Entergy, the US utility that took over London Electricity last year, has been given permission by the Department of Trade and Industry to build the pounds 390m plant at Damhead Creek, 30 miles east of London on the Thames estuary.
The 740-megawatt gas station will burn the equivalent of 1.75 million tonnes of coal - equal to the output of one large colliery.
The approval for the station follows National Power's announcement earlier this week that it is to construct a pounds 450m gas-fired station on a site near Newark.
That plant, built on the site of a former coal-fired station, will cut demand for coal by about 3.5 million tonnes.
Entergy already has approval to construct a 1,200-megawatt station in Hull, Yorkshire.
Construction of the Damhead Creek plant will start in April of next year and the station is due to come on stream in 2000.
The DTI has issued a Section 36 consent for construction of the plant - the second such authorisation it has granted since Labour came to power in May.
There had been hopes that the change of government would spell a more friendly approach to the coal industry but ministers appear to be keener of making sure Britain meets its environmental commitments to cut carbon dioxide gases than to protect coal-mining communities.
Terry Ogletree, president of Entergy Power Development Corporation, said that the technology being incorporated into the new station would deliver higher output at the same time as lower environmental emissions than conventional systems.