With planet Earth engaged in a heated race against global warming, "carbon capture and storage" has brought a ray of hope, and a Norwegian gas platform is leading the way.

The Sleipner platform in the North Sea, a mammoth steel and cement structure, has successfully buried millions of tons of CO2 under the seabed for the past 12 years in a pioneering project.

Using a simple metallic tube measuring 50 centimetres in diameter, the platform operator, Norwegian oil and gas group StatoilHydro, has injected some 10 million tons of CO2 into a deep saline aquifer one kilometre under the sea.

"We bury every year the same amount of CO2 as emitted by 300 000 to 400 000 cars," said Helge Smaamo, the manager of the Sleipner rig, a structure so large that the 240 employees ride three-wheeled scooters to get around.

Saving money

The project is far from a philanthropic initiative to save the climate: StatoilHydro decided to test the carbon capture and storage (CCS) idea 250 kilometres off the Norwegian coast for purely financial reasons.

The natural gas extracted by Sleipner has a carbon dioxide content of nine percent, almost four times the commercial quality target of 2.5 percent, requiring the company to reduce the level by filtering it with amines on a platform adjacent to the main structure.

Since it was already being filtered, the question was then whether to release the CO2 into the atmosphere or to capture it.

A carbon tax imposed as of 1991 on Norway's offshore sector led the group to opt for the second solution, despite an initial cost of $100-million to drill a well and install a compressor, and annual operating costs of $5-million.

"We save money by injecting (CO2) gas rather than releasing it," said Olav Kaarstad, a special advisor at StatoilHydro.

There are no figures available on how much StatoilHydro has saved, but with the carbon tax at its current level of $66 per ton, StatoilHydro would have to pay $66-million a year to release one million tons of CO2 into the atmosphere.

The Sleipnir platform, the named after the eight-legged steed that belonged to the Norse god of war Odin, has become a textbook case, with visitors flocking to the site by helicopter to study the project.

Far below the waves of the raging North Sea, the seabed of watertight calcium rock called mudstone has yet to leak any CO2, according to independent studies.

But all this does not make Sleipner a "green platform".

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