Bloomberg.com, Dec. 26, 2007
Dec. 26 (Bloomberg) -- Fifty-five million years ago the world's climate was catastrophically changed when volcanoes melted natural gas frozen in the seabed. Now
Billions of tons of methane hydrate, frozen chunks of chemical-laced water buried in sediment some 3,000 feet under the Pacific Ocean floor, may help
``Methane hydrate was a key cause of the global warming that led to one of the largest extinctions in the earth's history,' says Ryo Matsumoto, a
If successful, the gas drilling project could help
``We are closely watching the government's methane hydrate project, expecting some day to start receiving gas via pipelines from the continental shelf,' says Toshiharu Okui, deputy general manager of gas resources at Tokyo Gas Co., the country's largest distributor of natural gas.
500 Meters Thick
Trapped within sheets of ice up to 500 meters (1,640 feet) thick is an estimated 40 trillion cubic feet of crystalline methane encased in an ocean trench called the Nankai Trough, 30 miles (50 kilometers) off the coast of the main Honshu Island.
``Reserves aren't as much as Saudi Arabia's or
Exploiting the Nankai Trough depends on developing technical know-how through a test project in
``Test production in
Test Drilling Results
The most efficient method has proved ``depressurizing,' which requires deep bore holes being drilled into the ice sheets. Pressure within the chamber is reduced by a pump, causing gaseous methane to separate from the water and ascend to the well head.
A first round of drilling was completed in April by Jogmec and the Canadian government and a second set of tests are scheduled for early 2008. The two governments won't disclose results due to a confidentiality agreement, Jogmec's Yokoi says.
Commercial exploitation of methane hydrate is economically viable when oil trades above $54 a barrel,
While governments are attracted to an abundant clean fuel, drilling risks disturbing the seabed and triggering an uncontrolled release, says Matsumoto of the
``A mass release of methane into the sea and the atmosphere is a risk for global warming,' he says. ``Massive landslides at the ocean floor must be avoided when drilling at the Nankai Trough.'
Undersea Landslides
Undersea landsides triggered by volcanoes that occurred more than fifty million years ago resulted in the release of methane hydrate, contributing to global warming that lasted tens of thousands of years, says Matsumoto.
``Energy security and environment protection cannot be apart from each other,' says the trade ministry's Hashiba. ``We need a comprehensive assessment.'
Among other concerns are that the separation of sea water and colder fresh water will cause ocean temperatures in the Nankai Trough to fall, says Hashiba. The area is a habitat for red sea bream, a fish delicacy.
Fishing Bank Threat
``We're worried that drilling work might harm our fishing banks out there and eventually reduce our catches of red sea bream,' says Hironori Watanabe at the Katsuura City fishery association.
A bigger worry is evidence that the undersea ice may already be melting. In September, Matsumoto joined a research party in the
``It's ironically recurring,' Matsumoto says. ``Extinction of living organisms has repeatedly taken place in the earth's history, and dead bodies were accumulated in soil and under the sea bed, and turned to oil and natural gas.'
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