The Grid is now forecasting that the 'plant margin' - the difference between power station capacity and peak electricity demand - will vary between 24 and 48 per cent compared with its forecast last year of 60 per cent.
Grid executives said, however, that this would not throw a lifeline to coal-fired generating plants or the 20 coal mines being closed by British Coal and the Government.
In its latest seven-year statement the Grid says that of the 27 gigawatts of combined cycle gas fired stations given the go- ahead, only 10-14 GW were likely to be in service over the next five to seven years.
Ten power stations have closed entirely, or in part, since the National Grid's last forecast, and five planned gas-fired stations have been abandoned.
This had helped reduce its forecast plant margin, as had evidence of economic recovery leading to increased electricity demand.
However, the Grid added that it was quite likely that even the reduced plant margin would not be realised, since its figures did not take into account the possible closure at short notice of the Magnox nuclear stations and Britain's older coal-fired power stations.Reuse content