The Details of the Clean Power Plan (So You Want to See the Numbers)

by Nicholas Thompson

Two weeks ago I wrote an article on the Environmental Protection Agency’s Clean Power Plan at Nuclear Undone. I highly recommend you read that overview first. This is meant to be a follow-up to that article, for people who want more background on the rule and how it effects nuclear.

First, a brief overview: the Clean Power Plan aims to reduce emissions rates (not necessarily emissions) by setting goals for states in terms of lbs of CO2/MWh. According to the US Energy Information Agency (US EIA), in 2012 New York State’s electricity sector had a carbon emissions rate of 578 lbs/MWh. For scale, the average U.S. coal plant emits ~2250 lbs of CO2/MWh, and the average natural gas plant emits ~1100 lbs of CO2/MWh. New York’s carbon emissions rate is much lower than a state like Wyoming (2106 lbs/MWh) because while Wyoming is heavily reliant on coal (87.5 percent of net electricity generation was from coal), New York has a mix of natural gas, nuclear, hydroelectric, coal, and other renewables.

In the Clean Power Plan, state goals are set by calculating the total emissions of the electricity sector for that state, and dividing the electricity production of all fossil fuels, wind, and solar, but only 5.8 percent of nuclear (hydro is excluded completely). What this does is artificially increase the calculated initial emissions rate for the state, so that in setting state goals, states with a significant amount of nuclear have easier goals. Let’s use New York, Illinois, and Wyoming as examples to show this. Table 1 shows the various mixes of energy production for each state, in percentages.

Table 1: Electricity Generation by Source, 2012 EIA Data

Electricity Source [%]

New York











Natural Gas








Wind and Solar








I picked these three states because they each represent a different energy mix; New York with a mixture of sources (and it’s my home state), Illinois being nuclear and coal heavy, and Wyoming being dominated by coal. Table 2 shows the 2012 emissions rates for each of these states.

Table 2: Calculated Emissions Rates

Emissions Rate [lbs CO2/MWh]

New York



Actual 2012 Emissions Rate




Calculated 2012 Emissions Rate




Calculated 2030 Goal Emissions Rate




Goal with 100% Nuclear Accounted For




As expected, the states that rely the most on coal have the highest current emissions rates. However, also shown in Table 2 is the “Calculated 2012 Emissions Rate”, based on the EPA’s formula that only takes 5.8 percent of nuclear into account and doesn’t take into account hydroelectric. Illinois and New York show much larger “calculated” emissions rates, because it’s essentially only counting coal, natural gas, renewables, and a sliver of nuclear (Wyoming doesn’t change much because it doesn’t have any nuclear and barely any hydroelectric). So in setting emissions goals, it is the “calculated” emissions rate that the EPA uses as a baseline. Table 2 also shows the 2030 emissions goals based on this formula, and for New York there is barely a difference between the actual 2012 emissions rate and the 2030 calculated goal. Illinois is even a stranger situation, where the actual emissions rate in 2012 is lower than the calculated 2030 goal. Wyoming on the other hand will have to find a way to reduce emissions.

You might also wonder where the 5.8 percent for nuclear came from in the first place. According to the Clean Power Plan, this was the percentage of nuclear plants that are “under construction or at risk.” The goal of protecting economically-at-risk plants is a good one (although under the current formula it barely values nuclear at all), but the “under construction” is curious. It’s strange, because what this means is that in states where nuclear plants are under construction, the rule assumes that those plants are already operating and won’t take their additional contribution into account at all when it comes to compliance with the rule.

But back to the main point, if nuclear is accounted for at 100 percent of its generation (the last row in Table 2), then the emissions goals become more stringent, and states that shut down nuclear plants would have a hard time hitting emissions goals. Don’t take my word for it; when a Natural Resources Defense Council (NRDC) attorney was asked about only including 5.8 percent of nuclear generation, he responded by saying “I observe that most of those nuclear plants were built a long time ago…Including them all would imply that states need to make sure all of them continue to operate. Compliance in states that had to close them down would be more difficult.” The reason I bring up the NRDC is because of its involvement in writing the rule, as documented in the New York Times.

Only accounting for 5.8 percent of nuclear also means that states with large amounts of nuclear don’t have to do much to hit emissions targets; in fact certain states, Illinois being one of them, could close all of their nuclear facilities and replace them with natural gas plants, and their emissions rate would be less than the 2030 goal. This would of course lead to higher emissions in the real world, but it would be perfectly fine according to this rule.

If you’re wondering why I didn’t include hydroelectric in the calculation, it’s because:

  1. I wanted to just highlight the importance of fully taking nuclear generation into account, and…
  2. The EPA makes a pretty good point as to why it didn’t include hydroelectric in setting state goals.

The point the EPA makes (on page 200 of the Clean Power Plan) is that states are unlikely to build significantly more hydroelectric in the next 15 years, so including hydroelectric would drastically change the goals for states that have large amounts of hydroelectric versus those that don’t. The EPA does offer a caveat, however: “The exclusion of pre-existing hydropower generation from the baseline of this target-setting framework does not prevent states from considering incremental hydropower generation from existing facilities (or later-built facilities) as an option for compliance with state goals.”

This brings me to my final point. The Clean Power Plan does not clearly say what the formula for computing compliance will be. The formula for setting goals only includes 5.8 percent of nuclear and no hydro, but the quote above implies that additional hydro could be used to reduce the state’s emissions rate. So this could go one of a few ways:

  1. The EPA uses the same formula as it did for setting state targets (this would exclude all new hydroelectric, which goes against the quote above).
  2. The EPA calculates compliance emissions rates in a sane and logical way that includes all generation (in which their original goals don’t make much sense, since some states would already be in compliance).
  3. The EPA calculates compliance emissions rates with a new, yet-to-be determined formula that may or may not include the low carbon generation from nuclear facilities.

This is why this issue is so important. As the Clean Power Plan is written, targets are made extremely easy for states with nuclear plants, such that in some states they can be shut down with little to no consequence, even though actual emissions will be much higher. It also does not lay out how compliance will be calculated, but based on the comments about hydroelectric, hints at a different way of calculating compliance (which may or may not include nuclear). Either way, nuclear’s importance as a source of low carbon energy is not accounted for. This is in stark contrast to wind and solar, in which 100 percent of existing wind and solar is credited in target setting.

So if you care about the environment and want the Clean Power Plan to actual achieve real-world emissions reductions, and not just “calculated” emissions reductions where actual emissions stay the same or go up, nuclear must be included.

All the major environmental groups are submitting comments. Will you make your voice heard? Don’t be discouraged by the number of comments already submitted. Based on a quick search, only roughly 21,000 of the comments about the plan are unique. This means that each and every unique comment will be important, and even a few hundred comments will be a significant portion of those received.

Comments to the EPA Clean Power Plan are due by December 1, and if you are an American Nuclear Society member, make sure to identify that in your comment:

Also a major thanks goes out to Remy DeVoe, Justin Knowles, and Dr. Steve Skutnik for actually crunching the numbers and helping to get this issue the attention it needs. And if there are any students who would like to get involved with policy work, and actually meet with the EPA, the Nuclear Regulatory Commission, and the Department of Energy, apply for the Nuclear Engineering Student Delegation!


Nicholas ThompsonNicholas Thompson is a Ph.D. student at Rensselaer Polytechnic Institute studying nuclear engineering and science. His current research is on using a lead slowing-down spectrometer to measure various nuclear data at the Gaerttner Linear Accelerator Center.

5 thoughts on “The Details of the Clean Power Plan (So You Want to See the Numbers)

  1. Charlie

    Hi Nicholas,
    I have been reading the EPA ruling document, but see no mention of new nuclear *after* the currently being constructed. It seems that it will be counted for 100% of new generation, is that right? I noticed a mention of advanced nuclear, however, nothing concrete.
    In your opinion, is this positive for construction of new nuclear, esp advanced or small / modular?
    Thank you,

  2. Nicholas Thompson

    Under the current rule, 5.8% of existing + under construction nuclear would be accounted for in setting state targets. So they are treating currently under construction nuclear the same as existing nuclear. What we are saying is the nuclear under construction is not currently generating electricity, so it should be accounted for as an emissions reduction when evaluating compliance with the rule.

    I don’t think they just use a single number. Part of the rule (if implemented) would look at site specific emissions, and they do have data on specific sites, as well as state-wide data. That data can be found in the “Goal Computation” spreadsheets here:

  3. Keith Pickering


    Do you know if EPA uses one number for emissions from each powerplant type? And if so, what those numbers are, or where they can be found?

  4. Tim Wyant

    Nicholas, I understand that existing nuclear gets the 5.8% tag, and new nuclear gets 100% credit while under construction (using an average capacity factor). Question is, once the new reactor is built and operational, is it still counted at 100% of its actual output, or does it revert back to the 5.8%?

  5. Jim Hopf

    I can (begrudgingly) accept having EPA consider things like the fact that nukes and dams were built along time ago, but only with respect to determining the emissions reduction *goals* for each state. After all, it has always been clear the state reduction goals were based on their discretion and judgment.

    What I cannot accept is a bizarre (capricious and arbitrary) definition of emissions intensity (i.e., tons CO2 per MW-hr) , where the “MW-hr” means something other than the total MW-hrs generated in the state. They can use whatever basis they want for determining each state’s emissions intensity reduction goal, but emissions intensity needs to mean emissions intensity. Not all fossil plus renewable MW-hrs plus 6% of nuclear MW-hrs!!

    Under the bizarre, artificial definition, one may actually have an incentive to replace nuclear with gas. As long as emissions intensity actually means emissions intensity, that would always hurt, even if EPA gave the state a lax goal. A closed nuclear plant would still have to be offset by emissions reductions elsewhere.