Japan has achieved the world’s first gas extraction from offshore methane hydrate deposits, said energy explorer Japan Oil, Gas and Metals National Corp (JOGMEC), who is targeting commercial production within six years.

A Reuters report on Tuesday stated that since 2001, several hundred million dollars have been invested in developing technology to tap methane hydrate reserves, estimated to equate to about 11 years of gas consumption, off Japan’s coast.

State-run JOGMEC said the gas was tapped from deposits of methane hydrate, a frozen gas known as “flammable ice”, near Japan’s central coast.

Japan imports almost all of its energy needs and is the world’s top importer of liquefied natural gas. The lure of domestic gas resources has intensified following the Fukushima nuclear crisis two years ago, which triggered a shake-up of the country’s energy sector.

According to Reuters, Japan’s trade ministry said the production tests would continue for about two weeks, followed by analysis on how much gas was produced.

Methane hydrate is formed from a mixture of methane and water under certain pressure and conditions.

Methane is a major component of natural gas and governments including Canada, the US, Norway and China are also looking at exploiting hydrate deposits as an alternative source of energy.

JOGMEC used depressurisation to turn methane hydrate to methane gas, a process the government believed was more effective than using the hot water circulation method the country had tested in 2002.

In 2008, JOGMEC successfully demonstrated for the first time a nearly six-day continuous period of production of methane gas from hydrate reserves held deep in permafrost in Canada, using the depressurisation method.

A Japanese study has estimated that at least 40 trillion cubic feet of methane hydrates exist in the eastern Nankai Trough off the country’s Pacific coast – the equivalent of about 11 years of Japanese gas consumption.

Japan’s LNG imports hit a record 87.3 million tonnes last year after Japan shut down most of its nuclear power plants following the Fukushima nuclear disaster two years ago.