‘Methane hydrate’: A new energy source discovered off Andhra coast  

Researchers have discovered "methane hydrates" -- a potential fuel of the future -- just two meters below the sea floor in the Krishna-Godavari (K-G) basin off the coast of Andhra Pradesh in the Bay of Bengal.

The discovery has been reported by a team of scientists from the National Institute of Oceanography in Goa and the National Geophysical Research Institute in Hyderabad in the Journal of Earth System Science published by the Indian Academy of Sciences.

"This is the first report on the discovery of an active methane seepage site and the occurrence of shallow methane hydrate deposits in India's Exclusive Economic Zone (EEZ)," they report.

Methane hydrate, which is formed at low temperature and high pressure, is a solid crystal structure of water within which a large amount of methane gas is trapped.

This is a new and completely untapped reservoir of fossil fuel, because it contains, as its name suggests, a large quantity of methane, which is the main component of natural gas.

Global interest in the genesis of "methane seeps" in the oceans stems from the role of methane in global warming and in methane hydrate exploration.

According to the Indian researchers, the occurrence of methane gas hydrates at very shallow depths in K-G basin "is due to the presence of high methane flux and conducive pressure and temperature conditions, necessary for the stability of methane hydrate".

"High biogenic methane flux close to the sediment-water interface has resulted in the crystallisation of methane hydrate at shallow depths below the seafloor", they report.

The discovery was made during an expedition conducted in the K-G basin onboard the Sindhu Sadhana research vessel during January-February last year.

The active methane "seep sites" were detected by analysing the water-column images obtained through a multi-beam echo sounder. "The analysis of the images shows four distinct gas flares in the ridge area," says the report. "These gas flares are tell-tale signatures of methane ebullition from the seabed."

The mapping of the water column, coupled with precision sampling of sediment "led to the discovery of active cold seeps, associated biological communities and shallow gas hydrate."

The diversity, spatial distribution and growth of organisms thriving in such an ecosystem are primarily controlled by fluxes of hydrogen sulfide and methane gas across the sediment-water interface, the report said.

Marine cold seeps and associated ecosystems have been reported from numerous sites across the globe, including the Makran coast of neighboring Pakistan. "Ours is the first report on the discovery of methane gas flares in the water column and associated benthic biotic community at the cold seep sites off K-G Basin," the researchers report.

"The present discovery has brought India on to the global cold seep map and opened up the opportunity for future research on the possible role of methane emission on global warming, ocean acidification, extreme ecosystem, and bio-prospecting," they conclude.

"With an estimated trillions of cubic meters of methane gas available in the gas hydrate deposits in the Indian waters, gas hydrates can be the future source of energy for India," the Ministry of Earth Sciences, which spent Rs 1.43 billion in gas hydrate exploration during 2012-17, says on its website.