15-i

CHAPTER 15. EMISSIONS IMPACT ANALYSIS

TABLE OF CONTENTS

15.1 INTRODUCTION ......................................................................................................... 15-1

15.2 AIR QUALITY REGULATIONS AND EMISSIONS IMPACTS ............................... 15-1

15.3 METHODOLOGY ........................................................................................................ 15-2

15.4 EMISSIONS IMPACT RESULTS ................................................................................ 15-3

LIST OF TABLES

Table 15.4.1 Power Sector Emissions Forecast from AEO2012 Reference Case................... 15-3

Table 15.4.2 Power Sector Emissions Impacts for Liquid Immersed Transformer TSLs ...... 15-4

Table 15.4.3 Power Sector Emissions Impacts for Low-Voltage Dry Type Transformer 

TSLs ................................................................................................................... 15-5

Table 15.4.4 Power Sector Emissions Impacts for Medium-Voltage Dry Type 

Transformer TSLs .............................................................................................. 15-6
15-1 

CHAPTER 15. EMISSIONS IMPACT ANALYSIS

15.1 INTRODUCTION

In the emissions analysis, DOE estimates the reduction in power sector emissions of 

carbon dioxide (CO2), nitrogen oxides (NOX), sulfur dioxide (SO2), and mercury (Hg) from 

potential energy conservation standards for the considered products. 

DOE conducted the emissions impact analysis using the NEMS-BT model based on 

EIA’s Annual Energy Outlook 2012 (AEO 2012.1 EIA prepares the Annual Energy Outlook 

using the National Energy Modeling System (NEMS). 

 Each annual version of NEMS incorporates the projected impacts of existing air quality 

regulations on emissions. AEO 2012 generally represents current Federal and State legislation 

and final implementation regulations available as of the end of December 2011. 

15.2 AIR QUALITY REGULATIONS AND EMISSIONS IMPACTS 

SO2 emissions from affected electric generating units (EGUs) are subject to nationwide 

and regional emissions cap and trading programs. Title IV of the Clean Air Act sets an annual 

emissions cap on SO2 for affected EGUs in the 48 contiguous states and the District of Columbia 

(D.C.). SO2 emissions from 28 eastern states and D.C. were also limited under the Clean Air 

Interstate Rule (CAIR), which created an allowance-based trading program that that operates 

along with the Title IV program. 70 FR 25162 (May 12, 2005). CAIR was remanded to EPA by 

the U.S. Court of Appeals for the District of Columbia Circuit (D.C. Circuit) but it remained in 

effect. On July 6, 2011 EPA issued a replacement for CAIR, the Cross-State Air Pollution Rule 

(CSAPR). 76 FR 48208 (August 8, 2011). The AEO 2012 NEMS used for this analysis assumes 

the implementation of CSAPR.a

The attainment of emissions caps is typically flexible among affected Electric Generating 

Units (EGUs) and is enforced through the use of emissions allowances and tradable permits. 

Under existing EPA regulations, any excess SO2 emissions allowances resulting from the lower 

electricity demand caused by the imposition of an efficiency standard could be used to permit 

offsetting increases in SO2 emissions by any regulated EGU. In past rulemakings, DOE 

recognized that there was uncertainty about the effects of efficiency standards on SO2 emissions 

 

a On December 30, 2011, the D.C. Circuit stayed the new rules while a panel of judges reviews them, and told EPA 

to continue enforcing CAIR. See EME Homer City Generation, LP v. EPA, Order, No. 11-1302, Slip Op. at *2 

(D.C. Cir. Dec. 30, 2011). On August 21, 2012, the D.C. Circuit vacated CSAPR and related Federal 

Implementation Plans that would have superseded the State Implementation Plans that EPA typically approves for 

compliance with Clean Air Act stationary source regulations. See EME Homer City Generation, LP v. EPA, No. 

11-1302, 2012 WL 3570721 at *24 (D.C. Cir. Aug. 21, 2012). The court required EPA to continue administering 

CAIR. See id. The AEO 2012, however, had been finalized prior to both these decisions. DOE understands, 

however, that CAIR and CSAPR are similar with respect to their effect on emissions impacts of energy efficiency 

standards.
15-2 

covered by the existing cap-and-trade system, but it concluded that no reductions in power sector 

emissions would occur for SO2 as a result of standards.

Beginning in 2015, however, SO2 emissions will fall as a result of the Mercury and Air 

Toxics Standards (MATS) for power plants, which were announced by EPA on December 21, 

2011. 77 FR 9304 (Feb. 16, 2012). In the final MATS rule, EPA established a standard for 

hydrogen chloride as a surrogate for acid gas hazardous air pollutants (HAP), and also 

established a standard for SO2 (a non-HAP acid gas) as an alternative equivalent surrogate 

standard for acid gas HAP. The same controls are used to reduce HAP and non-HAP acid gas; 

thus, SO2 emissions will be reduced as a result of the control technologies installed on coal-fired 

power plants to comply with the MATS requirements for acid gas. AEO 2012 assumes that, in 

order to continue operating, coal plants must have either flue gas desulfurization or dry sorbent 

injection systems installed by 2015. Both technologies, which are used to reduce acid gas 

emissions, also reduce SO2 emissions. Under the MATS, NEMS shows a reduction in SO2

emissions when electricity demand decreases (e.g., as a result of energy efficiency standards). 

Emissions will be far below the cap that would be established by CSAPR, so it is unlikely that 

excess SO2 emissions allowances resulting from the lower electricity demand would be needed 

or used to permit offsetting increases in SO2 emissions by any regulated EGU. Therefore, DOE 

believes that efficiency standards will reduce SO2 emissions in 2015 and beyond. 

CSAPR established a cap on NOx emissions in 28 eastern States and the District of 

Columbia. Energy conservation standards are expected to have little effect on NOx emissions in 

those States covered by CSAPR because excess NOx emissions allowances resulting from the 

lower electricity demand could be used to permit offsetting increases in NOx emissions.

However, standards would be expected to reduce NOx emissions in the States not affected by 

CSAPR. Therefore, DOE estimated NOx emissions reductions from potential standards in those 

States. 

 The MATS limit mercury emissions from power plants, but they do not include 

emissions caps and, as such, DOE’s energy conservation standards would likely reduce Hg 

emissions. For this rulemaking, DOE estimated mercury emissions reductions using the NEMSBT based on AEO 2012, which incorporates the MATS. 

15.3 METHODOLOGY 

 The impact of the energy conservation standard on power sector air emissions is 

determined by calculating the difference between emissions projected in the NEMS-BT 

reference case run and emissions projected in the NEMS-BT policy run. The policy run was 

decremented with site energy savings resulting from the standard which were developed in the 

national impact analysis (chapter 10). The impact of the standard on power sector emissions was 

determined for each TSL (see chapter 14 for a description of the NEMS-BT model). 

 All extrapolations beyond 2040 are simple replications of year 2040 results. To 

emphasize the extrapolated results wherever they appear, they are shaded in gray to distinguish 

them from actual NEMS-BT results.
15-3 

15.4 EMISSIONS IMPACT RESULTS

Table 15.4.1 shows AEO2012 Reference Case power plant emissions in selected years. 

The Reference Case emissions are the emissions shown by the NEMS-BT model to result if none 

of the TSLs are promulgated (the base case). 

Table 15.4.1 Power Sector Emissions Forecast from AEO2012 Reference Case

NEMS-BT Results 2015 2020 2025 2030 2035 2040

CO2 (million metric tons) 2,011 2,067 2,179 2,258 2,330 2,358

NOX (million tons) 1.79 1.87 1.92 1.94 1.96 1.97

SO2 (million tons) 1.26 1.31 1.55 1.62 1.71 1.74

Hg (tons) 6.4 6.7 7.2 7.5 7.9 8.0

Tables 15.4.2 through 15.4.4 show the estimated changes in power plant emissions of 

CO2, NOX, SO2, and Hg in selected years for each of the TSLs considered in this rulemaking. 

There are seven TSLs for liquid immersed transformers, six TSLs for low-voltage dry type 

transformers, and five TSLs for medium-voltage dry type transformers. As in Table 15.4.1, 

values for CO2 are given in metric tons, while values for NOX, SO2, and Hg are given in short 

tons. Over the time period 2016 through 2045, cumulative CO2, NOX, SO2, and Hg emissions are 

reduced compared to the Reference case for all TSLs. For comparison, the cumulative power 

sector emissions in the Reference case, over the same thirty year period, are 67,037 Mt for CO2, 

57,696 kt for NOx, 47,079 kt for SO2, and 223 tons for Hg. 
15-4 

Table 15.4.2 Power Sector Emissions Impacts for Liquid Immersed Transformer TSLs

NEMS-BT Results* Difference from AEO2012 Reference Case

Total

2015 2020 2025 2030 2035 2040 2041 2045 2016-2045

Standard Level 1

CO2 (Mt/yr) 0.02 -0.50 -1.10 -1.48 -1.80 -1.67 -1.67 -1.67 -37.7

NOx (1,000 tons/yr) 0.02 -0.46 -0.97 -1.27 -1.51 -1.40 -1.40 -1.40 -32.2

SO2 (1,000 tons/yr) 0.01 -0.32 -0.78 -1.06 -1.32 -1.29 -1.29 -1.29 -27.4

Hg (ton/yr) 0.001 -0.002 -0.004 -0.004 -0.003 -0.003 -0.003 -0.003 -0.089

Standard Level 2

CO2 (Mt/yr) 0.04 -0.88 -1.92 -2.59 -3.13 -3.03 -3.03 -3.03 -66.5

NOx (1,000 tons/yr) 0.03 -0.80 -1.69 -2.22 -2.64 -2.53 -2.53 -2.53 -56.7

SO2 (1,000 tons/yr) 0.02 -0.56 -1.36 -1.85 -2.30 -2.24 -2.24 -2.24 -47.8

Hg (ton/yr) 0.001 -0.004 -0.008 -0.006 -0.005 -0.008 -0.008 -0.008 -0.171

Sandard Level 3

CO2 (Mt/yr) 0.04 -0.95 -2.06 -2.79 -3.38 -3.29 -3.29 -3.29 -71.9

NOx (1,000 tons/yr) 0.04 -0.86 -1.82 -2.40 -2.85 -2.75 -2.75 -2.75 -61.3

SO2 (1,000 tons/yr) 0.03 -0.60 -1.46 -1.99 -2.49 -2.43 -2.43 -2.43 -51.6

Hg (ton/yr) 0.001 -0.004 -0.008 -0.007 -0.006 -0.009 -0.009 -0.009 -0.185

Standard Level 4

CO2 (Mt/yr) 0.07 -1.56 -3.43 -4.69 -5.75 -5.65 -5.65 -5.65 -122

NOx (kt/yr) 0.06 -1.41 -3.03 -4.03 -4.85 -4.72 -4.72 -4.72 -104

SO2 (1,000 tons/yr) 0.04 -0.99 -2.44 -3.35 -4.23 -4.17 -4.17 -4.17 -87.5

Hg (ton/yr) 0.002 -0.007 -0.014 -0.011 -0.010 -0.015 -0.015 -0.015 -0.312

Standard Level 5

CO2 (Mt/yr) 0.07 -1.55 -3.41 -4.66 -5.72 -5.63 -5.63 -5.63 -121

NOx (1,000 tons/yr) 0.06 -1.40 -3.01 -4.01 -4.82 -4.70 -4.70 -4.70 -103

SO2 (1,000 tons/yr) 0.04 -0.98 -2.42 -3.34 -4.21 -4.15 -4.15 -4.15 -87.1

Hg (ton/yr) 0.002 -0.007 -0.014 -0.011 -0.010 -0.015 -0.015 -0.015 -0.311

Sandard Level 6

CO2 (Mt/yr) 0.08 -1.74 -3.85 -5.31 -6.57 -6.51 -6.51 -6.51 -139

NOx (1,000 tons/yr) 0.07 -1.57 -3.40 -4.56 -5.53 -5.43 -5.43 -5.43 -118

SO2 (1,000 tons/yr) 0.05 -1.10 -2.73 -3.80 -4.82 -4.80 -4.80 -4.80 -99.6

Hg (ton/yr) 0.002 -0.008 -0.015 -0.013 -0.011 -0.017 -0.017 -0.017 -0.355

Standard Level 7

CO2 (Mt/yr) 0.10 -2.44 -5.51 -7.72 -9.73 -9.81 -9.81 -9.81 -204

NOx (1,000 tons/yr) 0.09 -2.21 -4.86 -6.64 -8.20 -8.19 -8.19 -8.19 -174

SO2 (1,000 tons/yr) 0.07 -1.55 -3.91 -5.52 -7.15 -7.24 -7.24 -7.24 -147

Hg (ton/yr) 0.003 -0.011 -0.022 -0.019 -0.017 -0.026 -0.026 -0.026 -0.522

*CO2 results are in metric tons, NOX, SO2, and Hg results are in short tons.

Extrapolation
15-5 

Table 15.4.3 Power Sector Emissions Impacts for Low-Voltage Dry Type Transformer 

TSLs

NEMS-BT Results* Difference from AEO2012 Reference Case

Total

2015 2020 2025 2030 2035 2040 2041 2045 2016-2045

Standard Level 1

CO2 (Mt/yr) 0.04 -0.96 -2.13 -2.92 -3.60 -3.55 -3.55 -3.55 -76.0

NOx (1,000 tons/yr) 0.04 -0.87 -1.88 -2.51 -3.03 -2.96 -2.96 -2.96 -64.7

SO2 (1,000 tons/yr) 0.03 -0.61 -1.51 -2.09 -2.64 -2.61 -2.61 -2.61 -54.6

Hg (ton/yr) 0.001 -0.004 -0.008 -0.007 -0.006 -0.009 -0.009 -0.009 -0.195

Standard Level 2

CO2 (Mt/yr) 0.04 -1.03 -2.27 -3.12 -3.84 -3.79 -3.79 -3.79 -81.1

NOx (1,000 tons/yr) 0.04 -0.93 -2.00 -2.68 -3.24 -3.16 -3.16 -3.16 -69.2

SO2 (1,000 tons/yr) 0.03 -0.65 -1.61 -2.23 -2.82 -2.79 -2.79 -2.79 -58.3

Hg (ton/yr) 0.001 -0.005 -0.009 -0.008 -0.007 -0.010 -0.010 -0.010 -0.208

Sandard Level 3

CO2 (Mt/yr) 0.06 -1.29 -2.85 -3.92 -4.83 -4.76 -4.76 -4.76 -102

NOx (kt/yr) 0.05 -1.17 -2.52 -3.37 -4.07 -3.97 -3.97 -3.97 -86.9

SO2 (1,000 tons/yr) 0.03 -0.82 -2.03 -2.80 -3.55 -3.51 -3.51 -3.51 -73.3

Hg (ton/yr) 0.002 -0.006 -0.011 -0.009 -0.008 -0.013 -0.013 -0.013 -0.261

Standard Level 4

CO2 (Mt/yr) 0.08 -1.86 -4.12 -5.65 -6.96 -6.86 -6.86 -6.86 -147

NOx (1,000 tons/yr) 0.07 -1.68 -3.63 -4.86 -5.87 -5.73 -5.73 -5.73 -125

SO2 (1,000 tons/yr) 0.05 -1.18 -2.92 -4.04 -5.11 -5.06 -5.06 -5.06 -106

Hg (ton/yr) 0.002 -0.009 -0.016 -0.014 -0.012 -0.018 -0.018 -0.018 -0.377

Standard Level 5

CO2 (Mt/yr) 0.08 -1.89 -4.18 -5.74 -7.07 -6.97 -6.97 -6.97 -149

NOx (1,000 tons/yr) 0.07 -1.71 -3.69 -4.94 -5.96 -5.82 -5.82 -5.82 -127

SO2 (1,000 tons/yr) 0.05 -1.20 -2.97 -4.11 -5.20 -5.14 -5.14 -5.14 -107

Hg (ton/yr) 0.002 -0.009 -0.017 -0.014 -0.012 -0.019 -0.019 -0.019 -0.383

Sandard Level 6

CO2 (Mt/yr) 0.09 -2.03 -4.49 -6.16 -7.59 -7.48 -7.48 -7.48 -160

NOx (1,000 tons/yr) 0.08 -1.83 -3.96 -5.30 -6.40 -6.24 -6.24 -6.24 -137

SO2 (1,000 tons/yr) 0.05 -1.29 -3.19 -4.41 -5.58 -5.52 -5.52 -5.52 -115

Hg (ton/yr) 0.003 -0.009 -0.018 -0.015 -0.013 -0.020 -0.020 -0.020 -0.411

*CO2 results are in metric tons, NOX, SO2, and Hg results are in short tons.

Extrapolation
15-6 

Table 15.4.4 Power Sector Emissions Impacts for Medium-Voltage Dry Type 

Transformer TSLs

NEMS-BT Results* Difference from AEO2012 Reference Case

Total

2015 2020 2025 2030 2035 2040 2041 2045 2016-2045

Standard Level 1

CO2 (Mt/yr) 0.00 -0.06 -0.14 -0.19 -0.23 -0.23 -0.23 -0.23 -4.86

NOx (1,000 tons/yr) 0.00 -0.06 -0.12 -0.16 -0.19 -0.19 -0.19 -0.19 -4.15

SO2 (1,000 tons/yr) 0.00 -0.04 -0.10 -0.13 -0.17 -0.17 -0.17 -0.17 -3.50

Hg (ton/yr) 0.000 0.000 -0.001 0.000 0.000 -0.001 -0.001 -0.001 -0.012

Standard Level 2

CO2 (Mt/yr) 0.00 -0.12 -0.26 -0.35 -0.43 -0.43 -0.43 -0.43 -9.15

NOx (kt/yr) 0.00 -0.10 -0.23 -0.30 -0.36 -0.36 -0.36 -0.36 -7.79

SO2 (1,000 tons/yr) 0.00 -0.07 -0.18 -0.25 -0.32 -0.31 -0.31 -0.31 -6.57

Hg (ton/yr) 0.000 -0.001 -0.001 -0.001 -0.001 -0.001 -0.001 -0.001 -0.023

Sandard Level 3

CO2 (Mt/yr) 0.01 -0.22 -0.50 -0.68 -0.84 -0.83 -0.83 -0.83 -17.7

NOx (1,000 tons/yr) 0.01 -0.20 -0.44 -0.59 -0.71 -0.69 -0.69 -0.69 -15.1

SO2 (1,000 tons/yr) 0.01 -0.14 -0.35 -0.49 -0.62 -0.61 -0.61 -0.61 -12.7

Hg (ton/yr) 0.000 -0.001 -0.002 -0.002 -0.001 -0.002 -0.002 -0.002 -0.045

Standard Level 4

CO2 (Mt/yr) 0.01 -0.22 -0.50 -0.68 -0.84 -0.83 -0.83 -0.83 -17.7

NOx (1,000 tons/yr) 0.01 -0.20 -0.44 -0.59 -0.71 -0.69 -0.69 -0.69 -15.1

SO2 (1,000 tons/yr) 0.01 -0.14 -0.35 -0.49 -0.62 -0.61 -0.61 -0.61 -12.7

Hg (ton/yr) 0.000 -0.001 -0.002 -0.002 -0.001 -0.002 -0.002 -0.002 -0.045

Standard Level 5

CO2 (Mt/yr) 0.01 -0.34 -0.75 -1.02 -1.26 -1.24 -1.24 -1.24 -26.7

NOx (1,000 tons/yr) 0.01 -0.30 -0.66 -0.88 -1.06 -1.04 -1.04 -1.04 -22.7

SO2 (1,000 tons/yr) 0.01 -0.21 -0.53 -0.73 -0.93 -0.92 -0.92 -0.92 -19.2

Hg (ton/yr) 0.000 -0.002 -0.003 -0.002 -0.002 -0.003 -0.003 -0.003 -0.068

*CO2 results are in metric tons, NOX, SO2, and Hg results are in short tons.

Extrapolation
15-7 

REFERENCES

1. U.S. Department of Energy–Energy Information Administration. 2012. Annual Energy 

Outlook 2012. Washington, DC. http://www.eia.gov/forecasts/aeo/