Greenpeace maintains oil shale is the dirtiest fossil fuel - some four-times more greenhouse polluting than conventional oil - and has been campaigning against the project since 1998.

SPP has had problems finding a market for its naphtha, with Greenpeace holding protests at Caltex service stations after that company became the first of Australia's four refiners to buy the shale oil.

Caltex subsequently canned further purchases. Shell and BP have also said they will not buy shale oil.