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. 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.
Natural reservoirs of methane (i.e., natural gas) hydrate in deep seafloor sediments and arctic permafrost are estimated to contain about 3 x 1015 scm (standard cubic meters) of methane gas. To put this in context, in 2013, total natural gas consumption in the U.S. was approximately 7.4 x 1011 scm, which is a factor of about 4000 smaller. 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.
Methane is a potent greenhouse gas with a GWP (global warming potential) of 86 and 24 over 20 and 100 years, respectively, compared to a standardized value of 1 for CO2. This means that, for example, over a 20-year period, a kg of methane released in the atmosphere would trap 86 times more heat than a kg of CO2. Although carbon isotopic excursions detected in marine and terrestrial sediments suggest a correlation between past hyperthermal events and massive outgassings from natural methane hydrate deposits, it appears unlikely that the current warming cycle will precipitate a catastrophic dissociation of marine hydrates over the next few centuries. Nonetheless, methane leakage into the environment will occur, and associated impacts on the local and global environment need to be studied.
Besides 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 at 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.
Instrumentation and facilities employed to conduct hydrate research at HNEI include:
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.