On August 21, 2018, the Environmental Protection Agency (EPA) released a prepublication copy of its proposed Affordable Clean Energy (ACE) rule. If adopted, the rule would (1) establish emission guidelines for greenhouse gas emissions from existing electric utility generating units (EGUs); (2) revise the regulations governing how states implement the emission guidelines; and (3) revise the New Source Review (NSR) program to allow modification to existing EGUs without triggering permitting requirements.
The Clean Power Plan regulations adopted by the Obama administration would have limited GHG emissions by directing states to reduce emissions by applying a combination of three “building blocks” as the best system of emission reduction (BSER), which consisted of:
1) Improving heat rate at affected coal-fired steam generating units;
2) Substituting increased generation from lower-emitting natural gas combined cycle units for decreased generation from higher-emitting affected steam generating units; and
3) Substituting increased generation from new zero-emitting renewable energy generating capacity for decreased generation from affected fossil fuel-fired generating units.