JAPAN, which imports almost all its energy, yesterday produced gas in the world's first tests to extract the fuel from methane hydrate deposits under the seabed, Japan Oil, Gas & Metals National Corp said in a statement.

Gas was produced during drilling in the Nankai Trough about 50 kilometers off the coast of the country's main Honshu island, according to the government affiliate known as JOGMEC.

Deposits of methane hydrate, known as "burnable ice," may be large enough to supply the country's natural gas needs for about 100 years, according to JOGMEC. The government plans to develop technology to enable commercial use by fiscal 2018.

"Methane hydrate may start a revolution in Japan as shale gas did in the US, but there are still a lot of challenges ahead," said Yuji Morita, a senior researcher at the Institute of Energy Economics, Japan.

Eastern Nankai Trough deposits of methane hydrate, or natural gas locked in an ice-like cage of water molecules, may hold the equivalent of about 40 trillion cubic feet of methane, a primary element of natural gas, JOGMEC said. That's equivalent to about 11 years of Japan's LNG imports, it said.