ScottishPower hopes to build the plant on the site of the former Terra Nitrogen complex, close to the Severn Beach.
The company has said the new Avon Power Station power station would generate 1,200MW, enough power for 1.5m homes.
Power experts predict there will be renewed interest in building gas power stations because of fears that the nuclear programme will slip by a few years because of the review into safety and design in the wake of Fukushima.
Richard Escott, head of project development at ScottishPower, said: “A number of power stations in the UK are due to cease operating from 2015 onwards and, in order to guarantee long-term security of electricity supplies, it is important that energy companies continue to look at the best options for replacing the electricity generation that will be lost.
“The site we are examining has a long history of industrial usage, but our evaluation work will thoroughly consider all aspects of the surrounding environment.”
The gas-fired power station could end up being located next to an energy from waste plant.
Waste firm SITA is presently on tenterhooks to see if the Government will overturn the local planning committee decision to refuse permission for a 400,000 tonne incinerator.