Coal is one of the dirtiest fuels around and a major source of the world's carbon dioxide emissions. It's also hard to live without. In the U.S., half the electricity generated comes from coal. What if coal-fired plants stopped spewing their carbon dioxide fumes into the air and instead sequestered them—pumped them deep into the ground for storage?
Carbon sequestration is (despite its name) a simple-sounding idea that's exciting scientists, governments and energy companies as a way to cut emissions without disrupting energy supplies. One coal-fired plant in Denmark is working to trap carbon flue gases and store them in four spots, including an unused oil field off the coast of Spain. A Swedish utility is testing new ways to extract pure carbon dioxide from coal emissions in a lignite plant in eastern Germany. In the biggest test so far, a Norwegian energy firm is injecting 1 million tons of CO2 a year from the Sleipner gas field into a saline aquifer under the North Sea. "All the basic technology is already here," says Howard Herzog, an energy expert at the Massachusetts Institute of Technology. A report by the International Energy Agency (IEA) in Paris says sequestration would be second only to energy-saving measures in reducing CO2 emissions, far ahead of better-known efforts like renewable energy.
There are two major obstacles. The first is cost, which the IEA estimates to be as much as $50 for each ton of carbon captured. Those costs may drop if the technology is successful and utilities are given incentives not to spew out carbon dioxide. The other obstacle is a lack of detailed scientific knowledge. The pilot projects are going well, but M.I.T.'s Herzog says, "We'd like to see more large-scale demonstrations worldwide to really bolster confidence." In the meantime, watch for sequestration to move quickly up the energy agenda.