In a dramatic leap for global energy, Japan has cracked seabed "ice gas", which could open a super-resource for that country.

It has also raised hopes New Zealand will benefit from a potentially huge source of energy here, too.

Yesterday, in a world first, Japan said it had extracted natural "ice" gas from methane hydrates beneath the sea off its coasts in a technological coup. All the gas hydrates around the coast could meet the country's gas needs for the next century and radically change the world's energy outlook.

Tokyo hoped to bring the gas to market on a commercial scale within five years, with the immediate discovery potentially holding the equivalent of 11 years of gas imports.

New Zealand's potential methane hydrate deposits are similar to those in Japan.

One of New Zealand's "sweet spots" for the methane hydrates is just 22 kilometres off the south Wairarapa coast and about 80km from the Beehive in Wellington. It could contain half a trillion cubic feet of gas, about 1000 metres deep, according to a study carried out in 2009.

Former Centre for Advanced Engineering executive director George Hooper, now an independent consultant, said yesterday that methane hydrate was "no longer a scientific curiosity" for New Zealand.

"It is very exciting," he said of the Japanese breakthrough, which was likely to bring potential commercialisation forward.

"We should now acknowledge the technological advance allows the exploitation of the resource, but the question remains: When will it be economic?"

Methane hydrate was a long-term "backstop" to conventional gas resources , though any development here could be a decade away, Hooper said.

Gas prices would need to be $8 to $10 a gigajoule to make methane hydrates pay, and present prices were "much less than that".

Some estimates put recent large contract prices at about $5 a gigajoule.

There is a good supply of natural gas at present, with a major new contract signed by Methanex in Taranaki recently.

Past studies have suggested that the frozen form of methane gas could more than double the size of New Zealand's gas industry.

United States-based oil and gas company Anadarko is exploring the Pegasus Basin off the Wellington and south Wairarapa coast, but said yesterday that methane hydrates were not on its radar.

Japanese state-owned oil and gas company JOGMEC said yesterday that an exploration ship had successfully drilled 300 metres below the seabed into deposits of methane hydrate, an ice-like solid that stores gas molecules.

In Wellington, GNS head of marine geoscience Vaughan Stagpoole said it was a significant step forward.

"The technology to develop the resource is only just being developed, and Japan is at the forefront of that."

New Zealand is one of 15 countries looking to extract gas in their territorial waters.

"The key thing is economic viability," Stagpoole said.

"At the moment the costs are high compared to conventional gas production, but I think as the technology develops this will only come down."

New Zealand deposits were similar to those in Japan, he said, but a repeat of the Japanese experiment in New Zealand was unlikely.

"Our main goal is to investigate those deposits on the east coast, map them [and identify] the areas where gas hydrates are likely to be highly concentrated. Drilling is way beyond our budget."

Auckland University senior lecturer Ingo Pecher has researched gas hydrates since the 1990s. He has also been involved in the GNS hydrates project.

"It looks like it's technically feasible to produce offshore gas hydrates - that's a huge step," he said.

"The main obstacle has always been ‘how are you going to get it out of the ground?' That appears to have been solved.

"This is not commercial production, but it is a large step towards . . . a huge potential New Zealand gas resource."

AT A GLANCE

What is methane hydrate? A gas-rich ice crystal that has been called "sorbet-like" and "pure white, shaped like large cornflakes".

New Zealand has some of the biggest methane hydrate deposits in the world, with the potential to meet all New Zealand's needs and create a gas export for decades.

The largest gas hydrate province is on the Hikurangi Margin east of the North Island, with up 5 to 50 trillion cubic feet, compared with the Maui gasfield's 4 tcf at time of discovery.

New Zealand's methane hydrates potential is one of the largest in the world, according to studies by GNS Science, and possibly about 10 times as big as the giant Maui gasfield when it was first found.

The potential has been ignored because of much cheaper conventional gas sources.

- © Fairfax NZ News