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Zero Tolerance for Carbon-Dioxide Emissions

A Canadian government decides that coal plants must clean up their act.
February 28, 2007

Cleaner coal technologies have just received a vote of confidence from Canada, as a new provincial policy announced earlier this month would require new coal power plants in British Columbia to emit no carbon dioxide. But while British Columbia’s energy minister Richard Neufeld says that the policy is only calling for “the best technology available today,” some say the ambitious policy could be asking more than current technology can deliver.

Yesterday’s Coal Plant? Conventional pulverized-coal plants such as this one pump out carbon dioxide in a diffuse stream that’s hard to capture. Their days may be numbered as politicians translate rising public concerns about greenhouse-gas emissions into laws requiring carbon capture and sequestration.

Some energy experts say that meeting the policy, which states that coal plants must capture and sequester their carbon dioxide, effectively mandates the use of cleaner but more costly coal gasification technology called Integrated Gasification Combined Cycle (IGCC). In these power plants, coal is converted into a hydrogen-rich gas that burns clean like natural gas. Capturing carbon from these plants could be easier than capturing it from conventional coal plants. That’s because the chemical processes to separate carbon dioxidefrom other gases require less energy when operating on the more concentrated gas streams found in an IGCC plant. “If you’re going to do coal and capture the carbon dioxide, gasification is the least-cost alternative,” says James Childress, executive director of the Gasification Technologies Council, an industry group based in Arlington, VA.

Major utilities and technology providers in the United States say that IGCC technology is ready for commercial use. According to the National Energy Technology Laboratory, in Pittsburgh, IGCC is the technology selected for one-fifth of 159 new coal plants proposed since 2000. But so far, systems for capturing carbon dioxide from such power plants have not been engineered. And of the 32 proposed IGCC plants, only a handful are moving forward.

What is slowing the transition away from conventional pulverized-coal technology is IGCC’s higher up-front cost. General Electric, which is providing the designs for the IGCC project that is now the farthest along, estimates that the first 10 will cost at least 10 to 15 percent more to build than a pulverized-coal plant. Other experts estimate that the cost premium could be much higher. That has made IGCC a tough sell, even though it is cleaner, emitting levels of smog-producing NOx and sulfur dioxide closer to those of a natural gas-fired power plant.

British Columbia’s new carbon-dioxidepolicy, if adopted widely, could change the rules of the game. Adding the cost of capturing carbon would raise the price of power. But prices could go up less with IGCC technology, if it does indeed prove easier to capture carbon dioxide in such plants than in conventional plants. That could make IGCC plants the less costly alternative overall.

The proposed British Columbia policy, however, could have unintended consequences. John Thompson, director of the Coal Transition Program for the Clean Air Task Force, a nonprofit environmental consulting firm based in Boston, says that British Columbia’s seemingly IGCC-friendly policy may be too ambitious because it would force IGCC operators to find a place to store their captured carbon dioxide. In Thompson’s view, carbon-dioxide sequestration technology is not as mature as IGCC. “There’s a tendency to think that geological sequestration from coal plants can emerge in one fell swoop. But [carbon capture and sequestration] are really two distinct technologies,” argues Thompson. Sequestration is under way at several sites in Europe and the United States. (See “Carbon Dioxide for Sale.”) Still, Thompson says that more testing is needed to see whether deep geologic formations are capable of absorbing the carbon dioxide from multiple power plants and safely holding it long term. “Who’s liable if, God forbid, some of this carbon dioxide comes up?” he asks.

British Columbia’s policy poses an immediate dilemma for the two coal-power projects currently pending in the Canadian province. Proponents of one project, a pulverized-coal plant proposed for Tumbler Ridge, are exploring the feasibility of adding carbon capture and storage, Neufeld says. The other project, in Princeton, has found an entirely different way around the new policy: dumping coal from its plan. The plant was originally designed to burn a fifty-fifty mix of wood waste and coal. Neufeld says the developers are now talking about burning 100 percent biomass.

The new plans for Princeton are a reminder of the coal-power industry’s stake in IGCC technology. If it doesn’t find a means of reducing coal’s greenhouse-gas emissions, coal power may eventually be legislated out of existence. Neufeld says British Columbia will need 25 to 45 percent more electricity within 20 years, and that alternative forms of electricity such as wind power and new hydro power, which tend to be intermittent, can’t completely replace baseline power sources such as coal-fired plants. “We need firm energy,” says Neufeld, “hard, firm electricity … to make sure that the lights stay on.”

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