Methane gas hydrate is famous as one of the explanations for the mysterious disappearances of ships in Bermuda triangle. Methane gas hydrate is a “clathrate” compound in which methane molecule is trapped with the crystal structure of ice water. It just looks like an ice in stable condition, but when heated, its clathrate structure breaks to release methane gas molecule inside. Hence it is literally a “burning ice” when ignited.
Image source: U.S. DOE
Hydrate is known to be buried abundantly in the oceanic sediments along continental margins and in polar permafrost. The hydrate structure could unstabilize itself in certain conditions to release vast amounts of gas: 180 times solid volume. It is the explanation of the ship wreckages in the Bermuda triangle. Imagine that the ship is suddenly situated to float in the air while sailing in the middle of the ocean! However, some researcher also say that this famous story is mere a myth as there was no major release of methane gas from hydrate breakdown for the last 15,000 years.
Apart from this story, the focus of our interest here is the gas hydrate as an energy resource. The Minerals Management Service estimated the mean value of in-situ hydrates reserve in Gulf of Mexico to be 21,444 trillion cubic feet (TCF). When compared to the annual U.S. natural gas consumption of 23 TCF or technically recoverable reserve of the conventional natural gas in the U.S. of 1,300 TCF, it is a huge amount even though only some of them can be technically recoverable. Conservative value for the global carbon amount from hydrate reserve is also estimated to be twice that of all kinds of fossil fuels on the earth.
However, it is a unfortunate fact that there is no commercially viable technology at this moment to produce gas hydrates. It is a global initiative to develop hydrate production technology as hydrate reserves are located along the coast of many major natural gas consumers. Many countries set their goals to produce natural gas from hydrates commercially within 15~20 years.
Hydrate production poses some risks while production. They have to be safely mined or extracted, but scientists are reporting concerns in which the production may cause land sliding on the continental slope in the ocean. Land sliding itself could pose a serious problem; however, the exposure of methane gas to the atmosphere would be more serious. Methane is 72 times more powerful as a greenhouse gas than carbon dioxide over a 20-year timescale. The geologic mechanism to affect the stability of hydrates is not exactly known, but the uncontrolled methane burp would exacerbate the global warming. There are scientific evidences that the methane hydrate gasification might be the reason for the Permian-Triassic extinction which was the earth’s most severe extinction event occurred 251 million years ago.
Producing natural gas from hydrate would be a fascinating project if the production technology is developed and proven to be commercially viable, technically safe and environmentally compatible. As it is a long term project, it is expected that the financial investment will be continued both from industry and government even though there can be some fluctuations. The most important thing would be that we have to convince the technology is safe enough before we open the Pandora’s “clathrate”.