Offshore deposits of methane hydrate are a promising but little-understood energy source, experts say. The environmental impact would appear to be mixed, however.
TOKYO — Japan said Tuesday that it had extracted gas from offshore deposits of methane hydrate — sometimes called “flammable ice" — a breakthrough that officials and experts said could be a step toward tapping a promising but still little-understood energy source.
The gas, whose extraction from the undersea hydrate reservoir was thought to be a world first, could provide an alternative source of energy to known oil and gas reserves. That could be crucial especially for Japan, which is the world’s biggest importer of liquefied natural gas and is engaged in a public debate about whether to resume the country’s heavy reliance on nuclear power.
Experts estimate that the carbon found in gas hydrates worldwide totals at least twice the amount of carbon in all of the earth’s other fossil fuels, making it a potential game-changer for energy-poor countries like Japan. Researchers had already successfully extracted gas from onshore methane hydrate reservoirs but not from beneath the seabed, where much of the world’s deposits are thought to lie.
The exact properties of undersea hydrates and how they might affect the environment are still poorly understood, given that methane is a greenhouse gas.
Japan has invested hundreds of millions of dollars since the early 2000s to explore offshore methane hydrate reserves in both the Pacific and the Sea of Japan. That task has become all the more pressing after the Fukushima Dai-ichi nuclear crisis, which has all but halted Japan’s nuclear energy program and caused a sharp increase in the country’s fossil fuel imports. Japan’s rising energy bill has weighed heavily on its economy, helping to push it to a trade deficit and reducing the benefits of the recently weaker yen to Japanese exporters.
The Japanese Ministry of Economy, Trade and Industry said a team aboard the scientific drilling ship Chikyu had started a trial extraction of gas from a layer of methane hydrates about 300 meters, or 1,000 feet, below the seabed Tuesday morning. The ship has been drilling since January in an area of the Pacific about 1,000 meters deep and 80 kilometers, or 50 miles, south of the Atsumi Peninsula in central Japan.
With specialized equipment, the team drilled into and then lowered the pressure in the undersea methane hydrate reserve, causing the methane and ice to separate. It then piped the natural gas to the surface, the ministry said in a statement.
Hours later, a flare on the ship’s stern showed that gas was being produced, the ministry said.
“Japan could finally have an energy source to call its own," said Takami Kawamoto, a spokesman for the Japan Oil, Gas and Metals National Corp., or JOGMEC, the state-run company leading the trial extraction.
The team will continue the trial extraction for about two weeks before analyzing how much gas has been produced, JOGMEC said. Japan hopes to make the extraction technology commercially viable in about five years.
It is unclear how much the tapping of methane hydrate would affect Japan’s emissions or global warming. On one hand, natural gas would provide a cleaner alternative to coal, which still provides Japan with a fifth of its primary energy needs. But new energy sources could also prompt Japan to slow its development of renewable energies or green technologies, hurting its emissions in the long run. Any accidental release of large amounts of methane during the extraction process would also be harmful.
JOGMEC estimates that the surrounding area in the Nankai submarine trough holds at least 1.1 trillion cubic meters, or 39 trillion cubic feet, of methane hydrate, enough to meet 11 years’ worth of gas imports to Japan.
A separate rough estimate by the National Institute of Advanced Industrial Science and Technology has put the total amount of methane hydrate in the waters surrounding Japan at more than 7 trillion cubic meters, or what researchers have long said is closer to 100 years’ worth of Japan’s natural gas needs.