Carbon dating

Carbon sequestration makes sense: technology for it is in place and it could help the UK meet emissions targets. But it will have to happen soon in the North Sea. Julia Pierce reports.

Any proposal suggesting that an undesirable industrial by-product could be buried beneath the sea and forgotten about would be enough to make even the most vaguely green members of society foam at the mouth.

But scientists insist that such a scheme could not only provide a solution to global warming, but also create an alternative to the revival of nuclear power while new renewable energy technologies are developed.Carbon sequestration, the technology in question, uses carbon dioxide generated by coal-burning power stations.

This is captured at source and pumped to undersea storage reservoirs. The carbon dioxide can also be used for enhanced oil recovery, in which it is pumped instead to offshore oil reservoirs before being forced into the sea bed, pushing hard to extract light oils to the surface and dislodging supplies trapped in cracks.

Supporters say the method could improve the amount of oil extracted by 15 per cent, increasing the economic life of North Sea extraction by several years. This would avoid the UK relying on gas sourced from areas where political instability could cause wild fluctuations in energy prices.The UK is currently struggling to reach its Kyoto emissions targets. But last week scientists inflamed the situation by stating that even these reductions may not be sufficient.

At the EuroScience Open Forum 2004 in Stockholm the Intergovernmental Panel on Climate Change said current atmospheric targets for carbon dioxide could still cause global temperatures to rise by around 5.5 degrees, enough to melt the Greenland Ice Sheet and raise sea levels by 6m – putting low-lying cities such as London at serious risk. The technology necessary for sequestration is already in place.

Since 1996 the Norwegian Statoil company has been separating carbon dioxide from methane extracted from the North Sea’s Sleipner Field, before pumping it back into a subsurface layer of porous sandstone. So far around six million tonnes of CO2 have been returned, and studies show the gas has remained in place and is not leaking.

Though critics rightly point out that the venture has only been made economically viable by Norway’s high emissions tax, the Intergovernmental Panel on Climate Change found that carbon storage under the ocean could remove up to 2,500 giga-tons of carbon from the atmosphere in the coming years.

According to estimates, this represents between 1.5 and eight times the capacity needed over the next 100 years. Australia and the US have also invested heavily in the technology. However, the decline of North Sea operations means a system would have to be in place by 2008 to be effective.

Last year, Defra’s minister for the environment Elliot Morley appeared to lend his support to the technology, saying the UK needed carbon sequestration to meet its Kyoto targets.

But this was later dismissed by the DTI. ’We think the concept of carbon capture and storage is feasible, but we think it is something that is more likely to be medium term than something that’s going to happen over the next five years,’ said Brian Morris, head of the cleaner fossil fuels technologies unit of the DTI.

’The cost of CO2 capture is very high at the moment, and obviously R&D is needed to bring those costs down. Even those in the US programme, although prepared to put a lot of money into it, realise that they have got to get the cost of capture down quite considerably.’

Meanwhile, the sheer cost of developing a Carbon Capture and Storage (CCS) infrastructure has meant that the parties that stand to benefit from its development are in stalemate.

’You often get this exchange between the power companies and oil companies when you meet them round the table,’ said Morris. ’The oil companies say: “Give us the CO2 for nothing and we’ll think about it”, and the power companies say: “If you build us a CO2 capture facility, then we’ll certainly give you the CO2 for nothing”.

The government’s view is that it is up to oil companies to make commercial decisions and invest in the most appropriate technologies to do what they feel is worth doing.

’Though the cost of capturing carbon dioxide is high, current inflation of oil prices has narrowed this gap. But without support CCS is unlikely to go far. Dr Simon Shackley of the Tyndall Centre for climate change research at UMIST is involved in a three-year project to assess the potential for geological carbon sequestration in the UK.

He says that while the nuclear industry has a powerful and well-organised lobbying group, no such organisation exists for CCS. However, nuclear stations are designed to produce a fixed energy output, while coal-fired stations could prove more flexible in covering energy gaps created by intermittent flow from renewables – for instance, on days with little or no wind.

But CCS will almost certainly face a legal challenge from environmentalists. No national or international laws have been drawn up specifically to include carbon sequestration. However, existing marine agreements such as the 1972 London dumping convention preventing companies getting rid of industrial waste at sea could be open to interpretation on the issue. Solving these legal issues will take time, as will carrying out a proper risk assessment.

Meanwhile, EU law is pressuring the coal industry to clean up emissions or face limits on the number of hours plants can operate. Without investment to clean up their output, many coal-fired power stations face closure by 2015, forever removing the option of CCS at a time when planning challenges have halted the development of renewables, both on and offshore.

Shackley believes that government intervention must create the long-term energy strategy that cannot be provided by the current privatised and profit-driven energy market, with its focus on keeping household bills at artificially low levels.

Unless the squabbling over investment in CCS comes to an end, there will be little choice over the method of bridging the energy gap. ’2008 will be a crucial time,’ said Shackley. ’If CO2 capture has not made headway by then, the country will have to look to nuclear power.’