Major Energy Source Could Be Trapped In Ice Beneath Seas But Tapping, Burning Methane Could Be Ecological Disaster

Ice that burns? Yes, and so much of it that it could meet America’s natural gas needs for decades. But scientists have yet to figure out how to mine it without causing an environmental disaster.

Methane trapped in the pores of ice forms a frozen compound called gas hydrate. Vast deposits are held at high pressure 1,500 feet under the ocean floor on continental shelves around the world.

“It looks like dry ice, but if you put a lighted match to it, it will burn,” said David Howell of the U.S. Geological Survey. “It’s actually ice that burns.”

By some estimates, twice as much carbon energy is contained in gas hydrate as in all fossil fuels combined.

Harvesting that energy bonanza may be one of the great engineering challenges of the age, a panel of experts said Monday at the national meeting of the American Association for the Advancement of Science.

Gas hydrate forms under the seabed or under permanently frozen soil when methane, produced by biological action, collects as bubbles within water ice over hundreds of thousands of years.

Released from the pressure of the deep, the ice disappears within minutes.

“If you bring it to the surface, it bubbles and fizzes and is gone,” said Charles Paull of the University of North Carolina. “It’s difficult to study something that is fizzing away in front of you.”

There are serious environmental concerns about tampering with the hydrate deposits, said William P. Dillon of the U.S. Geological Survey.

An accident could cause ocean floor avalanches, leading to a sudden release of methane.

“Methane from the hydrate reservoir might significantly modify the global greenhouse,” said Dillon.

Gas hydrate deposits contain about three times the amount of methane now in the atmosphere, and methane has a greenhouse effect 10 times that of carbon dioxide. Both carbon dioxide and methane in the atmosphere trap heat about the Earth. Some scientists fear that an increase in the two gases could lead to global warming and a significant change of the world’s climate.

Paull is scientific leader of an expedition that will drill off the Carolina coast later this year to explore a Rhode Island-sized hydrate deposit that may contain 1,300 trillion cubic feet of methane. That’s enough gas to supply the U.S. for about 70 years.

Paull said an airtight container will be lowered into the deposit, filled with the ice and then sealed to keep the material at high pressure. It then can be brought up and studied in pressure chambers.

Researchers have proposed several ways of harvest hydrate energy. All involve making the gas escape from the ice while it is still in place under the ocean floor. The gas could then be captured and piped to the surface. There is doubt, however, that any of the methods will work.

“We don’t know now if we will be able to extract it for use,” said Paull. “It will involve a technique that is yet to be developed. That’s way out in the future.”