If all human-induced emissions were sequestered, enough capacity would exist to accommodate more than 100 years' worth of emissions, according to Benson, coordinating lead author of the IPCC chapter on underground geological storage.
With fossil fuels already comprising 85 percent of the world's energy consumption, and their use rapidly increasing due to the growth of developing countries, such as China and India, the need to find solutions to curb carbon emissions becomes even more crucial, Benson said.
From the air to the earth
In the capture process, carbon dioxide is extracted from a mix of waste gases. The most common method sends the exhaust through a chimney containing a three-dimensional mesh. As the gas goes up, a chemical solvent drizzles down, soaking up the gas where the two substances meet. The carbon dioxide is then extracted from the liquid and compressed, now ready for storage.
The best storage options today lie in geologic sequestration-storage in old oil fields, natural gas reservoirs, deep saline aquifers and unminable coal beds, hundreds to thousands of meters underground.
The carbon dioxide is pumped down through wells, like those used to extract oil, and dissolves or disperses in its reservoir.
Viable locations must have a caprock, or an impermeable layer above the reservoir shaped like an upside-down bowl, that traps the gas and keeps it from escaping, the researchers said.
Safety smarts
''The goal of carbon sequestration is to permanently store the carbon dioxide,'' Benson said, ''permanent meaning very, very long-term, geological time periods.''
The greatest concern surrounding carbon dioxide storage is the potential for it to leak, researchers said.
The most obvious worry, said Benson, is that leakage would lead to more
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
11-Jun-2007