Like an ice that burns, methane hydrate is cold, white and would light up like a gas stove if held to a flame. And so much of the frozen fuel naturally blankets the sea beds off Japan and elsewhere that scientists say it could power the world for centuries.
Yet, as soon as researchers plumb the depths and pull the potentially revolutionary energy source to the surface, the frosty crystalized methane starts to fizz and bubble into oblivion as it warms up, gassifies and then dissolves into the ocean.
Most nations don't even bother exploring offshore reserves for lack of harvesting technology. But in resource-poor Japan, plucking the deep-sea bounty off its shores is more than science fiction -- it is a national initiative that Tokyo hopes becomes reality in 15 years.
"Japan's domestic resources are almost zero, so non-conventional sources are a top priority," said Tetsuo Yonezawa of the methane hydrate research team at the government-backed Japan National Oil Corp. "There is more than 100 years' worth of Japanese natural gas consumption there."
Japan's push heats up next January, when a drilling ship sets sail for the choppy Pacific Ocean off central Japan to dig 10 to 20 wells in methane hydrate beds along the Nankai Trough, some 1,100m under water.
By 2011, Japan hopes to determine whether commercial methane hydrate mining is economically feasible and, if so, begin doing so four years later.
Methane hydrate is a crystal structure of methane gas surrounded by water molecules, held together by freezing temperature and crushing pressure. Separating the two yields the methane, or common natural gas.
Knowledge of the substance dates to the 1890s. But it never caught on as an energy source because it is found in hard-to-access Arctic permafrost and deep ocean sediments.
Worldwide resources, however, are massive -- at an estimated 25,000 trillion cubic meters, according to current estimates. That contains about twice the energy of the earth's coal, oil and gas resources combined.
Deposits around Japan are just a fraction of that, between 4 trillion and 20 trillion cubic meters.
But Japan believes it's worth shelling out US$120 million next year alone on methane hydrate research to try to boost its energy self sufficiency. The island nation now imports about 97 percent of its natural gas and virtually all of its crude oil.
Japan is not alone in pursuing methane hydrate, but perhaps is the most desperate.