An Apples-to-Apples Comparison of Mass-Based State Emission Goals under the Proposed and Final Versions of the Clean Power Plan Rule

As we outlined last week, comparing the rate-based goals presented by EPA in its proposed Clean Power Plan with those presented in the final Clean Power Plan could lead to a misleading conclusion about the relative stringency of those goals. 

It turns out that a similar hazard awaits those seeking to compare the mass-based goals. 

In both the proposed and final Clean Power Plan rules, EPA gave each state the option to use a mass-based emission limit instead of its rate-based goal.  How did states fare between the proposed and final Clean Power Plan with regard to mass-based goals?  As with rate-based goals, a simple comparison between the numbers presented in the proposed rule and those presented in the final rule would be misleading.  Below, we explain the issue, and provide adjusted goals that allow for a more accurate comparison

Mass-based Goals under the Proposed Clean Power Plan

Initially in the proposed Clean Power Plan, EPA gave states the opportunity to calculate their own equivalent mass-based goals and provided a Technical Support Document outlining the methodological considerations that states would be required to use when making such a calculation.  Facing pressure from states and stakeholders, EPA later released a Notice and associated Technical Support Document providing additional information on the rate-to-mass translation.  EPA included two acceptable methodologies for translation—one methodology for a state that only wanted to include existing fossil fuel-fired power plants in its compliance plan and a second methodology for states that chose to include both existing and new plants.  EPA emphasized that these were not “prescriptive” methodologies, but rather “represent[ed] one particular way” of converting rate-based goals to mass-based equivalents.”  In an appendix, EPA included Tables of mass-based Interim and Final goals under each methodology for each state. 

Mass-based Goals under the Final Clean Power Plan

While states and others largely relied on these presumptively approvable mass-based goals when analyzing the proposed rule, some uncertainty remained and many requested a more formal equivalence determination from EPA.  The final Clean Power Plan fulfills that request.  EPA includes in the final rule legally equivalent mass-based goals that each state may choose to adopt in lieu of the rate-based goal.  As in the proposed rule, EPA has included existing-unit-only mass-based goals and also mass-based goals for states that choose to include new units—which EPA calls the “new source complement.”

EPA made a number of changes to its translation methodologies and to the 2012 baseline of units used to calculate state goals that could have an effect on the stringency of those goals beyond what could be presented by a mere arithmetic comparison.  Cataloguing all of these changes is beyond the scope of this alert.  However, because of one critical change, direct comparison of the presumptively approvable state mass-based goals from EPA’s proposal with the mass-based goals included in the final Clean Power Plan is misleading as an indicator of the relative stringency of the proposed and final mass-based goals. 

Caught Short

In its proposed rule Notice and Technical Support Document, EPA presented mass-based goals in metric tons—a measure of mass equal to 1000 kilograms.  The final Clean Power Plan, however, presents mass-based goals in short tons—a distinct measure of mass equivalent to 2000 pounds, or 907.1847 kg kilograms. 

Any attempt to compare how states fared as between the proposed and final rules when it comes to mass-based goals must first put those goals in the same unit of measure.  Specifically, one can make an apples-to-apples comparison by going back to the proposed rule’s mass-based goals and converting them from metric tons to short tons. 

Because one metric ton contains approximately 10% more mass than one short ton, this adjustment has an impact on the perceived change in stringency of the final mass-based goals for a number of states.  So in comparing the final rule’s mass-based goals to the proposed goals, it is important to recognize that the units in the final rule are about 10 percent smaller, and thus the final rule’s mass-based targets are more stringent than a direct comparison of the two sets of “ton” limits would suggest.  For a handful of states, while the mass-based targets in the final rule appear less stringent, the adjustment reveals that they are, in fact, somewhat more stringent.  This is the case for Indiana, Michigan, Nebraska, and Ohio under the existing-unit-only targets and for Illinois, Louisiana, Michigan, Utah, and Wisconsin under the “new source complement” targets. 

In the tables below, we present an accurate comparison of mass-based goals between the proposed and the final Clean Power Plan—both for existing-unit-only state plans and for those that also include new sources. 

The adjustment allows for a better assessment of the differences in stringency between the proposed and final rules.  These differences reflect the many other modifications that EPA implemented, including changes to the BSER methodology, the 2012 baseline, and projections about new sources.  We have not attempted to quantify just how much the difference between the adjusted proposed mass-based goals and the final mass-based goals is attributable to each of these other modifications.  Using consistent units of measure provides the right launching point for such an analysis.

So, before you go the extra kilometer in evaluating the change in stringency between the proposed and final mass-based goals, we urge you first to use a comparable unit of measure.  

Preliminary State-by-State Analysis of Relative Stringency of Existing Unit Mass-Based Goals Between Proposed and Final Clean Power Plan Rule

Preliminary State-by-State Analysis of Relative Stringency of New Source Complement Mass-Based Goals Between Proposed and Final Clean Power Plan Rule

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Van Ness Feldman will be preparing a comprehensive analysis of these rules that will be available on a cost-share basis. Our professionals are also available to provide counsel to companies and others as they assess the implications of the rule and prepare to submit comments to EPA. Please contact Kyle Danish, Stephen Fotis, or any other professionals in Van Ness Feldman’s Environmental Practice for additional information on the analysis or on other matters related to these rules.

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