29 July 2011

Japan plans first-ever seafloor drilling of ‘fire ice’

By Melissa Mahony | July 28, 2011, 4:00 AM PDT

In the ongoing wake of the Fukushimi disaster, Japan has been eyeing a non-nuclear future. It would be a tall order. Nuclear power previously met one-third of the country’s energy consumption. Renewable resources like mandatory solar panels and wind farms are popular alternatives, but don’t currently comprise much of Japan’s power generation. Now rising from the Pacific is a less well known, and potentially dangerous, option: combustible ice.
That’s right, ice that burns.
A seabed off Honshū’s eastern coast is apparently full of “fire ice”, and Japan’s Ministry of Economy, Trade and Industry wants to go get it. Or at least try. There’s little wonder why: One cubic meter of combustible ice is roughly equivalent to 164 cubic meters of natural gas. According to media reports, they plan to request $127.5 million for an experimental project that would become the first offshore drilling operation of its kind.
Combustible ice, or natural gas hydrate, contains methane within its frozen lattice structure. When melted or depressurized, the ice turns to water and natural gas. This ice might be plentiful—past Department of Energy (DOE) estimates place the worldwide deposits as high as 400 million trillion cubic feet—but its methane is not easily retrieved from beneath the permafrost or seabeds where it typically rests.
Last year I discussed China’s desires to tap deposits of methane hydrate on the Qinghai-Tibet Plateau, in amounts equivalent to 35 billion ton of oil. On Alaska’s North Slope this winter, the DOE plans to test an extraction method that injects carbon dioxide into hydrate deposits to displace the methane. A possible twofer, the idea is to bury the carbon dioxide while producing natural gas. Methane did flow successfully from a well in northwestern Canada for a little while in 2008, during a joint Canadian and Japanese research project. In this case, the team depressurized the hydrates to release the methane.
The catch, of course, lies in doing all of this effectively and safely (without disrupting geological stability or leaking lots of methane, a potent greenhouse gas). And remember, past efforts were all on land, not at ocean depths that could exceed 1,500 feet. From the Pacific’s bottom, Japan hopes to commercially drill methane hydrate by the early 2020s.
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Images: DOE

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