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The new boom in natural gas from shale has changed America's energy economy and there are giant reservoirs of gas under the ocean floor all over the globe which could dwarf shale gas. No one had tapped this gas from the seabed until this week, when Japanese engineers drilled it up from beneath the Pacific. As NPR's Christopher Joyce reports, scientists are still trying to figure out how to get at this ocean of natural gas and whether it poses any risks.
CHRISTOPHER JOYCE, BYLINE: The stuff we're talking about is called methane hydrates. Methane is natural gas; hydrate means there's water in it. In this case, it's molecules of gas trapped inside a sort of cage of water molecules. Only a few people have actually seen methane hydrates. Ann Cook, a geophysicist at Ohio State University, is one of them.
ANN COOK: If you think about snow freezing in mud, that's what it would look like. You would think, oh, that's not so interesting, but then if you decided to, like, light it on fire, it would burn right in front of you.
JOYCE: You can find methane hydrates under land in the Arctic, in frozen soil called permafrost. But most of it lies under the sea floor, where it's very cold and under high pressure. It took millions of years for it to form, mostly from microbes eating dead plankton.
COOK: Those tiny little things that you can't see, and when those things die, they sort of rain down onto the ocean floor, and then later on that organic matter is eaten by little microbes, and in the eating process they spit out methane.
JOYCE: Scientists have brought up samples of the stuff and actually tapped clean gas from reservoirs under land. But only this week have they tapped an undersea reservoir. It was a Japanese crew drilling in the Pacific. There could be a lot of this gas. The U.S. government estimates that along U.S. coastlines there could be enough to supply the country for decades.
But there could be hazards in getting to it. Methane is a powerful greenhouse gas. If a lot of it escapes into the atmosphere, it could hasten global warming. Geologist Timothy Collett with the U.S. Geological Survey says it's still too early to either bet on a bonanza or worry about the climate.
TIMOTHY COLLETT: So anyone who gives you a definitive answer, including me, about the potential of it being either a climate issue, being a hazard, or being a resource, has got a 50-50 shot of being accurate, you know. So we don't know enough.
JOYCE: But not for lack of trying. The Department of Energy has been spending about $10 to $15 million a year studying methane hydrates. Ray Boswell is the technical manager on this at DOE's National Energy Technology Laboratory. He says drilling for them in the seabed doesn't really pose a risk of becoming some sort of gusher because methane hydrates like to stay put where they are.
RAY BOSWELL: You will have to exert constant effort to push the hydrate into an unstable condition. So our issue with gas hydrate production is not a runaway reaction. The challenge is figuring how to keep it going.
JOYCE: But the story on methane hydrates isn't just about drilling them up. There's lots of methane bound up in the Arctic permafrost and Boswell says that over the past 10,000 years the sea level has been rising and continues to rise. And when water inundates that permafrost, the methane could come bubbling up into the atmosphere and warm it - at least theoretically.
That process could take thousands of years though. Scientists agree there's lots to learn about these huge reservoirs of natural gas. In the meantime, though, several countries that are hungry for new energy sources - Japan, South Korea, China and India - are mounting drilling expeditions to get it out of the seabed and into pipelines. Christopher Joyce, NPR News.