Going underground

Norway’s power industry, with a lot of help from its government, plans to help cut its carbon dioxide emissions - by burying them. Neil Wilks delves into the back-story, and finds out about Hydro’s interest in what the future holds.

When a power station burns fuel, it gives off carbon dioxide. Carbon capture and storage (CCS) or sequestration involves grabbing that CO2 - chemically - and pumping it to somewhere with the right geology to store it underground. That, put simply, is the process. To test it, a million tonnes of CO2 a year have been being pumped into an underground reservoir 1km below the seabed off the coast of Norway, in the Sleipner field. The success of tests there, run by the state-owned energy company Statoil since 1996, has led to a host of initiatives to develop CCS further.

Norwegian oil and aluminium group Hydro sees the technology as having high potential. Ann Kristin Sjøtveit, project manager for Hydro’s CCS work, believes that the seismic data captured from Sleipner confirms that it’s a safe way of storing large quantities of CO2 for a very long time - “for thousands of years”.

The risk of a leak, she says, is unlikely when selecting an appropriate storage site. “The CO2 is compressed so it is in a liquid state and is pumped down at very high pressure, and at this point it’s heavier than water. If you look at the oil and gas we extract, that has stayed down there for millions of years.”

Hydro is involved in a major collaborative effort on this, as part of the CO2 Capture Project, also supported by the likes of BP, Chevron Texaco and Shell. Under way since 2000, the project’s first phase ended in 2004 and found that the cost of the best technologies could eventually be halved. The second phase will end later this year with the aim of building a pilot facility in 2008.

Safe storage is not the only issue to be tackled this year, of course. The huge price tag (the Norwegian government puts the cost of a full scale CCS plant, including transportation and storage at around £400 million) dictates that a lot of research must go into reducing costs, particularly of CO2 capture. To reduce the costs and risks involved, the Norwegian state and Statoil have taken an initiative to build a demonstration plant at Mongstad for capturing CO2, at a cost of around £100 million. But the state’s 80% share will be diluted, allowing several energy firms to be part of the consortium building and running the demonstration plant. Sjøtveit is optimistic that Hydro will be involved. “We’re in discussions with the ministry and it’s all been very encouraging,” she says.

The aim is to run several demonstration plants for various CO2 capture technologies and fit the best to the CHP plant at Mongstad. This should see the world’s largest CCS plant running alongside a gas-fired combined heat and power (CHP) plant by 2014, and the investments will be covered by the Norwegian state. “Our work is focusing on a post-combustion process that takes the flue gas from power stations and removes the CO2 from it,” Sjøtveit adds. The consortium members for the demonstration project are to be announced in May.

With the help of its energy and oil companies, Norway is unashamedly aiming to be a world leader in CCS. The motives are not entirely altruistic - any country burning fossil fuels will pay for the use of this technology to help cap their emissions.

The UK government has taken note too. If you need underground stores, depleted oil and gas fields are a good bet. And they’re something we’re not short of.

3 May 2007

Neil Wilks