"There is some near-surface gas hydrate, " she said Wednesday.

CNN: Study: Tap natural gas from Alaska's frozen areas

"This is especially important now that a growing body of evidence indicates that concentrated gas hydrate accumulations ... such as those in Northern Alaska, can be produced with existing technology, " he said.

CNN: Study: Tap natural gas from Alaska's frozen areas

"It is the world's first offshore experiment producing gas from methane hydrate, " an official from the economy, trade and industry ministry told the AFP news agency.

BBC: Production test

More than 50 million years ago, undersea landslides resulted in the release of methane gas from methane hydrate, which contributed to global warming that lasted tens of thousands of years.

FORBES: Energy's Most Dangerous Game

Engineers used a depressurisation method that turns methane hydrate into methane gas.

BBC: Production test

As temperatures rise or pressure rates fall, the hydrate disintegrates and the water releases the gas.

FORBES

One cubic foot of solid methane hydrate yields about 164 cubic feet of gas.

CNN: Japan warms to 'fire ice' potential

Methane hydrates are frozen water molecules that trap methane gas molecules in a crystalline, lattice-like structure known as a hydrate.

FORBES

Other countries, including the US and Canada, are also conducting research on methane hydrate, which experts say is at least twice as plentiful as all known reserves of natural gas.

CNN: Japan warms to 'fire ice' potential