Following on the heels of its January 8, 2014, publication of its revised proposed performance standards for carbon emissions from new power plants under section 111(b) of the Clean Air Act (see my previous blog post on these standards), the U.S. Environmental Protection Agency, on June 18, published its proposed carbon standards for existing coal- and gas-fired power plants under section 111(d) of the Act. 79 Fed. Reg. 34830 (June 18, 2014). Whereas the proposed standards for new power plants are, for now, largely theoretical–they would only apply in the future and their main target, new coal-fired power plants, are a dying breed–the proposed standards for existing plants, if passed, would pack a punch. Existing coal- and gas-fired power plants account for approximately 31 percent of anthropogenic greenhouse gas (GHG) emissions in the U.S. (including 38% of CO2 emissions), more than any other sector, including transportation and industry. By 2030, the proposed rule aims to reduce these emissions nationwide by 30 percent compared to 2005.

The proposed rule aims to reduce nationwide greenhouse gas emissions from coal-fired power plants like this one by 30% in 2023, compared to 2005 levels. (Source:

The proposed rule aims to reduce nationwide greenhouse gas emissions from coal-fired power plants like this one by 30% in 2030, compared to 2005 levels. (Source:

Under section 111 of the Clean Air Act, performance standards for pollutants such as GHGs must be based upon the degree of emission limitation achievable through the application of the “best system of emission reduction” (BSER). In this case, EPA identified four broad “building blocks” that together constitute BSER: making plants more efficient, increasing the use of low-carbon power sources such as natural gas, using more low-carbon power sources (e.g., solar, wind), and increasing energy efficiency.  EPA then applied these factors to come up power-sector CO2 emission rates for each state that EPA determined could be achieved by 2030, as well as a 2020 interim rate.

The required emission rates for each state–Minnesota’s 2030 goal is 873 pounds of CO2 per net MWh, or about 46% less than 2005 GHG emissions–vary widely and depend upon states’ existing energy balance and preexisting efforts to reduce GHG emissions. (This interactive map from EPA provides information on how it reached each state’s emissions rate.) As succinctly explained by Brad Plumer in this VOX article, states who must reduce a lower percentage of their GHG emissions won’t necessarily have an easier time meeting the target:

So why do different states have such different targets…? The EPA tried to take into account the state’s current energy situation when setting these goals. Some states are already on pace to reduce their emissions quickly: So take Washington, which is expected to reduce its emissions rate a whopping 72 percent. That’s partly because Washington is already on pace to phas eout a massive coal plant in 2020 anyway. So a big cut is relatively easier for Washington to achieve than it is for, say, North Dakota. That means these numbers don’t tell us how painful or costly it is for states to meet their emissions targets — it just tells us how much is likely to change in each state between now and 2030.

States can determine the methods they will use to comply with the goals, which could include shutting down old coal plants, switching to cleaner buring natural gas, bringing more renewable energy sources on line, and  instituting emissions credit trading between sources or even between states. EPA plans to finalize the rule in June 2015; states’ compliance plans would be due to EPA one year later, although extension waivers would be available. EPA will be accepting public comments on the proposed rule for 120 days after its date of publication in the Federal Register.