stepped up their proclamations that they are on board with the crusade, and they are counting on Yankee ingenuity in the form of research into technologies such as carbon sequestration to lead the way.
"Over the coming decades, it is potentially feasible for the U.S. electric sector to first slow down the projected increase in CO2 emissions, stop the increase, and then decrease emissions while meeting an ever-increasing demand for reliable and affordable electricity," Steve Specker, president of the Electric Power Research Institute, predicted in a forecast of the research priorities of the U.S. electricity industry in the coming years.
However, the development of carbon sequestration is considered to be in its infancy and not ready for prime time. The Energy Department estimates that using current sequestration technology would cost utilities $100-$200 for each ton of carbon emissions kept out of the atmosphere. MIT estimated that translates to another 1.5-3.0 cents per kilowatt hour of retail electricity -- the U.S. Energy Information Administration estimates that the average power consumption per household in the United States was 4,410 KwH in 2005.
The Bush administration wants to slash the cost of carbon sequestration to no more than $10 per ton of carbon emissions removed by 2015, a move the Energy Department said in a news release would "save the U.S. trillions of dollars."
So it isn't practical to assume power generators can simply start injecting CO2 into the ground.
"The challenges to actually achieving these reductions are daunting in their scope and complexity," Specker said. "They will require a decade or more of very aggressive development."
The $450 million ante thrown in by Jarrett was aimed primarily at studying the ability of underground reservoirs to securely contain large volumes of CO2 without the buoyant gas rising to the surface through porous rock and seeping into the atmosphere. An unrelated study released this month by researchers at MIT included the good news that CO2 injected into deep reservoirs of salty water would indeed stay put.
The costs of sequestration are varied and can include the cost of installing equipment, converting the emissions into a compressed form of CO2, pumping it to the storage site and maintaining the site. There is also a "penalty" in the form of the electricity needed to run the capture equipment, which means the benefits of sequestration require the generation of more electricity to run the equipment.
A top priority for the energy industry, according to the EPRI, is refinement of the compounds used to strip the CO2 out of a power plant's overall emissions stream. The most popular material is monoethanol amine, a smelly and corrosive chemical made from ammonia that was first developed to pull carbon out of natural gas prior to and degrades quickly enough that its must be replenished frequently.
The Indiana Center for Coal Technology Research at Purdue University stated in a report earlier this month that "CO2 capture and storage using amine-based scrubbers, the only proven process to date, can consume about one-third of the plant's power output and increase the cost of electricity by 60 to 80 percent."
Such numbers are definitely enough to throw cold water on the idea that the United States and the rest of the industrialized world can begin using sequestration to keep carbon out of sight and out of mind although the drive for an effective method of doing so is heating up fast.
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