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World: Pumping CO2 Into Earth's Crust -- Global Warming Cure Or Flaky Theory?

  • Jeremy Bransten

With mounting evidence that global warming could have a serious impact on the world environment in upcoming decades, some scientists are working on a formula that will allow industries to cut down on carbon dioxide emissions -- without reducing their use of fossil fuels. Is this a "miracle cure" or a dangerous delusion?

Prague, 13 September 2002 (RFE/RL) -- It's the environmental equivalent of the zero-calorie soda: consume all you want without any of the guilt. That's not quite how Norway's Statoil is marketing its new technique of "carbon sequestration," but the message comes close.

With the world continuing to discuss the need to cut global carbon dioxide emissions -- but unable to agree on the amount and timeframe for the reductions -- scientists in Norway say they have come up with a solution that could clean up the atmosphere without imposing crippling reductions on industry.

Over the past few years, Statoil, Norway's largest oil and gas producer, has pioneered a form of carbon sequestration that it says could be applied worldwide, with significant benefits for the environment.

In layman's terms, the process involves separating out the carbon dioxide, or CO2, that is discharged as a by-product of industrial production. Then, instead of allowing it to escape into the atmosphere where it could promote global warming, the CO2 is pumped into the earth's crust, in a type of semi-permanent storage.

At present, Statoil is using this technique on its drilling platforms in the Sleipner natural-gas field, off the western coast of Norway. Andy Chadwick, senior geophysicist at the British Geological Survey, has been monitoring the operation and described it to RFE/RL.

"The natural gas contains about 9 percent carbon dioxide when they take it out of the ground. So the carbon dioxide was already there in the natural gas. Now, this is more than is acceptable, so they have to separate out the CO2 as an impurity. In the normal course of events, this CO2 would just be vented into the atmosphere from the [drilling] platform. But instead of doing that, for environmental reasons, they have decided to reinject it into the ground. And so, essentially, it's being injected into what's called an aquifer, which is a sandstone area filled with saltwater at a depth of about 1,000 meters -- that's about 900 meters below the seabed. And so essentially, the carbon dioxide is being taken out of one rock formation and returned into another one."

Chadwick, who publicized Statoil's work at this week's annual meeting of the British Association for the Advancement of Science, says this type of carbon sequestration is only being used at present during the process of drilling for gas. But Chadwick believes the technique holds great promise for a much broader use in industry.

"That's the potential longer-term benefit -- in that it is technically possible to strip CO2 from the emissions of power stations, for example, and then sequester that in a very similar manner to the operation at Sleipner. It's rather more complex, because the flue gas streams from power stations are quite complicated themselves. And so, at the moment, it's quite an expensive technology, but there's a lot of work going on to try and reduce the costs of this technology, which is called 'carbon capture.' And hopefully, if that goes ahead, it could become a viable method of very much reducing our CO2 emissions in the longer term."

Once CO2 emissions are "captured" at an on-shore industrial plant, the gas could be compressed and shipped, in liquid form, by pipelines or cargo ship to the location of the underwater aquifer, into which it would be subsequently pumped.

Chadwick says the technique is safe and does not amount to dumping waste at sea. The Utsira Sand aquifer, into which Statoil has been pumping the CO2 it has extracted from the Sleipner gas field, is composed of layers of rock, which trap the CO2 and prevent it from bubbling up through the seabed.

"What's happening at Sleipner has nothing to do with ocean disposal. This is underground disposal, so the CO2 is pumped into rocks at great depth and so is, in fact, completely isolated from the marine environment and also from the atmosphere."

The Utsira Sand aquifer is vast: 400 kilometers long, 50 to 100 kilometers wide and up to 250 meters thick, making its storage capacity impressive. Chadwick says: "The storage capacity of Utsira Sand is immense. So for example, if you were to exploit just 1 percent of the storage volume within the aquifer, that would be enough to soak up emissions from about three years' worth of the EU's CO2 emissions from [non-nuclear] power stations."

There are also other alternative storage sites, according to Chadwick: "Perhaps the most obvious site for the storage of CO2 would be disused oil and gas fields because they actually have a proven storage ability and sealing ability, in that we know fluids don't escape from them -- that's one potential. The other potential are these [other] regional aquifers which have huge volumes. Providing you're careful in your site location, there's no reason to assume that they wouldn't be just as safe as oil and gas fields."

But Jes Fenger, a researcher at Denmark's state-funded National Environment Research Institute, is not convinced. He tells RFE/RL the long-term safety risks of underground carbon injection, as with other types of waste storage, are unknown. And he points to another potential problem.

"This issue about CO2 -- both emissions and sequestration -- is very complex. I don't think that any possibilities should be left untried. On the other hand, there are two objections to this. One is that you are never quite sure whether it will stay where it is -- and that's the same problem that you may have, for example, with radioactive waste from nuclear-power plants. The other thing is that at least some people would consider this as a sort of a 'technological fix' which would prevent the real issue, namely the phasing out of fossil fuels, [from being addressed]."

Andy Chadwick argues that environmentalists have to be more pragmatic. With the United States, among others, stalling on even modest CO2 emissions cuts advocated by the 1997 Kyoto Protocol, he says new methods to prevent the atmosphere from soaking up excess greenhouses will have to be tried. Carbon sequestration, he says, is not a permanent solution -- but neither should it be seen as a sleight of hand.

"We view it as an interim solution, in between moving from a fossil-fuel-based economy -- which is basically what's driving the world at the moment -- to a renewable economy sometime in the future. But when that is going to come about is uncertain. We've just had the failure to reach agreement at Johannesburg on renewable targets and so quite when, globally, we're going to move effectively to a renewable economy is anybody's guess. But it's unlikely to occur, I think, in the next few decades and possibly not for 100 years or more. So in between now and then, we actually have to reduce our CO2 emissions quite dramatically."

Jes Fenger says that for now, other Scandinavian countries, at least, are concentrating on other options: "We are, at least in Denmark, more inclined to favor alternative energy sources. Wind power, for example, is one of our main issues, it's hydropower in other Scandinavian countries."

He also cites other reasons why CO2 emission reductions must remain a primary goal: "By all means, yes, also because the cutting down of CO2 emissions gives you various other advantages. Because CO2 is not the only environmental load from the use of fossil fuels. You have oxides, [sulfur dioxide] and so on."

It is clear that reducing the overall use of fossil fuels is still the best way to safeguard the Earth's atmosphere from a panoply of dangerous pollutants. But given the world's inability to put into practice any meaningful emissions cuts despite a seemingly endless string of global environment summits, carbon sequestration may win over more fans in the near future. Scientists in Norway, France, Britain, and the Netherlands -- backed by funding from the oil industry and grants by the European Union -- are working to make it a reality.