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Unpacking the EPA’s Proposed Clean Power Plan: Understanding the Metric

On June 2, 2014, the U.S. Environmental Protection Agency (EPA) proposed the Clean Power Plan’s guidelines to states for regulating carbon dioxide (CO2) emissions from existing power plants under section 111(d) of the Clean Air Act. In the proposal, EPA defines the “best system of emission reduction” based on four building blocks and calculates state-specific goals from CO2 reduction measures under the four building blocks. The following presentation provides an overview of the EPA proposal, with a focus on the state goals.

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The metric of these state goals has been loosely termed an emission rate; however, without distinguishing the ways that the state goal equation deviates from an actual emission rate, it would be easy to misinterpret the proposed state goals and the effort required to reach them.

Although it is understandable that stakeholders and observers would want to put the proposed state goals in context by comparing them with something, a comparison to past emission rates is a bit like comparing a salad to lettuce because the state goal metric includes a lot more than just the fossil emission rate. In addition to the average emission rate of fossil-fired electric generating units in the state, the state goal includes a portion, but not all, of the zero carbon generation in the state and accounts for end-use energy efficiency as essentially carbon-free generation, or the megawatt hour (MWh) equivalent energy services provided. Furthermore, when a state looks at whether they will meet the state goal, they will need to include additional information beyond the emission rate in the formula to compare to the state goal.

The table below includes the 2012 historical fossil emission rate, the adjusted baseline rate, and the 2030 state goal for each state as proposed by the EPA in the June 2014 Clean Power Plan. In addition, the table includes the calculated contribution from each building block toward each state’s goal, as a percent reduction from the baseline rate. The EPA baseline rate is an adjusted rate that is lower for every state and — significantly lower for some states — than the 2012 fossil emission rate. Percent reductions are calculated from the adjusted baseline rate because a comparison of the state goal to the historic emission rate would confuse the difference in metric with the emission reduction and would not be indicative of how much emission reduction is required beyond current levels.

Download a larger version of the chart

Download a larger version of the chart

Source: Numbers calculated from pg. 26 of the Technical Support Document: Goal Computation. Percent Reductions represent the building block emission rate/baseline emission rate.

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