There’s no doubt that methane hydrates could offer a major source of fuel, with recent estimates suggesting they constitute about a third of the total carbon held in other fossil fuels such as oil, gas and coal. Several nations, notably Japan, want to extract it. It is not hard to find, often leaving a characteristic seismic signature that can be detected by research vessels. The problem is retrieving that gas and bringing it to the surface.

“One thing that’s clear is that we’re never going to go down and mine these ice-like deposits,” says Carolyn Ruppel, who leads the US Geological Survey’s Gas Hydrates Project.

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It all comes down to physics. Methane hydrates are simply too sensitive to pressure and temperature to simply dig up and haul to land. They form at typically several hundred metres beneath the seafloor at water depths of about 500 metres, where pressures are much higher than at the surface, and temperatures are close to 0C. Take them out of these conditions, and they begin to break down before the methane can be harnessed. But there are other ways to do it.

“Instead, you have to force those deposits to release the methane from the formation in the seafloor. Then you can extract the gas that comes off,” says Ruppel.