Fuelling the future

Though unstable in the earth's atmosphere, Clathrates seen deep under the sea could be a good fuel in the days to come, reports V K Joshi.

GAS HYDRATES: What was a laboratory curiosity upon discovery by Sir Humphrey Davy in 1810, the "clathrates" or gas hydrates are now being considered as a fuel for the future.

Clathrates are crystalline solids which look like ice in which water molecules form a "cage-like structure" around a smaller "guest molecule".

The guests being molecules of methane, ethane, propane, isobutene, normal butane, nitrogen, carbon dioxide and hydrogen sulfide with methane as one of the most abundant element.

The molecular structure of a clathrate cell is generally such that it has 46 molecules of water and up to eight molecules of methane.

Thus if all the cages were packed with methane, one cubic meter of hydrate could contain up to 170.7 meter cube of methane gas at standard temperature and pressure.

Apart from being a possible energy source, the clathrates are also under the scrutiny of geologists for their suspected role in undersea slumps which possibly result in disastrous tsunamis, as well as in climatic variability.

The rapid climate changes of the past have made some geoscientists think that they were caused by the methane released from the clathrates.

Clathrates occur in the abysmal depths of the oceans where high pressure of water and freezing temperatures keep them stored up in their crystalline form.

They have evaded scientific study so far mainly because they are extremely difficult to extract for study.

The moment they are pulled out of their dark lair, the hydrates change shape due to the change of pressure and by the time they are hauled to surface, they just fizz away.

These methane hydrates lie safely ensconced below the sea floor in regions that slope from the continents to the deep ocean basins thousands of meters underwater. Studies so far carried out by the marine geologists have identified clathrate deposits off the coasts of India, Japan, Costa Rica, New Jersey, Oregon and multitude of other sides around the globe.

Arctic permafrost in Siberia, Alaska and Canada is also supposed to be a store house of clathrates.

As a fuel

Realising the significance of clathrates the Ministry of Petroleum and Natural Gas, Government of India launched a National Gas Hydrate Programme in 1997 through ONGC, GAIL and Director General Hydrocarbons.

A rough estimate by the ONGC indicates the presence of about 350-900 billion cubic meters of Gas Hydrates trapped in the abysmal depths offshore western and eastern coasts of our country.

Affecting climate

Our atmosphere is plagued by the Green House Gases (GHGs) that are supposed to be the root cause of global warming.

Methane is one of the GHG that is known to cause global warming.

Studies by the climatologists prove that during the glacial era methane levels in the atmosphere were much lower than during the inter-glacial eras.

The polar ice sheets cause a fall in the sea level, thus pressure on the ocean margin clathrates is reduced and huge quantities of methane finds its way to the atmosphere - resulting in warming.

That is how some earth scientists conjecture that the last glacial phase ended about 18,000 years ago.

It has been estimated that the worldwide amounts of carbon locked in clathrates is twice than total amount of carbon to be found in all known fossil fuels on Earth. May be the scientists come out with

viable techniques to extract and run our vehicles with unlimited source of fuel.

A tsunami link

These gas hydrates are also linked with tsunamis. In Norwegian and Scotland coasts sudden release of trapped gas from clathrates is known to have caused tsunami in 1987 that rose 4 meters high on hitting the coast.

Agencies involved in the development of extraction

techniques of clathrates are also "keeping an eye" on the relationship between tsunamis and release of clathrates.

(Courtesy - Deccan Herald)