Can Coal Be Clean? New ways to burn a dirty old fuel
by Marilyn Berlin Snell
From mountaintops removed in West Virginia (above) to skies polluted in Wyoming, coal remains a dirty business.
COAL IS A POWER PLAYER, generating more than half of the electricity and about 22 percent of the energy produced in the United States. But it is also dirty and destructive: Entire mountaintops are removed to get at it; emissions from coal-fired power plants contribute to at least 24,000 premature deaths a year in this country alone; and it accounts for 36 percent of our overall releases of carbon dioxide, the main culprit in global warming. Despite the industry's hype, there's no such thing as "clean coal." But new technologies and policies can help reduce coal plants' deadly emissions, including carbon dioxide, sulfur dioxide, mercury, and nitrogen oxides.
What's an environmentalist to do about coal? If you're stuck with an old coal plant in your neighborhood, advocate installing state-of-the-art pollution-control technology. Better yet, call for the plant's replacement with efficiency measures, renewable energy, or a cleaner coal facility. Regardless of where you live, push for a carbon tax. To join the conversation, here's what you need to know:
PULVERIZED-COAL POWER PLANTS In these facilities, coal is crushed into a fine powder and burned in a boiler to produce steam, which powers a turbine that generates electricity. There are three types of pulverized-coal combustion plants, with varying levels of pollution--none of them satisfactory from either a health or an environmental perspective. Ninety percent of the world's coal power is produced by the dirtiest kind: "subcritical" plants. "Supercritical" plants, the next step up, produce less pollution and run more efficiently, so less coal is needed to generate the same amount of energy. Only Japan and Europe have top-of-the-line, "ultra-supercritical" plants; China's first is under construction and expected to begin operating in 2007.
IGCC POWER PLANTS The EPA considers integrated gasification combined cycle (IGCC) facilities "one of the most promising technologies" for reducing coal's environmental impacts. Crushed coal is mixed with oxygen and water in a high-pressure gasifier to make "syngas," a combustible fuel that produces extremely low emissions of sulfur dioxide, nitrogen oxides, mercury, and particulates. In contrast to the pulverized-coal technologies, the IGCC method uses less water, generates less solid waste, and can concentrate carbon dioxide emissions, making CO2 easier to capture and store.
Only two first-generation IGCC plants are operating in the United States, because the cost to produce electricity using the gasifier technology is 15 to 20 percent higher than that of conventional coal plants, and some utilities claim it is unreliable. That's not stopping American Electric Power, the nation's largest coal-consuming utility, which says it will build at least two 600-megawatt IGCC plants.
CARBON DIOXIDE CAPTURE AND STORAGE As greenhouse gases increase and politicians seem paralyzed or worse, scientists are attempting to control the damage. They are working on ways to corral the carbon dioxide emitted by the coal industry, transport it, and "sequester" it deep in the ocean, underground coal seams, or saline reservoirs. According to the National Academy of Sciences, annually 5 billion to 10 billion tons--as much as 40 percent of human-made CO2--"could be removed from the atmosphere and tucked safely away." For years, the oil industry has been injecting carbon dioxide into the ground to help increase oil production. But the capture and storage of CO2 from the world's coal-fired plants would be on a much larger scale.
Economics is the big hurdle. Carbon capture and storage would raise the cost of coal power by 40 to 90 percent. If polluters had to pay a tax of $100 per ton of carbon emitted, however, sequestration would become a more attractive option. The technology would work best with IGCC plants; retrofitting pulverized-coal plants would be costly and reduce efficiency.
CARBON TAX Fossil-fuel burning imposes severe health and environmental costs that aren't factored into the cost of producing electricity. A tax on all energy sources that release carbon dioxide into the atmosphere would correct this failure by reflecting the real cost of CO2 emissions--and make cleaner energy more financially viable. Norway and Sweden instituted carbon taxes in 1991, and the European Union is debating its own version. All is quiet on the U.S. political front, but Duke Energy, one of the country's largest utilities, has announced that it supports "mandatory federal action" with regard to a carbon tax.
Chart: John Blanchard; source: Energy Information Administration, U.S. Department of Energy Photo: Tending the Commons: Folklife and Landscape in Southern West Virginia, American Folklife Center, Library of Congress