1

MEMORANDUM

To: Toxics Rule docket, number EPA

- HQ

- OAR

- 2009

- 0234

From: Madeleine Strum, Emission Inventory and Analysis Group

Marc Houyoux, group leader Emission Inventory and Analysis Group Subject: Emissions Overview : Hazardous Air Pollutants in Suppor t of the Proposed Toxics Rule

Date : Mar ch 15, 2011

1 Introduction

Th e purpose of this document is to summarize the mercury (Hg) and non

- Hg Hazardous Air Pollutants (HAPs) emissions associated with the proposed Toxics Rule. This information incl udes both background on these pollutants as well as emissions totals from several emissions cases developed for the proposed Toxics Rule.

2 Mercury Mercury is an element. There is a fixed amount of it in the world. As long as it is bound up, for exampl e in coal, it cannot affect people or the environment. Once it is released, for example via the combustion process, it enters the environment and becomes available for chemical conversion. Once emitted, Hg remains in the environment and can bioaccumulate in organisms or be remitted through natural

processes. Mercury is emitted through natural and anthropogenic processes and previously deposited Hg from either process may be re

- emitted. The majority of natural Hg emissions arise from volcanoes, geothermal activity, Hg

- enriched topsoil, oceans/lakes, and vegetation. The category of natural Hg emissions may or may not include biomass burning, due to the difficulty in determining whether biomass burning events are started by anthropogenic or natural causes. Generally, natu ral Hg emissions are 95

percent elemental mercury ( Hg 0 ) , and as a result have more impact on the global pool of Hg than on deposition in the region of the emissions; however, the emissions from wildfires have a greater percentage of particu late mercury ( Hg P ) (15 percent ).

The categories for anthropogenic Hg emissions include the combustion of fossil

- fuels, cement production, waste incineration, metals production

, and other industrial processes. Anthropogenic Hg emissions consist of Hg 0

, Hg P , and divalent gaseous mercury ( Hg +2 )

.

Mercury re

- emissions include previously deposited Hg originating from both natural and anthropogenic sources. At this time, it is not possible to determine the original source of previously deposited Hg

, i.e., whet her its source is natural emissions or re

- emissions from previously deposited anthropogenic Hg. 1

, 2

, 3 Current publications on this topic estimate that half of re

- emitted Hg originates from anthropogenic sources. 4

, 5

1 Lindberg, S., Bullock, R., Ebinghaus, R., Engs trom, D., Feng, X., Fitzgerald, W., et al. (2007). A Synthesis of Progress and Uncertainties in Attributing the Sources of Mercury in Deposition. Ambio, 36 (1), 19

- 33.

2 Lohman, K., Seigneur, C., Gustin, M., & Lindberg, S. (2008). Sensitivity of the global atmospheric cycle of mercury to

emissions. Applied Geochemistry, 23 (3), 454

- 466.

3 Seigneur, C., Vijayaraghavan, K., Lohman, K., Karamchandani, P., & Scott, C. (2004). Global Source Attribution for Mercury Speciation in the United States. Environmental S cience and Technology (38), 555

- 569.

4 Mason, R., Pirrone, N., & Mason, R. P. (2009). Mercury emissions from natural processes and their importance in the global mercury cycle. In Mercury Fate and Transport in the Global Atmosphere (pp. 173

- 191): Springer U.S.

5 Selin, N. E., Jacob, D. J., Park, R. J., Yantosca, R. M., Strode, S., Jaeglé, L., et al. (2007). Chemical cycling and deposit ion of atmospheric mercury: Global constraints from observations. J. Geophys. Res, 112 , 1071

- 1077.2

Current estimates of total global Hg emi ssions based on a 2005 inventory range from 7,300 to 8,300 tons per year ( tpy )

. 6

, 7 The United Nations Environment Programme (UNEP) estimates of global Hg

emissions for 2005 are somewhat lower, at 5, 60 0 metric tpy 8

, 9 (which is about 6, 2 00 tpy). Global

anth ropogenic Hg emissions, excluding biomass burning, have been estimated by many researchers.

UNEP‟s estimate (2005) is approximately 2

, 100 tpy (with a range of 1

, 300 tpy to 3

, 300 tpy) 10 and the 2005 estimate by Pirrone, et al. is approximately 2

, 600 tpy. G lobal fossil

- fuel fired power plants total approximately 500 to 900 tpy, a large fraction (25 to 35 percent) of the total global anthropogenic

emissions. 11

, 12 The U.S. contribution to global anthropogenic emissions has declined from 10 percent in

1990 to 5 percent in 20 05 13 due to reductions in U.S. emissions and increases in emissions from other

countries. Although total U.S. anthropogenic Hg has decreased, the electric generating utilities ( EGU ) sector remains the largest contributor to the total. Table 1 below shows the trend of U.S. EGU Hg compared to the total U.S. inventory from 1990 through 2016.

In 1990, U.S. EGU Hg emissions were 59 tons out of a total of 264 tons, and by 1999 U.S. EGU Hg emissions were 49 out of 115 tons. In 2005, they were 53 t ons out of a total of 105 tons. As part of the development of the Toxics Rule, EPA completed in 2010 an Information Collection Request (ICR) that gathered the latest available emissions data from EGU sources . One hundred eighty

- six boilers reported

emissi on factors (EFs) for Hg

. These data were used to develop industry

- wide average emission factors (EFs) associated with boiler configuration, which considers combinations of fuel type, boiler type, and

control devices . The average emiss ion factors were assig ned to un tested boilers based on configuration. The

boiler

- specific EFs from the test data and the average EFs were applied to the operating data gathered for all units (tested and untested). The operating data used for these calculations were the 3

- year average capacity

factor for 2007 to 2009 and the boiler maximum heat input. The resultant estimates were used to represent a year 2010 EPA estimate of 29 tons of Hg from EGUs. More information on the ICR and the associated inventory is available in the To xics Rule docket ( EPA

- HQ

- OAR

- 2009

- 023 4)

. The 2010 estimates reflect t he

U.S. EGU Hg reductions achieved since 1990 , which include reductions resulting from the installation of Hg controls to comply with state Hg

- specific rules, voluntary reductions, as we ll as from the co

- benefits of Hg

reductions from control devices installed for the reduction of SO 2 and PM as a result of state and federal actions, such as New Source Review (NSR) enforcement actions.

6 Lindberg, S., Bullock, R., Ebinghaus, R., Engstrom, D., Feng, X., Fitzgerald, W., et al. (2007). A Synthesis of Progress and Uncertainties in Attributing the Sources of Mercury in Deposition. Ambio, 36 (1), 19

– 33.

7 Pirrone, N., Cinnirella, S., Feng, X., Finkelman, R. B., Friedl i, H. R., Leaner, J., et al. (2010). Global mercury emissions to the atmosphere from anthropogenic and natural sources. Atmospheric Chemistry and Physics Discussions, 10 (2), 4719

- 4752.

8 UNEP (United Nations Environment Programme), Chemicals Branch, 2008 . The Global Atmospheric Mercury Assessment:Sources, Emissions and Transport, UNEP Chemicals, Geneva.

9 The 5,600 metric ton estimate is from the Figure on page 37 of the report. The report also provides ranges in the executive

summary.

10 Study on Mercu ry Sources and Emissions and Analysis of the Cost and Effectiveness of Control Measures “UNEP Paragraph 29 study” , UNEP (DTIE)/Hg/INC.2/4. November, 2010.

11 Pirrone, N., Cinnirella, S., Feng, X., Finkelman, R. B., Friedli, H. R., Leaner, J., et al. (2010). Global mercury emissions to the atmosphere from anthropogenic and natural sources. Atmospheric Chemistry and Physics Discussions, 10 (2), 4719

- 4752.

12 Study on Mercury Sources and Emissions and Analysis of the Cost and Effectiveness of Control Measures “UN EP Paragraph 29 study” , UNEP (DTIE)/Hg/INC.2/4. November, 2010.

13 U.S. anthropogenic emissions of 105 tons in 2005 (Table 1) divided by global anthropogenic emissions of 2,100 tons (UNEP value for global anthropogenic emissions, stated above) is 5%.3

Table 1: U.S. anthropogenic Hg emissions trends for U .S. EGUs

.

1990 (tons) 1999

(tons) 2005

(tons) 2010 1

(tons) Final 2016 Base Case 2

(tons)

U.S. EGUs 59 49 53 29 2 9

Non

- EGU Anthropogenic

U.S. Mercury 205 66 52 Not

Available 3 35

Total U.S. Anthropogenic Mercury 264 115 105 Not

Available 3 6 4

Percent o f U.S. Anthropogenic Mercury Emissions from EGUs

1990 1999 2005 2010 2016

22% 43% 50% Not

Available 3 4 5 %

1. We believe the estimate of the current level of Hg emissions based on the 2010 ICR database may underestimate total EGU Hg emissions due to target ing of the 2010 ICR on the best performing EGUs.

2. The 2016 base case scenario represents predicted emissions including known Federal measures for all sectors. It reflects projected economic changes and fuel usage for the EGU and mobile sectors. Note that

t he projected future year inventory used for this analysis is generally representative of several years

around 2016 such as 2015. The term “Final” is used to indicate that the EGUs were projected utilizing the final version of the IPM version 4.10 developed for the Proposed Toxics Rule as opposed to the

Interim version. “ Base” indicates that these are the projected emissions in absence of the Proposed Toxics Rule policy.

3. Information on recent U.S. EGU emissions was obtained using an I nformation C ollection R equest for EGUs only . This same information is not available for other sources , which were not covered by the

I nformation C ollection R equest.

Table 1 above shows past U.S. emissions of Hg as well as future emission projections to the year

2016. The Integrated Planning Model (IPM) was used to estimate future

- year Hg emissions for U.S.

EGUs. 14 More information on IPM is available in the “Documentation Supplement for EPA Base Case

v.4.10 PTR

– Updates for Proposed Toxics Rule” which can be found in the Toxics Rule docket ( EPA

- HQ

OAR

- 2009

- 0234 )

.

Below, Table 2 provides the projections for non

- EGU emission sources that include expected future reductions from existing and proposed regulations for HAP s that were finalized or are expected to be finalized pr ior to this proposal. These regulations include Portland Cement; Industrial, Commercial and Institutional Boilers and Process Heaters; Gold Ore Mining and Production, Electric Arc Furnaces,

Hazardous Waste Incineration

, and Mercury Cell Chlor

- alkali facil ities. The projections also include the replacement of a smelter and a pulp and paper plant, which will result in the elimination of Hg emissions, along with other known plant closures. This projection shows that U.S. EGU emissions will continue to

compr ise a significant , dominant portion of the total U.S. anthropogenic inventory in 2016. In 2016, U.S. EGU Hg is projected to be 2 9 tons out of a total of 6 4 tons. More information on the non

- EGU projections of Hg is available in the Emission Inventory Tec hnical Support Document (TSD) for the pro pose d Toxics Rule.

14 IP M is a multi

- regional, dynamic, deterministic linear program model of the U.S. power sector that determines the least cost solution to meeting a set of environmental constraints while still meeting specified electric demand. For more detail on IPM see: h ttp://www.epa.gov/airmarkets/progsregs/epa

- ipm/index.html4

Table 2: Anthropogenic Hg emissions and projections in the Continental U.S.

Category 2005 Mercury (tons) 2016

Mercury (tons)

Electric Generating Units 53 29

Portland Cement Manufacturing 7.5 1. 1

Stainless and Nonstainless Steel Manufacturing: Electric Arc Furnaces 7.0 4.6

Industrial, Commercial, Institutional Boilers & Process Heaters 6.4 4.6

Chemical Manufacturing 3.3 3.3

Hazardous Waste Incineration 3.2 2.1

Mercury Cell Chlor

- Alkali Plant s 3.1 0.3

Gold Mining 2.5 0.7

Municipal Waste Combustors 2.3 2.3

Sum of other source categories (each of which emits less than 2 tons) 17 16

Total 105 6 4

3 Non

- Hg HAP Emissions

Fossil

- fuel fired boilers emit a variety of metal HAP, organic HAP and HAP that are acid gases. Acid gas

and metal HAP emissions are discussed below.

3.1 Acid Gases

Acid gas emissions from EGUs include hydrogen chloride ( HCl )

, hydrogen fluoride ( HF )

, chlorine ( Cl 2 ) and hydrogen cyanide (HC n ) . These pollutants are emitted as a result of fluorine, chlorine

, and nitrogen c omponents of the fuels. Table 3 shows emissions of certain acid gases from EGUs, based on the 2010 ICR data by fuel type. Although Cl 2 was not included in the data collected from the 2010 ICR, Cl 2 gas is e xpected to be emitted at significantly lower amounts than HCl (ratios of HCl

- to

- Cl 2 can be as high as

200:1 15 ).

Similar to the Hg estimates, the 2010 ICR data for the acid gases included emission factors generated

from boiler

- specific emission tests ( a cid gas emission factors based on test data were generated for 186

boilers ). Year 2010 estimates are not available for other U.S. anthropogenic emission sources, so the latest available complete set of data, 2005, were used to approximate the percentage c ontribution of EGUs to total U.S. anthropogenic emissions. As illustrated by Table 3, U.S. EGUs are estimated to emit the majority of

HCl and HF nationally

.

15 200:1 is based on testing done at the EPA‟s pilot facility in Research Triangle Park, NC. Personal communication, Nick Hu t son (email to Madeleine Strum from Nick Hutson 01/30/2011 11:16 pm )

.5 Table 3: Summary of acid gas emissions from EGU sources.

Selected Nationwide Acid HAP emissi ons (tons/yr) in 2010 from EGUs 2005 Acid HAP

Emissions (tons/yr)

from the inventory

used for the National

Air Toxics Assessment (NATA) 1 Percent of U.S.

Anthropogenic

Emissions from

EGUs , based on the inventory used

for the 2005 NATA

Coal IGCC 2 PC 3 Oil T otal 2010

EGU 4 Total

2005

EGU 2005

Non

EGU Hydrogen Cyanide 5 7,678 1 76 107 7,900 1,200 14,000 8%

Hydrogen

Chloride 105,507 2 72 304 106,000 350,000 78,000 82%

Hydrogen

Fluoride 36,345 1 8 79 36,000 47,000 28,000 62%

1 2005 NATA : http://www.epa.gov/ttn/atw/nata2005/ EGU emissions were extracted from the total using the MACT code field (1808)

2 IGCC = integrated gasification combined cycle

3 PC = petroleum coke

4 We believe our estimate of the curren t level of acid gas emissions based on the 2010 ICR database may underestimate total EGU emissions due to targeting of the 2010 ICR on the best performing EGUs.

5 Used cyanide emissions for hydrogen cyanide

3.2 Metal HAP Metals are emitted primarily be cause they are present in fuels. T able 4 shows selected metals emitted by EGUs and emission estimates b ased on data from the 2010 ICR. Similar to the Hg and acid gas estimates,

the 2010 ICR data for the metal HAPs included emission factors generated from boiler

- specific emission

tests (metal emission factors based on test data were generated for 196 boilers). Year 2010 estimates are not available for other U.S. anthropogenic emission sources, so the latest available complete set of data, 2005,

was used to approximate the percentage contribution of EGUs to total U.S. anthropogenic emissions.6 Table 4: Summary of metal emissions from EGU sources.

Selected Nationwide Metal HAP emissions(tons/yr) in 2010 from EGUs 2005 Metal HAP

Emissions from the

inv entory used for the

National Air Toxics Assessment (NATA) 1 Percent of U.S. Anthropogenic

Emissions from

EGUs , based on the inventory used for the

2005 NATA

Coal IGCC 2 PC 3 Oil Total

2010

EGU 4 Total 2005

EGU 2005 Non

EGU

Antimony 8 0 0 16 25 19 83 19%

A rsenic 42 0 1 1 43 200 120 62%
Beryllium 2 0 0 0 2 10. 13 44%

Cadmium 3 0 0 0 3 25 38 39%

Chromium 216 0 0 6 222 120 430 22%

Cobalt 11 0 0 8 19 54 60. 47%
Manganese 168 0 0 15 183 270 1800 13%

Nickel 198 0 0 188 387 320 840 28%

Selenium 257 0 0 1 25 8 580 120 83%

1 2005 NATA : http://www.epa.gov/ttn/atw/nata2005/ EGU emissions were extracted from the total using the MACT code field (1808)

2 IGCC = integrated gasification combined cycle

3 PC=petroleum coke

4 We believe our estimate of the current level of metal emissions based on the 2010 ICR database may underestimate total

EGU metal emissions due to targeting of the 2010 ICR on the best performing EGUs.

As shown by the table, U.S. EGUs are estimated to be a significant source of emissions nationally for

these metals

.

3.3 Expected Impact on Non

- Hg HAP Emissions from Existing Clean Air Act ( CAA ) and Other Regulations and Programs It is expected that acid gas and metal emissions will be reduced in the future due to existing CAA and other regulations and programs. Acid gases and metals are emitted by a number of other industries already regulated or scheduled for regulation under the National Emissions Standards for Hazardous Air Pollutants ( NESHAP ) or the Risk and Technology Review (RTR) program. In addition, because acid gases respond

somewhat to the same types of controls used for SO 2 , it is expected that acid gas emissions will be reduced at

both EGU and non

- EGU sources as a result of national, sta te

, and local control programs to control SO 2

. Likewise, metals respond to the same types of controls used for PM, and as a result it is expected that metal

emissions will be reduced at both EGU and non

- EGU sources due to national, state

, and local contro l programs

to control direct PM.

4

. Hg and non

- Hg HAP Emissions Used for the Quantitative Risk Characterizations to Inform the Appropriate and Necessary Finding

This section summarizes the emissions used in the national scale assessments conducted to i nform the appropriate and necessary finding . It also includes the 2010 ICR data , which is cited above and was used for

site

- specific case studies conducted to evaluate inhalation risks of U.S. EGU non

- Hg HAP emissions

. The

emissions used for the national scale efforts are described in more detail in the two emission inventory technical support d ocuments associated with this rule: (1) the 2005 version 4.1 Platform TSD and (2) the7

Emission Inventory TSD for the proposed Toxics Rule. The se documents and the IPM results are available in

the Toxics Rule docket. More information on the emissions used for the case studies can be found in the

memorandum entitled “Non

- Hg Case Study Chronic Inhalation Risk Assessment for the Utility MACT

„ Appropriate and Necessary ‟ Analysis

, Memorandum to Docket EPA

- HQ

- OAR

- 2009

- 0234”

.

The national scale mercury risk analysis is based on modeling mercury deposition associated with 2005 U.S. EGU mercury emissions and on 2016 projected mercury emissions before implementation of

fede rally mandated U.S. EGU mercury emissions controls. The emission sources and the basis for the analyses described in th is section are listed in Table 5

. The 2005 base

- year emissions case is used for air quality modeling of the 2005 base year and contains emissions of criteria pollutants, Hg

, HCl , and Cl 2 from all source categories. All emissions except Hg come from the 2005 version 4.1 m odeling platform, which is

derived from the 2005 National Emission s Inventory (NEI) . 2005 Hg emissions for all sources come from

the 2005 National Air Toxics Assessment (NATA) inventory

, a revised version 16 of the 2005 NEI , which

was further revised in thi s effort f or non

- EGU point and nonpoint sources based on data collected from the NESHAP for industrial, commercial and institutional boilers (a.k.a. the Boiler MACT)

. The 2010 ICR case contains emissions only for U.S. EGUs

, and the Hg, HCl , and metal emis sions in this inventory are based on

the 2010 ICR data

.

The interim 2016 base projected emissions were developed for use in modeling based on the latest available projection techniques and account for emissions reductions of all modeled pollutants from F ederal

measures. The interim 2016 policy c ase projected emissions are an interim version of the expected

emissions from EGUs after reductions associated with the Toxics Rule

. The interim 2016 EGU emissions for both the base and Toxics Rule policy cases were created using an interim version of the IPM because the modeling needed to be completed in advance of the final IPM revisions associated with the Toxics Rule

. The non

- EGU source emissions were created for the interim 2016 base projected emissions , an d these are described in the Emission Inventory TSD for the Toxics Rule. These emissions were used for all other 2016

e mission cases listed in Table 5.

After IPM was finalized and all policy decisions made for the proposed Toxics Rule , the resulting

emissions are labeled as the final 2016 base and policy cases. The final IPM emissions are cited in the preamble for the Toxic s Rule and in any summaries stating the final 2016 emissions associated with the rule generally

. Due to timing considerations, the final base and policy case emissions were not used in the modeling.

16 Mercury r evisions for NATA primarily affected non

- EGU sources suc h as cement kilns and hazardous waste combustors.8

Table 5: Emission sources and basis for current a nd future

- year emissions inventories.

Emissions

Case Pollutants Sector Emissions source

2005 base year Criteria

pollutants, hydrogen chloride, and

chlorine EGU

Non

- EGU point

Non

- point

Mobile 2005 emissions from the version 4.1

modeling platform, derived f rom the 2005 National Emission Inventory (NEI) data

Hg EGU

Mobile 2005 National Air Toxics Assessment

(NATA) data

Non

- EGU point

Non

- point 2005 NATA data, adjusted to account for

Boiler MACT ICR data

2010 ICR

Emissions Mercury,

hydrogen chloride, and

metals EGU 2010 Utility MACT ICR: EGU emissions inventory based on unit

- specific emission

factors for tested units and average emission

factors for untested units.

Interim 2016

Base Case projections Criteria

pollutants, mercury and hydrogen

chloride EGU I nterim IPM v.4.10, including the Transport Rule Proposal

Non

- EGU point Nonpoint

Mobile Emissions from the version 4.1 modeling

platform: projected 2005 emissions to account for all known national rules, consent decrees, and plant closures

Interim 2016 Policy Case projections Criteria

po llutants, mercury and hydrogen

chloride EGU Interim IPM v.4.10 , including the Transport Rule Proposal and interim Toxics Rule Proposal

Non

- EGU point Nonpoint Same as interim 2016 base projections

Final 2016

Base Case projections Criteria

pollutants, mercury and hydrogen

chloride EGU IPM v.4.10, including the Transport Rule Proposal

Non

- EGU point Nonpoint

Mobile Same as interim 2016 base projections

Final 2016 Policy Case projections Criteria

pollutants,

mercury an d hydrogen

chloride EGU IPM v.4.10 , including the Transport Rule Proposal and Toxics Rule Proposal

Non

- EGU point Nonpoint Same as interim 2016 base projections

Table 6 summarizes the Hg and HCl emissions for the anthropogenic sources of these emissio ns across the various cases

. The 2005 base case includes 105 tons of Hg and 430,000 tons of HCl from all sources, of which 53 tons of Hg and 350,000 tons of HCl are from EGUs. The 2010 ICR shows the EGU Hg and HCl totals are lower than in 2005, at 29 ton s and 1 06 ,000 tons respectively. The interim 2016 base total Hg emissions from all sources are 6 4 tons and HCl emissions are 140, 000 tons, with 29 tons of Hg and
74,0 00 tons of HCl from EGUs. For the interim Toxics Rule policy case, total Hg was estimate d to be 42 tons, with 6.8 tons from EGUs. For HCl, the interim Toxics Rule policy case shows a total of 75, 000 tons from all sources with EGU emissions emitting 8,80 0 tons. The final Toxics Rule policy case for Hg from all9

sources is 4 2 tons with E GU s contributing 6.4 tons. For HCl, total emissions are 7 7 ,000 tons with EGUs contributing 6,6 00 tons.

Table 6 . Summary of mercury and HCl emissions for emissions cases

.

Hg(0) (tons) Hg(2+)

(tons) Hg(p)

(tons) Total Hg

(tons) Hydrogen

chloride (tons)

2 005 Base Case Emissions (tons)

EGU * 30 21 1.6 53 35 0

, 000

NonEGU Point 30 11 6.2 46 49,000 Nonpoint 3.1 1.06 0.65 4.8 29,00 0

Mobile 0.79 0.29 0.13 1.2

All sources 64 33 8.5 105 430,000 2010 ICR Emissions (tons)

EGU 29 106,000

Interim 20 16 base case projections (tons)

EGU * * 21.1 6.9 0.67 28.7 74,0 00

NonEGU Point 16.9 7.9 4.4 29.2 38,000 Nonpoint 3.1 1.06 0.65 4.8 29,000

Mobile 0.79 0.29 0.13 1.2

All sources 42 16 5.9 64 140, 000

Interim 2016 policy case projections (to ns)

EGU * * 4.8 1.6 0.36 6.8 8,80 0

NonEGU Point 17 7.9 4.4 29 38,000 Nonpoint 3.1 1.06 0.65 4.8 29,00 0

Mobile 0.79 0.29 0.13 1.2

All sources 26 11 5.6 42 75, 000

Final 2016 base case projections (tons)

EGU 21 6 .8 0. 78 29 74,0 00

NonEGU Point 17 7.9 4.4 29 41,000 * *

Nonpoint 3.1 1.06 0.65 4.8 29,000

Mobile 0.79 0.29 0.13 1 .2

All sources 4 2 1 6 5. 8 6 4 140,000

Final 2016 policy projections (tons)

EGU 4.7 1. 4 0. 26 6.4 6, 6 00

NonEGU Point 17 7.9 4.4 29 41,000 * *

Nonpoint 3.1 1.06 0.65 4.8 29,00 0

Mobile 0.79 0.29 0.13 1.2

All sources 2 6 11 5. 4 4 2 7 7

, 00010

* For this table, the EGU Sector is d efined as follows: (1) For all pollutants other than mercury (Hg): 2005 NEI v2 point source EGU s mapped to the Integrated Planning Model (IPM) model using the National Electric Energy Database System (NEEDS) 2006 version 4.10 database. A few revisions were made to the 2005 NEI v2 annual

emission estimates as discussed in the 2005

- based, Version 4.1 platform document. (2) F or Hg : 6/18/2010 version of the inventory used for the 2005 National Air Toxics Assessment (NATA) mapped to IPM using NEEDS version 4.10. The NATA inventory is an update to the 2005 NEI v2 and was divided into EGU and non

- EGU sec tors consistent with the other pollutants. We additionally removed Hg from sources from the NESHAP for Industrial, Commercial, and Institutional Boilers and Process Heaters (aka “Boiler MACT”) Information Collection Request (ICR) database because we inclu ded these emissions in the non

- EGU sector. For more information, see the 2005

- based Platform Documentation, version 4.1

.

** EGU Sector for 2016 is consistent with the 2005 base case discussed above. The future year emissions were generated by the Interi m version of IPM 4.10 and adjustments were made to remove Hg associated with the Boiler

MACT ICR (which is accounted for in the Non

- EGU sector) , and to apply the impact of the final Boiler MACT for the other pollutants. For more information, see the Techn ical Support Document for the Proposed Toxics Rule,

Emissions Inventories.

** *NonEGU Point for the Final base and policy case projections are computed as 37,549 plus emissions for units < 25 megawatts

To summa rize t hat table for EGUs only, Table 7 lis ts only the EGU emissions totals for the various

cases. It also includes the average percent of divalent gaseous and particulate Hg for the EGUs in each case. As can be seen the divalent gaseous Hg ranges from 20% to 40% of the total Hg and the average particulate Hg ranges from 2 to 5% of total.

Table7 : EGU emissions of Hg and HCl for emissions cases.

Hg(0) (tons) Hg(2+)

(tons) Hg(p)

(tons) Total Hg

(tons) Hydrogen

chloride (tons) Hg(2+)

Percent of total Hg Hg(p)

Percent of total Hg

2005 Base Ca se Emissions 30 21 1.6 53 350,000 40% 3%

2010 ICR Emissions N/A * N/A N/A 29 106,000

Interim 2016 base case projections 21.1 6.9 0.67 28.7 74,000 24% 2%

Interim 2016 Toxics Rule policy case projections 4.8 1.6 0.36 6.8 8,800 24% 5%

Fin al 2016 base case projections 21 6.8 0.78 29 74,400 23% 3%

Final 2016 Toxics Rule policy case projections 4.7 1.4 0.26 6.4 6,600 22% 4%

* Speciation data were not collected for Hg in the 2010 ICR