February 29, 2004
Ocean Gas Hydrate Estimates Seen As Too High

Previous estimates of natural gas bound up in ocean floor hydrates may be too high.

One widely cited estimate proposes that 10,000 gigatonnes (Gt) of methane carbon is bound up as hydrate on the ocean floor.

But Dr Alexei Milkov of BP America says his research shows reserves are between 500 and 2,500 Gt, a significantly smaller figure than has been previously estimated.

Gas hydrates are still very expensive to extract from the ocean floor.

"Drilling gas hydrates is estimated to be six times more expensive than exploitation of oil and other gas sources," said Prof Bahman Tohidi, director of the Centre for Gas Hydrate Research in Edinburgh.

Even the lower estimate is still a huge amount of energy. To put it in perspective, from 1850 thru 2000 the total amount of natural gas burned in the world was only 61 gigatonnes measured in oil equivalent weight. (not sure how that compares to the gigatonnes figures above though) Gas hydrates researcher Anne Trehu at Oregon State University says previous models may be too high in some cases but there is still a lot of gas hydrate methane in the oceans.

Trehu and her colleagues have found that some widely cited previous models estimating the total mass of methane trapped in marine sediments are probably too high.

On the other hand, some local concentrated deposits may be larger than previously thought. “There is still a lot of methane out there, even if the models were wrong,” Trehu said.“

Arthur H. Johnson, Chairman and Chief Executive Officer of Hydrate Energy International, presented Congressional testimony in June 2003 on the potential of gas hydrates as an energy source.

Gas hydrate is a crystalline substance composed of gas and water. It forms when water and natural gas combine under conditions of moderately high pressure and low temperature. If gas hydrate is either warmed or depressurized it will revert back to water and natural gas, a process termed “dissociation”. Natural gas is concentrated in hydrate so that the dissociation of a cubic foot of hydrate will yield 0.8 cubic feet of water and approximately 160 cubic feet of natural gas. The conditions where hydrates occur are common in sediments off the coasts of the United States in water depths greater than approximately 1600 feet and at shallower depths in sediments associated with deep permafrost in the Arctic. Preliminary investigations indicate that considerable volumes of gas hydrate are present in at least some of these areas.

The total volume of gas hydrate in the United States is not known, although the results of a wide variety of investigations conducted over the past thirty years indicate that the volume is very large, on the order of hundreds of thousands of TCF. More important, however, is the amount of hydrate that can be commercially recovered. Characterization of hydrate resources that has been carried out, for example in the MacKenzie Delta of Canada, the North Slope of Alaska, offshore Japan, and elsewhere indicate that the total in less explored areas of the U.S. hydrate province is likely in the range of many thousands of TCF.

Gas hydrate investigations have been undertaken by many Federal agencies during the past 30 years. These include the U.S. Geological Survey, Naval Research Laboratory, National Science Foundation, and Department of Energy. The Methane Hydrate Research and Development Act of 2000 initiated a new program to study several aspects of gas hydrates, including seafloor stability, global climate change, and the potential of gas hydrate as a commercial resource. The resource target has been for production in the year 2020. Funding for the new program, which is managed by the DOE, has typically been on the order of $10 million per year.

Given the potential of gas hydrates as a huge energy source the $10 million per year spent on research by the US government strikes me as chump change. The United States spends tens of billions more on the military than it would if it was not dependent on Middle Eastern oil. Therefore basic research funding in alternative energy sources ought to be funded at a level commensurate with the recognition of how much Middle Eastern oil costs us in defense spending, money spend on aid in the region in order to achieve foreign policy goals, and in increased spending in homeland defense against the threat of terrorism.

For national security arguments on why energy research should be accelerated see my previous ParaPundit posts Intervention In Liberia Linked To Oil Dependency and Michael Scott Doran: The Saudi Paradox and China Energy Consumption Growth Complicates Anti-Terrorist Efforts.

Also see my previous post Natural Gas May Be Extractable From Ocean Gas Hydrates.

Share |      Randall Parker, 2004 February 29 03:55 PM  Energy Tech

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