The Federal Energy Regulatory Commission on Friday approved NRG Energy’s plan to buy 12.9 GW in gas-fired power plants, and a demand response company from LS Power in a roughly $12 billion deal, saying it wouldn’t hurt market competition.

FERC rejected calls by the PJM Interconnection’s market monitor to impose conditions on NRG designed to prevent it from exerting market power in PJM’s energy and capacity markets. Monitoring Analytics failed to show that NRG would be able to influence market prices after the deal is completed, FERC said.

Under the deal, NRG’s capacity in PJM would jump to 9.5 GW from 2.1 GW and NRG would own 2.2 GW in New York, up from 1.2 GW, according to the companies’ application at FERC. The Houston-based independent power producer will also acquire CPower, a commercial and industrial virtual power plant platform with 6 GW of capacity under contract, including about 4 GW in PJM, according to an investor presentation.

Once complete, the deal would roughly double NRG’s generating fleet. Besides the assets in PJM and New York, the transaction includes three power plants in Texas totaling nearly 2,060 MW and two power plants in New England totaling 940 MW.

NRG contends the U.S. power markets are in an “unprecedented supercycle,” after about 15 years of little demand growth. At the same time, new gas-fired generation generally cannot come online until the 2030s, partly due to supply chain and labor constraints as well as regulatory bottlenecks, according to the company.

NRG and LS Power expect to close the deal early next year. The transaction must be approved by the New York State Public Service Commission. As part of the deal, LS Power will receive about 11% of NRG’s outstanding stock and $6.4 billion in cash. NRG will assume about $3.2 billion in debt from LS Power.

The pending transaction follows NRG’s early-May purchase of Rockland Capital’s 738-MW stake in six gas-fired power plants in Texas for $560 million.

Separately, FERC on Friday approved LS Power’s planned purchase of BP Wind Energy North America’s 1.3-GW wind fleet in seven states. Power from the wind farms is under contract to more than 15 offtakers, according to the companies.

The wind farms are in Indiana, Kansas, South Dakota, Colorado, Pennsylvania, Hawaii and Idaho.

Terms of the mid-July deal weren’t announced. As of Sept. 30, the carrying amount of the wind assets was $570 million, with associated liabilities of $39 million, London-based BP said in a Nov. 4 filing with the U.S. Securities and Exchange Commission.

After the deal closes — expected this year — LS Power’s Clearlight Energy will own about 4.3 GW in solar, wind and energy storage assets, according to the company.