Both John McCain and Barack Obama have frequently mentioned their support for "clean coal" on the campaign trail, but neither one of them has fully explained what that means. The Union of Concerned Scientists (UCS) yesterday issued a report that examines the pros and cons of a proposed technology that would capture coal plant carbon dioxide emissions and store them underground.
"We’re on a collision course with a much hotter planet unless we drastically cut coal power plant emissions," said Barbara Freese, co-author of the report and author of the book Coal: A Human History. "Carbon capture and storage holds promise, but we can’t assume it will play a big role in cutting global warming pollution until we know whether it works at a commercial scale and what it will cost. In the meantime, we need to ramp up our reliance on energy efficiency and wind, solar and other renewable energy sources."
The United States has significant coal reserves and likely will continue to generate power from it for many years to come. Climate projections, however, indicate that the United States must swiftly cut carbon dioxide emissions and ultimately reduce them by at least 80% of 2000 levels by mid-century to avoid the worst consequences of climate change. Coal is the nation’s largest source of global warming pollution, representing approximately a third of U.S. emissions, equal to the combined output of all U.S. cars, trucks, buses, trains and boats.
The UCS report, "Coal Power in a Warming World," proposes that the federal government fund five to 10 full-scale demonstration projects to test carbon-capture-and-storage technology’s ability to cut coal power plant emissions. The report also calls for a halt in construction of new coal plants that do not capture and store carbon emissions, even though U.S. utilities are currently planning to build more than 100 plants without the technology. The country can meet its near-term energy needs and curb emissions, the report contends, using readily available renewable-energy and energy-efficiency technologies.
The report found that carbon-capture-and-storage technology, while promising, is saddled with many unanswered questions about scale, safety and cost:
SCALE: For the technology to make a meaningful contribution to reducing global warming pollution, it would require an enormous processing and transportation infrastructure that could handle a volume of liquefied carbon dioxide rivaling that of the oil consumed in the United States today. Put another way, the Department of Energy estimates that the annual storage space needed for a typical 600-megawatt plant’s emissions would be approximately four times the volume of the Empire State Building.
SAFETY: Demonstration projects will have to determine if carbon dioxide can be stored indefinitely and in what type of underground geologic formations. Slow carbon leaks could undermine the technology’s effectiveness as a global warming solution and contaminate groundwater. Fast leaks from a storage site or a pipeline could threaten local residents.
COST: Current coal plant designs cannot cost-effectively capture carbon dioxide. Studies estimate that adding the technology to a conventional coal plant would dramatically increase cost and reduce energy output. Although there are advanced coal plant designs that are better suited for carbon capture, it still would be extremely expensive to add the technology, particularly as a retrofit.
Despite these challenges, the report concluded that carbon-capture-and-storage technology has enough potential to help curb global warming to warrant large-scale demonstration projects. These projects would help determine how the technology compares with other low-carbon energy technologies and whether it merits broader deployment. However, the report cautions that coal’s other environmental and societal impacts must be factored into any assessment of the viability of carbon capture.
"Even if coal capture and storage works on a commercial scale, coal will still be dirty," said Steve Clemmer, UCS Clean Energy Program research director and co-author of the report. "The technology doesn’t address the environmental threat posed by mining, transporting and disposing of coal." To make coal cleaner, he said, the government should ban mountaintop removal mining, strengthen oversight of mine waste slurry impoundments, and tighten and enforce mine safety laws.
Given that coal has significantly worse health and environmental consequences than other energy options that may prove less expensive, less risky and less harmful to public health and the environment, the report calls on the federal government to dramatically increase the deployment of energy-efficiency, renewable-energy and energy-storage technologies while it invests in carbon-capture-and-storage-technology demonstration projects. Doing so would help ensure that federal research and development funding does not unduly favor coal. It also would expand the nation’s options for responding to climate change.
The report also recommends that Congress enact a strong federal cap-and-trade law that puts a price on carbon emissions and covers existing coal plants. An economywide cap-and-trade program would be essential to guarantee overall emission reductions, Clemmer said, and income from auctioning the right to emit could fund carbon capture-and-storage-technology demonstration projects and other carbon-cutting strategies.
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