Carbon dioxide is the dominant human-generated greenhouse gas responsible for changing climate. The two largest sources of carbon dioxide emissions in the U.S. are from electric utilities and transportation activities. In 2007, the U.S. Supreme Court ruled that if the U.S. Environmental Protection Agency (EPA) found that greenhouse gases are a threat to public health, their emissions needed to be regulated. In 2009 through the Endangerment Finding, the EPA indeed found that climate change is a threat to public health. As a result of these decisions, the Obama Administration implemented new fuel economy standards for vehicles and proposed standards of carbon dioxide emissions from existing powerplants through the Clean Power Plan (CPP). These policies were a large part of the U.S. commitment to decrease carbon dioxide in the Paris Climate Agreement. The Trump Administration has not been supportive of these initiatives. But due to the Endangerments Finding, they cannot just cancel but need to replace these policies. The Trump plan to replace the fuel economy standards was released earlier in August and the Affordable Clean Energy (ACE) plan was released a few weeks later to replace the CPP.
Professor Driscoll’s presentation examines the approaches, benefits and costs of ACE compared with the CPP and no policy options. Carbon dioxide emissions standards for U.S. power plants will influence the fuels and technologies used to generate electricity, alter emissions of pollutants, and influence ambient air quality and public and ecosystem health. ACE is an “Inside the fence line” approach which improves the heat rate efficiency of individual power plants. As a result, older coal plants are made more efficient and operate for longer periods resulting in increases in carbon dioxide and emissions of co-pollutants, such as sulfur dioxide, nitrogen oxides, mercury and fine particulate matter which impact human health. In contrast, the CPP would use a “beyond the fenceline” flexible approach that promotes energy efficiency and renewables. Carbon standards to curb global climate change can also provide immediate local and regional health and ecosystem co-benefits, but the magnitude depends on the design of the standards.