OVERVIEW OF NAVAJO GENERATING STATION 

STUDY BY NATIONAL RENEWABLE ENERGY

LABORATORY

Letty Belin

Counselor to the Deputy Secretary

U.S. Department of the Interior

February 8, 2012
NGS Options Study

by National Renewable Energy Laboratory

http://www.nrel.gov/ngs/

• Purpose: To provide independent technical 

analysis of the many interrelated and complex 

issues relating to NGS that can provide the basis 

for accomplishing those objectives

– Phase I: focused on EPA BART process 

proceeding while identifying a range of potential 

options to address long-term future of NGS

– Phase II: Technical, economic, environmental, 

social, regulatory and policy analyses of all 

feasible long-term power generation alternatives

2
PHASE I STUDY OBJECTIVES

• Costs of compliance

• Remaining useful life of NGS

• Degree of improvement in visibility that would 

result from BART installation

• Existing pollution control equipment

Goal No. 1: Provide EPA additional data

relating to 5 BART criteria
Goal No. 2: Identify economic and social benefits of 

NGS, needs met by NGS, and impacts of NGS

Goal No. 3: Provide information comparing NGS to 

other coal-fired plants (multiple criteria)

Goal No. 4: Assess risks and costs of NGS shutdown 

under various BART scenarios

Goal No. 5: Evaluate impacts of potential BART 

emission control alternatives

Goal No. 6: Identify generation alternatives for

full evaluation in Phase II (not yet complete)
Schedule for Phase I Report

• Sept. through December 2011: Data gathering

• January 18, 2012: Final NREL report (except 

Energy Generation Alternatives chapter) released

• February 6, 2012: Deadline for written 

comments to DOI

• February 2012: DOI submits compendium of 

written comments on NREL report to EPA

• Late February-Early March 2012: Energy 

Generation Alternatives chapter released
Summary of Tribal Impacts from BART

• Absent complete or partial NGS shutdown, direct 

economic benefits to Navajo and Hopi from 

mining and NGS operation will continue

• Economic impacts on CAP water tribes from BART 

compliance depend on type of emissions 

controls. Impacts range from zero (Low NOx

burners) to 29-32% increase in cost of CAP water 

(SCR + baghouses)

• Steep increase in CAP water cost is concern in 

Indian water settlements
NREL Study

Considered four options for BART emissions 

control technology:

– Already installed low NOx burners (40% emissions 

reduction)

– Selective non-catalytic reduction (SNCR) (50-60% 

emissions reduction)

– Selective catalytic reduction (SCR) (78% emissions 

reduction)

– SCR plus baghouses & sorbent injection
Costs of BART Compliance

Capital O&M

• Low Nox Burners: none none

• SNCR: $16.3 m $4.9 m/yr

• SCR: $544 m $12.7 m/yr

• SCR + baghouses $1,100 m $12.7m/yr
Burden of compliance costs for BART 

probably fall most heavily on those 

who rely on CAP water

NREL Study Findings

• Impacts of BART compliance fall most heavily 

on Reclamation and CAP water users rather 

than other utility owners and their customers

• Visibility: “Evidence suggests that NOx

emissions from NGS are a likely incremental 

contributor to haze at the Grand Canyon” and 

10 other Class 1 areas
NREL Study Findings (cont.)

• Impacts of installing SCR would probably be 

less than closing NGS and replacing it with 

power from other sources (but uncertainties 

mean this might not occur)

• For non-Reclamation utility owners, SCR at 

NGS would increase production costs by 3-4% 

and would increase utility rates by relatively 

small amounts
NREL Phase 1 Study: Final Chapter

• Final chapter addresses future cleaner energy 

alternatives for NGS

• No detailed analysis of alternatives -- instead, 

a list of what appear to be the most viable 

alternatives

• Expected by end of February

• Not directly relevant to BART