On June 17th, 2025, the Trump administration published its Proposed Rule to repeal the Biden administration’s regulations on greenhouse gas emissions on coal and natural gas power plants. This rule was formally entitled the “Repeal of Greenhouse Gas Emissions Standards for Fossil Fuel-Fired Electric Generating Units.”

Last week, we described how repealing these regulations would yield $404.1 billion in benefits in the Midcontinent Independent System Operator (MISO) region through 2055, which was far higher than the $19 billion estimated by the Trump administration because they used a fatally flawed bait-and-switch baseline.

However, there was a bigger issue with the Regulatory Impact Analysis (RIA) produced by the administration to justify the regulations than the lack of benefits: it showed the rules would impose a net cost on society due to $76 billion to $130 billion in economic damages from higher emissions of criteria pollutants, jeopardizing the legal standing of the rules under the Administrative Procedure Act and making it more vulnerable to legal challenges from climate advocates.

Thankfully, our modeling found that the Trump Administration’s proposal would result in $314.6 billion in net benefits in the MISO region through 2055, even when we account for the higher emissions of criteria pollutants.

Cooking the Books on Costs with Co-Benefits

When looking at the economic impact of rules like these, the standard practice is to weigh the benefits of less spending for the future grid against the costs of higher emissions of things like small particulates (PM2.5), nitrous oxides (NOx), and sulfur oxides (SOx), and also greenhouse gas (GHG) emissions.

However, the Biden administration’s cost/benefit analysis of their final GHG rules on power plants relied heavily on the calculation of co-benefits from reducing emissions of PM2.5, NOx, and SOx, as well as climate benefits from reducing greenhouse gases to make their regulations pencil out. There are serious shortcomings to this approach.

Improvements in current emissions reduction technology on existing power plants mean they emit very few pollutants already. EPA data show the vast majority of states, particularly those in the MISO region, are already in compliance with the National Ambient Air Quality Standards (NAAQS) established for these emissions, which are designed to protect even the most vulnerable populations, such as children and the elderly.

As such, the EPA’s supposition that reducing emissions below levels already considered safe for the most vulnerable populations makes no sense, as our friend Dr. wrote ...