United States Department of the Interior 

ORRCEOFTHESECRETARY 

Washington, D.C. 20240 

INTERIOR DEPARTMENT COMMENT ON NREL PHASE 1 REPORT 

The National Renewable Energy Laboratory's (NREL) Report, ''Navajo Generating 

Station and Air Visibility Regulations: Alternatives and Impacts" resulted from a request 

to NREL by the Department of the Interior (Interior) to develop and objectively 

synthesize factual infonnation and analyses pertinent to the determination by the U.S. 

Environmental Protection Agency (EPA) of Best Available Retrofit Technology (BART) 

in a Federal Implementation Plan (pIP) for NGS. The study focuses primarily on the 

compilation of additional detailed information and completion of a comprehensive and 

objective analysis consistent with the five statutorily prescribed BART factors. J The 

study made no presumption about what the appropriate BART determination should be. 

Rather, its goal was to provide NGS stakeholders, including EPA, with additional data 

and input regarding the technical and economic feasibility of options for compliance with 

the Clean Air Act's BART requirement. 

In preparing this report, NREL sought information from a wide array ofNGS 

stakeholders, including Interior, the Navajo Nation, Hopi Tribe and other Arizona tribes, 

Salt River Project, Central Arizona Water Conservation District (operator ofthe Central 

Arizona Project [CAP]), the non-federal owners ofNGS, conservation organizations and 

other groups representing local residents and stakeholders, and others. 

The time constraints ofEPA's BART rulemaking process required that NREL complete 

this report in a very short time period - about five months -- to allow EPA sufficient time 

to review and consider the report prior to issuing a proposed BART rule. In the face of 

this tight schedule, NREL carried out an extraordinary amount of very high quality work 

on an extremely complex set ofissues to produce this report. 

The short time frame for this report was further limited by NREL's independent peer 

review process for the report. Each chapter of the report was reviewed by an independent 

outside expert in the subject matter ofthe chapter. This independent peer review further 

ensures the objectivity and absence of bias in the NREL report. 

Interior has many different interests at stake in both the future ofNGS and the BART 

rulemaking. Through the Bureau ofReclamation (Reclamation), the Department is the 

largest owner ofNGS, with a 24.3% share ofthe plant's power production. Reclamation 

also constructed and oversees operation ofthe CAP. The Bureau ofIndian Affairs 

1 Cost of compliance; energy and non-air-quallty.environmental impacts of compliance; 

existing pollution control technology in use at the source; remaining useful life of the 

source; and the degree of improvement in visibility which may reasonably be 

anticipated to result from the use of the technology. 
supports the interests of the many tribes interested in the future ofNGS, including the 

Navajo Nation, the Hopi Tribe, and the many Arizona tribes which have contracts for 

CAP water. The National Park Service oversees all the national parks, including the 

Grand Canyon and the many other parks whose air quality is impacted by NGS 

emissions. Interior's Office of Surface Mining regulates the Peabody Coal Mine that 

provides coal to NOS. The U.S. Fish and Wildlife Service, as the agency charged with 

carrying out the federal Endangered Species Act and other federal wildlife laws, has 

interests in ensuring the protection ofthe species under its purview and the clean air and 

water on which those species depend. In addition, the Secretary's Indian Water Rights 

Office is in charge of negotiating and implementing Indian water settlements, including a 

number ofsettlements involving Arizona tribes that relinquished their senior water rights 

claims in return for affordable CAP water. 

Interior believes that, overall, the NREL report provides an excellent review and 

synthesis ofthe many interests and processes that could be affected by EPA's BART 

rulemaking for NOS. Interior and its agencies are continuing to review both the NREL 

report and other new reports and information relevant to this proceeding; should any DOl 

agency fmd it appropriate to comment on specific matters in the NREL report or 

elsewhere, it will provide comments directly to EPA. 
JANICE K. BREWER 

Governor 

SANDRA A. FABRITZ·WHrrfJt:V 

Direator 

ARIZONA DEPARTMENT OF WATER RESOURCES 

3550 North Central Avenue, Second Floor 

PHOENIX, ARIZONA 85012-2105 

(602) 771-8426 

February 6,2012 

Transmitted via e-mail to: 

NGS_Report_Comment@ios.doi.gov 

National Renewable Energy Laboratory 

1617 Cole Boulevard 

Golden, Colorado 80401 

The Arizona Department of Water Resources (ADWR) has reviewed Navajo Generating 

Station and Air Visibility Regulations: Alternatives and Impacts, prepared by the National 

Renewable Energy Laboratory (NREL). We are concerned about the broad-reaching 

consequences that the costs associated with nitrogen oxides (NOx) removal at the Navajo 

Generating Station (NGS) will have on water management efforts in the three-cOUnty 

Central Arizona Project (CAP) service area, and on existing and future Indian water 

rights settlements in Arizona. Further, the report fails to demonstrate an environrfiemtal 

benefit to those costs. EPA's effolts appear to be regulation for regulation's sake, rather 

than regulation designed to protect human health and welfare or provide a specific 

environmental benefit. In fact, the proposed action will have undesirable environmental 

and economic consequences throughout Arizona. 

ADWR is also concerned that the time allowed for commenting on the report and the 

two-page, 12-pitch font limitations are insufficient to comprehensively review and 

analyze the report and fully ex.press questions, concerns, and comments. We publish 

many reports that are subject to public review and comment. These processes are vital to 

fully vetting issues and providing the best possible public policy and work product. 

ADWR would never consider limiting comments in the manner prescribed in the 

instructions, particularly in light of the magnitude and breadth of potential consequences 

of the actions under consideration. 

The Report states that "EPA's statutory authority in this particular proceeding focuses on 

visibility at national parks and other priority areas." It further states that EPA is required 

to "take into consideration the costs of compliance, the energy and nonair qUUlity 

environmental impacts of compliance," and "the degree of improvement in visibility 

which may reasonably be anticipated to result from the use of such technology" (Pg ii, 

Executive Summary). 

The report fails to provide clear evidence of visibility improvements that may be enjoyed 

through the imposition of NOx controls at NGS. The report discusses discrepancies in the 

JANICE K. BREWER 

Governor 

SANDRA A. FABRITZ·WHrrfJt:V 

Director 

ARIZONA DEPARTMENT OF WATER RESOURCES 

3550 North Central Avenue, Second Floor 

PHOENIX, ARIZONA 85012-2105 

(602) 771-8426 

February 6,2012 

Transmitted via e-mail to: 

NGS_Report_Comment@ios.doi.gov 

National Renewable Energy Laboratory 

1617 Cole Boulevard 

Golden, Colorado 80401 

The Arizona Department of Water Resources (ADWR) has reviewed Navajo Generating 

Station and Air Visibility Regulations: Alternatives and Impacts, prepared by the National 

Renewable Energy Laboratory (NREL). We are concerned about the broad-reaching 

consequences that the costs associated with nitrogen oxides (NOx) removal at the Navajo 

Generating Station (NGS) will have on water management efforts in the three-cOUnty 

Central Arizona Project (CAP) service area, and on existing and future Indian water 

rights settlenlents in Arizona. Further, the report fails to demonstrate an environrtlemtal 

benefit to those costs. EPA's effolts appear to be regulation for regulation's sake, rather 

than regulation designed to protect human health and welfare or provide a specific 

environmental benefit. In fact, the proposed action will have undesirable environmental 

and economic consequences throughout Arizona. 

ADWR is also concerned that the time allowed for commenting 011 the report and the 

two-page, 12-pitch font limitations are insufficient to comprehensively review and 

analyze the report and fully express questions, concerns, and comments. We publish 

many reports that are subject to public review and comment. These processes are vital to 

fully vetting issues and providing the best possible public policy and work product. 

ADWR would never consider limiting comments in the manner prescribed in the 

instructions, particularly in light of the magnitude and breadth of potential consequences 

of the actions under consideration. 

The Report states that "EPA's statutory authority in this particular proceeding focuses on 

visibility at national parks and other priority areas." It further states that EPA is required 

to "take into consideration the costs of conlpliance, the energy and nonair qUUlity 

environmental impacts of compliance," and "the degree of improvement in visibility 

which may reasonably be anticipated to result from the use of such technology" (Pg ii, 

Executive Summary). 

The report fails to provide clear evidence of visibility improvements that may be enjoyed 

through the imposition of NOx controls at NGS. The report discusses discrepancies in the 
modeling prepared on behalf of Salt River Project (SRP) and modeling conducted by 

EPA. SRP's modeling results rely on baseline data from rural monitoring sites at Mesa 

Verde and other locations of interest in the Four Corners region, presumably some Of the 

very visual resources EPA is trying to protect. EPA's modeling results rely on 

"background ... data collected in more urban or agriculturally developed areas near 

Farmington that are impacted by local ammonia sources." The report further states that 

"If the model input ammonia values are too high compared to actual background 

ammonia concentrations that are mixed into the power plant plumes as they travel 

downwind of a source, the modeling process can significantly overestimate nitrate 

particle formation, thus overestimating visibility impact of the plumes." Such an 

overestimation of the visibility impact would also serve to overestimate the Visibility 

improvement that may be derived from imposition of NOx controls or closing NGS. The 

report further recommends on-going monitoring to assess the actual visibility 

improvements from NOx and S02 reduction. ADWR recommends that this monitoring 

be conducted to assess the impact on visual resources from the S02 reduction and regionwide NOx reduction already experienced prior to either imposition of selective catalytic 

reduction (SCR) or closure of NGS. 

CAP Water is an integral element of Arizona's water management efforts. Significant 

volumes of CAP water were originally allocated to Arizona Indian Communities. Indian 

contracts totaled 286,100 acre-feet when the Secretary of Interior approved the original 

allocations in 1983. CAP water has since been an invaluable tool in State and Federal 

efforts to settle Indian Water Rights claims. Today, 555,806 acre-feet of CAP water is 

under contract to Arizona Indian Communities, having largely contributed to 

comprehensive settlements in six of the seven Indian Water Rights Settlements achieved 

since 1983. An additional 67,300 acre-feet of CAP Non-Indian Agricultural priority 

water has been reserved for future Indian settlements, including the pending White 

Mountain Apache and NavajolHopi Settlements. 

The constluction of NGS was a Federal decision. Increased power costs associated With 

either SCR implementation or closure of NGS will unduly fall on Arizona's Indian 

Communities and hamper the economic development of these impoverished nations made 

possible by the settlements. In our opinion, imposition of these costs onto the Tribes 

violates the spirit of the settlements to which the United States is a party. 

Additionally, NGS and the Kayenta Coal Mine are collectively the largest employer on 

both the Navajo and Hopi Reservations. Closure of NGS would result in the direct loss 

of roughly 1,000 jobs and $100 Million in wages for members of these communities, 

thrusting additional poverty on the Navajo Nation and Hopi Tribe, greater than 35% of 

whose members already live in poverty. The indirect economic impact of the loss of 

these jobs would be substantially larger. Both the Navajo Nation and Hopi Tribe also 

receive considerable revenue from royalties paid by Peabody Energy. The Navajo Nation 

also receives lease revenues as the NGS is located on Navajo land. These revenue 

streams would be lost with the closure of NGS. 

modeling prepared on behalf of Salt River Project (SRP) and modeling conducted by 

EPA. SRP's modeling results rely on baseline data from lural monitoring sites at Mesa 

Verde and other locations of interest in the Four Corners region, presumably some Of the 

very visual resources EPA is trying to protect. EPA's modeling results rely on 

"background ... data collected in more urban or agriculturally developed areas near 

Farmington that are impacted by local ammonia sources." The report further states that 

"If the model input ammonia values are too high compared to actual background 

ammonia concentrations that are mixed into the power plant plumes as they travel 

downwind of a source, the modeling process can significantly overestimate I1itrate 

particle formation, thus overestimating visibility impact of the plumes." Such an 

overestimation of the visibility impact would also serve to overestimate the visibility 

improvement that may be derived from imposition of NOx controls or closing NGS. The 

report further recommends on-going monitoring to assess the actual visibility 

improvements from NOx and S02 reduction. ADWR recommends that this monitoring 

be conducted to assess the impact on visual resources from the S02 reduction and regionwide NOx reduction already experienced prior to either imposition of selective catalytic 

reduction (SCR) or closure of NGS. 

CAP Water is an integral element of Arizona's water management efforts. Significant 

volumes of CAP water were originally allocated to Arizona Indian Communities. Indian 

contracts totaled 286,100 acre-feet when the Secretary of Interior approved the original 

allocations in 1983. CAP water has since been an invaluable tool in State and Federal 

efforts to settle Indian Water Rights claims. Today, 555,806 acre-feet of CAP water is 

under contract to Arizona Indian Communities, having largely contributed to 

comprehensive settlements in six of the seven Indian Water Rights Settlements achieved 

since 1983. An additional 67,300 acre-feet of CAP Non-Indian Agricultural priOrity 

water has been reserved for future Indian settlements, including the pending White 

Mountain Apache and NavajolHopi Settlements. 

The constluction of NGS was a Federal decision. Increased power costs associated With 

either SCR implementation or closure of NGS will unduly fall on Arizona's Indian 

Communities and hamper the economic development of these impoverished nations 111ade 

possible by the settlements. In our opinion, imposition of these costs onto the Tribes 

violates the spirit of the settlements to which the United States is a party. 

Additionally, NGS and the Kayenta Coal Mine are collectively the largest employer on 

both the Navajo and Hopi Reservations. Closure of NOS would result in the direct loss 

of roughly 1,000 jobs and $100 Million in wages for members of these communities, 

thrusting additional poverty on the Navajo Nation and Hopi Tribe, greater than 35% of 

whose members already live in poverty. The indirect economic impact of the loss of 

these jobs would be substantially larger. Both the Navajo Nation and Hopi Tribe also 

receive considerable revenue from royalties paid by Peabody Energy. The Navajo Nation 

also receives lease revenues as the NGS is located on Navajo land. These revenue 

streams would be lost with the closure of NGS. 
The 2007 Interim Operating Guidelines quantify reductions to Arizona's fourth priority 

Colorado River water supply under specified, low-reservoir storage conditions. 

"Firming" of this supply is an integral part of the State's water management efforts, 

ensuring critical water needs are met in times of shortage on the Colorado River an 

increasing probability. These firming activities will benefit Colorado River water Users 

along the main-stem of the River, Indian Tribes with CAP allocations, CAP Municipal 

and Industrial Users, and others. Additionally, Arizona has stored water to assiSt the 

State of Nevada in firming their Colorado River entitlement. Through the Indian 

Settlements, Arizona has contractual obligations to firm supplies for the future benefit of 

the settling Tribes. The Arizona Water Banking Authority (AWBA) conducts these 

firming activities. Imposing increased costs on the AWBA could unnecessarily 

complicate Arizona's ability to meet its overall firming goals, including its Indian 

Firming obligations. 

In recent years, roughly 400,000 acre-feet of Excess CAP water has also been delivered 

to non-Indian agricultural users for direct use. ADWR fears that the increased cOSt of 

CAP water as a result of imposition of SCR or closure of NGS will force many USel'S to 

return to pumping groundwater, thereby placing the finned water at risk and resulting in 

water level declines and land subsidence, development and expansion of earth fiSSures, 

and water quality degradation. 

While ADWR appreciates the opportunity to provide limited comments to the NREL 

Report, the arbitrary limitation on the public comments is of significant concern. 

Additionally, we do not believe, based on this study, that imposition of SCR or closure of 

the Navajo Generating Station is warranted given the economic and environmental 

consequences of the proposed actions and the lack of demonstrable environmental benefit 

that will be derived. 

Respectfully Submitted, 

Sandra Fabritz-Whitney 

Director 
Comment submitted February 6, 2012 to the Navajo Generating Station NREL Study 

Team by Alberta Green Energy: 

Alberta Green Energy Inc. (AGE) offers the following viable solution in response to the request 

for comments to the National Renewable Energy Laboratory (NREL) Study on the Navajo 

Generating Station ("Study"). 

AGE is licensed to utilize and supply proven world-class gas plasma technology and/or plasma 

arc technology as developed by Advanced Plasma Power (APP). Data on the gas plasma 

technology is available at: www.advancedplasmapower.com (click on the Media icon both for 

videos and a 3D CAD walk-through of a gas plasma facility). Use ofAGE plasma technologies 

would resolve the NOx, arsenic, mercury, partjculates, and other air pollution issues at the 

Navajo Generating Station in a much more effective manner and at a much less expensive cost 

than the technology options currently presented in Chapter 3, "Control Technologies - Cost of 

Retrofits" on page 43 of the study. 

The gas plasma technology subjects the waste elements in the Navajo Generating Station exhaust 

flow to extreme high temperatures (6000 - 8000 degrees Celsius) as well as intense ultra violet 

light in an enclosed vessel and literally deconstructs the constituent elements of the waste stream. 

The gas plasma units have no air emissions themselves, and the units already satisfy European 

Union 2050 air emission standards. 

Based on the preliminary information available to us from the study and other sources we 

estimate capital costs for the installation of our systems to be in the 35 - 40% range of the SCR + 

baghouse control option as reflected in Table 1-9, page 18 of the Study. This includes 

operational redundancies in order to compensate for any scheduled or unanticipated maintenance 

and downtime of a gas plasma unit. 

Similarly gas plasma unit operation and maintenance (O&M) costs can be expected to be only 

40-50% of the O&M costs estimated in Table 3-11 "Costs for SCR and Polishing Baghouse" for 

operating SCR's and baghouses at NGS. 

With the implementation of our plasma technologies, air emissions including NOx, arsenic, 

mercury, and particulates would be reduced to a small fraction of those currently being emitted. 

We estimate an across-the-boards 90%+ emissions reduction, which would be verified through 

scientific and engineering data and design evaluatjons by AGE appointed technical resources. 

Waste products such as particulate, metals, ash and any other solids would be tapped from the 

plasma torch chamber and stabilized in the formation of either molten metal or inert plasmaroc 

both 0 f which then become reusable commercial products. At this point C02 could also be 

sequestered to be utilized for commercial purposes to generate income. 

Utilization of this gas plasma technology could result in making the Navajo Generating Station 

the first coal-fired facility in North America to meet or exceed all current and proposed air 

emission standards. This would establish the Navajo Generating Station as the cleanest power 

1
 
 
generation facility in the Western United States (excluding hydro and nuclear facilities) and 

thereby could be used as a role model for application to additional coal-fired plants. 

We respectfully encourage the Navajo Generating Station NREL Study Executive Committee to 

consider use of gas plasma technology as a viable air emission control option for the Navajo 

Generating Station. 

Sincerely, 

Douglas V. Fant 

.For Alberta Green Energy 

3655 W. Anthem Way 

Suite A-109, PMB 411 

Anthem, AZ. 85086 

(602) 770-5098 

Fax (623) 551-7930 

dfantlaw@earthlink.net 

2
 
 
amwaa
 
 

ONE FOR WATER~ Arizone Munldp.l Wat.r U",rJ A."od..tlon 

February 6, 2012 

Department of the Interior 

United States Federal Government 

Washington, D.C. 

RE:	 	Navajo Generating Station Comments 

To Whom It May Concern: 

The Arizona Municipal Water Users Association (AMWUA) is a non-profit corporation 

established by cities and towns in Maricopa County, Arizona, for the development of an urban 

water policy. AMWUA works to advance the rational and effective management of Arizona's 

water resources. The municipal water systems owned and operated by the AMWUA member 

cities of Avondale, Chandler, Glendale, Goodyear, Peoria, Phoenix, Mesa, Scottsdale, Tempe 

and the Town of Gilbert, collectively provide water for over 3 million people, roughly 60 percent 

of the population of the State of Arizona. Each of the AMWUA members holds a long-term M&I 

subcontract for Central Arizona Project (CAP) water and, as a result, relies on the Navajo 

Generating Station (NGS) to provide the electrical energy necessary to deliver this CAP water 

from the Colorado River into Maricopa County. Because of our members' heavy reliance on 

CAP water and our long-standing commitment to sound water management in Arizona, 

AMWUA is commenting on the NGS Report. 

The decision whether to require additional emission controls at NGS has significant implications 

for the AMWUA members who rely on CAP water as a critical component of their sustainable 

water supplies. The major goal of the State's water management efforts in central Arizona is to 

reduce and eventually eliminate the historical over-reliance on mined groundwater in order to 

protect the well-being of all residents and the economy of the State. Importation of Colorado 

River water through the CAP to the AMWUA municipalities and other water users in central 

Arizona has reduced Arizona's dependence on dwindling groundwater resources by providing a 

stable, renewable supply of water. AMWUA is concerned about any action that could 

negatively affect the CAP and the state's ability to achieve its water management objectives. 

Our specific comments follow: 

1.	 	 It appears from the report that additional emission controls at NGS may not result in any 

improvement in visibility. Page iv of the report states: 

"Evidence suggests that NOx emissions from Navajo Generating Station are a likely 

incremental contributor to haze at the Grand Canyon. Whether the incremental 

contribution is significant or even perceptible is a matter of debate among experts in the 

field of visibility science." (emphasis added) 
If this is the case, it seems prudent to weigh whether the unquantifiable benefits of such 

controls are justifiable in light of the likely negative impacts. 

2.	 	 Large increases in costs to install, operate, and maintain additional controls for the NGS will 

reduce the affordability of water in central Arizona. Increased water costs could force some 

users, such as agriculture, to revert to mining groundwater, threatening the State's ability to 

effectively manage its water supplies. Additionally, increases in the cost of CAP water may 

negatively impact both existing and future Indian water rights settlements. 

3.	 	 While the report provides a reasonable basis for the cost impacts of the closure alternative, 

importing water into central Arizona also requires a reliable, steady energy supply. 

Projecting the unit cost and reliability of replacement power under this scenario is highly 

speculative. With the debate over the continued use of fossil fuels for generating 

electricity, alternative energy sources may in fact become more prevalent, bringing with 

them the attendant increased costs of energy from those alternative sources. 

4.	 	 The report notes that one possible outcome is accepting the existing plant improvements to 

improve air quality, LNB/SOFA, with no additional retrofit, but the report does not evaluate 

this option. 

5.	 	 The conclusion that installing SCR at NGS would cost less than shutting down the plant does 

not take into account the relationship between the timing of the determination that the 

additional controls are required and the resolution of numerous uncertainties surrounding 

continued operation of NGS beyond 2019. 

6.	 	 Affordable electricity affects the health and well-being of Arizonans. The NGS provides 

significant amounts of power to three large electric utility providers in Arizona-Arizona 

Public Service, Salt River Project, and Tucson Electric Power. Substantial increases in 

electrical generation costs at the NGS will be passed on to Arizona residents and businesses 

through increased electricity rates. In many cases, these are the same residents and 

businesses that will also be impacted by increased water rates. 

The final decision on additional controls at the NGS is extremely important and must be 

thoroughly assessed, understood, and communicated. AMWUA appreciates the opportunity to 

comment on the report. 

Sincerely, 

Kathleen Ferris 

Interim Executive Director 

KF:VD:MLA 

Navajo Generating Station Comments 
Comments on National Renewable Energy Laboratory Technical Report 

Navajo Generating Station and Air Visibility Regulations: Alternatives and Impacts 

Prepared by: Arizona Public Service Company
 
 

Address: 400 N. 5th Street, Phoenix, Arizona 85004
 
 

Arizona Public Service Company (APS) appreciates this opportunity to provide comments on the 

National Renewable Energy Laboratory's report, "Navajo Generating Station and Air Visibility 

Regulations: Alternatives and Impacts" (NREL Report). APS is an investor-owned electric utility 

company serving over 1.1 million customers in Arizona. APS is owner/part-owner of three coal-fired 

power plants, several gas-fired power plants, and the nation's largest nuclear power plant, Palo Verde 

Generating Station. Specifically, APS is a part owner of the Navajo Generating Station (NGS), and 

therefore, is interested in commenting on the NREL Report. 

APS's comments are limited to Section 5 of the NREL Report, "Assessment of Visibility 

Science." Because our comments are not to exceed 2 pages, we wi Jl provide some general comments 

and would welcome the opportunity to supplement it later with more details, should NREL be interested 

in those. Our comments below are focused on three issues: S02 and NOx emissions and their relative 

contributions to total light extinction (visibility impairment); Use of CALPUFF 5.8 and IWAQM 

"default ammonia vales" which cause over-prediction of nitrate particle formation and their impacts on 

visibility impairment; and certain errors in Table 5-4 and 5-6 of the NREL Report. 

In general, Section 5 provides a good summary of visibility science, especially as it applies to the 

arid Southwest. The Colorado Plateau, home to numerous National Parks and Wilderness Areas, has the 

best visibility in the nation. A quarter century of monitoring under the IMPROVE program show 

improving visibility trend in this region. Analyses of those data by the Grand Canyon Visibility 

Transport Commission and its successor, Western Regional Air Partnership (WRAP) show that visibility 

impairment on the Colorado Plateau is caused by sulfates, dust, and elemental/organic carbon particles 

in roughly equal proportions. Nitrates, on an average contribute less than 5% to the impail1l1ent. 

APS agrees with the NREL Report's conclusion that it is unclear whether reducing NGS NOx 

emissions by retrofitting Selective Catalytic Reduction (SCR) would result in perceptible visibility 

improvement in the region. S02 and NOx emissions undergo complex chemical transfonnations in the 

atmosphere to form sulfate and nitrate particles. Those conversions are not linear; background ammonia 

concentrations and meteorological conditions play significant roles; and sulfate chemistry takes 

precedence over nitrate chemistry. The NREL Report concludes, "Even under cold weather conditions 

in this region, sulfate is usually dominant over nitrate, although the sulfate-to-nitrate ratio is smaller in 

the cold months." Figures 5-7 to 5-12 in the NREL Report show nitrate concentrations are much smaller 

than corresponding sulfate concentrations. 

Figure 1 below shows the relative contributors to total light extinction at the Grand Canyon 

National Park (data from VIEWS Website) during the best 20%, middle 20%, and worst 20% visibility 

days during 2006-2008. In each of the three cases, nitrates contribute less than 5% ofthe total extinction 

compared to 12% to 19% by sulfates. Recalling that NOx emissions fTom all coal-fired power plants 

contribute less than 30% of overall NOx emissions, it is reasonable to conclude that power-plants' 

contributions to the total extinction will be even less than 5%. Therefore, significant reductions in NOx 
emissions from NGS are not likely to produce significant reductions in their contributions to total 

extinction. 

GRCA2 200'6-2008 

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APS agrees with the NREL Report's conclusion, "Measurements specific to this region indicate 

that actual visibility impacts [from NOx emissions] may not be as great as those estimated by CALPUFF 

5.8 as applied by EPA" (Page 92). This over-prediction resuJts fTom 2 aspects: use of incorrect 

background ammonia concentrations and flaws in the chemistry module in CALPUFF 5.8. It has been 

well-established that CALPUFF 5.8 over-predicts nitrate concentrations (e.g., see studies by Morris, 

2001; Scire, 2003; Karamchandani, et aI, 2008; Hoffnagle, 2012, and others). At the suggestion ofthe 

Modeling Group at EPA-OAQPS, in 2011 Scire (who developed the CALPUFF Model) evaluated 

revisions to the model's chemistry module recommended by a study sponsored by the American 

Petroleum Institute. Those evaluations resulted in the revised CALPUFF 6.4, currently available for 

public use. Again, at the suggestion ofEPA-OAQPS, Scire tested the chemistry module against three 

other existing data sets; and the results ofthose tests are expected to be presented at the EPA's 10th 

Modeling Conference during March 13-15,2012. 

Background ammonia values were collected at numerous rural areas in the West and were 

summarized by Tombach (2011). Tombach showed that the IWAQM default ammonia value ofl ppb 

throughout the year is not appropriate for the Four Corners region and much lower values should be 

used for CALPUFF modeling, consistent with recent field measurements. For example, background 

ammonia concentration measurements at the Mesa Verde National Park ranged from 0.2 ppm during 

winter months to 1.0 ppm during summer months, with intermediate values during spring and fall at 0.5 

ppm (Sather, et. aI., 2008)..Accordingly, the NREL Report should recommend using revised CALPUFF 

6.4 model and actual ammonia concentrations in assessing potential visibility improvements from NOx 

emissions reductions at NGS. 

Finally, two tables (5.4 and 5.6) in the NREL report appear to be erroneous. Table 5.4 (page 75) 

lists two sets ofS02 and NOx emission numbers; unfortunately the two sets of numbers are identical. 

Clearly, one set of numbers is not valid. Table 5-6 (on page 84) lists two columns of ammonium nitrates 

concentrations during 2001-2005 and 2006-2010 for 9 Class I areas, and the last column shows "Percent 

Reduction." The numbers in the last column, presumably the difference between the other two, are not 

correct. NREL needs to review and correct the numbers in Table 5-6. 
l602) 2~2-9227 (p~)

~602) 252120 (1):) 

February 6, 2012 

U.S. Department of Interior 

NGS Report Comments@ios.doi.gov 

RE: Comments on NREL Report, Navajo Generating Station and Air Visibility Regulations: Alternatives 

and Impacts 

On behalf of the Arizona PIRG Education Fund, I am writing to comment on the National Renewable 

Energy Laboratory's recent analysis regarding Navajo Generating Station. 

Although, the NREL analysis addresses a broad spectrum of issues, our comments focus on just one of 

those issues - the impact of pollution controls on water costs in Central Arizona. In short, NREL's 

analysis misrepresents the impact of pollution controls on water customers in Central Arizona. 

NREL concludes that ItReplacing Navajo GS power required for CAP pumps with market power under 

high price conditions would dramatically increase water rates.ltl While the cost of raw water will 

increase by a substantial percentage, the impact on water rates for municipal households is minimal. 

Calculating the impact on municipal customers - not raw water costs - is a critical, but omitted, 

component of this analysis. For example, under the high power price scenario illustrated in Table 4-23, 

long term subcontract water rates are projected to increase by $64/AF. The City of Phoenix is one of the 

largest subcontractors for Central Arizona Project water; in Phoenix, the typical household uses 0.37 

AF/year (121,000 gallons/year).2 Phoenix's water supplies are comprised of a mix of CAP water (45%)3 

and water from other supplies (local surface water supplies, groundwater, and recycled water). Given 

these two factors, the typical Phoenix household uses 0.17 AF of water from CAP each year. Even under 

the high rate increases described above, the average Phoenix household would see water bills rise by 

$1O.66/yr, or $0.89/month. 

This rate impact is comparable to or less than rate increases the Phoenix water utility has imposed in 

recent years. For example, from 2009 to 2010, a typical household saw its annual water bill rise by over 

$17. Even with these rate increases, Phoenix households pay less for water than residents in many other 

cities in the region (Figure 1). 

In sum, the pollution controls may impose a cost on the price of raw water supplies that may indeed 

have a significant impact on agricultural users and Tribal users. However, the impact on municipal 

customers, who bear the brunt of the cost increases, is marginal. 

1 NREL, Navajo generating Station and Air Visibility Regulations: Alternatives and Impacts, p. 67.
 
 

2 Western Resource Advocates, 2010. Arizona Water Meter.
 
 

3 City of Phoenix Water Services Department, 2011, 2011 Water Resource Plan
 
 
Annual Residential Water Costs 

$500 

$400 

$300 

$200 

$100 

$­


Phoenix Phoenix Albuquerque Denver Las Vegas
 


(2009) (2010/2011) (2011) (2011) (2011)
 


Figure 1. Residential water costs in Phoenix in 2009 and 2010/2011 were lower costs in several other southwestern cities. 

(All costs reflect household use of 0.37 AF of water.) 

Second, the cost analysis is inconsistent with regard to the price of wholesale power. Wholesale power 

revenues are used to meet CAP's repayment obligations and are dedicated to the Development Fund. 

Accordingly, surplus power revenues (or the lack of) directly impact the prices paid by CAP water 

customers. In calculating the value of Navajo GS surplus power, NREL assumed power could be sold at 

$27/MWh.4 However, NREL assumes the cost of replacement power from an NGS shutdown would be 

$32.44 - $49.48/MWh (Table 4-19). The price of replacement power should be comparable to the prices 

paid (and revenues generated) by Navajo GS surplus power. 

In conclusion, the relationship between reliable, affordable drinking supplies in Central Arizona and the 

Navajo Generating Station is complex and critical to understand. In determining the appropriate 

pollution controls, we encourage EPA to consider the cost impact on ratepayers, not on raw water costs. 

The strictest pollution controls would lead to a small rise in municipal water rates. 

Sincerely, 

Diane E. Brown 

Executive Director 

4 NREL, Navajo Generating Station and Air Visibility Regulations: Alternatives and 1m pacts, p. 56. 
Comments to the NREL report, Navajo Generating Station ami Air Visibility Regulations: 

Alternatives and Impacts (the "Report") 

Central Arizona Water Conservation District ("CAP") 

23636 N. i h Street, Phoenix, Arizona 85024 

In the Report, NREL accurately declares that "the question fundamental to this proceeding" is 

"how reducing NOx from NGS would contribute to improved visibility at the Grand Canyon and 

other areas of concern." (Report, p. IV). The answer to this fundamental question is, at best, 

inconclusive. Consequently, there is no justification for installing SCR or other control 

technologies at a price tag of$500 million to $1.1 billion, as there is no known or expected effect 

on visibility that can reasonabl.y be anticipated to resul.t. The poll.ution control. system currentl.y 

in place at NGS, including LNB/SOFA, is BART. 

In determining what technologies constitute BART, the Clean Air Act ("CAA") requires EPA to 

consider five factors. While the fundamental factor of visibil ity trumps all others, the Report also 

addresses the costs of compliance, existing pollution control technology in use at the source, 

energy and non-air quality environmental impacts of compliance, and remaining useful life. 

NREL's analysis of these issues warrants comment as follows, including a more in-depth review 

of the visibility aspect. Note that CAP wiH also submit separate, more detailed comments to EPA 

and DOL 

1. Additional Control Technologies Yield Imperceptible Changes in Visibility. The 

CAA states that EPA "shall take into consideration... the degree of improvement in visibility 

which may reasonably be anticipated to result" from use of proposed BART technology. Id. 

NREL examined the modeling used by all parties to this proceeding, and concluded that whether 

any incremental contribution to haze by NGS "is significant or even perceptible is a matter of 

debate among experts in the field of visibility science." (Report, pp. 113, IV). 

According to the Report, NGS "is already using the best avail.able control for reduction of S02, 

the pollutant with the largest potential to impact visibility." (Report, p. 85). These sulfate 

particles are 3-5 times or more significant than nitrates in calculated visibility impacts in the 

Southwest. (Report, p. 90). With regard to NO;.;, upon completion of the installation of 

LNB/SOFA in 2011 at a cost of$45 million, NGS achieved a NO;.; emission rate of slightly more 

than 0.21 Ib/mmBtu, or nearly 25% less than the presumptive BART emission limit of 0.28 

lb/mmBtu established by EPA for facilities similar to NGS in design and type of coal used. 

Against this background, NREL could not conclude that additional retrofit would have any effect 

on visibility. Indeed, the Report states that "[t]he body of research to date is inconclusive as to 

whether removing approximately two-thirds of the current NO" emissions from NGS would lead 

to any perceptible improvement in visibility at the Grand Canyon and other areas of concern." 

(Report, pp. 113, IV). 

2. EPA's Visi bility Modeling Methodology is Flawed. NREL al so calls into question 

EPA's modeling, which suggests at least the possibility of perceptible haze, stating that 

"[m]easurements specific to this region indicate that actual visibility impacts may not be as great 

as those estimated by CALPUFF 5.8 as applied by EPA." (Report, p. 92). With respect to 

measures of background ammonia, which affect visibility outcomes, "EPA's ammonia 

background values correspond more closely with data collected in more urban or agriculturally 
developed areas near Farmington that are impacted by local ammonia sources." Id. On the other 

hand, SRP's ammonia background levels match more closely with similar rural and isolated 

sites, causing NREL to conclude that "use ofthe SRP ammonia background values in CALPUFF 

produces a much better comparison between model ed and measured values." (Report, p. 80). 

This is critical, because if ammonia values are too high, "the modeling process can significantly 

overestimate nitrate particle formation, thus overestimating visibility impact" of power plant 

plumes as they travel downwind ofa source. (Report, p. 92). 

3. Excessive Costs Do Not Support Additional Pollution Controls. The Report's "cost of 

compliance" analysis is incomplete and misleading. In light of the extremely high cost of retrofit 

and lack of resulting visibility benefits, the Report nonetheless fails to evaluate the recently 

added LNB/SOFA as BART. Failure to examine this alternative as BART results in a false 

choice between two stark alternatives-SCR retrofit or plant shutdown. 

Moreover, the Report's conclusions regarding the costs and likelihood of plant shutdown are 

based on a "best case" scenario that makes unrealistic assumptions and ignores critical 

considerations. While conceding that "key uncertainties could affect the basic economics," 

NREL disregards the likelihood of these uncertainties. (Report, p. iii). For example, the Report 

does not examine the critical relationship between the timing of the BART determination and the 

resolution of doubts pertaining to renewal of the plant site lease, rights-of-way, the cost of coal, 

and other factors-doubts that may not be resolved until 2019. Instead, the Report simply 

assumes the cost of SCR's would be amortized over 20 years, and a low cost of capital that is 

speculative at best. (Report, p. 59). With that, NREL concludes that installing SCR or SCR with 

baghouses and sorbent injection would "likely" be less expensive than shutdown of NGS. 

(Report, p. iii). In fact, it is entirely likely that mandated retrofit before the critical plant 

extension issues can be resolved would render shutdown as the least-cost option. 

4. Demand for CAP Water is not Inelastic - High Energy Costs Affect Demand. The 

Report does shed light on the substantial increases in the cost of CAP water should additional 

retrofit be required. However, NREL's assumption that demand for CAP water is inelastic is 

simply not realistic. CAP's tribal and agricultural customers will face price increases of 16-32% 

if EPA requires SCR or SCR with baghouses. This will prompt some users to return to the use of 

finite groundwater supplies, defeating one of the principal rationales for the existence of CAP 

and resulting in even higher costs for remaining CAP customers. 

5. Disproportionate Effect on Tribes and Agricultural Users. The Report accurately 

concludes that, should EPA select SCR or SCR/baghouses as BART, the economic impacts 

would fall disproportionately on tribes and agricultural users. Beyond the cost increases, non-air 

quality impacts to jobs and the economy ofNavajo and Hopi reservations would be significant. 

Ultimately, NREL's answer to the "fundamental question" is that the evidence fails to support 

that additional retrofitting of NGS will result in improved visibility. Without convincing 

evidence that any retrofit beyond LNB/SOFA will have a positive effect on visibility in the 

Grand Canyon and other Class 1 areas, the massive expenditures contemplated are not justified 

when taking into account the requirements of the CAA to consider costs and degree of 

reasonably anticipated visibility improvement. Finally, in addition to the comments specifically 

set forth above, CAP fully supports the comments submitted by the Salt River Project. 
February 6, 2012 

U.S. Department ofthe Interior 

NGS Report Comment@ios.doi.gov 

RE: Comments on the NREL Report, Navajo Generating Station and Air 

Visibility Regulations: Alternatives and Impacts 

The Environmental Defense Fund (EDF) submits its comments on the NREL report 

cited above. We are joined in these comments by the Forgotten People, the National 

Parks and Conservation Association, and Western Resource Advocates. 

EDF appreciates the extraordinary efforts taken by NREL to compile and present the 

multitude of issues surrounding the operation and financing of Navajo Generating 

Station and the associated Kayenta mine. Our comments focus on the assessment of 

visibility science and a concern about the lack of clarity regarding the financing of 

sulfur dioxide (S02) emissions controls in the early 1990's. 

Visibility Analysis 

On page 77, Table 5-2 compares the modeling procedures used by Salt River Project 

(SRP) and the Environmental Protection Agency (EPA). The background ammonia 

used in the most recent SRP assessment is taken from a regional model (CMAQ) 

rather than monitored data. That CMAQ model run was quality-assured for best 

results in the southeastern U.S., not for predictions in the southwest. As noted later 

on page 92, the largest difference in visibility impact modeling is due to the input 

value of background ammonia. Choosing modeled ammonia concentrations from 

efforts focused on predicting air quality in the southeastern U.S. rather than 

monitored ammonia data from across the desert southwest region is highly 

questionable. 

On page 73 and again on page 80 the report mentions a study by R. Henry that finds 

the consistent deciview (dv) threshold of perceptible change is higher than the 1.0 

threshold that EPA defines as generally perceptible. That study examined the 

threshold for color perception changes. Other studies suggest that observers may 

be more sensitive to achromatic changes.l The report also states that the SRP 

studies find no perceptible improvement from installation of SCR while the EPA 

study finds perceptible impairment. 

It is important to note that both the SRP and EPA modeling find significant 

contribution to visibility impairment from NGS as defined by the regional haze 

regulations. This is especially true when considering the cumulative impacts of NGS 

across eleven Class J areas. AJI visibility assessments done to date demonstrate that 

NGS' NOx emissions are a significant contributor to human-caused visibility 

1 Tombach I., R. Henry, L.W. Richards. 1998 A Critical Review of Knowledge About 

Human Perception and Visibility Change, 98-MALOl 
impairment at many Class I areas. EPA noted in the preamble to the final BART rule 

requiring SCR levels of control at the San Juan Generating Station that u . ..a 

perceptible visibility improvement is not a requirement of the BART determination 

as a visibility improvement that is not perceptible may still be determined 

significant" 2 

Table 5-8 compares the cost/benefit calculations for various facilities based on 

maximum dv impact in a Class I area for various sources in the region. It does not 

include a number of BART determinations by States and EPA where SCR was 

determined to be BART for NOx emissions. Examining final BART decisions 

requiring SCR at 11 power plants in the West, using the metric of annualized cost 

per 1 dv improvement ofthe 98th percentile at the most affected Class I area, finds a 

range from approximately $6.4 million per year per dv to $51.4 million per year per 

dv. The cost benefit metric for SCR at NGS at approximately $33 million per year 

per dv is within that range. In addition, most ofthe power plants do not 

significantly affect as many Class I areas as NGS. The large number of Class I areas 

that would see a significant contribution toward visibility improvement strengthens 

the cost benefit consideration for SCR at NGS. 

Financing ofBureau ofRecJamation's Share of Environmental Controls 

On page 22 the report indicates that the U.S. Bureau of Reclamation costs of S02 

scrubbers in 1992 was $102 million, close to the projected costs of installing SCR at 

$113 to $132 million. The estimates of water rate changes developed by NREL for 

SCR plus other controls assumed the Central Arizona Water Conservation District 

(CAWCD) would finance capital costs at 5% and recover capital and operating costs 

from CAP rates. It is unclear from the report whether that was the mechanism used 

to finance the S02 scrubbers. The report implies that the Bureau's costs for S02 

scrubbers at NGS are paid by the CAWCD to the Lower Colorado Basin Development 

Fund over a 50-year period. The report should have clearly presented the funding 

mechanism the Bureau of Reclamation used for the S02 scrubbers as well as 

historical CAP water rates during the period of payment for the S02 scrubbers. Such 

information would illuminate how water rates might be affected by the costs of 

additional environmental controls. 

We appreciate the opportunity to provide comments on the NREL study. We 

encourage the Department and the EPA to cooperate in addressing the 

environmental impacts of NGS as well as protecting economic and social val ues of 

the region. 

Bruce Polkowsky, contractor on behalf of 

Environmental Defense Fund 

Boulder CO 

276 FR 52427 
USDA United States Forest Washington 1400 Independence Avenue, SW 

??:Z5i Department of Service Office Washington, DC 20250 

A riculture 

File Code: 2580 

Date: FEB 0 3 2012 

Letty Belin 

Counselor to the Deputy Secretary 

Department of Interior 

NGS_Report_Comment@ios.doi.gov 

Dear Ms. Belin: 

The United States Forest Service is grateful for the opportunity to provide the following 

comments on the document entitled Navajo Generating Station and Air Visibility Regulations: 

Alternatives and Impacts generated by the Department of Energy's National Renewable Energy 

Laboratory (NREL). The report provides significant information regarding air pollution control 

options at the Navajo Generating Station (NOS), the economics of water and power delivery, and 

potential social/economic impacts of Native American interests. We are encouraged by the 

report findings that installing selective catalytic reduction controls would not significantly 

change the amount of energy provided by NGS, and that on-site power plant and mine 

employment would be unchanged. 

The USDA Forest Service plays a significant national role in the development and assessment of 

visibility science. As such, our review is focused primarily on this aspect of the study, 

Importantly, we are concerned that the third party visibility modeling results presented in this 

report have not met the burden of scientific testing and documentation needed to support the 

modeling conclusions. These undocumented methods may jeopardize the integrity of the Best 

Available Retrofit Technology (BART) modeling process and potentially undermine prior BART 

determinations (and thus emissions reductions) made in other states and EPA Regions. Our 

technical comments are attached . 

.....-t:::H~D5.-JIE A. C. WELDON 

ty Chief, National Forest System 

Enclosure 

""­

Caring for the Land and Serving People Prinled on Recycled Paper ~I
1 

01/3112012 

Attachment 

USDA Forest Service Technical Comments on Study:
 
 

"Navajo Generating Station and Air Visibility Regulations: Altematives and Impacts"
 
 

Visibility Science 

While the report provided a cursory summary of the myriad of issues affecting visibility science, 

much of the focus of the visibility science section is on CALPUFF modeling studies that were 

conducted by Salt River Project (SRP) and the Environmental Protection Agency (EPA) and two 

key underlying elements in that modeling (regardless of model version): assumptions of 

background ammonia values and horizontal grid resolution. 

The report concludes that the largest source of difference in the modeling conducted by EPA and 

SRP lies in the background ammonia values assumed without addressing additional differences 

in modeling techniques. Summaries of modeling conducted for SRP using a version of the 

CALPUFF system (v6.302) with updated chemistry for the Hayden Power Plant BART 

detennination in Colorado showed that the use of the ammonia limiting method (ALM) yielded 

approximately a 70% reduction in the maximum impact with 104 and 115 fewer days above the 

0.5 and 1.0 dv thresholds respectively. 1 Change in grid resolution alone accounted for 

approximately a 17% reduction in maximum impacts and 50 fewer days above either the 0.5 or 

1.0 dv thresholds at the Mt. Zirkel Wilderness Area. I Cbanging to the newer chemical 

mechanism within the CALPUFF model only accounted for approximately a 25% reduction in 

maximum impact and only 28 and 8 fewer days above the 0.5 and 1.0 dv thresholds 

respectively.' These summaries clearly indicate that the ALM technique and enhanced horizontal 

grid resolution as the primary drivers in reducing modeled impacts in the CALPUFF system 

(v6.4) and that the effect of the enhanced chemistry is secondary to these techniques. 

The report cited that in August 2011 EPA rejected the newer CALPUFF version for use in 

BART because it "...has not been adequately tested and subjected to public review and 

comment. ,,2 We believe it is important to for the reader to note that, while the v 6.4 may indeed 

refine CALPUFF's secondary aerosol estimates, the SRP analysis (noted above) for Hayden 

demonstrated that it was the ALM technique and the increased horizontal grid resolution that 

likely accounted for the greatest changes in modeled impacts noted between the 2011 SRP and 

2009 EPA modeling analyses. It is crucial to understand that it was insufficient technical 

justification provided by the CALPUFF model developer for either technique which ultimately 

led to the EPA rejection of the v6.4 analysis provided by Public Service Company of New 

Mexico (PNM) to EPA for its federal implementation plan (FIP) for the San Juan Generating 

Station (SJGS). EPA identified a number of issues with the appropriateness of the techniques 

and estimates using v6.4. Most of the modeling procedures employed by the 2011 SRP analysis 

are identical to the procedures of the PNM analysis for the SJGS FlP and 2010 SRP Hayden 

analysis. EPA noted the following in the SJGS FIP: 

•	 	 Commenters Jailed to establish the scientific basisJor use oja higher resolution 

meteorological grid (I -Ian) Jor modeling ojvisibility impacts using the CALPUFF modeling 
2 

system. Commenlers did not provide statistical analysis showing better performance ofthe 

higher resolution meteorological fields were provided, did not established the relationship 

between grid resolution and chemistry conversion equations, and did not adequately explain 

the relationship ofgrid resolution to better air quality model performance. 3 

•	 	 Lack ofdocumentation, adequate technicaljustification. and validation for the development 

and use ofthe ammonia limiting method (ALM). EPA and the FLMs have previously 

reviewed protocols proposing using ALM and the EPA and FLMs have not approved the use 

ofthe proposed AIMprocedure. 3,5 

o	 	 Each ofthe papers cited were presented as part ofgeneral proceedings at 

conferences, and therefore do not reflect the thoroughness ofa formal peer review 

process that would be associated with submission to mainline scientific journals and 

did not consider these references suitable for establishing the validity ofthe model or 

post-processing techniques or demonstrating that these models have undergone 

independent scientific peer review as necessary for reviewing models in accordance 

with federal regulations. 4 

o	 	 The evaluation techniques utilized by the developer are not appropriate for 

evaluation ofthe chemical mechanisms ofthe CALPUFF system. These techniques 

were deemed not satisfactory for purposes ofmodel performance evaluations for full 

science chemistry models and did not consider the analysis techniques presented by 

the model developer sufficient to demonstrate that the model is not biased in 

accordance with federal modeling regulations. 4 

While more accurate quality modeling methodologies should always be sought, federal air 

quality modeling regulations have been developed to ensure that the selection and application of 

air quality models are done so in a consistent manner. Consistency ensures that the public has a 

common basis for estimating pollutant concentrations and specifying emissions limitations. The 

federal modeling regulations provide a consistent basis for selecting the most accurate models 

and databases for air quality assessments such as BART.6 EPA published guidance on May 15, 

2009 which included a significant discussion on the use of i-km grid resolutions with the 

CALPUFF system. 7 In this guidance, EPA cited the lack of technical foundation for use of 

higher resolutions as the primary basis of its recommendation to maintain grid resolutions at no 

higher than 4-km. Likewise, EPA's dismissal ofv6.4 for the SJGS FIP was done so on this 

basis. Despite the publication of EPA guidance in 2009 describing the necessity of greater 

documentation prior to acceptance, the SRP and PNM analyses continued to proffer the same 

techniques without offering any concrete technical analysis to demonstrate that the techniques 

enhance meteorological and air quality model accuracy. Without this, the public cannot be 

assured that the proposed techniques do not bias model predictions towards underestimation as is 

required under federal modeling regulation. 8 Unfortunately, the report yields significant 

deference to the 2011 SRP analysis to draw conclusions that modeling conducted by EPA as part 

of its 2009 ANPR likely overestimates the benefit ofNOx controls on nitrate formation without a 

proper analysis of the 2011 EPA decision to disallow use ofv6.4. Therefore, we believe it to be 

imprudent of a government report to lend such strong credence to modeling results when such 

modeling has not met the burden of scientific testing and documentation necessary as mandated 

by federal regulation. 
3 

Further, while the report correctly explains that CALPUFF is used as a screening tool to provide 

a relative comparison on the visibility change that might result from various control options, it 

does not adequately explain that screening methods are, by their very nature, intended to provide 

preliminary, conservative estimates of air concentrations and that the modeling methodologies 

described in the BART guidelines were developed bearing in mind that CALPUFF concentration 

estimates would be conservative.9

,lo 

References 

1.	 	 SRP,2010: Preliminary Prehearing Statement of Salt River Project Agricultural 

Improvement and Power District Regarding Proposed Revisions to the Regional Haze State 

Implementation Plan and Regulation No.3, Part F Best Available Retrofit Teclmology 

Requirements 

2.	 	 NREL, 2011: Navajo Generating Station and Air Visibility Regulations: Altematives and 

Impacts, p. 77. 

3.	 	 EPA, 2011: Approval and Promulgation oflmplementation Plans; New Mexico; Federal 

Implementation Plan for Interstate Transport of Pollution Affecting Visibility and Best 

Available Retro~t Technology Detennination. See 76 FR 52436 

4.	 	 EPA, 2011: Approval and Promulgation of Implementation Plans; New Mexico; Federal 

Implementation Plan for Interstate Transport of Pollution Affecting Visibility and Best 

Available Retrofit Teclmology Detennination. See 76 FR 52432 

5.	 	 USFS,2011: CALPUFF Reviewer's Guide, p. 5-1,2 

6.	 	 Section 1.0(d) to 40 CFR Part 51, Appendix W 

7.	 	 EPA, 2009: Model Clearinghouse Review of CALPUFF Modeling Protocol for BART. 14 

pp. 

8.	 	 Section 3.2.2 to 40 CFR Part 51, Appendix W 

9.	 	 Section 4.2.1.1(a) to 40 CFR Part 51, Appendix W 

10. EPA 2005, Final Rule, Regional Haze Regulations and Guidelines for Best Available Retrofit 

Technology (BART) Detenninations. See 70 FR 39123 
COMMENTS OF THE GILA RIVER INDIAN COMMUNITY AND THE AK CHIN
 
 

INDIAN COMMUNITY ON THE NREL NGS REPORT
 
 

February 6,2012 

The National Renewable Energy Laboratory (NREL) conducted a study entitled "Navajo 

Generating Station and Air Visibility Regulations: Alternatives and Impacts" under an 

Interagency Agreement between the Department of the Interior (Interior) and Department of 

Energy (DOE). The Gila River Indian Community ("Community") and theAk Chin Indian 

Community ("Ak Chin") jointly submit these initial limited comments to the NREL Report. The 

Community and Ak Chin reserve the right to submit additional, more extensive comments in 

writing to the Department of the Interior and the Environmental Protection Agency as part of the 

on-going consultations with those agencies. 

I The impact of the proposed BART implementation scenarios on the Lower Colorado River 

Basin Development Fund (LCRBDF) as described in the NREL report are seriously understated. 

Because the impacts on the LCRBDF were estimated improperly, the important, negative effects on 

the GRIC and the other CAP contract entitlement tribes from reduced monies into the LCRBDF were 

missed. The problem lies in the understated NGS surplus power revenue projections which feed the 

LCRBDF. 

This shortcoming is explained by the incorrect assumption in the NREL report related to the 

relationship between the cost ofNGS power generation and the price ofNGS surplus power. NREL 

assumes the cost and price which existed at the time oftheir study would continue over the long 

term. In fact, costs ofNGS power have recently been high due in part to spiking coal prices (nearly 

double nationwide since 2000) , and a depressed market price for power due to economic conditions, 

among other factors. For example, the NREL impact estimates on the LCRBDF assume that the 

current NGS surplus power sales price will stay at current levels. 

The current market ranges between $19 per megawatt-hour (MWI-I) off-peak to $35MWH 

on-peak. This is compared with the market price five or so years ago when power was selling for $40 

- $45 for MWH power off-peak, $80 per MWH on-peak. The point is, by fixing in place the cost and 

price ofNGS surplus power, the negative effects ofthe BART scenarios on the LCRBDF are not 

apparent. However, projecting even a return to more normal market conditions, much less power 

price escalation over the long term, would reveal the diminished revenues to the LCRBDF from the 

proposed BART scenarios. 

Why is this important to the Community, Ak Chin and the other CAP Settling Tribes? A 

primary purpose of the LCRBDF is to pay the Tribes' portion of CAP fixed operations, maintenance 

and replacement costs for CAP water. lfthe LCRBDF cannot pay those obligations, then the CAP 

Settling Tribes would be obligated to do so, which would result in a tripling of CAP water costs at 

current rates. Such an increase would render CAP water use by the C to be infeasible, resulting in: 

• A breach of understanding that the GRIC would only be obligated to pay CAP energy costs. 

• A reduction or cessation of GRIC and perhaps other Indian agriculture. 
•	 	 A loss of investment in GRlC and other Indian irrigation facilities. 

•	 	 A lost opportunity for the GRIC using the CAP water for non-agricultural purposes. 

•	 	 A possible return ofthe CAP water to the CAWCD with unpaid costs, prompting a fiscal 

crisis for that organization and the rest of the CAP water users throughout Arizona. 

We believe these risks are real and that they are heightened by the proposed BART implementation 

impacts on the LCRBDF. 

2. In the NREL Report, on pages 2 to 3, NREL notes that the its study will include a 

supplemental volume examining alternative generating options to prepare for a smooth transition 

[Tom coal to cJean energy. 

As an initial comment, the Community and Ak Chin disagree with the notion that coal 

cannot be "clean energy". The very measures under consideration now in the current BART 

proceeding, and in simultaneous rulemaking proceedings, are supposedly intended to make coal 

a cleaner source of power. The underlying assumptjon that coal can never be clean enough is 

problematic and indicates a troubling pre-disposition on the part ofNREL as it approached this 

subject. 

Ifthe Administration position, however, is to transition away from coal-generated 

electrical power at NGS, we agree with NREL that it is important now to prepare for a smooth 

transition for the affected Tribes from coal to a different source of energy for both the CAP and 

for the subsidies on which those tribes with water settlements in Arizona rely. 

To that end, we strongly urge NREL to include in its supplemental study an examination 

of the need to develop solar or other renewable energy facilities, on Indian Reservation lands, 

with the net revenues of which solely dedicated to replacing the loss in subsidy supports to those 

tribes with water settlements in Arizona ("CAP Settling Tribes"). 

While solar facilities developed on any Indian Reservation arguably could have the 

revenues of the facility dedicated to such a purpose, it would make most sense to site such a 

faci Iity on the lands of an affected CAP Settling Tribe. Such a solar facility would need to be 

subsidized to a certain degree, in order to produce a revenue stream that would suffice to offset 

the lost subsidies on which CAP Settling Tribes rely. The extent of such a subsidy would be 

directly rel ated to the amount of lost subsidies. 

Finally, we note that given the substantial underestimation of the effect of the BART on 

the sale of surpl us NGS power, and the failure to take account of other concurrent regulatory 

rulemakings, it is possible that the issue of transition to solar based subsidies may already be one 

that needs to be addressed, and not something that can wait for the future supplemental report. 
Le Roy N. Shingoitewa THE Chairman 

~OP' TRIBE Herman Honanie 

Vice-Chairman 

February 6, 2012 

Navajo Generating Station Study Commission 

U.S. Department of the Interior, 

1849 C StreetNW 

Washington, DC 20240 

Dear Commissioners: 

In response to the Phase One Navajo Generating Station Study ("NREL NGS Report") comment 

period, the Hopi Tribe submits the following: 

o	 	 In December 2011 comment period; the Hopi Tribe requested that the NREL NGS 

Report distinguish the tribal membership of the employees at the Kayenta Mine. We note 

that Peabody Energy and the Salt River Project state they do not collect specific 

membership however the NREL NGS Study statement generalizes that both the Navajo 

and Hopi Tribes constitute a significant portion of the on-site labor force at the plant and 

at the mine. We point to the NREL NGS Report Page 95 that eighty-three (83) of the 

management or a professional role at the Power Plant are Navajo-preference positions 

and does not make the distinction out of how many management positions. 

o	 	 NREL NGS Map 6-1 does not reflect the Hopi Tribe's Moenkopi District Reservation 

which consists of over 60,000 acres of Hopi Land, nor does the Map accurately reflect 

the partitioned lands as well as the Hopi Tribe's ranch lands. 

o	 	 The Hopi Tribe submits for the record Vice Chairman Herman G. Honanie's testimony 

given at the Arizona Inter-Tribal Council Department of the Interior Navajo Generating 

Station Meeting on August 31, 2011. 

o	 	 Correction: The Navajo Generating Station accounts for 65% of the Hopi Tribe's 

revenues. 

On July 21, 2011, the Hopi Tribal Council enacted Resolution H-066-20ll requires the Tribe's 

stance as neutral in response to developments regarding the Environmental Protection Agency's 

(EPA) proposed actions against the Navajo Generating Station. This Council action is a result of 

P.O. BOX 123 ----- KYKOTSMOVI, AZ ---- 86039 ----- (928) 734-3000 
the Little Colorado River Adjudication settlement and how it would be tied into the operability 

ofNGS resulting in significant costs and increased rates to NGS power users. 

The NGS issue is a difficult one for the Hopi Tribe. We are acutely aware ofthe decisions made 

by our Trustee, the Department of Interior, and how those federal policy decisions impact the 

Hopi Tribe. The Hopi Tribe has always been concerned about the effects ofNGS on the pristine 

quality of our air and water used by Peabody in supplying coal to NGS. We also understand that 

coal revenues are important to the Tribe and benefit the Hopi people. 

Thank: you for providing the Hopi Tribe an opportunity to submit further comments and if you 

have any questions, please feel free to direct them to me. 

Re~p~

/)<' "'7 7

LeRoy N. Shingoitewa 

Chairman 

The Hopi Tribe 

Attachments 

P.O. BOX 123····· KYKOTSMOVI, AZ .... 86039 .••.. (928) 734·3000 
Navajo Nation Comments on National Renewable Energy Laboratory Energy Analysis for 

Navajo Generating Station and Air Visibility Regulations: Alternatives and Impacts 

Given the limited amount of time the NREL had to develop this study, the report satisfies the 

study objectives of describing alternatives and impacts of air visibi lity regulations on the Navajo 

Generating Station ("NGS"). The report captured some important aspects of Navajo Nation 

("Nation") concerns and perspectives regarding impacts to the Nation. However, the report 

disregarded a number ofimportant primary references that are considered by the Nation as 

significant in understanding the larger context ofNGS and the impacts of air regulations, 

particularly the non-air quality impacts. The Nation submits the following comments. 

Trust Responsibility 

Understandably, the time limitations and scope ofthe study precluded an examination ofa 

number of issues and topics that the Nation advocated for inclusion to convey a more realistic 

portrayal of the importance of federal responsibilities to tribes in the context of federal 

rulemaking. USEPA, like all federal agencies, bears a trust responsibility to Indian tribes that 

derives from treaties and federal common law. The trust responsibility includes the obligation to 

consult with tribes when agency action is likely to affect them. The duty to consult is 

memorialized in Executive Order 13175 and USEPA's own Policy on Consultation and 

Coordination with Indian Tribes. Tribal consultations are necessary to evaluate any substantial, 

direct etlects that agency decisions will have on tribes. In the BART determinatjon for NGS, 

USEPA will make a regulatory decision concerning a coal-fired power plant located on the 

Nation pursuant to a lease approved by the Navajo government. The Kayenta Mine, located on 

Navajo Land, which produces the coal fuel for NGS, also faces impacts from the BART 

determination. While a BART decision for NGS has the potential to have far-reaching 

implications for many Indian tribes, no tribe will be affected more significantly than the Navajo 

Nation. 

Permit Limit Unchanged 

The Nation had recommended a change to the Pre-LNB/SOFA permit limit that appeared in the 

table for NOx Permit Limits and Technological Performance in the draft NREL study. However, 

the Nation notes that the Pre-LNB/SOFA permit limit is unchanged in Table 3-2. The Nation 

recommended a correction to reflect the change 0[0.36 Ib/MMBtu to OAO JbIMMBtu, and a 

change in the percent reduction from 33% to 40% reduction. This also remained unchanged. 

Models, Future Studies and Other Evidence-Based Reports 

Throughout the NREL study, numerous qualifying statements allude to improvements in 

instruments, such as studies, models and other evidence-based reports that could provide better 

interpretation, analysis, and understanding ofthe wide-range of issues implicated by the BART 

rulemaking for NGS. The potential to increase the understanding of stakeholders, including 

USEPA, regarding the issues surrounding NGS and the impacts of air visibility regulations can 

be addressed partly through objective analysis of improved model ing results that USEPA refuses 

to accept and new studies and reports that currently do not exist. 

1 
The Nation continues to support future dedicated efforts, particularly support by the respective 

federal agencies, that will result in studies or reports that can be used to chart courses to achieve 

the best reductions in emissions, and simultaneously continue to meet the economic and 

environmental needs of the Nation. 

Groundwater Issues 

The study discusses concerns raised by NGOs about alleged injury to groundwater attributable to 

the Kayenta Mine. The Nation has participated in numerous assessments of the impacts of the 

mine's groundwater use. These include the on-going USGS Black Mesa Monitoring Program 

(http://az.water.usgs.gov/projects/967 L-9E9/), development of groundwater models by the USGS 

and others, and participation in preparation of Cumulative Hydrologic Impact Assessments by 

OSMRE. Based on these assessments, the Nation has concluded that the mine's pumping has 

not affected water quality, and drawdown effects are localized and temporary. Pumping from the 

N-Aquifer does not impact springs issuing from overlying aquifers; the data on impacts on NAquifer springs are inconclusive. 

Visibility Science 

The section of the study pertaining to visibiLity science effectively related that there have been 

significant reductions in regional S02 and NOx emissions. The reductions have occurred in large 

part due to federal rules established to improve visibility in Class I areas, including the 

install.ation of emissions controls at NGS, and the Nation assuming its role as environmental 

regulator for purposes of the Clean Air Act ("CAA"). Most notably, NGS voluntary installed 

LNB/SOFA during the period from 2009 to 2011, meeting the presumptive BART limits for 

NOx, which Iikely contributed to the overall decl ine in emissions of S02 and NOx. 

The Nation concurs in the findings in this section and finds the information encouraging with 

respect to the potential for future collaboration among agencies to design studies that will serve 

in the eval uation of visibility improvement and use of appropriate control technology that will 

meet the national visibility goal while protecting tribal resources. The fact that there are different 

and somewhat conflicting positions on whether installation ofSCR will result in perceptible 

visibility improvement underscore the need to strengthen, and collaborate on, the best 

methodology(ies) to use in evaluating the degree of improvement in visi bility on a case-by-case 

basis. 

Finally, the Nation does not concede that SCR is BART for NGS. The Nation continues to 

support a detennination that LNB/SOFA is BART for NGS.LNB/SOFA presents the best 

scenario for meeting BART, with reasonable costs of compliance that wiH mitigate the economic 

impact to the Nation. The Nation has previously stated, in its comments to the Advance Notice of 

Proposed Rulemaking, that it supports a phased approach to emission controls consistent with the 

glide path to pristine conditions. Installation of LNB/SOFA as a first step is consistent with the 

CAA and the Regional Haze Rule, and satisfies the BART requirement for the current planning 

period. 

2 
From: doug.kupel@phoenix.gov [mailto:doug.kupel@phoenix.gov] 

Sent: Monday, February 06, 2012 12:44 PM 

To: NGS_Report_Comment 

Subject: City of Phoenix Comments on Navajo Generating Station NREL Study 

City of Phoenix Comments on "Navajo Generating Station and Air Visibility Regulations: Alternatives and 

Impacts" 

The City of Phoenix (City) has a large interest in projected impacts from the Navajo Generating Station 

(NGS) being required to adopt Selective Catalytic Reduction (SCR) or SCR plus baghouse and sorbent 

injection (SCR plus BH&SI) as Best Available Retrofit Technology (BART) to control NOx emissions. The 

additional possibility of plant closure, now raised as an alternative in the NREL report, and the resulting 

projected increase in CAP water rates for municipal and industrial users estimated from $33.00 to $64.00 

per acre foot, could have serious implications on water rates in the City and for the City's water 

customers. 

The population in the City's water service area is an estimated 1.455 million persons based on the 2010 

US Census. The Phoenix service area represents about 39 percent of Maricopa County's population and 

23 percent of the total population of Arizona. The incorporated area of Phoenix covers 546 square miles. 

In addition to the Phoenix service area, the City also serves portions of the Town of Paradise Valley and 

provides treatment services to adjacent providers on a limited basis. In a normal supply year, the City 

meets more than 90 percent of its water demands from surface sources. These include water from the 

Salt and Verde Rivers delivered through the Salt River Project and water from the Colorado River 

delivered by the Central Arizona Project. For the years from 2007 thru 2010 forty-four percent (44%) of 

the City's surface water supplies were delivered through the CAP. 

Costs for CAP water form a large percentage - from 75 to 80 percent - of the City's overall cost for water. 

The City and its water customers have strong concerns regarding financial and water supply impacts that 

may stem from the three proposed actions discussed in the NREL report. 

In October of 2011, the City provided information requested by NREL during the study. We appreciate 

the opportunity to provide these comments on the final report. 

1. Large increases in costs to install. operate. and maintain additional controls for the NGS will 

reduce the affordability of water and energy in central Arizona. These increased costs could have a 

negative impact on the local and regional economy. 

2. High energy prices and resulting higher rates for CAP water could reduce the ability of water users 

in Arizona to purchase CAP water. As one example, these increased CAP water costs might negatively 

impact the ability of the Arizona Water Banking Authority (AWBA) to store water in anticipation of future 

droughts and shortages. With the addition of increased CAP water costs due to emissions controls at 

NGS, the ability of the AWBA to store water for emergencies could be hampered. If the AWBA is unable 

to meet the City's need for water banking the City would likely have to expend additional resources to 

acquire and develop other water supplies for drought protection. 

3. The City anticipates that it will continue to use CAP water even if the price of that water increases. 

A major reason that the City must have CAP water is to demonstrate that it has a 100 year Assured 

Water Supply (AWS) or it will be out of compliance with state law. As a matter of state law, water 

providers in Arizona must demonstrate a 100 year AWS that must be based primarily on renewable 

supplies such as surface water. The main goal of this legislation is to reduce reliance on non-renewable 

supplies such as groundwater in order to achieve "safe yield" as required by the 1980 Arizona 

Groundwater Management Act. While the rationale for concluding that CAP demand is inelastic appears 

to have been based on the fact that municipal water providers do not have alternate supplies to replace 
CAP water should prices rise, this does not imply that the price increase is free from impacts. 

4. Because the report assumes that CAP water use will be unaffected by price increases, the report 

does not recognize the potential impact of significant increases in the cost of CAP water on both existing 

and future Indian water rights settlements. Existing settlements may be challenged by increasing CAP 

costs. As part of these settlements, Phoenix leases or plans to lease CAP water from several Tribes, 

including the Fort McDowell Indian Community, the Salt River Pima-Maricopa Indian Community, the Gila 

River Indian Community, and the White Mountain Apache Tribe. These settlements and leases are the 

foundation for the successful resolution of long-standing water rights issues in central Arizona. 

5. Affordable water is a fundamental resource that affects the health and well-being of Arizonans. 

Substantial increases in electrical generation costs at the NGS more than likely will be passed on to 

Phoenix residents and businesses through increased water rates. This creates a hardship for those 

ratepayers. Phoenix must protect its ratepayers by keeping rates as low as possible while maintaining a 

strong and reliable system. Increased energy costs attributable to emission controls for visibility 

improvements may compromise this delicate balance. 

Douglas E. Kupel, Ph.D. 

For Jerome E. Miller 

Deputy City Manager 

City of Phoenix Law Department 

200 W. Washington, Suite 1300 

Phoenix, A 85003-1611 

doug.kupel@phoenix.gov 

(602) 495-5853 
Paul R. Orme, P.c. 

2850 E. Camelback Rd. 

Phoenix, Arizona 85016 

Ladies & Gentlemen: 

This communication provides the comments of the Central Arizona Irrigation and Drainage 

District (CAIDD), Maricopa-Stanfield Irrigation & Drainage District (MSIDD) and New Magma 

Irrigation and Drainage District (NMIDD) (the "Districts") on the above referenced NREL NGS 

Study. I serve as General Counsel to the Districts, which combined, serve Central Arizona Project 

("CAP") water to over 200,000 acres in Pinal County, Arizona. 

In 2011, the Districts delivered nearly 500,000 acre feet of CAP water, both for direct and in 

lieu storage uses, to their growers and landowners. These deliveries constitute roughly 70% of total 

CAP agricultural water deliveries in 2011. In addition, MSIDD and CAIDD also pumped 

substantial amounts of groundwater for delivery to their growers from wells either owned or leased 

by these Districts. The farming in these Districts, as well as neighboring districts and Reservations, 

constitute an important part of the local and regional economy for Central Arizona. 

The foregoing background is important because the NREL NGS Study significantly 

underestimates the amount of CAP water currently being utilized by non-Indian agricultural users. 

In addition, it severely underestimates the price impact on those non-Indian agricultural users 

should either the Sel.ective Catalytic Reduction ("SCR") scenario, the SCR plus Baghouse & 

Sorbent Injection ("BH & SI") scenario, or the NGS Shut Down scenario, be the final BART as 

determin ed by EPA. 

The primary focus of these comments is on Chapter 4, "Central Arizona Project and Navajo 

Generating Station". Nevertheless, it is extremely important to focus on the legal standard EPA 

must follow in making its BART decision: 

" ...take into consideration the costs of compliance, the energy and non air
 
 

quality environmental impact of compliance, any existing pollution control
 
 

technology in use at the source, the remaining useful life of the source, and
 
 

the degree of improvement in visibility which may reasonably be anticipated
 
 

to result from the use of such technology." (Emphasis Added)
 
 

The NGS Shut down scenario clearly does not meet the BART legal standard when 

considering the impact on the Tribes as set forth in Chapter 6, and the unclear and highly disputable 

beneficial impact on air visibility as outlined in Chapter 5,. A more comprehensive analysis by 

NREL on the economic impacts of all but the "Base" scenario on Indian and non-Indian CAP 

agricultural water users alike would have revealed a similar result. 

Figure 4-2 on page 58 of the NREL NGS Study indicates that non-Indian Agriculture 

received deliveries of only 400,000 acre feet in 2010. This chart does not take into account the 

considerable amount of water under contract to "M&I Subcontractors", "M&l Excess" contractors, 

and "Federal Subcontract-Off Reservation" users that actually were delivered to non-reservation 

agricultural lands for in-lieu storage purposes. When these amounts are taken into consideration, 

the non-Indian agriculture sector uses over 50% of total CAP water deliveries annually. This serves 

two important federal and state water policy goals. It allows Arizona to utilize its full CAP annual 

entitlement which was one of the primary purposes of the creation of the Arizona Water Banking 

Authority and in-lieu storage programs. It also serves to significantly reduce groundwater pumping 

in Central Arizona, a key condition of the original CAP Enabling Legislation in 1968. These 
critical water management goals would be placed in jeopardy should CAP agricultural water cost be 

increased by the EPA BART decision as outlined in Chapter 4. 

Evidence of the foregoing was presented to NREL representatives on September 21,2011 

by members of the agricultural CAP water user community at the offices ofMSIDD. Attending that 

meeting was a representative from Farm Credit Services, the primary agricultural crop financing 

entity in Central Arizona. He presented to NREL annual crop budgets that clearly show current 

water costs as the highest input cost for farmers in Districts receiving CAP water. The Farm Credit 

study provided to NREL concluded the following: 

"From a competitive standpoint, the Pinal County water districts have some
 
 

of the highest water costs in areas financed by Farm Credit Services
 
 

Southwest. Ifwater costs were increased by $16.30 (per acre foot), it would
 
 

raise the per acre cost by $44 ... leaving a negative margin which is not
 
 

flnanceable." (Emphasis Added)
 
 

Nowhere does this discussion or documentation appear in the NREL Study. Instead, on 

page 60, the following conclusion is stated: 

"Although high prices for CAP water may prompt some water users to seek
 
 

other available water sources, there is no easy way to quantifY such a
 
 

curtailment in CAP water demand. Therefore, the analysis in this section
 
 

assumes that CAP water demand will remain fixed regardless of price."
 
 

The underscored portion of this conclusion is clearly erroneous and cannot be supported by 

the clearly understandable data presented to NREL. If crop financing is not available due to much 

higher water costs, CAP water use will be substantially reduced, agricultural lands will go out of 

production, and the local economies will suffer. It's troubling that NREL made no effort to include 

these analyses let alone evaluate their merit. In section 6.2, reference is made to reduced farm profit 

margins for the Gila River Indian Community as a result of selection of certain BART scenarios by 

EPA, but no such comment is made regarding non-Indian agriculture when similar data provided by 

MSIDD, an adjacent neighbor to GRIC. Recent history for these Districts illustrates that when CAP 

water costs substantially increase, CAP water use dramatically decreases, groundwater use increases 

to a degree, and lands go out ofproduction. This exact scenario resulted in two ofthe Districts 

seeking municipal bankruptcy protection in the 1990's. These results are much more severe than 

"reduced margins". Again, it must be emphasized that the only "other available water sources" for 

most ofthe Districts is pumped groundwater, which, as mentioned previously, runs at cross 

purposes with the CAP enabl jng legislation. 

The critical impact of the BART decision on the 2004 Arizona Water Settlement Act, is 

referenced only in passing. One such impact is the lost promise of "affordable" CAP water for 

Indian and non-Indian agriculture water users (until 2030) which was a key to achieving the final 

settlement. Should EPA undo this important benefit agreed to in contract by the Department of 

Interior, and blessed by Congress, much of the settlement could unravel and the resulting chaos in 

the Arizona Water Community can not be overstated. 

In conclusion, although NREL accurately predicts resulting cost increases to CAP water 

users (including agricultural water users - as clarified above) under the various BART scenarios, it 

fails to draw some obvious conclusions which are clearly relevant in applying the legal standard of 

"cost of compliance" which EPA must follow in making its BART decision. Hopefully EPA will 

not ignore these clear conclusions as well. 
Water Resources 

PHONE 480-312-5685 

9388 E. San Salvador FAX 480-312-5615 

Scottsdale, AZ 85258 WEB www.ScottsdaleAZ.gov 

6 February 2012 

VIA EMAIL: NGSReportComment@ios.doi.gov 

Department ofthe Interior 

Washington DC 

RE:	 	 Report regarding "Navajo Generating Station and Air Visibility Regulations: Alternatives 

and Impacts" prepared by the National Renewable Energy Laboratory ("NREL") 

The City of Scottsdale, Arizona Water Resources Division provides drinking water and sewer 

service to more than 87,000 customers within Scottsdale, which is located in the metropol itan 

Phoenix area of central Arizona. We are the third largest subcontractor for Central Arizona 

Project (CAP) municipal water in the state, and we expect to rely upon CAP water for over twothirds of our projected demand for potable water. 

The CAP relies exclusively on the NGS to supply the energy needed to deliver water to its customers, including Scottsdale. Therefore, we have a great deal at stake in the outcome of the 

BART rulemaking currently underway at EPA. The NREL study is a key input into EPA's development of that rule. We read it with great interest, and appreciate the opportunity to comment 

on the report and its findings. Our comments wiH focus primarily on those aspects of the report 

that relate to the direct cost impacts on the City of Scottsdale as a CAP water customer. 

Scottsdale is supportive of protecting our environment. However, it appears some of the emission control alternatives go beyond providing reasonable and rational environmental protection 

to the point of requiring significant financial commitments with no guarantee of achieving perceptible visibility improvements as a justifiable return on those investments. 

The use of CAP water is a critical component of Scottsdale's long-term water supply sustainability strategy. Key components of this strategy are maximizing use of renewable water supplies 

while minimizing groundwater pumping, reusing reclaimed wastewater for non-potable purposes 

such as golf course irrigation, and recharging our groundwater aquifer in order to balance any 

necessary groundwater pumping. Any increase in the cost orCAP water (the City's primary renewable water supply) would negatively affect the City'S ability to continue to provide an assured and sustainable water supply for its customers. The various cost alternatives evaluated in 

the report could result in increases in the City's raw water costs of up to 52%. This increased water cost would directly result in a significant rate increase to the City's water customers. 
The report concludes that the only alternative proposed that would significantly increase the cost 

of power to CAP's municipal water customers is the complete shutdown of the NGS. It infers 

that this shutdown is unlikely. This conclusion ignores the critical relationship between the timing of the BART determination and the resolution of numerous uncertainties surrounding continued operation of the NGS and the Kayenta mine beyond 2019. These uncertainties, combined 

with the potential increase in costs associated with installing emission controls, could very well 

result in a decision by the plant's owners to shut down the plant in a time frame that would leave 

very little opportunity for CAP to develop alternative and affordable power sources to the NGS. 

Another issue of direct concern to the City is the cost burden that installation of unreasonable 

emissions controls on the NGS would impose upon the Tribal users of CAP water, particularly 

the potential availability of power revenues from the Lower Basin Development Fund. These 

funds were a key component of the Arizona Water Settlement Act, and we are concerned that 

settlements may be challenged on the grounds of a breach of federal trust responsibility to the 

Tribes and that future settlements could be derailed by increasing CAP water costs.. 

The City is a party to water rights settlements with several Tribal CAP customers. These settlements have helped provided the City with water supply certainty by settling of significant tribal 

water rights claims. Scottsdale has also entered into leases with these communitieS, which are a 

major component of the City'S water supply. The reopening and renegotiating of any of these 

settlements would increase the uncertainty related to our water supply future. This is of great 

concern to the City of Scottsdale as it works to provide a secure sustainable water supply for its 

citizens. 

Again, we appreciate the opportunity to review and comment on the NREL report. We urge the 

EPA to fully consider the critical role that the NGS plays in providing a sustainable water supply 

future for Arizona as it evaluates this report and proceeds with the BART rulemaking. We look 

forward to further participation in the rulemaking process. 

Elizabeth Mill 

Water R sourdks Advisor 

City of S ottJlale Water Resources Division 

9379 E. San Salvador Dr 

Scottsdale, AZ 85258 
Comments on National Renewable Energy Laboratory Technical Report 

Navajo Generating Station and Air Visibility Regulations: Alternatives and Impacts 

Prepared by: Salt River Project Agricultural Improvement and Power District
 
 

Address: P.O. Box 52025 PAB352, Phoenix, Arizona 85072-2025
 
 

Salt River Project AgricuJturalimprovement and Power District (SRP) appreciates the 

opportunity to provide comments on the technical report prepared by the National Renewable 

Energy Laboratory (NREL) on the Navajo Generatjng Station (NGS) ("NREL Report"). SRP is 

a pol itical subdivision of the State of Arizona that provides retail electric services to more than 

930,000 residential, commercial, industrial, agricultural and mining customers in Arizona. SRP 

is an owner ofNGS and is the operating agent for the plant. 

SRP's comments on the NREL Report are outlined below. Since NREL restricted comments on 

the report to two pages, this document was prepared to comply with that limitation. SRP wi U 

submit more detailed comments on the report in a separate document. 

1.	 	 NREL's assessment ofvisibility science clearly supports SRP's position that Selective 

Catalytic Reduction (SCR) is not Best Available Retrofit Technology (BART) for NGS. 

In its assessment of visibility science in Chapter 5 of the report, NREL reaches conclusions that 

are missing fTom the Executive Summary and Conclusions sections of the report, and are 

critically important in the pending BART determination for NGS: 

•	 	 Page 76: "[Sulfur dioxide] S02 has been the initial focus [ofpower plant emission 

control requirements] because sulfate has a larger impact on regional haze compared to 

ni trate." 

•	 	 Page 92: "Measurements specific to this region indicate that actual visibility impacts 

[from nitrogen oxide emissions] may not be as great as those estimated by CALPUFF 

v5.8 as applied by EPA." 

•	 	 Page 90: "Installation of (Selective Catalytic Reduction] SCR technology on Navajo GS 

would result in a calculated cost/benefit ratio [in dollars per deciview] larger than those 

calculated for [Best Available Retrofit Technology] BART controls proposed for other 

units in the region.... even ifEPA determines that these other facilities should install 

SCR, the cost/benefit values for Navajo GS based on EPA modeling/analysis for Navajo 

would be higher. .. " 

NREL's assessment of visibility science clearly supports SRP's position that SCR is not BART 

for NGS. NREL's conclusions in this chapter are further supported by the data provided in 

SRP's updated BART report submitted to the United States Environmental Protection Agency 

(EPA) on January 20, 2011. 

2.	 	 NREL's economic analysis is flawed because it ignores critical considerations involved in 

a decision to keep NGS online. 

NREL's statement that the cost of SCR and baghouses is less than the cost of shutting down 

SRP's Comments on NREL NGS Report	 	 Page 1 
NOS and replacing it with purchased power ignores the following considerations: 

•	 	 Site Lease and Coal Supply Costs. NREL's analysis is conducted based on the current 

cost of operating NOS. In reality, the future cost of coal and the plant site lease will be 

meaningfully higher due to the renegotiation of the existing agreements, assuming that 

those agreements can be successfully extended. 

•	 	 Cost Recovery Timeline. 	The report assumes that the capital costs associated with SCR 

would be recovered over 20 years. However, from an investment risk perspective, each 

owner must also take into consideration the possibility that those costs may need to be 

recovered by 2019 in the event that the equipment is installed and the plant is still 

shutdown due to other factors. 

•	 	 Assumptions about Resource Alternatives. 	The report assumes that NOS capacity could 

be easily replaced with market purchases since there is excess capacity in the region. 

While this may be the case from a near-term regional perspective, the assumption is 

inconsistent with a utility'S obligation to serve its customers, which requires dependable 

capacity and cost control. These requirements are not met with an assumption of marketbased energy purchases. Moreover, to the extent load continues to grow, any excess 

regional capacity will diminish and the capacity will need to be replaced. 

•	 	 Uncertainties Concerning Future Ownership. 	The continued participation of each of 

the owners, especially LADWP, is uncertain for the reasons discussed by NREL on 

Page 10 of the report. 

NREL should have clearly recognized that if the EPA requires costly additional emISSIOn 

controls such as SCR as BART, the NOS owners would be forced to decide whether to make 

large capital investments without any certainty that the plant could continue to operate beyond 

2019 and without certainty regarding the future costs of operating NOS due to the potentially 

higher lease and coal costs. These factors could put the plant at a significant risk of closure. 

NREL's economic conclusions are flawed because they fail to account for these considerations. 

3.	 	 While the report does not recommend or endorse a specific control technology as BART, it 

clearly supports SRP's position tltat Low-NOx Burners and Separated Overfire Air 

(LNB/SOFA) is BARTfor NGS. 

The NREL Report was commissioned to provide factual and objective information to the United 

States Environmental Protection Agency (EPA) for consideration in the development of a BART 

proposal for NOS. The requirement to assess and install BART comes from EPA's Regional 

Haze Rule (RHR). The RHR requires BART to be determined based on a case-by-case 

evaluation of each control option, considering factors such as the cost of each technology and the 

degree of visibility improvement that can be achieved by each technology. 

NREL concludes that it is not clear that installing SCR would result in a perceptible visibility 

improvement at nearby national parks and wi ldemess areas (Class I areas). NREL also 

acknowledges the significantly higher capital cost of SCR relative to LNB/SOFA. This 

significantly higher SCR cost, coupled with NREL's uncertainty regarding whether SCR can 

achieve a perceptible improvement in Class I areas, supports SRP's posHion that LNB/SOFA - a 

technology voluntarily installed by the NOS owners between 2009 and 2011 - is BART for NOS. 

SRP's Comments on NREL NGS Report	 	 Page 2 
WESTERN RESOURCE 

ADVOCATES 

February 6, 2012 

U.S. Department of the Interior
 
 

NGS_Report_Comment@ios.doi.gov
 
 

RE:	 	 Comments on NREL Report, Navajo Generating Station and Air Visibility Regulations: 
 

Alternatives and Impacts 
 

Western Resource Advocates hereby submits its comments on the NREL report cited above. 
 

We are joined in these comments by the Grand Canyon Trust, the Sierra Club, the 
 

Environmental Defense Fund, and Forgotten People. 
 

We recognize the vast amount of review and analysis undertaken in the preparation of the 

report and commend NREL for accomplishing a wide range of assessments within a very limited 

time period. In these comments we address the report's conclusions: a) that the cost of SCR is 

likely less than the cost of shutting down the Navajo Generating Station (NGS) and replacing the 

foregone power and energy with purchases from the market, and b) that early retirement of 

NGS must necessarily be inimical to the Navajo Nation and Hopi Tribe. 

The all-or-nothing options studied for NGS are inappropriately narrow and stuck in time; 

what's also needed is a forward-looking analysis that considers a full range of scenarios for a 

gradual transition from coal to cleaner resources. In particular, the report evaluates only two 

sets of options - a) continued operation of NGS with a set of possible environmental controls to 

reduce some emissions, and b) complete shutdown of NGS and replacement of the energy and 

capacity with wholesale market purchases. 

Given the complexity of the situation and the need to invent more creative solutions, additional 

options must be addressed as is being done regarding the Four Corners power plant. One such 

option is an early shutdown of one or two NGS units and replacement of some of the foregone 

energy and capacity with renewable resources. This might occur, for example, if some owners 

of NGS turn to other resources while the Bureau of Reclamation continues to receive power 

from one of the NGS units. Investment in renewable resources could benefit the Navajo Nation 

and Hopi Tribe by providing income and jobs and while reducing air pollution. 

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www.westernresourceadvocates.org 
The study fails to explicitly account for important aspects of energy industry economics, such 

as uncertain coal prices, uncertainty over what happens to LADWP's share of NGS, and 

safeguards against the costs of complying with possible future carbon dioxide regulations. At 

16 million metric tons in 2010] NGS is the largest emitter of carbon dioxide in Arizona and one 

of the largest in the nation (http://ghgdata.epa.gov/ghgp/main.do).This situation imposes a 

significant risk on the plant owners by exposing them to the potential cost of complying with 

future regulation of greenhouse gases. 

The NREL report does not address the health impacts of operating NGS or the health benefits 

of reducing emissions from the power plant. The Clean Air Task Force 

(http://www.catf.us/coal/problems/power plants/existing!) presents estimates of the health 

impacts of fine particulate matter associated with NGS emissions in 2010. These include the 

following annual impacts at a combined cost of $128 million a year: 16 premature deaths] 25 

heart attacks, 300 asthma attacks] 12 hospital admissions] 11 chronic bronchitis cases, and 15 

asthma emergency room visits. Over a 1S-year period, these are large impacts on the public. 

Additional work should be carried out to assess the health benefits of reducing emissions from 

NGS] including retiring some or all of the units and replacing them with cleaner resources. Such 

studies have been conducted in other cases. One example is found in the Declaration of 

George D. Thurston in Opposition to Petitioners' Motion for Stay] Public Service of New Mexico 

v. EPA] filed in the u.S. Court of Appeals] Tenth Circuit] Case No. 11-9557. Another example is 

the Supplemental Answer Testimony of Leland Deck in Docket No. 07A-447E before the 

Colorado Public Utilities Commission] filed on May 27, 2008 on behalf of Western Resource 

Advocates. 

In sum, resolution of the air pollution problems at NGS requires a much more comprehensive 

analysis that considers realistic transition options, health impacts, and uncertainties in coal 

costs and costs of compliance with potential future environmental regulations. The NREL 

analysis is simply too constrained to lead to any policy conclusions. 

We appreciate the opportunity to provide comments on this important matter and urge the 

Department of the Interior and EPA to address the many issues surrounding the future of NGS] 

to accelerate the transition to cleaner energy resources to benefit Arizona] the tribes] the 

agriculture sector] and the environment] and to foster creative solutions among stakeholders. 

David Berry 

Chief of Policy Analysis 

Western Resource Advocates 

2 
ARLEN QUETAWKI, SR. 

Governor PUEBLO OF ZUNI 

LOREN L. LEEKEI.A, SR. 

Councilman 

~~~~~

STEVE K. BOONE 

Lt. Governor P.O. Box 339 

1203-B State Highway 53 

GERALD HOOEE, SR. 

Councilman 

.. ' .. ARDEN KUCATE Zuni, New Mexico 87327-0339 MARK MARTINEZ 

Head Councilman www.ashiwi.oyg Councilman 

VACANT 505-782-7000 (~) BIRDENA SANCHEZ 

Councilman 505-782-7202 (&!L) Councilwoman 

Officially known as the ZWli Tribe of the ZWli Indian Reservation 

February 1,2012 

Letty Belin, Counselor to the Deputy Secretary 

U. S. Department of Interior 

1849 C Street NW 

Washington, DC 20240 

RE: Comments on Navajo Generating Station and Air Visibility Regulations: 

Alternatives and Impacts 

Dear Ms. Belin, 

The Pueblo ofZuni provides the following comments on the National Renewable Energy 

Laboratory (NREL) Analysis ofthe Navajo Generating Station and Air Visibility Regulations: 

Alternatives and Impacts dated January 2012. 

The Pueblo ofZuni has been pursuing renewable energy projects opportunities, and recently 

completed feasibility studies ofseveral solar power generation projects on its lands in Arizona and 

New Mexico. Zuni has excellent solar resources, very good proximity to high voltage electric 

transmission lines, and suitable project sites. Proposed solar projects from 10 MW to 200 MW are 

considered feasible at their current sites at Lich-N- HavenlDavis in Arizona and Western Border in 

New Mexico. Zuni is pursuing\ development at this time, with the intention to construct projects 

within a 2 to 5 - year time horizon. 

Zuni requests that its proposed solar generation facilities be included in the supplemental study 

planned by NREL as possible replacements for some ofthe Navajo Generating Station electric 

generation, should NGS be shut down. Zuni is also interested in participation in a possible tribal 

consortium effort to replace NOS generation discussed at the Inter-Tribal Council ofArizona 

January 27,2012 meeting. 

We look fOlWard to the release offurther analyses ofthe options and would be pleased to provide 

additional information as needed. 

Sincerely, 
Enclosure 

EPA Corrections to NREL Phase I Study on Navajo Generating Station 

1.	 	 EPA regulatory actions on pages 12 and 14 are not accurately described. The Report states 

that the plant will be subject to a number of regulations and implies that they will require 

additional investments. In many cases, we do not know whether NGS would be affected 

(e.g., in cases where standards have not been set, rules have not been finalized, or 

designations have not been completed). IfNGS were affected by many of these actions, it is 

likely that actions NGS has already taken or will take for MATS or BART would cover some 

of their obligations. Therefore, except in the case of finalized rules, EPA actions should be 

presented as "potentially affecting NGS," including in the title of the table on page 12. 

a. Utility Mercury and Air Toxics Standard. The report incorrectly states that MATS 

sets emission limits for organic compounds. The final rule sets work practice 

standards for organic compounds. 

b. Cooling water intake. The rule will "minimize" not "prevent" 

impingement/entrainment of aquatic life. 

c. Coal Combustion Residues. EPA has no public date for finalizing this rule. The status 

should read "pending". The summary should read "EPA has proposed to regulate coal 

ash to address the risks from the disposal of the wastes, such as residues from the 

combustion of coal in power plants, generated by electric utilities and independent 

power producers. The target date for release of a final rule will be detennined 

pending a full evaluation of all the infonnation and comments EPA received on the 

proposal." 

d. Ozone and PM NAAQS. The report states that EPA has proposed a revised ozone 

standard. In September 2011, EPA chose not to final ize that revised standard and 

instead has begun implementing the ozone NAAQS promulgated in 2008. EPA is also 

conducting the 5 year review of the ozone NAAQS required by statute and expects a 

proposal in 2013. As a result, the schedule box for this action should read "pending". 

The text under "summary of action" for the PM NAAQS should also be used for the 

summary of action for the ozone NAAQS. Finally, since the ozone and PM NAAQS 

are the same type ofprocess now, both should be characterized as "reviews" or 

neither should be characterized as a "review." 

e. Transport Rule. Also on the table on pg. 12, the Transport Rule II is no longer on 

EPA's Regulatory Agenda. As a result, this rule should be removed from the table. 

r. Utility Boiler GHG NSPS. The Summary should read "EPA is under a court 

settlement to set NSPS standards for this source category for GHG emissions. Under 

the NSPS provisions, the agency will also establish guidelines for states to use in 

regulating existing sources such as Navajo GS. This process could lead to GHG 

requirements for Navajo GS. 

g. California Senate Bill 1368. The California GHG emission perfonnance standards 

does not impose any requirements on NOS, rather it affects one ofthe co-owners of 

NGS (Los Angeles Department of Water and Power). We suggest the text be adjusted 

to reflect this. 

1 
2.	 	 The discussion on MATS on page 51 is not current - it describes the potential need for 

baghouses and sorbent injection to control S03 and sulfuric acid mist (both contribute to the 

condensable fractions ofparticulate matter). The final MATS rule set a filterable only PM 

limit of 0.03 Ib/MMBtu, therefore, discussion ofS03 and sulfuric acid controls is not 

relevant for MATS implementation and should not be characterized as such. EPA notes that 

source tests show that NGS generally already achieves 0.03 Ib/MMBtu (filterable PM). 

Additionally, references to proposal and final rule dates associated with MATS are 

inconsistent in the report and do not correctly distinguish between signature dates and 

publication dates. The publication date of the final MATS rule in the Federal Register is 

February 16,2012. 

3.	 	 In Table 3-11 on page 51, the costs labeled "SCR with sorbent injection and polishing 

baghouse" appear to be consistent with Sargent and Lundy cost estimates for SCR and DSI 

only (i.e., polishing baghouse not included). As noted above, theses costs are unlikely to be 

applicable to MATS implementation based on the final MATS rule. 

4.	 	 Page 88. Most sources will have 4 years to comply with MATS, until early 2016 (3 years 

available to all sources + 4th 

year that EPA expects to be widely available from permitting 

authorities to enable sources to complete compliance activities). 

5.	 	 Table 5-1 on page 75 reports emissions ofNOx and S02 emissions that are identical. This 

appears to be a typographi cal error. 

6.	 	 The narrative describing Table 5-6 on page 84 and the numerical values in the table are 

inconsistent. The narrative describes a reduction in nitrate concentrations over time, but the 

values in the table shows a dramatic increase. Additionally, the percent reduction numbers do 

not seem to reflect the actual values in the table. 

7.	 	 On page 93, the statement that Mohave Generating Station in southeastern Nevada closed at 

the end of 2005, due largely to the cost of retrofitting the power plant with S02 scrubbers is 

misleading. EPA understands that the spray dryers with high velocity baghouses were 

expected to cost $250 million, and that additional expenses at the time that were unrelated to 

the new scrubbers included a new slurry pipeline ( $250 million) and upgrades/life extension 

of the plant ($500 million) were three times higher than the cost of new controls. Therefore, 

Mohave closed in part, due to the cost of new air pollution controls, but many other factors 

existed that affected decisions related to closure. 

8.	 	 On page 101, the report is misleading in its description of the permitting ofDesert Rock. 

Although EPA requested a voluntary remand of the final permit to incorporate new 

applicable requirements, the project applicant has not responded to our multiple requests for 

an amended permit application; we most recently sent a Jetter in December 2011 and will 

follow up with another letter providing a deadline after \vhich we wilJ consider the 

application withdrawn. 

9.	 	 Table 3-4 on page 45, should also list Springerville Units 3 and 4 as plants with installed 

SCR technology. Although Springerville is operated by Tucson Electric Power, Unit 4 is 

owned by SRP. These units came on line in 2007 and 2009. 

10. The information on pages 45-47 should include any available cost information for the 

planned retrofit of Unit 2 at Coronado Generating Station - another SRP facility. The 

Consent Decree for Coronado requires the SCR be installed and operational by June 1, 2014. 

2 
11. On pg. IV of the Executive Summary, the report states that LNB with SOFA have reduced 

NOx emissions at the plant by 40% relative to the plant's air pennit before controls were 

added. The percent control would be lower (~30% reduction from LNB/SOFA) ifthe 

calculation was done comparing pre-project actual emission rates to limits after installation 

of LNB/SOFA. 

12. On pg IV of the Executive Summary, the report then cites a 78% reduction if SCR were 

installed and 50-60% reduction ifSNCR were installed. A control efficiency of 50-60% from 

SNCR is higher than typically cited for SNCR alone. SRP recently estimated SNCR could 

achieve 0.15 - 0.] 8 lb/MMBtu at NGS (a 25 - 38% reduction on top ofperrnitted JeveJs of 

0.24 Ib/MMBtu with LNB/SOFA). Because LNB/SOFA is already instaJled and operational 

at NGS, control efficiencies from SNCR and SCR alone should either be calculated using a 

baseline of 0.24 lb/MMBtu, or if 0.35 lb/MMBtu is used as the baseline, should be reported 

as a control efficiency based on SNCR + LNB/SOFA or SCR+LNB/SOFA (i.e., to be more 

consistent with values reported in Table 3-2 ofNREL report). 

3