The so-called shale gas revolution has changed the face of the energy industry in the United States. Natural gas production in the United States is at an all-time high. Proposals for, and the actual construction of, liquefied natural gas export terminals in the United States have replaced plans for liquefied natural gas import terminals. But shale gas deposits as a proportion of global natural gas supplies may seem minor in comparison to methane hydrates.
Methane hydrates form at a specific range of low temperatures and high pressures. They occur in the Arctic permafrost and along continental slopes, typically at water depths greater than 500 meters (1,640 feet). Once considered only a hindrance to conventional extraction, emerging technologies to tap methane hydrates mean they now have the potential to alter the global energy outlook. Estimates for total methane hydrate gas in place are rough, but range anywhere from 3,000 trillion cubic meters to more than 140,000 trillion cubic meters, the large range illustrating the uncertainty of the estimate. By comparison, combined global technically recoverable conventional natural and shale gas reserves total roughly 640 trillion cubic meters. (In 2011, global natural gas consumption stood at approximately 3.4 trillion cubic meters.)
Despite the promise of methane hydrates, the technology for their extraction is still under development, and potential risks have not been neutralized. These include the uncontrolled release of natural gas formerly trapped in ice, which could result in large amounts of the greenhouse gas methane entering the atmosphere. They also include the possibility of destabilizing the ocean floor, leading to underwater landslides and subsequently the possible sinking of drilling rigs.
Drilling likely will be required to access the natural gas in the hydrates. A number of drilling techniques could be used to destabilize the equilibrium of the hydrates and release natural gas. These include thermal injections, which involve increasing temperatures, often by injecting steam, to dissociate the gas. They also include depressurization, or reducing the pressure of the formation to release the gas. Finally, and perhaps most promising, is carbon dioxide injection. In this process, carbon dioxide essentially replaces the natural gas within the hydrate, allowing for the release of natural gas and the capture of carbon dioxide.
Research programs focused on methane hydrate detection and extraction can be found in numerous nations, including Japan, South Korea, India, China, Norway, the United Kingdom, Germany, the United States, Canada, Russia, New Zealand, Brazil and Chile. Much of the initial research has been highly collaborative, with the government and private companies from the United States playing a prominent role.