The CCGT will add additional capacity to the existing 498MW natural gas power plant. It will feature GE’s gas turbine technology and an air cooling system.
The project is part of Exelon’s strategy to provide low-carbon electricity in Texas.
Exelon is also developing another 1,000MW CCGT unit for installation at its Wolf Hollow generating station in Granbury, Texas.
The two units are planned to be commissioned in 2017.
Exelon Generation president and CEO Ken Cornew said: "Exelon is a forward-looking company, and what we see is a clean energy future that includes this kind of new technology, which uses little water and produces few emissions while generating electricity at a very low cost."