SINGAPORE — Starting this month and extending through May, South Korea will resume exploratory drilling in waters off its east coast to find out whether a long-hidden energy resource can be turned into a new wellspring of natural gas. Other major energy users and importers, including the United States, China, Japan and India, are in the midst of similar research and development programs to unlock what they hope will be a treasure trove of methane hydrates on land and at sea. All of them aim to be in commercial production by 2020 at the latest.

Gas hydrates have very high energy yield. One cubic meter of methane extracted from hydrate expands into 164 cubic meters of regular natural gas, the least-polluting of fossil fuels. Gas hydrates are icelike compounds of methane and water molecules, and are so far untapped on large scale. They are concentrated in permanently frozen (permafrost) land zones, such as the Arctic and China’s Qinghai-Tibetan plateau, and offshore in sediments on the continental shelf margins of many countries.

The full extent of the global gas hydrate resource is gradually being uncovered. Although there is still much to learn, energy specialists estimate it may amount to between 1,000 and 10,000 billion metric tons — or as much as twice the known reserves of conventional fossil fuels (coal, oil and natural gas).

A U.S. government-energy industry partnership last month announced that recent drilling and seismic surveys had confirmed high saturations of methane hydrate in reservoir-quality sands under the seabed in U.S. waters in the Gulf of Mexico, already a major production zone for conventional gas and oil.

At a cost of $37 million, South Korea has hired a deep-water drilling ship to sink 32 holes over the next few weeks in a sea basin south of the Dokdo Islands, which are disputed with Japan. South Korean officials say that initial estimates indicate there is enough recoverable methane in the hydrate deposit to meet the country’s gas demands for up to 30 years.

China has recovered small amounts of methane hydrate from the South China Sea. Chinese officials last month said that land deposits found in permafrost areas of the Qinghai-Tibetan plateau were estimated to contain the equivalent of at least 35 billion metric tons of oil, enough to supply the country for 90 years.

Japan has spent more than $260 million since 2001 on research into methane hydrates and plans to start deep-sea drilling trials in 2012. The main focus of its program is the Nankai Trough, about 50 km off the Pacific coast of the island of Honshu.

However, there are challenges. For one, it has so far proven difficult to extract the methane from the hydrates in a continuous and cost-effective way. In addition, some scientists are concerned that exploiting the resource could intensify climate change. Methane from wetland rice farming, sheep and cattle grazing, urban landfills and other sources already accounts for about 17 percent of greenhouse-gas emissions resulting from human activity, second only to carbon dioxide. When released into the atmosphere unburned, methane is at least 25 times more potent as a global-warming gas than carbon dioxide (although it only persists for a decade or so, versus over a century for much of the CO2.

A team of Russian, American and Swedish scientists last month reported that a relatively shallow section of the Arctic Ocean seafloor that holds vast stores of gas hydrate is showing signs of instability and widespread venting of methane into the atmosphere. However, it is not clear whether these emissions are new and are being triggered by the increasing temperature of bottom waters, or whether they have been there unnoticed for decades or longer.

In its most recent annual report on greenhouse gas emissions, the U.S. National Oceanic and Atmospheric Administration reported that in 2008 methane levels rose for the second consecutive year, after a 10-year lull.

The annual report for 2009 is due later this month. In its report for 2007, the NOAA said that rapid industrialization in Asia and rising wetland emissions in the Arctic and tropics were the most likely causes of the recent methane increase.

“We’re on the lookout for the first sign of a methane release from thawing Arctic permafrost,” said NOAA scientist Ed Dlugokencky. It was too soon to tell whether the spike in emissions of methane since 2007 marked the start of a sharply rising trend, he said.

Methane hydrate promises to be a relatively clean fuel source for the future. But as commercial development proceeds, governments and the energy industry will need to put safeguards in place to ensure that it does not intensify global warming and cause dangerous climate change.

Michael Richardson is a visiting senior research fellow at the Institute of South East Asian Studies in Singapore.

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