Exelon is one of the nation’s most important regional utilities. Even though past CEO John Rowe retired three years ago, he’s not shy about expressing his thoughts on the Clean Power Plan and climate. Rowe explained in an interview last week why Illinois, where Exelon is a dominant utility, should adopt a carbon tax for Clean Power Plan compliance:

[The Clean Power Plan] is not going to have optimal or efficient results. Because they just don’t have the tools. I have suggested to several people, including NRDC [Natural Resources Defense Council] and a couple of [Illinois] Gov. [Bruce] Rauner’s people that I think the Illinois means for compliance ought to be a carbon tax. I don’t think he’s going to buy it, but I made the suggestion. I do know that trying to do it by piecemeal reductions will be very expensive.

In short, a carbon tax is a more elegant, cost-efficient way to reduce greenhouse gas emissions. What Rowe doesn’t say is that carbon tax revenue could be used to fill the state’s massive budget hole. When Clean Power Plan compliance is already expensive, why not solve two problems with a carbon tax?

Sarah E. Hunt is Director, Center for Innovation and Technology at ALEC. She leads the Center’s Energy Innovation Project. Her policy work focuses on free-market solutions for the energy future.