The Polk plant captures all its fly ash, 98 percent of its sulfurâ€”which causes acid rainâ€”and nearly all its nitrogen oxides, the main component of the brown haze that hangs over many cities. Built to demonstrate the feasibility of a new way to wring economical power from coal without belching assorted toxins into the air, the $600 million plant has been running steadily since 1996. “It makes the lowest-cost electricity on TECO’s grid,” Shorter says. “It also has very, very low emissions. Particulate matter is almost undetectable.”
What is both distressing and remarkable about the Polk plant is that it could do much more. “There’s no requirement for mercury capture, but 95 percent of it could be captured very easily,” Shorter adds. More important, the plant could also capture nearly all of coal’s most elusive and potentially disastrous emissions: carbon dioxide, the main gas that drives global warming.
Industry advocates brag that the United States, which has 27 percent of all known coal reserves, is “the Saudi Arabia of coal,” with enough to burn for the next 180 years at the current rate of use. Unfortunately, coal is as filthy as it is cheap and abundant. When burned it releases three pounds of sulfur dioxide and four pounds of nitrogen oxide for every megawatt-hour of operation. The nation’s plants produce a total of about 48 tons of mercury annually. “If all the coal-burning power plants that are scheduled to be built over the next 25 years are built, the lifetime carbon dioxide emissions from those power plants will equal all the emissions from coal burning in all of human history to date,” says John Holdren, a professor of environmental policy at Harvard University’s Kennedy School of Government.