Zero Tolerance for Carbon-Dioxide Emissions

A Canadian government decides that coal plants must clean up their act.

By Peter Fairley

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.

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.

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 dioxide from 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-dioxide policy, 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.