Norway's experimental Mongstat carbon capture plant
5 August 2013 Last updated at 10:45 BST
A structure the size of a football pitch has been sent plunging to the bottom of the ocean, 125 miles off the coast of Norway.
The Statoil equipment has been designed to pump some £20bn ($30bn/23bn euros) worth of gas from a depleted gas field.
The Norwegian energy giant is also developing carbon capture and storage technology that might allow the world to carry on burning fossil fuels.
The experimental Mongstat technology centre is testing two types of carbon capture equipment on two types of exhaust.
Roger Harrabin visited the facility, which is run by a consortium of companies led by Statoil.