Photo: Wikimedia Commons
A half mile below the ground at Prudhoe Bay, above the vast oil field that helped trigger construction of the trans-Alaska pipeline, a drill rig has tapped what researchers think could be the next big 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.
The nearly $29 million science experiment on the North Slope produced 1 million cubic feet of methane, according to the Associated Press.
Now, researchers have begun the complex task of analysing how the reservoir responded to extraction.
“If you wait until you need it, and then you have 20 years of research to do, that’s not a good plan,” Ray Boswell, technology manager for methane hydrates within the DOE’s National Energy Technology Laboratory, remarked.
Much is unknown but interest has accelerated over the last decade, Tim Collett, a research geologist for the U.S. Geological Survey in Denver, added.
U.S. operators in Alaska, he said, may want to harvest methane so they can re-inject it into the ground. Crude oil is more lucrative than natural gas, which is routinely injected into North Slope fields to maintain underground pressure to aid in oil extraction. Japan, Korea, India and China, however, want to cut down on natural gas imports by burning methane. Japan is setting up for a production test on a gas hydrate accumulation in the Nankai Trough south of Honshu, its main island.
“That will be the first marine gas hydrate test anywhere in the world,” Collett said.
The U.S. Energy Department describes methane hydrate as a lattice of ice that traps methane molecules but does not bind them chemically. They are released when warmed or depressurized.
Methane comes from buried organic matter after it’s ingested by bacteria or heated and cooked. The gas migrates upward, under high pressure and low temperature, and can combine with water to form methane hydrate.
But global warming fears inevitably arise when there is discussion of a new source of energy.
Most deposits are below the sea floor off the continental shelf or under permafrost, and the Associated Press writes that shallow pockets of methane hydrate release a potent greenhouse gas that would exacerbate climate change.
Brendan Cummings of the centre for Biological Diversity said research money should be poured into renewable resources, not more fossil fuel sources. Methane is 20 times more effective at trapping heat in the atmosphere than CO2, though not as long-lived.
“Any exploration activities designed to extract methane hydrates run the risk of unintended consequences, of unleashing the monster,” he said. Even if methane is extracted safely, burning it will add to climate warming, he said.
The world has a lot of methane hydrate, though not all of it is accessible. A Minerals Management Service study in 2008 estimated methane hydrate resources in the northern Gulf of Mexico at 21,000 trillion cubic feet, or 100 times current U.S. reserves of natural gas. The combined energy content of methane hydrate may exceed all other known fossil fuels, according to the DOE.
And it will not be simply dug out of the ground, Boswell noted.
“One of the basic messages is, we’re not mining,” he said. “It’s using existing drilling techniques.”
The Alaska research focused on a method aimed at preserving the underground ice structure. Researchers in a laboratory injected carbon dioxide into methane hydrate, and CO2 molecules swapped places with methane molecules– freeing the methane to be harvested but preserving the ice.
The DOE worked with ConocoPhillips and Japan Oil, Gas and Metals National Corp. to see if it would work in the field. They named the North Slope well Ignik Sikumi, an Inupiat Eskimo phrase that translates as “fire in the ice.”
Researchers are optimistic.
“From the lab data we had, it seemed like it was some strong evidence that it was not a lot of wholesale destruction of the solid hydrate,” Boswell said.
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