The U.S. Geological Survey recently released the first-ever assessment of technically recoverable gas hydrate resources – and as the fall 2008 American Geological Institute/American Association of Petroleum Geologists Science and Public Policy intern, I had the good fortune to listen in as AAPG member Tim Collett, the lead USGS scientist on the assessment team, gave a small group of Congressional staffers a crash course in gas hydrates.
Collett also presented assessment findings during the informal briefing, hosted by the Senate Committee on Energy and Natural Resources.
What is a gas hydrate?
It is a gas molecule, usually methane, encased in a cage of water molecules. Although the gas is surrounded by water, the two molecule types do not chemically bond. Gas hydrates are an ice-like solid that forms under moderate pressures and low temperatures.
These conditions occur naturally in two geologic settings: beneath zones of permafrost and in deepwater continental shelves.
The USGS assessment focuses on a region of permafrost on the North Slope of Alaska, where they estimate 85.4 trillion cubic feet of undiscovered gas resources could be produced from gas hydrates.
To put that into perspective, consider that the United States uses about 23 TCF of natural gas per year, and that the North Slope gas hydrate deposit accounts for 11.5 percent of all undiscovered, technically recoverable gas resources (mostly conventional natural gas) assessed in the onshore and state waters of the United States.
In fact, North Slope gas hydrate resources are comparable in scale to the conventional natural gas resources of the Wyoming Basin.
Gas hydrate deposits also have been identified in many locations around the world and have huge potential as an energy resource – the USGS estimates that the world’s gas hydrate deposits may contain more organic carbon than all coal, oil and conventional natural gas combined.
The history of gas hydrate research and development is a great example of why basic research is important – even if it is not immediately obvious what the applications might be.
Some of the very first research relevant to gas hydrates was conducted in the early 1800s, when scientists formed chlorine hydrates experimentally in a lab. No natural occurrences of this lattice-andguest class of compound, called clathrates, were known at that time, but experiments to determine the various types of molecules that could co-exist in such an arrangement and under what conditions continued simply to satisfy scientific curiosity.
It was not until the 1930s, when gas hydrates were found to be clogging pipes carrying natural gas in cold climes, that the basic research in clathrates finally found an application.
Today the occurrence of naturally forming gas hydrates is known to be globally widespread and a potential major source of energy. The North Slope assessment is the most recent product of more than 25 years of research by the U.S. Department of Energy, USGS and other organizations. Congress formally recognized the need for a nationally coordinated effort to explore the potential of methane hydrates in the Methane Hydrate Research and Development Act of 2000, which was reauthorized in 2005 for another five years.
Much remains to be done before gas hydrates could become a mainstream energy source. For example, the North Slope assessment was based on the assumption that gas hydrates can be produced with technologies used for conventional oil and gas extraction; the DOE is now collaborating with the private sector to field-test production potential of gas hydrates using those existing technologies.
The Senate briefing on gas hydrates was one of those key places where the spheres of science and policy overlap. The USGS North Slope assessment will be a valuable resource for policymakers as they work to design comprehensive new energy legislation in the 111th Congress and beyond.
Attending the briefing on gas hydrates was just one of many experiences I have had as an AGI/AAPG intern in Washington, D.C., that have helped show me how interconnected research (basic and applied) and policy are. Although it is impossible for one person to be deeply involved at all levels, the most effective scientists and policymakers are those who understand how science research, its applications and policymaking are interconnected.
As I continue to pursue a career as a geologist I will have a much greater sense of purpose with this new understanding of the larger context in which I conduct research.
Editor’s note: Merilie Reynolds recently graduated from Smith College with a bachelor’s degree in geology. After completing her internship she accepted a position as exploration geologist with Barrick Gold.