Ice That Burns May Eventually Warm Us All

Flammable ice is becoming a hot topic in Alaska.

Methane hydrate, a chemical combination of methane and water that looks like dirty ice, will ignite when touched by a lit match. This curious contradiction has fueled hopes that methane hydrate may be the world's great untapped energy source. With those hopes also come fears that these dirty ice deposits may contribute to global warming.

Methane hydrate is found in and around Alaska because it forms naturally in the deep ocean and below or in permafrost. At low temperatures and under high pressure, water molecules form "cages" that contain molecules of methane gas, said Keith Kvenvolden of the U.S. Geological Survey in Menlo Park, Calif. When methane hydrate is warmed, the cage walls disintegrate, liberating methane, the main ingredient in natural gas. Methane is the product of bacteria that consume organic matter in non-oxygenated places, such as in the sea floor, in the earth under permafrost, and in the stomachs of cows and moose.

The carbon locked up as methane hydrate in the earth's oceans and permafrost areas is double the amount of carbon in the combined reserves of oil, coal and conventional natural gas, according to a recent Science News article. With ample supplies of deep ocean floors and permafrost, Alaska no doubt holds an impressive amount of methane hydrate.

Oil companies have known about the abundant substance since drill rigs began biting into methane hydrate deposits in the 1970s. Soon, developers will try to tap this energy source. In early 1998, Japanese National Oil Company workers will drill into deposits of methane hydrate near Prudhoe Bay, Kvenvolden said. The Japanese hope to learn cost-effective methods of how to extract methane from the methane hydrate. A country without many natural energy sources, Japan has large offshore deposits of methane hydrate that might be exploited.

Because the water cages of methane hydrate pull methane molecules closer together than they would be in open air, methane hydrate traps an impressive amount of methane. When exposed to temperatures and an atmospheric pressure humans are comfortable in, one cubic meter of methane hydrate expands to 164 cubic meters of methane and 0.8 cubic meters of water, Kvenvolden said.

There's a lot of methane down there, and tests such as those the Japanese will conduct near Prudhoe Bay next year will determine whether fuel-peddling companies can make a go at extracting it.

The downside to these tremendous stores of methane is what might happen if enough of it escapes into the atmosphere. Methane, like water vapor and carbon dioxide, is a greenhouse gas. Methane molecules floating in the atmosphere intercept heat from the earth and radiate it back to the surface rather than letting heat drift into the upper atmosphere. More methane added to other greenhouse gases in the atmosphere may warm the planet.

A warmer planet may, in turn, increase the amount of methane released by methane hydrate. If warmer weather melts polar ice caps, for instance, sea level will rise and flood coastal areas that are underlain by permafrost. If methane hydrate deposits exist under that permafrost, the relatively warm sea water will melt the methane hydrate, releasing methane. But the escape of methane would probably take about 10,000 years after ocean water touches permafrost, said Tom Osterkamp, a Geophysical Institute professor of physics.

If it turns up Earth's thermostat, methane hydrate will be a very bad thing for humankind. Or it may be a very good thing. Or it may not noticeably affect us. The only sure thing is that those two words will be mouthed by many Alaskans in the next few years.