OREGON STATE UNIVERSITY

Quarter century later, methane deposits intrigue scientists, industry

07/13/2011

CORVALLIS, Ore. – A quarter-century after the discovery of methane seeps in the Pacific Ocean – cold undersea vents associated with deposits of gas hydrates – researchers are still trying to figure out whether this is an energy resource that can be extracted, or poses a potential environmental threat because of climate change.

One of the scientists who first located those methane seeps in 1985 off the coast of Oregon is being honored this month (July 17-21) with a lifetime achievement award at the seventh International Conference on Gas Hydrates in Edinburgh, Scotland.

Erwin Suess was an oceanographer at Oregon State University when he and his colleagues found the seeps. He subsequently moved to GEOMAR, a marine research center in Germany, where he collaborated with colleagues at OSU on seep research for many years.

In 1996, an international expedition with researchers from Oregon State, Germany, Canada and Japan located a rich methane hydrate deposit within a seep field about 55 miles off the Oregon coast. The location has since become known as Hydrate Ridge and is a famous site for gas hydrate research. That discovery has launched numerous international initiatives and piqued the interest of scientists and industry leaders, who are intrigued by the potential of the deposits and frustrated by the complexities.

Though the methane hydrate deposits are rich, the hydrates are highly unstable and the cost of extracting them has precluded an industrial push – so far. But the interest in hydrates has evolved over the years from initial thoughts of extraction, said Suess, a professor emeritus of the University of Kiel in Germany, and a courtesy faculty member in OSU’s College of Oceanic and Atmospheric Sciences.

“Views about gas hydrates have changed a lot over 25 years,” Suess said. “They were first looked at as an energy resource, and then as a potential means for mitigating atmospheric carbon dioxide. Now gas hydrates are looked at as a potential danger if global warming continues and methane is released.”

Gas hydrates are crystalline substances that look like packed snow, or ice. They form when water and methane are combined at high pressure and low temperature. Commonly found along the continental margins, they are created from the natural gas that occurs after decomposition of organic material within ocean sediments.

Marta Torres, an Oregon State University marine chemist who has worked with Suess, says worldwide deposits of methane hydrates are significant, yet remained untapped.

“When you bring a piece up from deep water, it just melts,” Torres said. “As soon as these methane chunks get warm, or the pressure eases, they disappear and the methane escapes into the ocean or atmosphere, unless it is trapped and confined.”

In recent years, scientists began looking at methane hydrates as a way to sequester carbon dioxide and mitigate global warming. The approach, Suess said, involves pumping liquid CO2 deep into a methane hydrate deposit to create an exchange – a carbon dioxide hydrate would form and remain trapped at depth, while releasing methane gas that could be tapped.

Several patents exist on the technology and a pilot test was scheduled – until the Gulf of Mexico oil spill derailed plans, said Suess, who has published extensively on the topic.

"There is a lot of resistance to even testing the idea, especially in Europe,” he said.

Now the concern about gas hydrates has shifted toward global warming and what may happen if those undersea deposits become destabilized if the oceans warm significantly. Suess said that such an event may have happened long ago.

“Fifty-five million years ago, there was a hot period in our Earth’s history that include a high level of CO2, which has not been explained,” he pointed out. “At least one group of scientists believes that the cause was a methane hydrate release into the atmosphere.”

Suess says there are several hundred methane seeps now known around the world, usually occurring in subduction zones where tectonic plates are colliding. When he and his colleagues documented the first methane seep back in 1985, however, it was a significant discovery.

Suess is being honored this month at a major international meeting of gas hydrate scientists and industry participants. Nearly 900 people are expected at the event, which takes place every three years.