Energy & Environment

How can states respond to EPA’s power plant carbon reduction goals?

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The Environmental Protection Agency’s (EPA) Clean Power Plan is built on states proposing mitigation actions in each of the four building blocks pictured below. Once this plan finishes the approval process, expected in August, the challenges with developing a compliance plan and the related political battles will shift to state governments. At that point, not only governors, state legislators and state environmental agencies, but also nongovernmental organizations, utilities and the energy industry within those states will need a better understanding to determine the optimal strategy for their states.

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Luckily, researchers Paul Fischbeck, Haibo Zhai and Jeffrey Anderson from Carnegie Mellon University’s Scott Institute for Energy Innovation have developed an easy-to-use free model, in a gigantic Excel spreadsheet, to help both states and stakeholders determine the best strategy for their states. Called ISOMAP for “Interactive State On-Site Mitigation Analytical Policy,” the tool allows users to evaluate a range of electric generating unit-specific technical options that will reduce carbon dioxide emissions from each major U.S. coal-fired power plant.

Users of the tool can study difficult trade-offs between costs and carbon dioxide reduction while still complying with the EPA regulation. While the EPA proposal and guidelines are based on national and state-averaged information, the actual mitigation plans that states must create will require plant-level assessments. Therefore, for over 600 coal-fired electricity generating units, ISOMAP calculates the unique cost and effectiveness of eight different carbon dioxide-control technologies including co-firing with natural gas, upgrading the boiler technologies, fuel switching, and adding a carbon capture and storage system to allow each state to meet the EPA guidelines for each state-specific scenario.

The model allows user-specified, state-level mitigation measures to be compared and evaluated on costs and emission levels, and is completely interactive. So just as you might use Excel to manage your financial budget, it will help manage a state’s pollution budget. It comes with boiler-level analysis data for each state, including a detailed emerging model of emission compliance and carbon dioxide mitigation. All data are visible and major parameters can be modified as necessary. Users can explore future scenarios of their own design, while at the same time having the historical context to understand those scenarios. So, for example, users can answer questions as to what happens to an existing coal-fired power plant if EPA forecasts are over- or under-optimistic or if the price of fuel goes higher or lower.

In developing the tool, the research team identified several concerns about the EPA’s approach in the Clean Power Plan.

While EPA examines carbon dioxide emission reductions from a national level, the Carnegie Mellon team examined these emissions from an electric generating unit (EGU) level. This led to insights and results that differed from the EPA’s analysis, as well as demonstrating flexibility for states beyond those outlined in the proposal. For example, an important factor in an EGU’s operation is the heat rate — simply put, this is the rate at which fuel (in this case, coal) is consumed to generate a specific amount of power. While we want a plant’s efficiency to be high, we want the heat rate to be low — like in golf, the less “strokes” to reach the goal, the better — so, in this case, the less coal that we use per kilowatt of electricity generated, the better. This lowers both costs and emissions. When the EPA analyzed the possible EGU heat rate improvements at a national level, they estimated that a 6 percent improvement could be achieved. When the Carnegie Mellon team analyzed it at an EGU level, only a 4 percent improvement is likely — a bad thing. This means that some EGUs might require additional mitigation measures or states must increase their electricity generation from low or zero carbon sources in order to be compliant with the Clean Power Plan. So applying 6 percent for all EGUs may be too optimistic.

In addition, the EPA identified some mitigation methods as less likely to be effective when viewed from a national-level average, while ISOMAP determined that these methods would be effective and should be considered as options for some states when examined at the EGU under various scenarios. And although non-heat rate mitigation measures were found to increase a state’s levelized cost of electricity, states could balance this increased cost by taking less efficient EGUs offline and using more efficient EGUs instead.

The current version of the tool is available at no cost on the Scott Institute website at As the EPA modifies their ruling, the Carnegie Mellon research team will update the tool to meet the new requirements.

Stine is associate director for policy outreach at the Scott Institute for Energy Innovation and professor of the practice, Engineering and Public Policy (EPP) at Carnegie Mellon University. Fischbeck is a professor of EPP and interim head of the Department of Social and Decision Sciences. Zhai is assistant research professor of EPP. Anderson is a doctoral student in EPP at Carnegie Mellon.

Tags Carbon dioxide carbon dioxide reduction Clean Power Plan Environmental Protection Agency EPA

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