Carbon capture and storage (CSS) is fast becoming the oil industry’s favorite solution to the climate crisis, but the seductive simplicity of the idea masks a series of doubts about its viability.

But ask an expert when the technique could be deployed on a large enough commercial scale to make a significant reduction in global CO2 emissions, and the response is often less than confident.

“That’s a very difficult question,” said Olav Kaarstad, a leading expert and special advisor to front-running Norwegian energy group StatoilHydro.