Existing Power Plants
EPA regulates greenhouse gas emissions from power plants under Section 111 of the Clean Air Act, which allows EPA and the states greater flexibility in crafting and implementing a standard. Emissions from new and modified power plants have been finalized under Section 111(b), as described below. Emissions for existing power plants are still being developed under Section 111(d).
In June 2019, EPA issued GHG emission regulations for existing fossil fuel-fired power plants in the Affordable Clean Energy (ACE) Rule. The rule would direct states to require coal-fired power plants to use prescribed technologies to improve their heat rate (i.e., increase efficiency), as a best system of emission reduction for carbon dioxide.
The ACE Rule is not expected to reduce power sector emissions from a business-as-usual scenario. It would replace the Clean Power Plan, finalized in August 2015, that had set state-specific emission rates and provided various market-based flexible compliance provisions.