Alaska ice tested as possible new energy source


The U.S. Department of Energy and industry partners over two winters drilled into a reservoir of methane hydrate, which looks like ice but burns like a candle if a match warms its molecules. There is little need now for methane, the main ingredient of natural gas. With the boom in production from hydraulic fracturing, the United States is awash in natural gas for the near future and is considering exporting it, but the DOE wants to be ready with methane if there's a need.

"If you wait until you need it, and then you have 20 years of research to do, that's not a good plan," said Ray Boswell, technology manager for methane hydrates within the DOE's National Energy Technology Laboratory.

The nearly $29 million science experiment on the North Slope produced 1 million cubic feet of methane. Researchers have begun the complex task of analyzing how the reservoir responded to extraction.

Much is unknown but interest has accelerated over the last decade, said Tim Collett, a research geologist for the U.S. Geological Survey in Denver.





Most deposits are below the sea floor off the continental shelf or under permafrost. Shallow pockets of methane hydrate release the potent greenhouse gas into the atmosphere and that process is exacerbated by climate warming.




Not all is accessible, but high concentrations in permeable rock where there's existing drilling infrastructure would be among early candidates for development. The USGS in 2008 estimated 85 trillion cubic feet of undiscovered, technically recoverable gas within methane hydrate deposits on Alaska's North Slope.

It will not be simply dug out of the ground, Boswell said.


Methane could be extracted by lowering pressure or increasing temperature in an underground reservoir.

"One of the issues with that, though, is that you are melting the ice, and adding a lot of gas and water to the reservoir, which can compromise the reservoir's strength," Boswell said.

The Alaska research focused on a method aimed at preserving the underground ice structure. The extraction technique was based on studies done by ConocoPhillips and the University of Bergen in Norway. Researchers in a laboratory injected carbon dioxide into methane hydrate. CO2 molecules swapped places with methane molecules, freeing the methane to be harvested but preserving the ice.


Researchers injected 210,000 cubic feet of carbon dioxide and nitrogen into the underground reservoir through perforated pipe. Instruments measured pressure, temperature and produced gases. They tracked injected gases without fracturing the formation.

Scientists collected data from 30 days of methane production, five times longer than anyone had done before. They are now trying to determine if methane produced was from an exchange with CO2, a reaction to the nitrogen, or a reaction to pressure changes down the hole.

Researchers are optimistic.
