Affordable Clean Energy (ACE) rule replaces Clean Power Plan

Summary

In June 2019, EPA replaced the Clean Power Plan with the Affordable Clean Energy rule. The old rule had set carbon limits for existing power plants. The new one was narrower — plant-by-plant efficiency, not a shift in how the grid made electricity. Courts later vacated it. The record here is the rollback itself: one administration's power-plant climate rule taken off the books by the next.