As much as 18 percent of the nation's coal-fired power units could be headed to retirement because of the cost to upgrade to current pollution controls, according to an analysis the Union of Concerned Scientists plans to release Tuesday.
The study, which the authors called a "stress test," found that 59 gigawatts of capacity, comprised of 353 generating units in 31 states, compare unfavorably to natural gas and renewables if the cost of pollution equipment is considered. Of that total, as much as 40 percent are already more expensive to run than cleaner alternatives, they found.
The additional capacity at risk for closure would come on top of about 41 gigawatts that power companies have already said they would shut down.
Authors Steve Frenkel and Jeff Deyette of the UCS said in an interview on Monday that they did not factor in the costs of new regulations from the Environmental Protection Agency, which utilities have said are driving some retirements.
Rather, they looked at the cost to operators of adding controls for sulfur oxides, nitrogen dioxide, mercury and fine particulates. .
"It's more than regulatory issues that are driving older and dirtier coal plants out," Deyette said. The low price of gas, higher costs of coal and the impact of state renewable energy policies are also factors that put older plants at a disadvantage, the authors said.
Frenkel and Deyette said they reached their estimates based on a conservative application of slightly more expensive natural gas prices in the future, based on government projections.
Much of the capacity at risk is in the south and Midwest, with Southern Company and the Tennessee Valley Authority ranking first and second respectively in plants that could be or are already uneconomic under the USC analysis.
Their analysis is to be issued at the fall meeting of the National Association of Regulatory Utility Commissioners in Baltimore that runs through Wednesday.
Frenkel stressed that the analysis was not intended to identify plants either for closure or continued use, but for regulators and utilities to consider future costs of using the plants compared to other alternatives.