Modelling on how the state government would compensate for the estimated 22 million tonnes of greenhouse gases generated by the proposed two new coal-fired power stations is yet to be undertaken.

The government believes the new plants, based on extensions to existing stations at Mount Piper near Lithgow and Bayswater in the Hunter Valley, would probably displace slightly less efficient plants elsewhere on the east coast power grid.

But a series of freedom-of-information requests that Greenpeace has put to the government show that no work has yet been done on how the emissions would be offset, despite the NSW government developing a new strategy for deeper greenhouse gas cuts.

Demand for cheap electricity in NSW is not rising as quickly as predicted in the Owen inquiry into electricity supply, with the most recent data suggesting a trend towards more gas-fired power.

Greenpeace said the lack of work done so far to factor in the greenhouse impact of the two plants suggested that many in government did not believe they were necessary.