The Affordable Clean Energy Rule (ACE) provides a plan for states to make realistic assessments and upgrade their power plants with clean technologies so that they can operate in a more environmentally friendly manner. ACE refocuses the Environmental Protection Agency (EPA) on sound science, transparency, supply diversity, and the rule of law, rather than bureaucratic overreach and politics. Obama’s Clean Power Plan, which ACE replaces, was never implemented. The United States Supreme Court stopped the rule, partly due to claims from over half the states that they would suffer “irreparable injury” without intervention. The stay on implementation was an extraordinary step for the Supreme Court, which many Court-watchers at the time said indicated displeasure with a vast rule with enormous consequences.

Affordable Clean Energy Rule

On June 19, 2019, EPA issued ACE, replacing the Obama administration’s Clean Power Plan with a rule that establishes emission guidelines for states to use when developing plans to limit carbon dioxide at their coal-fired electric generating units. ACE regulates the electric industry on a plant-by-plant basis, allowing older plants to keep operating as they adopt improved, more-efficient technology. The new plan removes the federal government’s power to set emissions-reduction targets across the industry, regulating only “inside the fence line of” each plant. It creates a menu of technological options the plants can choose from to boost efficiency, using less coal to generate the same amount of electricity. States have the authority to design plans for power plants within their borders, with three years to develop and submit the plans to the EPA for approval.

More specifically, ACE establishes heat rate improvement—a measure of the amount of energy required to generate a unit of electricity—as the best system of emissions reduction for carbon dioxide from coal-fired generating units. ACE provides six “candidate technologies:”

• Neural Network/Intelligent Sootblowers
• Boiler Feed Pumps
• Air Heater and Duct Leakage Control
• Variable Frequency Drives
• Blade Path Upgrade (Steam Turbine)
• Redesign/Replace Economizer

ACE does not set a specific target for the power sector to reduce carbon dioxide emissions, giving states the authority to write their own plans for reducing carbon dioxide at individual plants. The Trump EPA estimates that carbon dioxide emissions would be reduced through both market forces and ACE by as much as 35 percent below 2005 levels in 2030, which is similar to reduction estimates calculated by Obama’s EPA for the Clean Power Plan. Trump’s EPA estimates ACE will directly reduce carbon dioxide emissions by 11 million metric tons by 2030—a 0.7 percent reduction compared to no regulation. There would also be benefits from reducing sulfur dioxide, nitrogen oxide, particulate matter, and mercury emissions, which are already controlled by other regulations and have been declining rapidly.

EPA Finalizes the Affordable Clean Energy Rule, Replacing Clean Power Plan