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Methane Hydrate Opens Possibility for New Energy
June 24, 1998
Methane hydrate burns readily in air, producing a blue, luminous flame. (Osaka Gas Co.)
Deep in the ocean, beneath the seabeds surrounding Japan, lie large amounts of "flammable ice"--methane hydrate, a frozen form of methane, the main constituent of natural gas. The Agency of Natural Resources and Energy and the Japan National Oil Corporation plan on researching and developing a technology for digging up this treasure. If their endeavor succeeds, this underwater store of methane hydrate could bring Japan a steady source of "clean" energy, raising it to the ranks of net energy exporters.
Methane is formed by the decomposition of vegetable matter. When the temperature is around the freezing point of water and the pressure is extremely high (26 atmospheres or more), methane combines with water and condenses into methane hydrate, which looks like dry ice. Such conditions are said to exist under are the permafrost of Siberia and Alaska as well as under seabeds where the waters more than 500 meters deep. Results of sonar surveys suggest that large amounts of methane hydrate lie in the seabeds off the Pacific coast of the central part of the Japanese archipelago.
When brought to normal air pressure (1 atmosphere), the crystalline substance will provide more than 160 times its original volume in gaseous methane; one might think of it as a highly pressurized can of natural gas. Furthermore, methane is a relatively clean source of energy, releasing less than half the amount of carbon dioxide when burned that oil and coal do.
There are many obstacles to commercialization. First, methane hydrate lies in ocean depths approaching 1,000 meters, far deeper than underwater oil and gas fields, meaning that special vessels must be developed for its excavation. Finding an effective method of extracting methane gas from the solid poses another problem: Those being considered now include pouring hot water. The agency and corporation hope to develop feasible technologies as quickly as possible.
Experts say that the entire reserve of methane hydrate in the waters near Japan could provide 6 trillion cubic meters of methane. This is enough to support Japan's expenditure of natural gas for a century. Since Japan imports 100% of its crude oil and 82% of all its primary energy (energy directly obtained from natural resources, such as oil, coal, natural gas, hydro, and geothermal), the prospect of gaining an extensive domestic pool of energy comes with high expectations.
The worldwide total of methane hydrate is estimated to be equivalent to 250 trillion cubic meters of methane gas. Research on this substance has been active overseas since the early 1990s, but attention is focused more on its potential to contribute to climate change than to provide energy. If temperatures were to rise on a global scale, causing some permafrost to melt, then massive amounts of methane would be released into the atmosphere to aggravate global warming. This would create a relentless cycle by melting yet more permafrost, thereby releasing even greater amounts of methane.
But methane hydrate--a potential villain to the global environment--could be good news instead if Japan succeeds in exploiting it as a clean energy source.
Edited by Japan Echo Inc. based on domestic Japanese news sources. Articles presented here are offered for reference purposes and do not necessarily represent the policy or views of the Japanese Government.