'Clean coal,' the idea of using new technologies to make coal-fired power plants less environmentally damaging, has been a long-sought solution to the climate crisis and the world's growing energy demands. As the world's most abundant and cheapest energy source, coal is widely used around the globe.
But both the mining and the burning of coal for power has huge environmental costs, and proponents of clean coal technologies hope to solve at least the costs associated with burning it for energy. By capturing and storing the greenhouse gas emissions from coal-fired power plants, clean coal researchers hope to make it a viable energy source in a low-carbon economy.
Proving the viability and sustainability of carbon capture and sequestration (CCS) projects has been a significant challenge in recent years. One significant concern is whether sequestered CO2 would remain in place or would leak out an further boost global warming.
The new study, by Stuart Gilfillan at the University of Ediburgh's Scottish Centre for Carbon Storage along with Barbara Sherwood Lollar of the University of Toronto and Chris Ballentine of the University of Manchester, looks at naturally occurring CO2 sinks in North America, China and Europe to identify if CO2 is leaking from these sinks, as a way of determining if sequestration can be proven as a successful way to store GHGs.
"We looked at nine CO2 fields, ranging from 10,000 years to about 42 million years old, and they have all stored CO2 for this length of time without obvious leakage signs," Gilfillan told Agence France-Presse. "Basically, if you store it in the right location, the CO2 should be contained on that sort of time scale."
The big finding of the report is that the key factor in containing the CO2 appears to be simply underground aquifers of water.
The team explored the ratio of isotopes of CO2 and isotopes of other inert gases, like helium and neon, and found that CO2 dissolves in groundwater and doesn't resurface into the atmosphere.
"By combining two techniques, we've been able to identify exactly where the carbon dioxide is being stored for the first time," Gilfillan said. "We already know that oil and gas have been stored safely in oil and gas fields over millions of years. Our study clearly shows that the carbon dioxide has been stored naturally and safely in underground water in these fields."
Clean coal has long been in the crosshairs, both as a hope for the coal industry and utilities looking to keep their power plants viable for as long as possible, but also for environmentalists and advocacy groups that want to end the mining and burning of coal as quickly as possible.
A central plank of clean coal is the FutureGen clean coal power plant project, which was terminated in December of 2007 when costs appeared to be spiraling out of control. A report from the Government Accountability Office released last month found that those cost overruns were exaggerated. As a result, the FutureGen project may be given new life, and the hopes of clean coal advocates will continue.
Power plant photo CC-licensed by Flickr user Maltesen.