OG&E has switched on the first of two new power units at its Horseshoe Lake plant in Harrah, delivering nearly 450 megawatts of fresh generation capacity months ahead of schedule and under budget. Unit 11 passed all of its contractual performance tests on August 31, and it already helped carry the grid through some of the summer's hottest days before its official commercial debut. Unit 12 is close behind, in the final stage of completion.
Together, the two simple-cycle combustion turbines are expected to enter commercial service in October, adding roughly 448 megawatts of generation capacity — enough to power about 300,000 homes, according to News 9. The new turbines will replace two 60-year-old, less-efficient units that had served customers for decades, and OG&E plans a ceremonial ribbon-cutting for both new units in November. Notably, Unit 11's ability to provide winter power wasn't part of the original schedule, meaning the plant will be ready to lean on the unit sooner than planned as cold-weather demand approaches.
OG&E Chairman, President and CEO Sean Trauschke tied the early finish directly to the utility's workforce, saying that completing Unit 11 ahead of schedule and under budget reflects the team's commitment to safety, operational execution and customers, per the same News 9 report. Units 11 and 12 are designed to add flexible generation that can respond quickly when customers need it most, according to the outlet's reporting.
A Century-Old Plant Gets a Modern Upgrade
A Century-Old Plant Gets a Modern Upgrade Horseshoe Lake has been in operation for more than 100 years, according to Power Engineering. The new Units 11 and 12 both use GE Vernova 7FA.05 gas turbines engineered to eventually burn hydrogen as fuel once supplies become available, giving the century-old site a long-term decarbonization option even as it runs on natural gas today.
The project also has an environmental upside tied to what it's replacing. Swapping out the two 60-year-old gas-fired boilers, Units 6 and 7, for modern dry low-NOx combustion turbines is expected to reduce the facility's total emissions of nitrogen oxides, volatile organic compounds and carbon monoxide, per a draft air quality construction permit evaluation from the Oklahoma Department of Environmental Quality.
What the Project Cost, and Who Pays for It
The self-build project for Units 11 and 12 carries an estimated capital cost of $394.3 million, or roughly $880 per kilowatt for the 448 megawatts, and was selected through a competitive bidding process evaluated by an independent monitor, according to filings OGE Energy Corporation submitted to the Oklahoma Corporation Commission. Regulators there approved a Generation Capacity Rider that lets OG&E recover costs on customer bills only after the units enter service, while denying Construction Work in Progress charges during construction, per SEC filings outlining the state's rate treatment.
That approval wasn't limited to Units 11 and 12. In November 2025, the Oklahoma Corporation Commission also pre-approved OG&E to build two more combustion turbines at the same Harrah site, Units 13 and 14. OG&E serves approximately 910,000 residential, commercial and industrial customers across a 30,000-square-mile territory spanning Oklahoma and western Arkansas, and the utility also plans generation, transmission and distribution work.
Fast-Ramping Turbines Built for Extreme Weather
The simple-cycle design behind Units 11 and 12 matters for how OG&E operates inside its regional grid. The turbines are designed to provide flexible generation that can respond quickly when customers need it most, according to Oklahoma Energy Today.
Statewide, lawmakers have moved to make sure this kind of buildout doesn't land on residential customers' bills. The Oklahoma Senate passed an amended House Bill 2992, the Data Center Consumer Ratepayer Protection Act, and the bill returned to the House; it would require large-load facilities that add 75 megawatts or more to cover 100% of their own grid upgrade costs, according to the Oklahoma Senate. The Senate described growing data-center activity in the state. The legislation addresses how large-load facilities would cover grid upgrade costs.
For eastern Oklahoma County residents, the practical upshot is a plant built to respond fast during the region's most punishing heat and cold. It's the latest chapter for a facility that has anchored the local grid for more than a century, and it arrives alongside broader scrutiny of how Oklahoma pays for the power its growing economy demands.
