Technical Support Document (TSD)
          for the Final Revised CSAPR Update for the 2008 Ozone NAAQS
                      Docket ID No. EPA-HQ-OAR-2020-0272

                        Ozone Transport Policy Analysis
                                Final Rule TSD

                     U.S. Environmental Protection Agency
                          Office of Air and Radiation
                                  March 2021
      The analysis presented in this document supports the EPA's final Revised Cross-State Air Pollution Rule Update for the 2008 Ozone NAAQS  (Revised CSAPR Update). This TSD includes analysis to help quantify upwind state emissions that significantly contribute to nonattainment or interfere with maintenance of the 2008 ozone NAAQS in downwind states and quantification of emission budgets (i.e., limits on emissions) and the resulting effects on air quality. The analysis is described in Sections VI and VII of the preamble to the rule. This TSD also broadly describes how the EPA used historical data and the Integrated Planning Model (IPM) to inform air quality modeling, budget setting, and policy analysis aspects of this rule.   Finally, this TSD includes an assessment on the effects of ozone concentrations on forest health.  This TSD is organized as follows:

A.  Background on EPA's Analysis to Quantify Emissions that Significantly Contribute to Nonattainment or Interfere with Maintenance of the 2008 Ozone NAAQS
B. 	Using Engineering Analytics and Integrated Planning Model (IPM) to Assess Air Quality Modeling, EGU NOx Mitigation Strategies, and Policy Impacts
C.	Calculating Budgets from Historical Data and IPM Analysis
	1. Calculating 2021-2025 engineering baseline for NOx (from adjusted historical data)
   2. Estimating impacts of combustion and post combustion controls on state emission budgets
   3. Estimating emission reduction potential from generation shifting
   4. Variability limits and RIA scenarios
D. Analysis of Air Quality Responses to Emission Changes Using an Ozone Air Quality Assessment Tool (AQAT)
   1. Introduction: development of the ozone AQAT
   2. Details on the construction of the ozone AQAT
   3. Description of analytical results
   4. Comparison between the air quality assessment tool estimates
E. Observations on Cost and Air Quality Factors for 2024
F. Assessment of the Effects of Ozone on Forest Health

 Background on EPA's Analysis to Quantify Emissions that Significantly Contribute to Nonattainment or Interfere with Maintenance of the 2008 Ozone NAAQS

      In the preamble, EPA describes the 4-Step Good Neighbor Framework that it is applying to identify upwind states' emissions that significantly contribute to nonattainment or interfere with maintenance with respect to the 2008 ozone National Ambient Air Quality Standard (NAAQS) in other states and to implement appropriate emission reductions. This framework was used in the original CSAPR rulemaking to address interstate transport with respect to the 1997 ozone NAAQS and the 1997 and 2006 PM2.5 NAAQS and was also used in the 2016 CSAPR Update to address interstate transport with respect to the 2008 ozone NAAQS.
      The first step of the Good Neighbor Framework uses air quality analysis to identify nonattainment and maintenance receptors for the 2008 ozone NAAQS. The second step of the framework uses further air quality analysis to identify upwind states whose ozone pollution contributions to these monitoring sites meet or exceed a specified threshold and therefore merit further analysis. See section V of the preamble for details on applying these steps with respect to interstate emissions transport for the 2008 ozone NAAQS.
      The third step in the Good Neighbor Framework quantifies upwind state emissions that significantly contribute to nonattainment or interfere with maintenance of the 2008 ozone NAAQS at the downwind receptors, and identifies the electricity generating unit (EGU) NOX emission budgets and/or non-EGU emissions reduction for each state that represent the reduction of these emissions levels. See section VI of the preamble with respect to interstate emissions transport for the 2008 ozone NAAQS.  Finally, the fourth step of the Good Neighbor Framework implements the emission budgets in each state through the CSAPR NOX ozone season allowance trading program or other enforceable mechanism.  See section VII of the preamble for details on implementation for this rule.
      This TSD primarily addresses step three of the Good Neighbor Framework related to EGU emissions as well as to the effects on air quality of both EGU and non-EGU emissions reductions.  In order to establish EGU NOX emissions budgets for each linked upwind state, EPA first identifies various possible uniform levels of NOx control stringency based on available EGU NOX control strategies and represented by cost thresholds. The EGU emission reductions pertaining to each level of control stringency are derived using historical data, engineering analyses, and EPA's integrated planning model (IPM) for the power sector as described in sections B and C of this TSD. The adjusted historical data and the model data are combined in order to quantify a series of potential EGU NOX emission budgets for each linked upwind state at each level of uniform NOX control stringency. A similar assessment for one scenario was done for non-EGUs.  Next, EPA uses the ozone Air Quality Assessment Tool (AQAT) to estimate the air quality impacts of the upwind state emissions reductions on downwind ozone pollution levels for each of the assessed cost threshold levels. Specifically, EPA looks at the magnitude of air quality improvement at each receptor at each level of control, it also examines whether receptors change status (shifting from either nonattainment to maintenance, or from maintenance to attainment), and looks at the individual contributions of each state to each of its receptors. See section D in this TSD for discussion of the development and use of the ozone AQAT.
      Finally, the EPA uses this air quality information within the multi-factor test, along with NOX reduction potential, cost, and other considerations to select a particular level of uniform NOX control stringency that addresses each state's significant contribution to nonattainment and interference with maintenance (see Section VI.D of the preamble for additional information).
      In this TSD, EPA assesses the EGU NOX mitigation potential for all states in the contiguous U.S. EPA assessed the air quality impacts for all monitors in the contiguous U.S. from emission reductions that met the criteria for developing air quality contribution estimates. In applying the multi-factor test for purposes of identifying the appropriate level of control, the EPA evaluated NOX reductions and air quality improvements at the four receptors from the two home states and the 12 upwind states that were linked to downwind receptors in step two of the 4-Step Good Neighbor Framework.  The 12 upwind linked states are listed in Table A-1 below.

      Table A-1.  Upwind States Evaluated in the Multi-factor Test

                               Ozone Season NOX
Illinois
New Jersey
Indiana
New York
Kentucky
Ohio
Louisiana
Pennsylvania
Maryland
Virginia
Michigan
West Virginia

 Using the Engineering Analytics Tool and the Integrated Planning Model (IPM) to Assess Air Quality Modeling, EGU NOx Mitigation Strategies, and Policy Impacts

      Similar to the final CSAPR Update, EPA relied on adjusted historical data (engineering analytics) and its power sector modeling platform using IPM as part of the process to quantify significant contribution at step three within the 4-Step Good Neighbor Framework.  Historical data were adjusted through the engineering analytics tool and used along with IPM to analyze the ozone season NOX emission reductions available from EGUs at various uniform levels of NOX control stringency, represented by cost per ton, in each upwind state. Finally, IPM was used to evaluate compliance with the rule and the rule's regulatory control alternatives (i.e., compliance with the emission budgets, with a more stringent alternative, and with a less stringent alternative). EPA also used its engineering analytics tool and IPM projections to perform air quality assessment and sensitivity analysis for steps 1 and 2.
      The engineering analytics tool uses the latest historical representative emissions and operating data reported under 40 CFR part 75 by covered units (which were 2019 ozone-season data at the time of this analysis). It is a tool that builds estimates of future unit-level and state-level emissions based on exogenous changes to historical heat input and emissions data reflecting fleet changes known to occur subsequent to the last year of available data. See Section C. Calculating Budgets from Historical Data and IPM Analysis for a detailed description of the engineering analytics tool.
      IPM is a multiregional, dynamic, deterministic linear programming model of the U.S. electric power sector that EPA uses to analyze cost and emissions impacts of environmental policies. All IPM cases for this rule included representation of the Title IV SO2 cap and trade program; the NOX SIP Call; the CSAPR and CSAPR Update regional cap and trade programs; consent decrees and settlements; and state and federal rules as listed in the IPM documentation referenced above.
      Application of the 4-Step Good Neighbor Framework requires robust data collection, IPM modeling and engineering analytics is time consuming.  Rather than freezing all IPM and engineering analytic data sets at the outset of EPA's analysis for the rule, the EPA allowed for ongoing improvement of the relied-upon EGU data.  As a result, each step of EPA's analysis for the final rule is informed by the best available data at the time the analysis was conducted.
      In the power sector modeling done for this rule, the EPA needed to quantify emissions for three different analytic purposes.  The first purpose was to provide future base case EGU emissions for input to air quality modeling to identify nonattainment and maintenance receptors and quantify interstate contribution to inform steps 1 and 2 of the 4-Step Good Neighbor Framework. This base case incorporated the most important fleet changes and retrofits identified through comments up to Fall of 2019 using the National Electricity Energy Data System (NEEDS) EGU inventory, January 8, 2020 version. The version of the NEEDS file reflects EGU fleet updates through November 2019.
      The second purpose was to construct an illustrative base case and control case to study the potential cost and reduction potential of different uniform technology scenarios. This set of cases is referred to as the "Illustrative Cases." These illustrative cases are primarily cost threshold runs that EPA performed where the agency would first adjust the base case to reflect the relevant control technologies being considered and would then perform a sensitivity where a dollar per ton price constraint (e.g., $1,600 per ton) was applied to that adjusted base case to estimate the additional reductions to be expected from generation shifting at a dollar per ton level commensurate with the technology operating cost.
      The third purpose was to estimate system impacts of the final rule and confirm the impact of implementing the state emissions budgets in a region-wide trading program. This set of cases is referred to as the "Final Policy Cases." For the Final Policy Cases, the EPA applied the state emission budgets and corresponding state and regional caps to the same base case used in the illustrative cases.  EPA also performed a "less stringent" and "more stringent" control scenario policy case using lower and higher state emission budgets respectively. The "Final Cases" were used to inform the cost and benefits of this rulemaking, as described in the Regulatory Impact Analysis, or RIA, for this rule.
      Table B-1 below summarizes the various IPM runs conducted and Appendix C provides further details on each of these scenarios.

Table B-1. Summary of Sets of Scenarios.

Air Quality Modeling Base Case
Illustrative Cases
Final Policy Cases
Scenarios Run
Base Case (IPM)

Base Case Sensitivity (Engineering Analytics)

Base Case (IPM)

Base Case (Engineering Analytics)

Uniform Control/Cost Threshold (IPM and Engineering Analytics)

Policy Cases (IPM)
What Analysis Each Set of Runs Informs
Base Case air quality modeling to identify nonattainment and maintenance receptors and estimate upwind contributions (steps 1 and 2)
Development of a set of state emission budgets for each cost threshold (step 3)

RIA analysis to gauge system impacts when budgets are implemented through a trading program (step 4)
EGU Updates Captured in Each Set of Runs
Updates as of November 2019 for IPM scenarios, and as of December 2020 for Engineering Analytic Sensitivity

 Updates as of June 30, 2020 for IPM scenarios and December 2020 for Engineering Analytic scenarios

Updates as of December 2020

      For the "Illustrative Case" IPM runs, the EPA modeled the emissions that would occur within each state in a Base Case. The EPA then designed a series of IPM runs that imposed increasing cost thresholds representing uniform levels of NOX controls and tabulated those projected emissions for each state at each cost level.  The EPA has referred to these runs as "Cost Threshold Runs" and these tabulations, when combined with adjusted historical data, as "cost curves."  The cost curves report the remaining emissions at each cost threshold after the state has made emission reductions that are available up to the particular cost threshold analyzed.
      In each Cost Threshold run, the EPA applied the applicable ozone-season cost level to all fossil-fuel-fired EGUs with a capacity greater than 25 MW in all states, though only the estimates for the four receptors, the two "home states" for those receptors, and the 12 linked states affect the results in Step 3. As described in the EGU NOX Mitigation Strategies Final Rule TSD, because of the time required to build advanced pollution controls, the model was prevented from building any new post-combustion controls, such as SCR or SNCR, before 2025, in response to the cost thresholds.  Similarly, the model was not enabled to build incremental new units in that time frame. In response to the ozone-season NOX cost, the modeling allows turning on idled existing SCR and SNCR, optimization of existing SCR, shifting generation to lower-NOX emitting EGUs, and adding or upgrading NOX combustion controls (such as state-of-the-art low NOX burners (LNB)) in 2021/2022.  In this TSD, we refer to state-of-the-art combustion controls, or SOA CC, generally, as combustion controls, or LNB).
      In these scenarios, EPA imposed cost thresholds of $500, $1,600, $1,800, $3,900, $5,800, $9,600 per ton of ozone season NOX. See Preamble Section VI for a discussion of how the cost thresholds were determined. Table B-2 below summarizes the reduction measures that are broadly available at various cost thresholds.

Table B-2. Reduction strategies available to EGUs at each cost threshold.
Cost Threshold ($ per ton Ozone-Season NOX)
Reduction Options
                                                                           $500
-Generation shifting
                                                                        $1,600
-Above option; and
-Retrofitting state-of-the-art combustion controls;
-Optimizing idled SCRs (to 0.08 lb/MMBtu);
-Optimizing operating SCRs (to 0.08 lb/MMBtu);
                                                                        $1,800
-Above options; and
-Optimizing operating SNCRs ($3,900 for optimizing idled SNCR)
                                                                        $5,800
-Above options; and
-Installing SNCR on certain coal units lacking post-combustion retrofit
                                                                        $9,600
-Same as above options; and
-Installing SCR on certain coal units lacking SCR post-combustion controls (rather than SNCR).

For both Engineering analytics and IPM:
 At $500/ton:
 Engineering Analytics  -  no change.
 IPM  - cost of $500 per ton applied to base case for EGUs > 25 MW.
 At $1,600/ton:
 Engineering Analytics  -  If 2019 adjusted baseline rate was greater than 0.08 lb/MMBtu for SCR controlled units, that rate and corresponding emissions were adjusted down to 0.08 lb/MMBtu starting in 2021; for units with LNB upgrade potential and an adjusted historical rate greater than 0.199 lb/MMBtu, their rates were adjusted downwards to 0.199 lb/MMBtu starting in 2022.
 IPM  - cost of $1,600 per ton applied for EGUs > 25 MW; units with existing SCRs have their emission rates lowered to the lower of their mode 4 NOX rate in NEEDS and the "widely achievable" optimized emissions rate of 0.08 lbs/MMBtu.
 At $1,800/ton:
 Engineering Analytics  -  Same as $1,600/ton; additionally, units with SNCRs were given their mode 2 NOx rates if they were not already operating at that level or better in 2019.
 IPM  -  Same as $1,600/ton;

 At $5,800/ton:
 Engineering Analytics  -  Same as $1,800/ton; additionally, coal units greater than 100 MW and lacking a post-combustion control were given a 25% reduction to adjusted historical baseline emissions starting in 2024 to reflect SNCR installation.
 IPM  -  Same as $1,800/ton; additionally, coal units greater than 100 MW and lacking a post combustion control were given a 25% reduction from their mode 2 rate reflecting SNCR installation, starting in model run year 2025.  Cost of $5,800 per ton applied for EGUs > 25 MW. Additionally, units with idled SNCRs were identified as units equipped with SNCR and mode 2 NOX rates in NEEDS greater than 0.30 lbs/MMBtu. These units were given NOX rates 25% lower to reflect SNCR operation.

 At $9,600/ton:
 Engineering Analytics  -  Same as $1,800/ton; additionally, coal units greater than 100 MW and lacking a SCR were given an emission rate equal to the greater of a reduction of 90% or 0.07 lb/MMBtu reflecting SCR installation starting in 2024.
 IPM  -  Same as $3,900/ton; additionally, coal units greater than 100 MW and lacking SCR were assigned a mode four emission rate of 0.07 lb/MMBtu reflecting SCR installation starting in model run year 2025. Cost of $9,600 per ton applied for EGUs > 25 MW.

	As described in preamble section VI.B, the EPA limited its assessment of generation shifting to reflect shifting only to other EGUs within the same state as a proxy for generation shifting that could occur during the near-term implementation timeframe of the rule. EPA did this by limiting state generation in each Cost Threshold run to not go below the level in its respective Base Case. EPA also limited the potential for any new build in response to the price signal in the near term as it was interested in capturing generation shifting among the existing fleet.
      Section C.1-3 of this TSD describes how state emissions budgets were calculated using a combination of historical data and data from the IPM cost threshold cases. Once these budgets were calculated, EPA used the budgets for covered states to conduct IPM Final Policy Cases to investigate the impact of compliance with the budgets calculated from the $500, $1,800, $9,600 per ton cases. These cases reflect a less stringent scenario, the final policy scenario, and a more stringent scenario. Specifically, the budgets informed by the Illustrative $1,800 per ton Cost Threshold case were used for the final policy scenario, and the budgets informed by the  Illustrative $500 and $9,600 per ton cost threshold cases informed the less and more stringent scenarios. These scenarios were used to inform the RIA.
	To model these scenarios in IPM, EPA used the calculated state emissions budget and assurance levels (121% of the state emission budget) to set state and regional ozone-season NOX emissions limits. Additionally, EPA assumed a starting bank of allowances equal to 21% of the sum of the 12 states' budgets. States could individually emit up to their assurance levels in each run year, and collectively could not have emissions exceeding the sum of their regional budget and banked allowances in each run year. In the final policy scenario and the more stringent scenario, units with existing operating SCRs were assumed to operate them at the lower of their mode 4 NOX rate in NEEDS and the "widely achievable" emissions rate of 0.08 lb/MMBtu, as EPA determined this was a cost-effective mitigation strategy. Additionally, for these same two scenarios, coal units with identified combustion control upgrade potential were assumed to upgrade to state-of-the-art combustion controls. In all scenarios, the model provided the units the option to retrofit with post-combustion controls. While the EPA conservatively limited generation shifting in developing the state emission budgets, through use of state-level generation constraints, the EPA believes that generation shifting may occur broadly among states as a compliance mechanism and so removed that constraint for the IPM Final Policy Cases reflecting program implementation.

 Calculating Budgets from Historical Data and IPM Analysis

      As described in Section VII.B of the preamble, similar to CSAPR Update, the EPA determined it was appropriate to calculate state emission budgets by combining historical emissions and heat input data with projections from IPM to derive state emission budgets. Section VII.B notes there are three primary steps in this process: 1) EPA determines a future year baseline using historical data, 2) EPA adjusts that baseline to reflect the combustion and post-combustion control mitigation measures deemed cost-effective at a given cost threshold, and 3) EPA factors in emission reduction potential from generation shifting at a cost threshold commensurate with that mitigation technology's control operation cost. Similar to CSAPR Update, in this final rule the EPA calculated state budgets with the following formula:

      2021 State OS NOX Budget = 2021 State OS Baseline Heat Input*[2021 State OS NOX Emissions Rate-
         (2021 IPM Base Case OS NOX Emissions Rate - 2021 IPM Cost Threshold OS NOX Emissions
      Rate)]

The first two variables in the equation are derived from historical data and are the primary determinants of states' emissions budgets. They are described in sections C.1 and C.2 below.  The last two variables are identified through IPM analysis and described in section C.3 below. In section C.4, EPA discusses variability limits and RIA scenarios.

 Calculating 2021-2025 Engineering Baseline for NOx (from adjusted historical data)
The underlying data and calculations described below can be found in the workbook titled (Appendix A  -  Final Rule State Emission Budget Calculations and Engineering Analytics). They are also available in the docket and on the EPA website.

EPA starts with 2019 reported, seasonal, historical NOx emissions and heat input data for each unit. This reflects the latest representative owner/operator reported data available at the time of EPA analysis. The NOx emissions data for units that report data to EPA under the Acid Rain Program (ARP), the Cross-State Air Pollution Rule (CSAPR) and CSAPR Update Rule are aggregated to the summer/ozone season period (May-September). Because the unit-level NOx emissions for the summer/ozone-season period are relevant to determining ozone-season emissions budgets, those files are shown in the "unit 2021" through "unit 2025" sheets in the "Appendix A: Final Rule State Emission Budget Calculations and Engineering Analytics" file accompanying this document. In that file, unit-level details such as facility name, unit ID, unit type, capacity, etc. are shown in columns A through H of the "unit 2021" through "unit 2025" worksheets.  Reported historical data for these units such as historical emissions, heat input, generation, etc. are shown in columns I through L.  The 2019 historical emissions value is in column I.  The assumed future year baseline emissions estimate (e.g., 2021-2025) is shown in column U, and reflects either the same emissions level as that observed in 2019, or a modification of that value based on changes expected to the operational or pollution control status of that unit.  These modifications are made due to:

 Retirements - Emissions from units with upcoming confirmed retirement dates prior to that designated year are adjusted to zero. Retirement dates are identified through a combination of sources including EIA Form 860, utility-announced retirements, stakeholder and commenter feedback provided to EPA, and the National Electricity Energy Data System (NEEDS) December 2020 file. The impact of retirements on emissions is shown in column M. The retiring units are flagged in column N.

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
0 MMBtu x .2 lb/MMBtu = 0 ton

 Coal to Gas Conversion  -  Emissions from coal units with scheduled conversions to natural gas fuel use by the designated future year are adjusted to reflect reduced emission rates associated with natural gas. To reflect a given unit's conversion to gas, that unit's future emission rates for NOx are assumed to be half of its 2019 coal-fired emission rates while utilization levels are assumed to remain the same.  Therefore, the future year estimated emissions for these converting units are expected to be half of 2019 levels for NOx.  Units expected to convert to gas are flagged using EIA Form 860, NEEDS June 2020, and stakeholder feedback.  The impact of coal to gas conversion for the future year is shown in column Q, flagged in column R. The example below pertains to NOx emission estimates.

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
10,000 MMBtu x .1 lb/MMBtu = .5 ton

 Retrofits  -  Emissions from units with scheduled SCR or SNCR retrofits are adjusted to reflect the emission rates expected with new SCR installation (0.075 lb/MMBtu of NOx) and new SNCR (~25% representative decrease in emission rate)  and are assumed to operate at the same 2019 utilization levels.  These emission rates were multiplied by the affected unit's 2019 heat input to estimate the future year emission level.  The impact of post-combustion control retrofits on future year emissions assumptions is shown in column S, flagged in column T.

         For SNCR:

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
10,000 MMBtu x .15 lb/MMBtu = .75 ton

   For SCR:

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
10,000 MMBtu x .075 lb/MMBtu = .375 ton

 Other  -  EPA also made several unit-specific adjustments to 2019 emission levels to reflect forthcoming emission or emission rate requirements specified in consent decrees, BART requirements, and/or other revised permit limits.  The impacts for future year emission assumptions are shown in column U, flagged in column V.

 New Units  -  Emissions for new units are identified in the "New units" worksheet. They reflect under-construction and/or permitted units greater than 25 MW that are expected to be in commercial operation by the designated future year.  These assumed emission values for new units are reflected in column F and the online years are in column H. To obtain these emissions, EPA identified all new fossil-fired EGUs coming online after 2019 according to EIA Form 860 and in NEEDSv.6 December 2020.  EPA then identified the heat rate and capacity values for these units using EIA Form 860, NEEDSv.6 December 2020 and stakeholder-provided data.  Next, EPA identified the 2019 average seasonal capacity factor for similar units that came online between 2015-2019.  EPA used these seasonal capacity factors (e.g., 65% for NGCC), the unit's capacity, the unit's heat rate, and the unit's estimated NOx rate to estimate future year emissions (capacity x capacity factor x number of hours in ozone season x heat rate x NOx emission rate = NOx emissions).[,]

                                     2019
                           Future Year (e.g., 2021)
Unit x
0 MMBtu x .0 lb/MMBtu = 0 ton
          100 MW * .65 *(153x24) *8000 Btu/KWh *.01 lb/MMBtu = 9 tons

After completing these steps, EPA has unit-level and state-level future year baselines that originate from the most recently reported representative data (2019) and incorporate known EGU fleet changes. The state-level file reflects a summation of the unit-level values and provides the state-level heat input value used as the first variable in the emissions budget formula below. It also provides the starting value for the second variable (i.e., showing the future year baseline emission rate) before any mitigation technologies beyond the baseline are incorporated.

      2021 State OS NOX Budget = 2021 State OS Baseline Heat Input*[2021 State OS NOX Emissions Rate-
         (2021 IPM Base Case OS NOX Emissions Rate - 2021 IPM Cost Threshold OS NOX Emissions
      Rate)]
    Estimating impacts of combustion and post combustion controls on state emission budgets

Next, EPA evaluates the impact of the different combustion and post-combustion controls and establishes the impact on the state OS NOx Emission rate to complete the second variable in the equation above. Similar to the methodology above, EPA continued to adjust the historical data to reflect a future year with specific uniform control assumptions.  However, these adjustments were to capture changes incremental to the baseline reflecting different uniform control measures. EPA applied these adjustments for analytical purposes to all states, but only the 12 linked states' adjustments are relevant for emission budgets finalized in this rule. Each of these adjustments is shown incrementally for the relevant mitigation technology in the "unit 2021" through "unit 2025" worksheets.

 SCR optimization  -  Emissions from units with existing SCRs, but that operated at an emission rate greater than 0.08 lb/MMBtu in 2019, were adjusted downwards to reflect expected emissions when the SCR is operated to achieve a 0.08 lb/MMBtu emission rate.  The 0.08 lb/MMBtu emission rate was identified as the emission rate that reflected the fleet-average optimization assumption for SCR controlled units that were not currently optimizing their controls. The optimized emission rate is multiplied by baseline heat input levels to arrive at the future year emissions estimate.  The impact on future year emission assumptions is shown in column W and flagged in column X of the "unit 2021" through "unit 2025" worksheets. EPA notes this assumption only applies to ozone-season NOx as that is the season in which the Revised CSAPR Update Rule would likely incentivize such operation. In the final rule, EPA also incorporated a flag in column X, based on commenter input, for units with SCRs and a shared stack. For these units, based on commenter provided data, EPA did not assume potential emission reductions attributable to SCR optimization as explained in preamble section VI.B.

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
10,000 MMBtu x .08 lb/MMBtu = .4 ton

 State-of-the- art combustion controls  -  Emissions from units that were operating in 2019 without state-of-the-art combustion controls were adjusted downwards to reflect assumed installation of, or upgrade to, these controls and their expected emission rate impact.  EPA assumed a future year emission rate of 0.199 for units expected to install/upgrade combustion controls.  These emission rates were multiplied by each unit's future year baseline heat input to estimate its future emission level.  Details of EPA's assessment of state-of-the-art NOx combustion controls and corresponding emission rates are provided in the EGU NOx Mitigation Strategies Final Rule TSD.  The impact of state-of-the-art combustion controls on future year emission assumptions is shown in column Y and flagged in column Z of the "unit 2021" through "unit 2025" worksheets. EPA also incorporated a flag in column Z, based on commenter input, for units with a shared stack. For these units, based on commenter provided data, EPA did not assume potential emission reductions attributable to state-of-the-art combustion controls as explained in preamble section VI.B.  Note, these assumptions apply to both winter and ozone season emissions adjustments as the controls operate continuously once installed.

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .4 lb/MMBtu = 2 ton
10,000 MMBtu x .199lb/MMBtu = ~1 ton

 SNCR optimization -  Emissions from units with existing SNCRs, but that operated at an emission rate greater than the SNCR optimization rate, were adjusted downwards to reflect expected emissions when the SNCR is optimized. This emission rate was identified specific to each unit based on historical data and is described in the EGU NOx Mitigation Strategy Final Rule TSD. The optimized emission rate is multiplied by future year baseline heat input levels to arrive at the future year emissions estimate.  For the units affected by this adjustment, the impact on future year emission assumptions is shown in column AA and flagged in column AB of the "unit 2021" through "unit 2025" worksheets. Note, this assumption only applies to ozone-season NOx as that is the season in which the Revised CSAPR Update Rule would likely incentivize such installation and operation.

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
10,000 MMBtu x .15 lb/MMBtu = .75 ton

 SNCR retrofit -  Emissions from coal units greater than 100 MW without post-combustion controls were adjusted downwards to reflect expected emissions if an SNCR were to be retrofitted on the unit. The emission rate was identified as 75% of the unit's baseline emission rate level (i.e., reflecting a 25% reduction from the technology). The adjusted emission rate is multiplied by future year baseline heat input levels to arrive at the future year emissions estimate for that technology.  For the units affected by this adjustment, the impact on future year emission assumptions is shown in column AC and flagged in column AD of the "unit 2021" through "unit 2025" worksheets. Note, this assumption only applies to ozone-season NOx as that is the season in which the Revised CSAPR Update Rule would likely incentivize such installation and operation.

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
10,000 MMBtu x .15 lb/MMBtu = .75 ton

 SCR retrofit- Emissions from coal units greater than 100 MW without SCR controls were adjusted downwards to reflect expected emissions if an SCR were to be retrofitted on the unit. The emission rate was identified as 10% of the unit's baseline emission rate or 0.07 lb/MMBtu (i.e., a 90% reduction with an emission rate floor of 0.07 lb/MMBtu). The adjusted emission rate is multiplied by future year baseline heat input levels to arrive at the future year emissions estimate for that technology.  For the units affected by this adjustment, the impact on future year emission assumptions is shown in column AE and flagged in column AF of the "unit 2021" through "unit 2025" worksheets.  Note, this assumption only applies to ozone-season NOx as that is the period in which the Revised CSAPR Update Rule would likely incentivize such installation and operation.

                                     2019
                           Future Year (e.g., 2021)
Unit x
10,000 MMBtu x .2 lb/MMBtu = 1 ton
10,000 MMBtu x .07 lb/MMBtu = .35 ton

These adjustments for each uniform control technology resulted in adjusted OS NOx emissions, heat input, and emission rates at the unit-level.  When summed up to the state level, these changes resulted in the State OS NOx Emission Rate listed second in the formula below.  EPA notes, this emission rate for any given uniform control level times the baseline heat input would provide the state emissions budget without generation shifting. These pre-generation shifting emission budget levels at the state-level are visible in the worksheets titled "State 2021" through "State 2025" in the Appendix A: Final Rule State Emission Budget Calculations and Engineering Analytics workbook accompanying this document.

      State 2021 OS NOX Budget = 2021 State OS Baseline Heat Input*[2021 State OS NOX Emissions Rate-
         (2021 IPM Base Case OS NOX Emissions Rate - 2021 IPM Cost Threshold OS NOX Emissions
      Rate)]

    Estimating Emission Reduction Potential from Generation Shifting

The last two variables in the equation relate to emission reductions from generation shifting.  Here, as in the CSAPR Update, EPA uses the Integrated Planning Model (IPM) to capture the change in emission rate in a state's fossil-fuel fired power fleet when. While holding everything else equal, EPA applies a given dollar per ton marginal cost constraint.  EPA relies on IPM for this analysis as generation shifting occurs on a cost continuum and is a function of least-cost dispatch under different constraints.  To derive this value, EPA first prepares an adjusted base case that reflects all the combustion or post-combustion mitigation measures discussed above for a given cost threshold.  These adjusted base cases are specific to the uniform mitigation scenario.  For instance, for the $1,600 per ton scenario EPA adjusts its base case to reflect the optimization of SCRs and combustion control upgrades by adjusting the emission rates to the levels discussed above for relevant units not already achieving that level.  EPA then executes an IPM run with these new exogenous assumptions and observes the state-level emission rate for fossil-fuel fired units greater than 25 MW. This is the third variable in the emissions budget formula.

Next, EPA performs a sensitivity for these adjusted base case runs where it applies the same set of assumptions in variable three, but layers on a commensurate marginal cost price signal (e.g., $1,600 per ton).  In addition to the mitigation measures assumed, the entire fossil-fuel fired EGU fleet greater than 25 MW in the state is subjected to a cost-per-ton price associated with that technology.  The model solves for least-cost dispatch given this additional marginal cost constraints for seasonal ozone emissions. EPA observes the state-level emission rate for fossil-fuel fired units greater than 25 MW. This data point becomes the fourth variable in the state-emissions budget formula.  The difference between the third and fourth variables reflects the change in emission rate due solely to generation shifting at a given dollar per ton level.

      State 2021 OS NOX Budget = 2021 State OS Baseline Heat Input*[2021 State OS NOX Emissions Rate-
         (2021 IPM Base Case OS NOX Emissions Rate - 2021 IPM Cost Threshold OS NOX Emissions
      Rate)]

This difference in the state-level emission rate between the two IPM cases is shown in columns B through F in the worksheet titled "Generation Shifting". These values are in the Appendix A: Final Rule State Emission Budget Calculations and Engineering Analytics workbook accompanying this document.

      Once EPA calculated the change in emissions rate between the IPM adjusted base case and each cost threshold case, the EPA then subtracted this change in emissions rate from the state OS NOx emission rate without generation shifting (the second variable in the formula). This yielded state-level, historically-anchored, emission rates reflecting NOX reduction potential for a given uniform control measure.

      Finally, the EPA multiplied these rates by each state's adjusted heat input (historical heat input adjusted for retirements and new builds identified in variable one of the formula) to yield emission budgets for each cost threshold. The state budgets for the different cost thresholds are displayed in Table C-1 through C-5. EPA notes that budgets are calculated for all states for the purpose of AQAT analysis, as explained in section D of this TSD, even if the state is not covered by the Revised CSAPR Update Rule.

      In addition to being shown below, the state-level emission budgets are calculated in the far right-hand side columns of each "State" worksheet for each mitigation technology scenario available that year.  These budgets reflect an application of the formula described above to the data in the spreadsheet.  These state-emission budgets reflect the inclusion of generation shifting. The difference between these final state-emission budgets shown in the far right columns that include "generation shifting" it the column title and the immediately preceding columns with the same column title but without "generation shifting" reflect the additional reduction due to generation shifting at a given cost threshold.

      Generation shifting accounts for a small amount of emissions reductions relative to the combustion and post combustion control mitigation measures (see Table C-10). In its cost threshold modeling, EPA limited generation levels in a state to its base case level so that states would not achieve emission reductions by importing more generation from out-of-state EGUs and reducing in-state generation (e.g., emissions leakage).  This assumption ensures that the generation shifting-based reductions are, and can be achieved, within a state. EPA also only assumes generation shifting from the projected baseline fleet, it does not incorporate generation shifting from any assumed incremental new build capacity that could be incentivized by a price level. Finally, in EPA's budget setting process it only includes generation shifting at dollar per ton levels that encourage the optimization of existing or newly installed controls considered at that cost level.  Capturing reduction potential from generation shifting in the state's emission budgets is meant to preserve the incentive to implement EPA's identified control strategy.  Factoring generation shifting into the state emissions budgets helps promote an allowance price commensurate with these levels. In this rule, generation shifting is intended to be a mitigation measure supportive to those combustion and post-combustion control measures, not incremental to it.  Therefore, EPA designed its IPM analysis and utilized the results for emission budget purposes in a manner that did not allow for, or include, emission reductions from projected model new builds or retirements that occurred in response to a dollar per ton price signal.  Instead, EPA examined generation shifting that was expected to occur among the baseline fleet at cost threshold levels commensurate with post-combustion control operation (e.g., $1,600 per ton) at fossil fuel-fired units greater than 25 MW for 2021.

Table C-1. 2021 Emissions for States at Different Uniform Control Scenarios (Reflected by dollar  per ton)

                                 OS NOx (tons)

2021 Baseline
 $500/ton
 0.08 SCR Optimization ($1,600/ton)
0.08 SCR Optimization + LNB ($1,600/ton)
0.08 SCR Optimization + LNB + SNCR Optimization ($1,800/ton)
Alabama
                                                                          7,786
                                                                          7,785
                                                                          7,786
                                                                          7,693
                                                                          7,693
Arizona
                                                                          5,389
                                                                          5,100
                                                                          4,616
                                                                          4,616
                                                                          4,616
Arkansas
                                                                          8,731
                                                                          8,655
                                                                          8,708
                                                                          8,708
                                                                          8,708
California
                                                                          1,112
                                                                          1,111
                                                                          1,062
                                                                          1,062
                                                                          1,061
Colorado
                                                                          7,484
                                                                          7,487
                                                                          7,471
                                                                          7,471
                                                                          7,449
Connecticut
                                                                            344
                                                                            316
                                                                            307
                                                                            307
                                                                            307
Delaware
                                                                            223
                                                                            223
                                                                            206
                                                                            206
                                                                            205
Florida
                                                                         15,286
                                                                         15,276
                                                                         13,869
                                                                         13,869
                                                                         13,788
Fort Mojave
                                                                             53
                                                                             53
                                                                             53
                                                                             53
                                                                             53
Georgia
                                                                          7,833
                                                                          7,833
                                                                          7,808
                                                                          7,808
                                                                          7,808
Idaho
                                                                            204
                                                                            204
                                                                            204
                                                                            204
                                                                            204
Illinois
                                                                          9,368
                                                                          9,348
                                                                          9,198
                                                                          9,198
                                                                          9,102
Indiana
                                                                         15,856
                                                                         15,677
                                                                         13,085
                                                                         13,085
                                                                         13,051
Iowa
                                                                          8,567
                                                                          8,447
                                                                          7,714
                                                                          7,659
                                                                          7,659
Kansas
                                                                          6,057
                                                                          6,053
                                                                          5,384
                                                                          5,384
                                                                          5,338
Kentucky
                                                                         15,588
                                                                         15,606
                                                                         15,307
                                                                         14,057
                                                                         14,051
Louisiana
                                                                         15,476
                                                                         15,430
                                                                         15,389
                                                                         15,389
                                                                         14,818
Maine
                                                                             67
                                                                             67
                                                                             67
                                                                             67
                                                                             67
Maryland
                                                                          1,501
                                                                          1,501
                                                                          1,499
                                                                          1,499
                                                                          1,499
Massachusetts
                                                                            336
                                                                            333
                                                                            333
                                                                            333
                                                                            331
Michigan
                                                                         13,898
                                                                         13,126
                                                                         12,732
                                                                         12,614
                                                                         12,610
Minnesota
                                                                          5,969
                                                                          5,842
                                                                          5,448
                                                                          5,448
                                                                          5,448
Mississippi
                                                                          8,070
                                                                          8,067
                                                                          8,065
                                                                          7,739
                                                                          7,739
Missouri
                                                                         12,439
                                                                         12,379
                                                                         11,352
                                                                         11,352
                                                                         11,276
Montana
                                                                          3,553
                                                                          3,553
                                                                          3,553
                                                                          3,553
                                                                          3,553
Navajo
                                                                          1,319
                                                                          1,319
                                                                          1,319
                                                                          1,319
                                                                          1,319
Nebraska
                                                                          8,078
                                                                          8,013
                                                                          8,037
                                                                          7,530
                                                                          7,530
Nevada
                                                                          2,434
                                                                          1,833
                                                                          1,456
                                                                          1,456
                                                                          1,456
New Hampshire
                                                                            386
                                                                            386
                                                                            299
                                                                            299
                                                                            299
New Jersey
                                                                          1,346
                                                                          1,346
                                                                          1,253
                                                                          1,253
                                                                          1,253
New Mexico
                                                                          4,656
                                                                          4,624
                                                                          4,502
                                                                          4,502
                                                                          4,488
New York
                                                                          3,469
                                                                          3,463
                                                                          3,416
                                                                          3,416
                                                                          3,416
North Carolina
                                                                         15,911
                                                                         15,814
                                                                         11,227
                                                                         11,227
                                                                         11,083
North Dakota
                                                                         11,885
                                                                         11,829
                                                                         11,774
                                                                         11,774
                                                                         11,135
Ohio
                                                                         15,829
                                                                         15,487
                                                                          9,690
                                                                          9,690
                                                                          9,690
Oklahoma
                                                                          8,964
                                                                          8,878
                                                                          8,717
                                                                          8,717
                                                                          8,717
Oregon
                                                                            350
                                                                            350
                                                                            350
                                                                            350
                                                                            350
Pennsylvania
                                                                         11,896
                                                                         11,807
                                                                          8,379
                                                                          8,379
                                                                          8,379
Rhode Island
                                                                            233
                                                                            233
                                                                            233
                                                                            233
                                                                            233
South Carolina
                                                                          4,979
                                                                          4,979
                                                                          3,839
                                                                          3,839
                                                                          3,839
South Dakota
                                                                            591
                                                                            583
                                                                            581
                                                                            581
                                                                            581
Tennessee
                                                                          4,547
                                                                          4,549
                                                                          4,367
                                                                          4,367
                                                                          4,367
Texas
                                                                         44,767
                                                                         43,841
                                                                         42,349
                                                                         42,349
                                                                         42,308
Utah
                                                                          6,729
                                                                          4,862
                                                                          4,837
                                                                          4,837
                                                                          4,837
Ute
                                                                          2,144
                                                                          2,144
                                                                          2,144
                                                                          2,144
                                                                          2,144
Vermont
                                                                             51
                                                                             51
                                                                             51
                                                                             51
                                                                             51
Virginia
                                                                          4,664
                                                                          4,661
                                                                          4,614
                                                                          4,345
                                                                          4,284
Washington
                                                                          1,609
                                                                          1,609
                                                                          1,609
                                                                          1,609
                                                                          1,603
West Virginia
                                                                         15,165
                                                                         15,017
                                                                         13,686
                                                                         13,205
                                                                         12,884
Wisconsin
                                                                          5,251
                                                                          5,120
                                                                          4,952
                                                                          4,952
                                                                          4,945
Wyoming
                                                                         11,480
                                                                         11,480
                                                                         11,366
                                                                         10,623
                                                                         10,623
12 Linked States Total
                                                                        124,057
                                                                        122,469
                                                                        108,248
                                                                        106,130
                                                                        105,037
*Note  -  For 2021 EPA shows $1,600 ton with and without LNB upgrade; given it is  not requiring budgets reflecting LNB controls until 2022.

Table C-2. 2022 Emissions for States at Different Uniform Control Scenarios (Reflected by dollar per ton)

                                 OS NOx (tons)

2022 Baseline
 $500/ton
0.08 SCR Optimization + LNB ($1,600/ton)
0.08 SCR Optimization + LNB + SNCR Optimization ($1,800/ton)
Alabama
                                                                          7,786
                                                                          7,785
                                                                          7,693
                                                                          7,693
Arizona
                                                                          5,389
                                                                          5,100
                                                                          4,616
                                                                          4,616
Arkansas
                                                                          8,731
                                                                          8,655
                                                                          8,708
                                                                          8,708
California
                                                                          1,104
                                                                          1,103
                                                                          1,055
                                                                          1,053
Colorado
                                                                          7,484
                                                                          7,487
                                                                          7,471
                                                                          7,449
Connecticut
                                                                            341
                                                                            313
                                                                            304
                                                                            304
Delaware
                                                                            220
                                                                            220
                                                                            203
                                                                            202
Florida
                                                                         14,976
                                                                         14,966
                                                                         13,641
                                                                         13,560
Fort Mojave
                                                                             53
                                                                             53
                                                                             53
                                                                             53
Georgia
                                                                          7,833
                                                                          7,833
                                                                          7,808
                                                                          7,808
Idaho
                                                                            204
                                                                            204
                                                                            204
                                                                            204
Illinois
                                                                          9,368
                                                                          9,348
                                                                          9,198
                                                                          9,102
Indiana
                                                                         15,383
                                                                         15,206
                                                                         12,615
                                                                         12,582
Iowa
                                                                          8,567
                                                                          8,447
                                                                          7,659
                                                                          7,659
Kansas
                                                                          6,057
                                                                          6,053
                                                                          5,384
                                                                          5,338
Kentucky
                                                                         15,588
                                                                         15,606
                                                                         14,057
                                                                         14,051
Louisiana
                                                                         15,476
                                                                         15,430
                                                                         15,389
                                                                         14,818
Maine
                                                                             67
                                                                             67
                                                                             67
                                                                             67
Maryland
                                                                          1,267
                                                                          1,267
                                                                          1,266
                                                                          1,266
Massachusetts
                                                                            336
                                                                            333
                                                                            333
                                                                            331
Michigan
                                                                         13,459
                                                                         12,688
                                                                         12,295
                                                                         12,290
Minnesota
                                                                          5,888
                                                                          5,761
                                                                          5,369
                                                                          5,369
Mississippi
                                                                          8,070
                                                                          8,067
                                                                          7,739
                                                                          7,739
Missouri
                                                                         12,439
                                                                         12,379
                                                                         11,352
                                                                         11,276
Montana
                                                                          3,249
                                                                          3,249
                                                                          3,249
                                                                          3,249
Navajo
                                                                          1,319
                                                                          1,319
                                                                          1,319
                                                                          1,319
Nebraska
                                                                          8,078
                                                                          8,013
                                                                          7,530
                                                                          7,530
Nevada
                                                                          1,500
                                                                            931
                                                                            575
                                                                            575
New Hampshire
                                                                            386
                                                                            386
                                                                            299
                                                                            299
New Jersey
                                                                          1,346
                                                                          1,346
                                                                          1,253
                                                                          1,253
New Mexico
                                                                          4,656
                                                                          4,624
                                                                          4,502
                                                                          4,488
New York
                                                                          3,469
                                                                          3,463
                                                                          3,416
                                                                          3,416
North Carolina
                                                                         15,326
                                                                         15,231
                                                                         10,658
                                                                         10,514
North Dakota
                                                                         11,885
                                                                         11,829
                                                                         11,774
                                                                         11,135
Ohio
                                                                         15,927
                                                                         15,569
                                                                          9,773
                                                                          9,773
Oklahoma
                                                                          8,964
                                                                          8,878
                                                                          8,717
                                                                          8,717
Oregon
                                                                            350
                                                                            350
                                                                            350
                                                                            350
Pennsylvania
                                                                         11,896
                                                                         11,806
                                                                          8,373
                                                                          8,373
Rhode Island
                                                                            233
                                                                            233
                                                                            233
                                                                            233
South Carolina
                                                                          4,979
                                                                          4,979
                                                                          3,839
                                                                          3,839
South Dakota
                                                                            591
                                                                            583
                                                                            581
                                                                            581
Tennessee
                                                                          4,547
                                                                          4,549
                                                                          4,367
                                                                          4,367
Texas
                                                                         44,773
                                                                         43,835
                                                                         42,326
                                                                         42,285
Utah
                                                                          6,729
                                                                          4,862
                                                                          4,837
                                                                          4,837
Ute
                                                                          2,144
                                                                          2,144
                                                                          2,144
                                                                          2,144
Vermont
                                                                             51
                                                                             51
                                                                             51
                                                                             51
Virginia
                                                                          4,274
                                                                          4,270
                                                                          3,957
                                                                          3,897
Washington
                                                                          1,609
                                                                          1,609
                                                                          1,609
                                                                          1,603
West Virginia
                                                                         15,165
                                                                         15,017
                                                                         13,205
                                                                         12,884
Wisconsin
                                                                          4,992
                                                                          4,864
                                                                          4,700
                                                                          4,693
Wyoming
                                                                         10,918
                                                                         10,918
                                                                         10,061
                                                                         10,061
12 Linked States Total
                                                                        122,619
                                                                        121,016
                                                                        104,797
                                                                        103,705

Table C-3. 2023 Emissions for States at Different Uniform Control Scenarios (Reflected by dollar  per ton).

                                 OS NOx (tons)

2023 Baseline
 $500/ton
0.08 SCR Optimization + LNB ($1,600/ton)
0.08 SCR Optimization + LNB + SNCR Optimization ($1,800/ton)
Alabama
                                                                          7,786
                                                                          7,785
                                                                          7,693
                                                                          7,693
Arizona
                                                                          5,389
                                                                          5,100
                                                                          4,616
                                                                          4,616
Arkansas
                                                                          8,731
                                                                          8,655
                                                                          8,708
                                                                          8,708
California
                                                                          1,104
                                                                          1,103
                                                                          1,055
                                                                          1,053
Colorado
                                                                          6,663
                                                                          6,666
                                                                          6,650
                                                                          6,629
Connecticut
                                                                            341
                                                                            313
                                                                            304
                                                                            304
Delaware
                                                                            220
                                                                            220
                                                                            203
                                                                            202
Florida
                                                                         14,496
                                                                         14,486
                                                                         13,162
                                                                         13,080
Fort Mojave
                                                                             53
                                                                             53
                                                                             53
                                                                             53
Georgia
                                                                          7,154
                                                                          7,154
                                                                          7,129
                                                                          7,129
Idaho
                                                                            204
                                                                            204
                                                                            204
                                                                            204
Illinois
                                                                          8,413
                                                                          8,393
                                                                          8,275
                                                                          8,179
Indiana
                                                                         15,357
                                                                         15,179
                                                                         12,587
                                                                         12,553
Iowa
                                                                          7,647
                                                                          7,531
                                                                          6,753
                                                                          6,753
Kansas
                                                                          6,057
                                                                          6,053
                                                                          5,384
                                                                          5,338
Kentucky
                                                                         15,588
                                                                         15,606
                                                                         14,057
                                                                         14,051
Louisiana
                                                                         15,476
                                                                         15,430
                                                                         15,389
                                                                         14,818
Maine
                                                                             67
                                                                             67
                                                                             67
                                                                             67
Maryland
                                                                          1,267
                                                                          1,267
                                                                          1,266
                                                                          1,266
Massachusetts
                                                                            320
                                                                            317
                                                                            317
                                                                            315
Michigan
                                                                         11,182
                                                                         10,386
                                                                          9,980
                                                                          9,975
Minnesota
                                                                          4,655
                                                                          4,545
                                                                          4,198
                                                                          4,198
Mississippi
                                                                          8,070
                                                                          8,067
                                                                          7,739
                                                                          7,739
Missouri
                                                                         12,160
                                                                         12,101
                                                                         11,074
                                                                         10,997
Montana
                                                                          3,249
                                                                          3,249
                                                                          3,249
                                                                          3,249
Navajo
                                                                          1,319
                                                                          1,319
                                                                          1,319
                                                                          1,319
Nebraska
                                                                          8,078
                                                                          8,013
                                                                          7,530
                                                                          7,530
Nevada
                                                                          1,386
                                                                            828
                                                                            479
                                                                            479
New Hampshire
                                                                            386
                                                                            386
                                                                            299
                                                                            299
New Jersey
                                                                          1,346
                                                                          1,346
                                                                          1,253
                                                                          1,253
New Mexico
                                                                          1,693
                                                                          1,673
                                                                          1,594
                                                                          1,594
New York
                                                                          3,474
                                                                          3,468
                                                                          3,421
                                                                          3,421
North Carolina
                                                                         15,326
                                                                         15,231
                                                                         10,658
                                                                         10,514
North Dakota
                                                                          9,166
                                                                          9,128
                                                                          9,091
                                                                          8,452
Ohio
                                                                         15,927
                                                                         15,569
                                                                          9,773
                                                                          9,773
Oklahoma
                                                                          8,964
                                                                          8,878
                                                                          8,717
                                                                          8,717
Oregon
                                                                            350
                                                                            350
                                                                            350
                                                                            350
Pennsylvania
                                                                         11,896
                                                                         11,806
                                                                          8,373
                                                                          8,373
Rhode Island
                                                                            233
                                                                            233
                                                                            233
                                                                            233
South Carolina
                                                                          4,979
                                                                          4,979
                                                                          3,839
                                                                          3,839
South Dakota
                                                                            591
                                                                            583
                                                                            581
                                                                            581
Tennessee
                                                                          4,547
                                                                          4,549
                                                                          4,367
                                                                          4,367
Texas
                                                                         44,582
                                                                         43,646
                                                                         42,138
                                                                         42,097
Utah
                                                                          6,729
                                                                          4,862
                                                                          4,837
                                                                          4,837
Ute
                                                                          2,144
                                                                          2,144
                                                                          2,144
                                                                          2,144
Vermont
                                                                             51
                                                                             51
                                                                             51
                                                                             51
Virginia
                                                                          4,361
                                                                          4,357
                                                                          4,041
                                                                          3,980
Washington
                                                                          1,609
                                                                          1,609
                                                                          1,609
                                                                          1,603
West Virginia
                                                                         15,165
                                                                         15,017
                                                                         13,205
                                                                         12,884
Wisconsin
                                                                          4,857
                                                                          4,734
                                                                          4,576
                                                                          4,569
Wyoming
                                                                         10,337
                                                                         10,337
                                                                          9,480
                                                                          9,480
12 Linked States Total
                                                                        119,453
                                                                        117,824
                                                                        101,620
                                                                        100,526

Table C-4. 2024 Emissions for States at Different Uniform Control Scenarios (Reflected by dollar  per ton).

                                 OS NOx (tons)

2024 Baseline
 $500/ton
0.08 SCR Optimization + LNB ($1,600/ton)
0.08 SCR Optimization + LNB + SNCR Optimization ($1,800/ton)
0.08 SCR Optimization + LNB + SNCR Optimization + SNCR Retrofit ($5,800/ton)
0.08 SCR Optimization + LNB + SNCR Optimization + SCR Retrofit ($9,600/ton)
Alabama
                                                                          7,786
                                                                          7,785
                                                                          7,693
                                                                          7,693
                                                                          7,694
                                                                          7,515
Arizona
                                                                          5,389
                                                                          5,100
                                                                          4,616
                                                                          4,616
                                                                          4,816
                                                                          3,916
Arkansas
                                                                          8,731
                                                                          8,655
                                                                          8,708
                                                                          8,708
                                                                          6,642
                                                                          4,661
California
                                                                          1,104
                                                                          1,103
                                                                          1,055
                                                                          1,053
                                                                          1,053
                                                                          1,053
Colorado
                                                                          5,950
                                                                          5,953
                                                                          5,938
                                                                          5,916
                                                                          5,085
                                                                          3,826
Connecticut
                                                                            341
                                                                            313
                                                                            304
                                                                            304
                                                                            302
                                                                            302
Delaware
                                                                            220
                                                                            220
                                                                            203
                                                                            202
                                                                            194
                                                                            194
Florida
                                                                         14,505
                                                                         14,495
                                                                         13,170
                                                                         13,089
                                                                         12,446
                                                                         11,752
Fort Mojave
                                                                             53
                                                                             53
                                                                             53
                                                                             53
                                                                             53
                                                                             53
Georgia
                                                                          7,154
                                                                          7,154
                                                                          7,129
                                                                          7,129
                                                                          7,097
                                                                          7,097
Idaho
                                                                            204
                                                                            204
                                                                            204
                                                                            204
                                                                            204
                                                                            204
Illinois
                                                                          8,292
                                                                          8,272
                                                                          8,154
                                                                          8,059
                                                                          7,239
                                                                          6,891
Indiana
                                                                         12,232
                                                                         12,083
                                                                          9,585
                                                                          9,564
                                                                          8,923
                                                                          8,430
Iowa
                                                                          7,647
                                                                          7,531
                                                                          6,753
                                                                          6,753
                                                                          5,201
                                                                          2,817
Kansas
                                                                          6,057
                                                                          6,053
                                                                          5,384
                                                                          5,338
                                                                          4,815
                                                                          3,658
Kentucky
                                                                         15,588
                                                                         15,606
                                                                         14,057
                                                                         14,051
                                                                         12,322
                                                                          9,775
Louisiana
                                                                         15,476
                                                                         15,430
                                                                         15,389
                                                                         14,818
                                                                         14,378
                                                                         12,622
Maine
                                                                             67
                                                                             67
                                                                             67
                                                                             67
                                                                             67
                                                                             67
Maryland
                                                                          1,350
                                                                          1,350
                                                                          1,348
                                                                          1,348
                                                                          1,168
                                                                          1,168
Massachusetts
                                                                            320
                                                                            317
                                                                            317
                                                                            315
                                                                            307
                                                                            307
Michigan
                                                                         10,968
                                                                         10,188
                                                                          9,791
                                                                          9,786
                                                                          8,670
                                                                          7,344
Minnesota
                                                                          4,655
                                                                          4,545
                                                                          4,198
                                                                          4,198
                                                                          3,034
                                                                          2,581
Mississippi
                                                                          8,070
                                                                          8,067
                                                                          7,739
                                                                          7,739
                                                                          7,081
                                                                          6,436
Missouri
                                                                         12,160
                                                                         12,101
                                                                         11,074
                                                                         10,997
                                                                         10,744
                                                                          9,301
Montana
                                                                          3,249
                                                                          3,249
                                                                          3,249
                                                                          3,249
                                                                          2,445
                                                                          1,544
Navajo
                                                                          1,319
                                                                          1,319
                                                                          1,319
                                                                          1,319
                                                                          1,319
                                                                          1,319
Nebraska
                                                                          7,347
                                                                          7,283
                                                                          7,299
                                                                          7,299
                                                                          5,966
                                                                          4,246
Nevada
                                                                          1,386
                                                                            828
                                                                            479
                                                                            479
                                                                            332
                                                                            100
New Hampshire
                                                                            386
                                                                            386
                                                                            299
                                                                            299
                                                                            299
                                                                            299
New Jersey
                                                                          1,346
                                                                          1,346
                                                                          1,253
                                                                          1,253
                                                                          1,257
                                                                          1,257
New Mexico
                                                                          1,693
                                                                          1,673
                                                                          1,594
                                                                          1,594
                                                                          1,187
                                                                          1,187
New York
                                                                          3,456
                                                                          3,450
                                                                          3,403
                                                                          3,403
                                                                          3,297
                                                                          3,297
North Carolina
                                                                         15,326
                                                                         15,231
                                                                         10,658
                                                                         10,514
                                                                          7,981
                                                                          4,691
North Dakota
                                                                          9,166
                                                                          9,128
                                                                          9,091
                                                                          8,452
                                                                          7,237
                                                                          2,250
Ohio
                                                                         15,927
                                                                         15,569
                                                                          9,773
                                                                          9,773
                                                                          9,644
                                                                          9,222
Oklahoma
                                                                          8,964
                                                                          8,878
                                                                          8,717
                                                                          8,717
                                                                          7,820
                                                                          7,251
Oregon
                                                                            350
                                                                            350
                                                                            350
                                                                            350
                                                                            350
                                                                            350
Pennsylvania
                                                                         11,896
                                                                         11,806
                                                                          8,373
                                                                          8,373
                                                                          7,921
                                                                          7,851
Rhode Island
                                                                            233
                                                                            233
                                                                            233
                                                                            233
                                                                            233
                                                                            233
South Carolina
                                                                          4,903
                                                                          4,903
                                                                          3,769
                                                                          3,769
                                                                          3,762
                                                                          3,762
South Dakota
                                                                            591
                                                                            583
                                                                            581
                                                                            581
                                                                            583
                                                                            583
Tennessee
                                                                          4,547
                                                                          4,549
                                                                          4,367
                                                                          4,367
                                                                          4,280
                                                                          4,280
Texas
                                                                         43,265
                                                                         42,338
                                                                         40,845
                                                                         40,804
                                                                         35,342
                                                                         29,460
Utah
                                                                          6,729
                                                                          4,862
                                                                          4,837
                                                                          4,837
                                                                          5,094
                                                                          3,174
Ute
                                                                          2,144
                                                                          2,144
                                                                          2,144
                                                                          2,144
                                                                          1,608
                                                                            573
Vermont
                                                                             51
                                                                             51
                                                                             51
                                                                             51
                                                                             51
                                                                             51
Virginia
                                                                          4,025
                                                                          4,021
                                                                          3,707
                                                                          3,663
                                                                          3,618
                                                                          3,184
Washington
                                                                          1,609
                                                                          1,609
                                                                          1,609
                                                                          1,603
                                                                          1,603
                                                                            761
West Virginia
                                                                         15,165
                                                                         15,017
                                                                         13,205
                                                                         12,884
                                                                         12,837
                                                                         10,568
Wisconsin
                                                                          4,161
                                                                          4,043
                                                                          3,893
                                                                          3,886
                                                                          3,862
                                                                          3,862
Wyoming
                                                                         10,337
                                                                         10,337
                                                                          9,480
                                                                          9,480
                                                                          6,997
                                                                          3,972
12 Linked States Total
                                                                        115,722
                                                                        114,138
                                                                         98,038
                                                                         96,975
                                                                         91,274
                                                                         81,609

Table C-5. 2025 Emissions for States at Different Uniform Control Scenarios (Reflected by dollar  per ton).

                                 OS NOx (tons)

2025 Baseline
 $500/ton
0.08 SCR Optimization + LNB ($1,600/ton)
0.08 SCR Optimization + LNB + SNCR Optimization ($1,800/ton)
0.08 SCR Optimization + LNB + SNCR Optimization + SNCR Retrofit ($5,800/ton)
0.08 SCR Optimization + LNB + SNCR Optimization + SCR Retrofit ($9,600/ton)
Alabama
                                                                          7,786
                                                                          7,785
                                                                          7,693
                                                                          7,693
                                                                          7,694