Future of 'Clean Coal' Power Tied to [Uncertain] Success of Carbon Capture and Storage

A new report confirms that coal has a large role to play in meeting the world's energy demands, but to avoid runaway climate change, technologies to sequester its carbon need to advance quickly

The world emitted 25 billion metric tons of carbon dioxide (CO2) in 2003—more than one third, 9.3 billion metric tons, came from burning coal. The dirty rock provides half of the electricity in the U.S. and its role (or the nation's dependence on it) is likely to grow, according to a new report from the Massachusetts Institute of Technology. "It's cheap, there's lots of it and there's lots of it in places with high demand, namely the U.S., China and India," says co-author and M.I.T. physicist Ernest Moniz. "Sequestration," he adds, "is a key enabling technology for coal use in a carbon-constrained world."

Sequestration, as envisioned in the report, involves capturing the CO2 from coal-fired power plants, compressing it into a liquid and injecting it deep beneath the earth into old oil fields or saline aquifers. There, according to geologists, the CO2 would be trapped by sealing cap rock to prevent it from seeping back to the surface and into the air. It is relatively cheap to get it there, the report says. The difficulty is capturing it at the power plant without sapping too much energy or pushing electric costs up too high. For example, one 500-megawatt coal-fired power plant (there are the equivalent of 500 of these in the U.S. and China is building the equivalent of two of them each week) produces three million tons of CO2 annually. Adding carbon capture technology to that plant sucks up 40 percent of the power it can produce and adds at least 2.7 cents to the retail price of that electricity.