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Methane clathrate (CH 4 ·5.75H 2 O) or (4CH 4 ·23H 2 O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice.
The existence and depth of a hydrate deposit is often indicated by the presence of a bottom-simulating reflector (BSR). A BSR is a seismic reflection indicating the lower limit of hydrate stability in sediments due to the different densities of hydrate saturated sediments, normal sediments and those containing free gas. [2]
Methane clathrate block embedded in the sediment of hydrate ridge, off Oregon, USA. Clathrate hydrates, or gas hydrates, clathrates, or hydrates, are crystalline water-based solids physically resembling ice, in which small non-polar molecules (typically gases) or polar molecules with large hydrophobic moieties are trapped inside "cages" of hydrogen bonded, frozen water molecules.
The present-day global methane hydrate reserve was once considered to be between 2,000 and 10,000 Gt C (billions of tons of carbon), but is now estimated between 1500 and 2000 Gt C. [37] However, because the global ocean bottom temperatures were ~6 °C higher than today, which implies a much smaller volume of sediment hosting gas hydrate than ...
Mount Elbert Methane Hydrate Site (or Mount Elbert Gas Hydrate Test Well, Mount Elbert test well) is a natural gas test site within the Alaska North Slope.The well was first drilled in 2007 as part of a Cooperative Research Agreement with BP Exploration (Alaska), Inc. (BPXA) and the U.S. Department of Energy (DOE) in collaboration with the U.S. Geological Survey (USGS). [1]
Nonpolar molecules such as methane can form clathrate hydrates with water, especially under high pressure. Although there is no hydrogen bonding between water and guest molecules when methane is the guest molecule of the clathrate, guest–host hydrogen bonding often forms when the guest is a larger organic molecule such as tetrahydrofuran.
The low hydrate saturation can be explained due to the very small pore size and low permeability in clay-rich sediments, which hinder the mobility of both water and gas, necessary for hydrate formation (see UNEP Global Outlook on Methane Gas Hydrates (2012, in progress) for more details). In contrast, Japanese scientists were able to discover ...
Methane is an important greenhouse gas, responsible for around 30% of the rise in global temperatures since the industrial revolution. [58] Methane has a global warming potential (GWP) of 29.8 ± 11 compared to CO 2 (potential of 1) over a 100-year period, and 82.5 ± 25.8 over a 20-year period. [59]