A regional haze program final rule for Texas expected soon from the Environmental Protection Agency (EPA) could speed up the retirement of about 4.7 GW of coal-fired capacity, warns the Electric Reliability Council of Texas (ERCOT) in a new generation outlook.

The grid operator’s Dec. 1–released “Report on the Capacity, Demand and Reserves (CDR) in the ERCOT Region, 2016–2025,” predicts peak loads will average more than 500 MW higher than previously forecast through 2021, but planning reserve margins have also increased for all years—with the exception of 2016.

The higher reserves are due to about 6,250 MW of new planned resources that became eligible for addition to the CDR report since ERCOT’s last report in May. That capacity includes about 1.6 GW of natural gas–fueled generation, 1.15 GW of utility-scale solar power, 590 MW of wind energy, and 320 MW of compressed air energy storage.

The EPA’s final regional haze rule as well as the Clean Power Plan could change that, however, ERCOT warns. The final regional haze rule, expected within the next few months, will establish a federal implementation plan (FIP) for Texas and could require scrubber or retrofits at 12 coal units between 2018 and 2020.

The independent system operator that manages about 90% of Texas’ electric load warned in an Oct. 16 study that the Clean Power Plan and the regional haze rule could force the retirement of up to 4.7 GW of coal capacity in the region starting as soon as 2022. In its Dec. 1–released CDR report, it says that depending on requirements in the forthcoming final regional haze FIP, those retirements may occur within the next five years.

But according to the CDR report, ERCOT’s fuel mix isn’t expected to change significantly. In the summer of 2016, ERCOT anticipates about 24.3% of its capacity will be coal-fired. In comparison, about 21.6% of its capacity in 2025 is expected to be coal-fired. Natural gas will make up the same 63.7% share of ERCOT’s power mix both in 2016 and 2025, the report forecasts.

Sonal Patel ­is a POWER associate editor (@sonalcpatel)