Known as inflammable ice, or clathrates, the new potential fuel is a sherbet-like substance consisting of methane trapped in water ice. To the eye, it looks remarkably like ice and typically resides just below the seabed off our continental shelves.

Japanese calculations suggests the resources-poor country has enough supply just off its coasts to meet the economic superpower’s energy needs for the next 100 years. The frozen gas is also prevalent in other parts of the globe and can provide more energy than all the world’s known gas and oil reserves combined, according to one estimate.

“The initial area of study in Japan was the coastal region stretching 400 km (from Tokyo to the western tip of Japan’s Honshu island). This region alone is thought to hold enough reserves to supply all of Japan with natural gas for nearly 14 years,” says the Japanese government, which is leading the trials.

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Japanese researchers working for the government were the first to tap natural gas from seabed methane hydrates this March. Massive technological hurdles stand in the way of extracting the gas, which is difficult to access, as it is often deep below sea level. Some say these resources will never be commercially applicable.

Tokyo points to the challenges of fracking in the 1990s and says similar technological advances will make energy from methane hydrate a possibility. With few natural resources of its own, a stalled nuclear power program, and little in the way of renewables, Japan is hoping methane clathrate can save it from energy dependency.

Revised estimates, based on data collected over the last year and released last week, say there are massive deposits of methane hydrate below the Sea of Japan. These will be easier to reach than most gas deposits as they are located close to the seabed surface, officials say. Methane hydrates are believed to collect along geological fault lines, and Japan sits atop a nexus of three of the world’s largest deposits.

“Methane hydrate could become an important energy source for Japan, because a substantial part of the known or proven resources globally are around Japan,” says energy technology analyst Gerhard Fasol of Eurotechnology Japan.

Good news for Japan Inc., which showed boosted figures for manufacturing output recently. With nearly all nuclear power stations offline, Tokyo is fueling its mini boom with imported fossil fuels, particularly propane gas. At $16 per million metric units, compared to around $3.50 in the U.S., this has proven to be very expensive, particularly in light of the recent fall in the yen’s purchasing power and a ballooning trade deficit.

The state-owned Japan Oil, Gas and Metals National Corporation (JOGMEC) is behind the successful methane hydrate drillings so far, but it says private companies will take over once test drilling finishes sometime between 2016 and 2018.

The Japanese team say they have cracked technical difficulties by sending down what officials describe as “an excavator” one kilometer below the waves. There the machine separates solidified methane hydrate into water and natural gas, and funnels the gas up to the surface.

“Holes are drilled into the methane deposits to produce water to decrease the pressure, allowing the methane to separate out from the ice-like material and flow up the wellhead,” explains Koji Yamamoto, project director of JOGMEC’s Methane Hydrate Research Team.

While some welcome the potential benefits a new supply of energy, others point to the dangers of tampering with unstable beds of frozen gas and adding more CO2 to the atmosphere.

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“Environmentalists are horrified by the idea of releasing huge quantities of methane from under the seabeds,” says Leo Roodhart, director of the Roodhart Energy Consultancy. (Methane gas is a greenhouse gas that’s 20 times more potent than carbon dioxide.)

“Although methane is a cleaner-burning fossil fuel than coal or oil, the as-yet untapped methane hydrates represent ‘captured’ greenhouse gasses that some believe should remain locked under the sea. The mining of methane ice could also wreak havoc on marine ecosystems.”

Yamamoto disagrees that there is any danger of such blowouts or major environmental damage — although a small methane hydrate blowout was linked to the BP (BP) spill in the Gulf. Larger releases of methane from clathrate beds throughout history, known as the actions of a “Clathrate gun,” have been responsible for mass extinction events.

Researchers do not agree on the risks associated with methane hydrate exploration for commercial energy use. Oceanographer and Rice University professor Gerald Dickens agrees with the Japanese research team, arguing that there is little danger of such catastrophes coming from human action.

“The only potential issue in regards to drilling would be if there is greatly over-pressured gas immediately beneath the gas hydrate,” Dickens says. “However, there is growing belief and rationale to suggest that this cannot occur in nature. So, as far as drilling is concerned, there should be no issue.”

Tim Collett of the United States Geological Survey, a leading expert on methane hydrate, believes it is possible that both natural and human induced changes can lead to hydrate destabilization, triggering catastrophic landslides.

“Evidence implicating gas hydrates in triggering seafloor landslides has been found along the Atlantic Ocean margin of the United States and off northern Europe,” he told the U.S. Congress in 2004. “These processes may release large volumes of methane to the Earth’s oceans and atmosphere.”