A magazine of forecasts, trends, and ideas about the future
November-December 2007 Vol. 41, No. 6
| World Trends | & Forecasts |
ENVIRONMENT
Is Clean Coal Feasible?
The world looks to carbon capture and
storage for a cleaner energy future.
A growing body of scientists,
government officials, and even environmentalists are looking toward carbon
capture and storage (CCS) as they best way to reduce
the carbon emissions from power plants, including highly polluting
coal-fired power plants, by as much as 90%.
"Carbon capture and storage has massive potential to allow us to meet our energy needs at the same time as cutting carbon emissions," says United Kingdom Trade and Industry Secretary Alistair Darling, adding, "It opens up huge possibility, not just for Britain but also for the world." The United Kingdom is sponsoring a competition to attract engineers and scientists to build the world's first full-scale CCS demonstration plant.
According to Darling, the U.K.'s foray into carbon capture makes sense not just environmentally, but economically, as it positions private U.K. firms to provide CCS technologies to a global client base. "Rapid deployment of CCS technology in growth economies such as China and India will be vital," he says.
The United States is also
investing in the development of a functional CCS power plant. The $1.5
billion FutureGen initiative, sponsored by the U.S. Department of Energy
(DOE), seeks to create a coal-powered plant that emits a fraction of the
carbon expelled by a conventional coal plant and produces both electricity
and hydrogen, which can be stored for a limited time to produce energy
later.
However, several obstacles stand in the way of wider implementation of CCS, such as where to put sequestered carbon. U.K. researchers are looking at pumped-out oil and gas fields in the shallow oceans surrounding the Kingdom as a potential depository. Other researchers point out that sequestering carbon in sea beds could increase ocean acidification.
"The risks of sequestering CO2 in the oceans are not well understood, and ocean sequestration is most certainly not in the mainstream of CCS," says George Peridas, a science fellow at the Natural Resources Defense Council. "The best candidates for sequestration are geological reservoirs, and in particular oil/gas fields and deep saline formations. These are typically thousands of meters underground, and trap CO2 in the rock. Many have trapped hydrocarbons and CO2 for millions to hundreds of millions of years."
DOE is focusing its efforts on storing carbon in geological formations, such as saline formations, coal seams, and oil and gas bearing seams, in addition to storage options on dry land. DOE has recently released a Carbon Sequestration Atlas that discusses the carbon storage capacity of the United States and Canada.
An arguably greater challenge is reducing the high costs of capturing and storing CO2. The Intergovernmental Panel on Climate Change has estimated that the price of running a CCS plant can range from 10% to 40% higher for a conventional coal-burning plant.
"Once you add the cost of CCS, coal is no longer particularly cheap. Indeed, it's expensive," argues David Roberts, a writer with the online environmental magazine Grist. " Why would China choose expensive CCS over cheap dirty coal? It wouldn't, unless we [the United States] pay it to do so. It will cost China a lot of money to choose green development over dirty coal, and [the United States] has both a moral and a practical obligation to pick up part of the bill."
Government researchers are optimistic that the costs of CCS can be reduced through research and development. "The projected high cost associated with the capture of CO2 from coal-based power systems is a key driver of the DOE's Carbon Sequestration Program." says Thomas Feeley, the technology manager for existing plants at the National Energy Technology Laboratory (a DOE affiliate). "In response, the Program is carrying out the research and development of advanced carbon capture technologies capable of achieving 90% CO2 reductions while significantly reducing the costs compared to state-of-the-art capture technology."
Feeley reports that the DOE's research is focused on three technology pathways for limiting carbon emissions from power plants: turning the coal into a gas before using it for power and sequestering the carbon in that gas elsewhere (pre-combustion capture), trapping carbon emitted during energy production from raw coal (post-combustion capture), and infusing power plant emissions with an oxygen/chemical mixture to neutralize the carbon (oxy-fuel combustion).
While many researchers see CCS as one promising method for limiting CO2 emissions, few disagree that governments should pursue a range of options to decrease their nations' carbon footprints. According to Roberts, these should include:
• Expanded research for other energy alternatives.
• Rescinding subsidies for energy companies except in areas where companies are conducting research.
• Mandating that companies internalize the external costs of energy production such as climate change and pollution.
• Revising electrical energy regulations that discourage conservation.
The success of many young CCS projects, such as the ten-year-old Sleipner gas plant in the Norwegian North Sea and the seven-year-old Weyburn facility in Canada, indicates that, while other options will remain part of the discussion, CCS will likely play a growing role in the world's energy future.
"The debate is not whether or not CCS will perform," says Feeley, "it is a question of when." --Patrick Tucker
Sources: The United States Department of Energy. Address 1000 Independence Avenue, S.W., Washington, D.C. 20585. 1-800-DIAL-DOE. Website www.fossil.energy.gov/programs/powersystems/futuregen/ .
The United Kingdom Department of Trade and Industry, Press Office, 1 Victoria Street, London, SWIH OET, United Kingdom. Website, www.dti.gov.uk .
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