WILL PEAK OIL turn out to be a non-event after all?

This is the question raised in a recent edition of the respected weekly journal, New Scientist (27 June 2009). It challenges ideas and beliefs that have become basic to new, community based organisations such as the Transition Towns movement that set up to chart a pathway through peak oil and climate change and to other organisations acting on the possibility, many say likelihood, of peak oil.

The article raises the question of whether the planet can sidestep the peak oil challenge by exploiting a huge and so-far untapped reserve of carbon-based energy below the permafrost of far northern latitudes and on the continental shelves. Futhermore, reports the magazine, doing so might also sequester the atmospheric carbon dioxide blamed for global warming.

The potential energy source consists of molocules of methane, itself a greenhouse gas with 20 times the potency of carbon dioxide, trapped in the lattice structure of ice crystals. These clathrates, as they are known, are found below the sub-Arctic permafrost and at locations on the continental shelves to around 400 metres deep.

The attraction of extraction

There are several ways to extract methane from the clathrates. Pumping heated water from the surface is the least promising as it yields the lowest energy return on energy invested. That is, it consumes nearly as much energy to obtain the methane as the methane itself would yield in useable energy.

Another method is to tap to the reserve and allow depressurisation to force a flow of methane to the wellhead.

More promising, however, is displacing the methane bonded into the clathrates by pumping in carbon dioxide. The attraction of this method is that laboratory experiments show that the carbon dioxide replaces the methane in the ice crystals, in effect sequestering the carbon dioxide. The appeal of doing this is obvious – it could provide a means of offsetting the carbon dioxide emitted from the burning of coal and oil fuels to produce energy. As the clathrate layer loses its methane it becomes a sink for carbon dioxide.

The devil in the detail, however, is that if global warming continues to increase, the clathrates could melt, releasing that sequestered carbon dioxide, just as they would release the methane presently trapped in the crystals.

Fuel for a millennia

With estimates of the scale of the methane clathrate reserve as high as three trillion tonnes, it may constitute an energy replacement for transportation fuel oils lasting to1000 years, at equivalent rates to the present  extraction to natural gas.

As a replacement for all fossil fuels the reserve could provide an energy source for the next 100 years, buying time to move to a global hydrogen economy if research an development funding is focused on its development.

And the risks?

With new technologies, the potential for solution and risk are often bound together. While the methane clathrate solution seems to offer a fix that could reduce global warming and its consequent climate change, it carries the contradictory potential risk of accelerating climate change.

One risk is the loss of methane from leakages during the extraction process. The other is more dramatic – a ‘methane burp’. This can be envisioned as a chain reaction of rapid methane release through a clathrate layer as depressurisation and expansion occurs due to extraction. In effect, the clathrate tumbles into instability and the instability cacades through the deposit, releasing a large volume of methane. Such events are believed to have occurred a number of times in the distant past and to have played a major role in climate change. The rapid release of gas can trigger landslides on the continental shelf – evidence has been found for this having occurred – and the consequent generation of tsunamis.

Another risk must be added to that which comes from the methane bound into clathrates. And it, too, could take the form of a methane burp although it is not associated with attempts to extract methane by pumping. It is this: methane releases may be triggered in the seabed clathrate deposits on the continental shelves as global warming increases the temperature of the seas.

A similar process could see methane more slowly released to trap even more heat in the atmosphere as rising air temperatures trigger the release of methane from permafrost. Some scientists believe this process has started, with evidence of melting in high latitudes.

Both of these are viewed by atmospheric scientists as potential triggers or tipping points that could suddenly trip global warming into a new, accelerated phase fed by the positive feedback (self-reinforcing) mechanism of more methane leading to more atmospheric heating which accelerates the release of more methane, and so on.

The intention of Japan to start methane extraction from sea bed clathrates by 2016 (what happens to Australia’s natural gas exports if the clathrates become a major energy source?) illustrates the need for an international agreement on the proposal. Given the Kyoto global warming saga, however, the effectiveness of a global agreement on whether to go ahead with methane extraction, and how to do so in a way that minimises risk, is an open question. Dangers, and how to manage them effectively, could be ignored in the rush to a new energy source.

This is not unlike the possibility that, without an international agreement and international cooperation, nations could go it alone on geoengineering were climate change to follow the worst case scenario of rapid warming and sea level rise. They could act unilaterally, or in regional or political blocs, to seed the atmosphere with sulphur dioxide to reflect a portion of incoming solar energy, or to seed the seas with iron particles to stimulate the growth of carbon-absorbing algae. So could they decide unilaterally to start exploiting the clathrate deposits on the continental shelves

If methane clathrate becomes a new source of energy, the sometimes unshakable, core beliefs about peak oil and energy supply shortfall, held by government, business and community-based action groups, may start to sound like crying wolf once to often. Especially so is hydrogen is developed as a fuel in the window of R&D opportunity opened by hydrogen-clathrate extraction. The danger in this is that future, valid concerns may be ignored, to our peril.