New gas turbines at a plant near Nashville are adding 500 megawatts to the Tennessee Valley Authority’s grid capacity, the utility announced Wednesday.

The completion of 10 new aeroderivative gas turbines at Johnsonville Combustion Turbine Plant brings its total capacity to more than 1,200 megawatts, TVA said in a news release.

Justin McBath, TVA senior project manager, said the turbines are designed to ramp up and down quickly or be turned off when not needed.

“They have a fast-start option,” McBath said. “You can go from a cold engine to full power in five minutes, generating 50 megawatts per unit – and these will actually generate up to around 57 to 59 megawatts under the right conditions.”

According to TVA, 500 megawatts is enough to power almost 300,000 homes. The TVA serves more than 1.2 million customers through 25 local power companies in northern Alabama, including Huntsville Utilities.

The aeroderivative turbines’ fast-start feature will help meet daily and seasonal peaks in electricity demand, TVA said. The Johnsonville turbines are the first to come online for TVA, but the utility is working on another 16 at its 1,500-megawatt energy complex on the site of Kingston Fossil Plant in Roane County, Tennessee.

TVA has near-term plans for 6,200 megawatts of new generation, with over 3,500 of those megawatts already under construction. That’s enough to power about 2 million homes, the utility said.