The electric sector is the largest concentrated source of carbon emissions in the United States, accounting for more than one-third of all domestic greenhouse gas (GHG) emissions. Before the United States Environmental Protection Agency (EPA) took steps to regulate GHG emissions under the Clean Air Act, there were no federal limits. In a presentation to sustainable energy policy students at the University of Vermont, Dave Farnsworth explores the reasons for federal environmental law, implications of using Section 111(d) of the Clean Air Act as a basis for the Clean Power Plan, and some of the ways in which states are likely to respond in their state compliance plans.

Under Section 111(d), the EPA is required to establish a “best system of emissions reduction.” In response, the agency instituted four building blocks for compliance—energy efficiency, non-emitting generation like renewable and nuclear power, heat rate improvements, and re-dispatch to natural gas. EPA also encourages states to think beyond the four building blocks and affords regulators the discretion to implement a broad spectrum of technology and policy options in crafting approvable, least-cost compliance plans.