The two plants deactivated in 2018 and 2019 generated more than 1,400 megawatts, enough power for more than 1 million homes. //

More nuclear power plant retirements may be on the horizon: PJM, the Pennsylvania-based coordinator of wholesale electricity in 13 states plus the District of Columbia, has already begun planning for the planned retirements of the dual-reactor, 1,813-megawatt Beaver Valley Power Station in Pennsylvania and the Davis–Besse and Perry nuclear power plants that together generate 2,143 megawatts in Ohio.

PJM’s grid, which covers Pennsylvania and New Jersey, had 183,454 megawatts of installed generating capacity available as of May 2019. The company puts the total capacity of the recently retired nuclear plants and the three planned for retirement at 5,387 megawatts, or about 3% of overall capacity. (PJM says its all-time highest power use was 165,563 megawatts in the summer of 2006.) //

The grid counts 11,415 megawatts of new natural gas-fired electricity generation coming online in 2018 and 2019 and an additional 10,514 megawatts from gas expected to go in-service in 2020 through 2023. Operators of those future plants have signed what are called interconnection service agreements with PJM.

"That's sort of a stage at which the projects are likely to get built," Shields said of the agreements.

All told, new gas, wind and solar plants are projected to add 29,097 megawatts to the grid, as 19,037 megawatts of capacity are lost from retired coal, gas and nuclear plants, PJM says. That's a net increase of more than 10,000 megawatts. //

PJM projections show that if all three nuclear plants planned for retirement in Pennsylvania and Ohio go offline, carbon dioxide emissions would rise by about 3.7% above 2019 levels. Other emissions, sulfur dioxide and nitrogen oxide, would drop, thanks to older fossil fuel plants shutting down. If those nuclear plants remain online and all or even half of the new gas plants open, all three pollutants would drop across PJM’s territory.