Researchers unlock mystery of how methane hydrate, or 'burning ice,' emits gas

April 16, 2014

By YASUJI NAGAI/ Senior Staff Writer

Researchers at Okayama University have discovered the process whereby methane hydrate emits methane gas, a discovery that could lead to the development of mining technology of the new energy source.

Known as "burning ice" on the ocean floor, methane hydrate contains methane gas that is trapped within ice molecules. The ice molecules form a slushy solid of sorts and are found in very cool environments under extreme pressure, such as under the Siberia tundra or the floor of oceans.

Since methane hydrate can release approximately 170 times more methane gas per volume of hydrate, it is expected to be an abundant source of energy in the future.

The research team at Okayama University was headed by special-appointed associate professor Takuma Yagasaki and included Hideki Tanaka, a professor of molecular chemistry. The team used the supercomputer "K computer" at the Riken national research institute in Kobe to simulate the changes methane hydrate undergoes when it is removed from its cool, highly pressurized natural environment and exposed to normal atmospheric pressure.

The supercomputer calculated the movements and reactions of all the crystallized methane hydrate molecules. It was able to simulate the natural attraction and repulsion that occurs at the atomic level during the transition. The computer slowed down the process, allowing for a more accurate and time-specific result.

The results showed that the rate of breakdown, slow at first, sped up over time. The team found the speed abruptly increased once 40 or so methane molecules bond together to make a microscopic gas bubble. It was discovered that certain temperatures prolong the process, as well.

"We have found the possibilities of controlling the process of methane gas generation," Tanaka said.

Hideo Narita, head of the Methane Hydrate Research Center of the National Institute of Advanced Industrial Science and Technology, said, "This is highly innovative research that has accurately simulated the breakdown of methane hydrate molecules and shows the potential to control the rate of breakdown.”

“This not only shows us a way to sustainably mine methane hydrate, but also can lead to technological advancements in its future storage and transportation, and perhaps even the development of heating systems using its thermal characteristics."

The ocean waters surrounding the Japanese archipelago alone are estimated to contain methane hydrate equal to 100 years’ worth of Japanese natural gas consumption.

By YASUJI NAGAI/ Senior Staff Writer
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A computerized image showing how methane hydrate (center) emits methane gas. (Provided by associate professor Masakazu Matsumoto from Okayama University)

A computerized image showing how methane hydrate (center) emits methane gas. (Provided by associate professor Masakazu Matsumoto from Okayama University)

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  • A computerized image showing how methane hydrate (center) emits methane gas. (Provided by associate professor Masakazu Matsumoto from Okayama University)

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