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Life Support: NURP Unfolds the Mystery of Gas Hydrates

 NOAA's Undersea Research Program supports an interdisciplinary array of experts in researching gas hydrate ecosystems and their extraordinary potential as a source of bio-products.

By Taylor Sisk

NURP’s Interest in Gas Hydrates

NURP has been actively involved in gas hydrate research for nearly a decade. “It started about 1993,” says Shepard, “when Harry Roberts at Louisiana State University discovered a gas hydrate mound in the Gulf of Mexico. At the same time, NURP started looking at the oil and gas seeps, because we knew that there were chemosynthetic communities in the Gulf of Mexico. That’s when we ran into the gas hydrate.

“It wasn’t until 1997 that a team of scientists, led by Chuck Fisher, found a new species of iceworm living burrowed into a gas hydrate, probably grazing on the microbes that Dr. Sobecky is after.”

A dense colony of small polychaete worms that live on the surface of methane hydrate.

This dense colony of 1-2 inch polychaete worms was discovered in 1997, living on the surface of a methane hydrate. © Chuck Fisher, Penn State.

 

Carolyn Ruppel and Gerald Dickens confer over science operations plans.

Figure 1. Carolyn Ruppel (Georgia Tech) and Gerald Dickens (Rice) plan scientific operations at the Bush Hill gas hydrate site aboard the R/V Seward Johnson.

Carolyn Ruppel’s hands precede her, shaping the words that just won’t come quite quickly enough. They describe, they mold: the right hand, a cage of solid gas hydrate, intended to represent but one molecule of an untold global store – the left, a sound wave, descending to encounter said hydrate. They’re giving form to a mystery, the mystery of a life, way down deep in the ocean.

Ruppel is an Associate Professor of Geophysics in Georgia Tech’s School of Earth and Atmospheric Sciences (Figure 1). She’s at the forefront of interdisciplinary research into gas hydrates that is engaging a growing number of scientists with divergent interests and expertise.

Gas hydrates are crystalline lattices of gases and water that remain frozen and stable at just the right balance of high pressure and low temperature – conditions found, as we’re now learning, beneath the seafloor all over the globe, generally at depths in excess of 500 meters, as well as in the Arctic permafrost (Figure 2). Light a match to a gas hydrate, and it’ll burn like a candle. In many locations, the primary gas in gas hydrates is methane.

Model of a gas hydrate shows gas molecules trapped within a cage of water molecules.

Figure 2. A gas hydrate consists of a gas molecule (green) trapped in a cage of water molecules (red). © USGS.

Gas hydrates remain a great mystery, but less so every day. Which is why in 2001 the National Oceanic and Atmospheric Administration’s Undersea Research Program (NURP) funded Ruppel and a team of scientists and students, headed by biologist Cyndy Van Dover, to learn more about the Blake Ridge, an area off the coast of South Carolina, where large deposits of gas hydrates are known to occur in the deep sediments.

What’s behind all this attention?

First, we must consider the economic driver: The methane held within gas hydrates may have an astonishing, heretofore unrealized potential as an energy source. It is estimated that the energy potential within is well in excess of that of the Earth’s combined conventional gas reserves.

Second, they’re known to be associated with seafloor stability, a matter of increasing interest to oil companies as they drill ever deeper into the oceans. Drilling through hydrates can cause the gas and water within to separate, potentially destabilizing the sediment on the ocean floor.

Third, the release of methane during meltdown of hydrates is believed to contribute to global warming.

A spider crab in a bed of mussels.

Figure 3. Gas hydrates are inhabited by unique chemosynthetic ecosystems, where organisms create energy through chemical reactions. Pictured here is a spider crab in a bed of mussels. © NURP and Texas A&M.

And, finally, knowledge gained through gas hydrate research is informing the study of the deep biosphere, a largely unexplored frontier in which life forms sustained by means other than photosynthesis have been discovered – discoveries for which we may find numerous practical applications (e.g. bio-products).

The unfolding of the mystery of gas hydrates and of the world in which they live – and the examination of how they might help us humans meet our energy needs – is also an excellent example of interdisciplinary science at work to mutual and manifest benefit.

“There’s been a real convergence of interest [in gas hydrates],” says Ruppel. “We’re all trying to get educated in other, related fields, because to make fundamental breakthroughs in science now, we’re going to have to think in a more integrative way; we’re going to have to rely on people who are not in our area of expertise.”

Andrew Shepard understands full well the importance of an interdisciplinary approach to a venture as complexly textured as the understanding of gas hydrates. Shepard is Associate Director of the National Undersea Research Center at the University of North Carolina at Wilmington, one of six NURP Centers across the U.S., which supports undersea research off the southeastern coast of the U.S. and in the Gulf of Mexico. Interdisciplinary effort, he says, “is really the only way you should do these kinds of expeditions. Due to the time and resources required, the opportunities you get are very rare.”

NURP has been actively involved in gas hydrate research for nearly a decade. NURP realized long ago that hydrates and the deep-sea biosphere hold tremendous potential for advancing scientific knowledge and useful applications. Among the uses of extremophiles – organisms that thrive in extreme environments without light – recovered from land and sea are bio-products that have been used for cancer detection, DNA amplification in criminal cases, and proteases and lipases for dairy products (Figure 3).

How much gas hydrate is out there? No one knows for certain. But Bilal Haq of the Division of Ocean Sciences at the National Science Foundation, wrote in 1999: “Even relatively conservative estimates indicate that on the order of 10,000 gigatons of carbon, or double the amount of all known fossil fuel sources, may be stored in gas hydrates.”

On May 2, 2000, Bill Clinton signed the Methane Hydrate Research and Development Act, authorizing a $47.5 million, five-year program for research of gas hydrates. Interest continues to rise; uncertainties are many.

“The reasons hydrate can be difficult to view as an energy resource,” says Ruppel, “are primarily related to the technological advances we’re going to need. There is a demonstration project that’s aimed at producing methane from gas hydrate as an alternative energy resource. Some of the technological problems include difficulty extracting the resource and, even more fundamentally, locating the resource.

“It’s going to require an investment of intellect and energy and time to really move from what we know in the lab or on the basis of computer models to understanding the so-called ‘dirty system’” – in other words, in the real world, which is complicated and heterogeneous and very unlike a lab, which can be arranged just so.

“My guess,” says Patricia Sobecky, an Assistant Professor of Microbiology at Georgia Tech whose work is very much interrelated to Ruppel’s, “is that once you know what the microbes are doing, once you know the activity, once you know the rate, then you can answer the question of whether they’re renewable and on what kind of time scale we’re talking – days, months, years, decades?”

Which is precisely what Carolyn Ruppel’s hands are doing at this moment: molding the broader perspective. It’s exciting work.


Additional information about Carolyn Ruppel's research on gas hydrates can be found at:
http://hydrate.eas.gatech.edu/gthydrates/

 

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Updated: August 18, 2004