Icy interest hots up

26.06.2013
The first planned output of gas hydrates has begun in energy-short Japan. This forms part of an urgent search for alternatives to nuclear power after the Fukushima reactor accident two years ago.
  • Astri Sivertsen

Future energy source? Producing gas hydrates off Japan.

Future energy source? Producing gas hydrates off Japan.
Photo: Japan Oil, Gas and Metals National Corporation (Jogmec)

 

Deposits of gas hydrates – methane packed into a lattice of ice crystals – off the Japanese coast are probably sufficient to meet national energy needs for several hundred years.

So trial production by state-owned Japan Oil, Gas and Metals National Corporation (Jogmec) is also being closely followed internationally.

Looking like ice but catching fire when ignited, hydrates form under high pressure and low temperature. They are accordingly found in Arctic regions – including tundra – and deep water.

Half the output from Messojakha in Siberia, the world’s biggest gas field, has been provided by the melting of this hydrocarbon ice since 1970.

But the hydrate deposit was not known when the discovery came on stream, so the pilot project off Japan can claim to be the world’s first planned production.

Some researchers have estimated that gas hydrates could contain twice as much energy as all existing fossil fuel resources put together, including coal.

But the size of these deposits is uncertain, and they have to be very concentrated before extracting and utilising them becomes worthwhile.

 

Unstable

One disadvantage of hydrates is that they are chemically unstable, and methane is a greenhouse gas with about 25 times the warming effect of carbon dioxide if emitted to the air.

“These deposits are unique,” explains Bjørn Kvamme, professor of petroleum and process technology in the department of physics at the University of Bergen. “Each is different from the rest.”

Hydrates melt on contact with heat and minerals, he adds. Their properties depend on local groundwater flows. That makes the picture far more complex than for oil and gas reservoirs.

But Kvamme notes that producing them is much simpler than extracting shale gas, for instance, where the rocks have tiny pores and low permeability.

“The oil industry has been sceptical, and has regarded hydrates as rather mystical. But it’s only a case of modifying technology already available.”

Research on hydrate production has largely been pursued by geoscientists, Kvamme explains. But this work has been short of expertise on physics and flow dynamics.

Together with fellow professor Arne Graue, Kvamme has developed a technique to replace the methane molecules in hydrates with carbon dioxide through injection.

This makes the gas more stable and the methane easier to produce, while providing a carbon storage solution for this problematic greenhouse contributor.

 

Tested

The method has been tested in Alaska and Canada in cooperation with ConocoPhillips and Jogmec – and with good results. But interest fell once shale gas made the USA self-sufficient in gas.

However, Asia remains very keen. Kvamme and Graue do not know if the pilot production in Japan uses their technology. Big carbon deposits in this part of the world would make it natural, though.

Gas from the Sleipner area of the North Sea contains about 10 per cent carbon dioxide, and this high proportion represents a problem.

The greenhouse gas is accordingly stripped out and stored in an underground formation. By comparison, gas from the huge Natuna field off Indonesia is 70 per cent carbon dioxide.

Indeed, hydrocarbon reserves throughout south-east Asia contain extremely high carbon proportions. But the region lacks potential storage formations with good capacity and sealing properties.

“A market clearly exists for this technology in Asia, where some countries have few energy resources but a huge demand,” observes Graue.

In addition to Japan, Malaysia, Indonesia, South Korea and India are making a heavy commitment to research into and pilot output of gas hydrates. If they succeed, much could be different.