Hydrates: energy future or no?

Mark Jones Jones_M at netcomuk.co.uk
Mon Sep 7 17:34:52 PDT 1998

[this from The Guardian: Greg Nowell and I have been discussing this question. Mark J.]

Beneath the ocean bed lies enough frozen fuel to power the planet for centuries

By Tim Radford, Science Editor Tuesday September 8, 1998

A newly-discovered source of frozen fuel packed below the ocean floor could power the planet for centuries - if scientists can think of a safe way to tap it.

The vast untapped energy source that is locked away in methane compressed into solid form by the weight of the ocean above it could be double all the coal, natural gas and oil ever burned, or likely to be burned.

The ocean is 70 per cent of the planet, and the Earth's last unexplored region. Oceanographers have pointed out repeatedly that the surfaces of Venus and Mars are better mapped than the ocean floor. But that could change with the gradual revelation of huge potential resources, now including awesome stores of energy frozen in veins and lodes in the ocean muds.

The frozen methane exists on the edge of continents in mud a few metres below the ocean floor in a layer a few hundred metres thick. It was produced by bacteria feeding on the sediment and producing methane as a waste product.

At huge pressures, this methane reacts with ultra-cold water to turn into a kind of room temperature ice, to be preserved for millions of years. This product of natural chemistry is called a hydrate. Each cubic metre of the hydrate contains an estimated 160 cubic metres of pure methane, or natural gas.

World oil reserves are finite: world oil production is expected to peak in the next decade and then start falling. But demand for energy is likely to go on rising exponentially. A new source of fuel would be regarded as a kind of gold. But like gold, methane hydrates could be difficult to exploit.

"It's in fine grained sediment, it's deep in the oceans, we think it is spread in quite thin layers - we don't know for sure - and somebody has to try and get it out," said Joe Cann, of the Natural Environment Research Council's British mid-ocean ridge research group. "There are lodes, there are veins, there are tiny little dusty bits. We still know very little about it."

One proposal has been to pump warm water down into the sediments to release the gas. Another has been to suck it up through drill pipes.

"Or should you put some kind of enormous tent under the sea floor and begin to decompose it on a large scale underneath the tent, and collect the bubbles and lead them up to the surface? There are all sorts of possibilities - but it is not going to be like getting natural gas out from under the sea floor," Prof Cann said.

Scientists have known about hydrates for more than a decade, but the staggering scale of the potential submarine wealth became apparent only very recently, after ocean drilling and seismic experiments.

Huge concentrations have been detected by scientific drilling experiments off North Carolina in the US, and off Norway. A sudden escape of the gas 7,000 years ago may have triggered a tsunami or tidal wave which swamped Shetland and washed huge boulders ashore. It could happen again: exploitation could even result in a sudden submarine landslide which could trigger calamity on the crowded shore line.

But paradoxically, according to Dr Clennell, the methane ice is already concentrated in the zones of greatest natural danger. The biggest sources seemed to be where tectonic plates meet, off Japan, Indonesia, New Zealand and so on - the Pacific "ring of fire" marked out by continual earthquakes and volcanoes.

Exploiting the new submarine bonanza would not only be difficult and dangerous in the short term: it would be a problem in the long term as well. Methane is a greenhouse gas, 10 times more potent than carbon dioxide.

Any large-scale escapes would accelerate global warming. But the hydrates remain a tantalising prize. Japan is investing huge sums in research because it has no fossil fuel reserves. India, too, is interested in the energy El Dorado under the sea off its coasts. The US is also interested in the phenomenon as a source of clean fuel.

"We have the technology to drill in deep waters - between 500 and 2,000 metres, where the majority of these gas hydrates are found," Dr Clennell said. "However, that is very expensive. We also have the technology to drill wells that go straight down and then horizontally, so we can follow these gas pockets along."

The research is only just beginning. "The history of hydrates is a history of false dawns," Dr Clennell warned. "The massive amount of hydrate present has to be set against the impossibility - at present - of doing anything with it."

© Copyright Guardian Media Group plc.1998

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