Large quantities of methane hydrates exist in deep ocean sediments and arctic permafrost. The energy content of hydrocarbon fuel gases (mostly methane) trapped in these ice-like solids is believed to exceed the total of all other conventional fossil fuels (i.e., oil, natural gas, and coal). Purposeful or inadvertent destabilization of natural hydrate accumulations could also result in slope failures and the release of methane, a potent greenhouse gas. In consideration of these factors, the U.S. Government established a national methane hydrate R&D program in 2000 to explore hydrates as a potential future energy resource and to evaluate associated safety hazards and impacts on the local and global environment. Although commercial production of methane gas from the solid hydrate is not trivial, the magnitude of this energy resource has led to the establishment of national methane hydrate R&D programs in the U.S., Japan, India, and China.
Besides their obvious value as an energy resource in remote arctic regions and in the deep ocean, hydrate in marine sediment provides stability on slopes by serving as a kind of cement, and also can affect the acoustic signatures of the seafloor. These factors are of interest to the design of offshore structures, marine geohazards and navigation. Hydrates and associated microbial communities are also believed to modulate the leakage of greenhouse methane gas into the water column and atmosphere. Furthermore, hydrates have been proposed as a means to desalinate and purify seawater or contaminated water sources, remove chemical contaminants, and to store and transport both potable water and fuel.
In addition to the energy and environmental implications of methane recovery and leakage from natural gas hydrate reservoirs, hydrates also are relevant to a number of practical applications. Solid hydrates can form in natural gas pipelines and result in blockages that are expensive and difficult to clear. During the 2010 Deepwater Horizon accident that released approximately 200 million gallons of crude oil and 200,000 tonnes of natural gas from a broken riser a mile down in the ocean, hydrate formation complicated early attempts to control the spill. Since hydrate formation tends to exclude contaminants in water, other than specific hydrate guest molecules, they also have been proposed as a selective filter for removing or concentrating target substances (e.g., desalination). Finally, a pilot program is underway in Japan to store and transport methane in hydrate pellets for domestic use, and studies have been initiated to explore hydrogen storage in binary hydrates for fuel cell propulsion systems.
Hydrate research has been a major activity of the Hawaii Natural Energy Institute’s (HNEI’s) Ocean Resources and Applications Laboratory since the late 1990s. This effort is being pursued in partnership with the U.S. Naval Research Laboratory. Initially, work focused on CO2 hydrate formation under deep ocean conditions. That study was undertaken in support of an international collaboration between the Governments of the U.S., Japan, Norway, Canada, and Australia to conduct a field experiment on ocean sequestration of CO2. More recently, emphasis has shifted to natural gas and binary hydrates.
HNEI currently focuses on the development of methods to destabilize methane hydrates in situ for strategic defense applications, such as to provide modest levels of subsea power, and to address flow assurance issues. Work also is being pursued on methane seepage from hydrate reservoirs, the effects of hydrates in deep oil spills, and a range of hydrate engineering applications such as desalination and hydrogen storage.
Our primary research partner is the U.S. Naval Research Laboratory. We also have collaborated on a number of field and experimental studies with colleagues at universities, government laboratories, and the private sector in the U.S., Japan, Norway, Chile, Canada, New Zealand, Germany, and India. Under sponsorship from ONR Global and other agencies, HNEI established the International Workshop on Methane Hydrate Research & Development in 2000. The inaugural meeting was held in Honolulu, Hawaii. The 9th Workshop of the series will take place in India in November 2014. Previous Workshops venues have included, Washington, D.C., Chile, Canada, Scotland, Norway, New Zealand, and Japan.