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Harnessing methane to power the future

Most people know methane as a component of natural gas. But chemists have developed a way to create a solid form of the gas that looks like granulated sugar and can be stored and poured.
/ Source: Discovery Channel

Most people know methane as a component of natural gas. But chemists in the U.K. have developed a way to create a solid form of the gas that looks like granulated sugar and can be stored and poured.

Methane could power the world. Two methane hydrate deposits off the coast of South Carolina reportedly hold enough natural gas to power the United States for a hundred years. Other estimates say that worldwide methane deposits contain more energy than coal, oil and all other fossil fuels combined.

"There is a huge amount of energy in these resources," said Cooper. "The question is how much of that material can we recover."

Most of that methane is locked inside ice crystals in the Arctic or at the bottom of the ocean, where the pressure is high, the temperature is low, or both, which makes extracting those deposits difficult.

A chunk of white methane hydrate from the ocean depths is ice cold in your hand, but hold a lit match to it and yellow and blue flames rise from the methane released by the melting ice.

Once you get the hydrate to the surface, methane can be difficult and expensive to store and transport, which is where Cooper and his colleagues' work could prove useful.

To store and transport methane it usually has to be cooled down to about -113 degrees Celsius (-171 degrees Fahrenheit) or pressurized around 50 atmospheres, both of which require large amounts of energy and can be dangerous and flammable. Storing methane in a water and silica mix that looks and feels like a powder would make it easier and possibly cheaper to store.

Creating powdered methane is fairly simple. Cooper and his colleagues took dry water, or water mixed with very fine particles of silica, pumped methane into the container, and mixed the dry water and methane gas together with a blender bought at a local store.

The tiny silica particles increase the surface area of the water and make it easier and faster for the methane gas to become absorbed by the water. After about 30 minutes the white powder was fully saturated with methane; one liter of methane gas can be stored in about six grams of powdered methane, roughly the same as in most pressurized containers.

The powdered methane still needs to be held under light pressure and cooler temperatures of about -70 degrees Celsius (-94 degrees F).

Releasing the methane simply requires raising the temperature or decreasing the pressure, said Cooper.

Powdered methane could just be the beginning. Cooper says that the team can store other gases as powders, including hydrogen and carbon dioxide, although under different environmental conditions. Storing CO2 as a powder could make carbon sequestration easier or bring a hydrogen-powered economy closer to realization.

Easily trapping gases like CO2, methane and hydrogen could be useful, but first it has to be economical, said both Cooper and outside experts who are cautious about its expense.

Michael Max, who uses hydrates for desalination at Marine Desalination Systems, echoes Cooper.

"It's an interesting result," said Max. "But we don't see how this could be developed commercially."

Max points to Mitsui Group technology that mechanically presses methane hydrate into pea-sized pebbles, making them more stable for transportation and use. However it's stored and transported, finding a cheaper way to gather, store and transport methane and other gasses may eventually help use alternative natural resources.

"The economics of this are far from obvious," said Cooper. "This is a preliminary result and we have to think hard about the costs involved."