Norway bets on CO2 capture, storage despite risks

By Wojciech Moskwa and Karina Lavik

SLEIPNER PLATFORM, North Sea (Reuters) - Norway sees carbon capture and storage (CCS) as a leading weapon to combat climate change and says the Sleipner field where it has buried carbon for 13 years demonstrates the technology is safe.

Green groups are skeptical about storing millions of tons of carbon dioxide underground without risking leaks, even though the United Nations believes a fourth of the cuts in emissions needed to keep climate change under control can come from CCS.

"There are quite big areas in the North Sea that are likely to be suitable for safe CO2 storage," said Olav Kaarstad, senior adviser on CCS for Norway's oil and gas producer StatoilHydro.

"We are learning as we go along but we are very optimistic," he said during a visit to the Sleipner T platform, which houses a treatment plant that takes carbon dioxide (CO2) out of the natural gas stream.

StatoilHydro calls Sleipner "the mother of all CCS projects" but its green status came partly out of necessity as gas found there naturally has a higher CO2 content than clients wanted.

So StatoilHydro and partners Exxon Mobil and Total built the sequestering plant several hundred meters from Sleipner's main A platform, a football stadium-sized rig resting 30 meters above an often raging North Sea on four cylindrical concrete columns. The platforms are linked by a bridge which doubles as a pipeline for the removed CO2.

Instead of emitting the CO2 to the atmosphere and paying Norway's carbon tax of around $30 per metric ton, it is pressurized and injected into a sandstone layer some 1 km under the seabed.

StatoilHydro monitors the injected CO2 by regular seismic scans to gain a picture of how it moves within the reservoir. It also tests miniscule changes in gravity on the seafloor, which indicate CO2 density in the reservoir underneath.