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How to win the war on coal

Mississippi may prove the first state in the U.S. to help coal fight global warming. A new facility rising from Kemper County's loamy soil will take the dirtiest coal from a local mine, turn it to gas, strip out the climate change-causing carbon dioxide, and then burn the gaseous fuel—resulting in pollution rates comparable with a power plant that burns natural gas. If coal use can truly be made (atmospherically) clean, it could act as a powerful counter to global warming.

The enabling technology to achieve this goal is a still relatively unknown form of recycling called carbon capture and storage, or CCS. Think of it as a way to shorten the geologic eras it takes for natural systems to pull carbon dioxide back out of the atmosphere. Instead, CCS traps the CO2 emitted whenever a fossil fuel is burned and then makes that gas available for disposal, perhaps deep underground. Various proposals for CCS have circulated for decades and technology demonstrations have ranged from large chemical facilities attached to coal-fired power plants to simple filters to capture the CO2 directly from the air.

Yet, when it comes to using CCS to solve the climate change brought on by ever-increasing CO2 emissions from human fossil-fuel burning, the technology has been, at best, stalled. A variety of projects exist (or existed) but the technology has failed to take off, largely because it remains more expensive to capture CO2 than to dump such fossil carbon for free into the atmosphere, where the trillions of freshly freed molecules can freely trap the heat causing global warming.

Regulators now want to make CCS more alluring. New rules from the U.S. Environmental Protection Agency mandate that any new coal-fired power plant will require at least part of its CO2 pollution to be captured and stored. The levels in the proposal would allow 1,100 pounds of CO2 per megawatt-hour of electricity produced to be emitted, the amount of gas spewed by the average new power plant burning natural gas. (Of course, to truly combat climate change, even that pollution would have to be captured and stored.)

The question now relates to whether the technology is ready for wide deployment. "It is happening now," argues Secretary of Energy Ernest Moniz, a point backed up by a Congressional Research Service report from October and the new Kemper power plant. In fact, that facility is the first large-scale effort to move CCS beyond the scale of demonstration projects. The 550-megawatt coal-gasification power plant, fitted with CCS, is scheduled for completion in 2014. "It's a monster," says Moniz, who recently toured the site.

Kemper will use lignite or brown coal—the most polluting form of the dirtiest of fossil fuels as well as the cheapest—but only after it has been transformed into a gas. This gasification process also allows the facility to strip out CO2. The captured CO2 will then be pumped into a dedicated 100-kilometer-long pipeline at the end of which sits an oil field.

Carbon dioxide has long been used in the oil industry to help scour extra petroleum out of the ground in old fields. "Today we are producing with CO2 [enhanced oil recovery] 300,000 barrels per day of oil," Moniz notes. "This is not so small," and there is the potential for as much as three million barrels a day of oil to be produced using this technique, according to some estimates. "You ain't going to find that much CO2 except at things like power plants or large industrial facilities."

Source: Scientific American