Fire and Ice
Will Methane Hydrates Help Power the World in 2020?
Research over the last decade has shown that the oceans around the United States hold immense amounts of methane (the primary component of natural gas) concentrated in cage-like ice structures known as methane hydrates. Occurring naturally both in permafrost regions where cold temperatures persist in shallow sediments, and at ocean depths of 500 meters or more where high pressures dominate, these unique structures encase methane at very high concentrations. In fact, a single unit of hydrate can release as much as 160 times its volume in gas when heated and depressurized.
Hydrates are typically found a few meters below the ocean floor in layers a few hundred meters thick. The majority of methane hydrates were formed from accumulations of biogenic methane excreted by deep-sea bacteria over thousands of years. These hydrates are concentrated in areas of organic detritus accumulation or where rapid accumulation of sediments protected the detritus from oxidation. Another less prominent source of hydrates occurs when natural gas migrates up through faults in the Earth's crust to areas of the seabed with sufficient pressure and temperature. Although less common, many geologists believe that these type of hydrates will be easier to recover because of their more localized distribution.
The sheer magnitude of methane hydrate deposits obliges us to explore this potential energy source. Although once considered a nuisance that in colder climates plugs up natural gas pipelines or, at best, a laboratory oddity, if only 1 percent of the methane hydrate resource could be made technically and economically recoverable, the United States could more than double its domestic natural gas resource base.
In 1995, the United States Geological Survey (USGS) completed the most comprehensive assessment of U.S. gas hydrate resources. This assessment, which was revised in 1997, determined that, to date, about 200,000 Trillion Cubic Feet (Tcf) of gas have been identified off our coasts and in Alaskan permafrost deposits. This incredible reserve dwarfs the United States' 1,400 Tcf of conventional reserves. Worldwide estimates are similarly staggering. They approach 400 million Tcf -- several orders of magnitude greater than the 5,000 Tcf that make up the world's known gas reserves. Thus, even a small fraction of this huge energy source could satisfy the current level of world energy consumption for several thousand years.
Of course the enormous hydrate reservoirs are of little use unless economically profitable techniques are devised to extract the methane. Unfortunately, the current level of technology and the market rate for gas from land-based reserves make extracting methane hydrates uneconomical. Other factors may also hinder development.
Drilling several hundred meters into potentially explosive gas fields is a risky proposition. Some scientists fear that drilling could destabilize hydrate deposits, triggering major submarine landslides. Around 7,000 years ago, unstable gas hydrates caused a huge landslide off Norway that produced a tidal wave that swamped much of the Shetlands.
The role of methane hydrates in a warming world is also a concern. Much of the gas hydrate in the world is close to melting and a slight temperature increase may induce a massive release of methane gas -- a greenhouse gas 10 to 20 times more powerful than carbon dioxide. Additionally, there are concerns that a vast new source of fossil fuels will only serve to delay the adoption of more climate-friendly renewable energy technologies.
Federal R&D that helps find technological solutions to these problems may be a wise investment in America's future. Natural gas is certain to take on a greater role in power generation due to increasing pressure for clean fuels and the relatively low capital and operating costs of new natural gas-fired power equipment. Hydrates also have the inherent advantage of reducing dependency on foreign oil imports.
Maintaining U.S. leadership in energy technologies is critical. Several resource-poor countries like Japan and India have already begun researching methane hydrates. The Japan National Oil Company has invested $60 million on a hydrate research program and was the first to attempt a large-scale drilling operation in November of 1999.
Next Section: Water World: Powering the Nation with Hydrogen