To:

Ann Lyons/R9/USEPA/US@EPA, Steve Frey/R9/USEPA/US@EPA, Eugene 

Chen/R9/USEPA/US@EPA, Scott Bohning/R9/USEPA/US@EPA, 

Cc: Amy Zimpfer/R9/USEPA/US@EPA, 

Bcc:

Subject: Responses to Reid Gardner Questions

From: Colleen McKaughan/R9/USEPA/US - Sunday 03/18/2012 08:39 AM

----- Forwarded by Colleen McKaughan/R9/USEPA/US on 03/18/2012 08:38 AM -----

From: Mike Elges <melges@ndep.nv.gov>

To: Colleen McKaughan/R9/USEPA/US@EPA

Date: 03/16/2012 04:46 PM

Subject: RE: Reid Gardner Questions

Colleen,

Attached is a brief document that provides information and responses to the questions raised below. 

Please feel free to contact me with any questions that you or your staff may have.

Thanks,

Mike Elges

Deputy Administrator

Nevada Division of Environmental Protection

From: Colleen McKaughan [mailto:McKaughan.Colleen@epamail.epa.gov] 

Sent: Wednesday, March 14, 2012 5:25 PM

To: Mike Elges

Cc: Amy Zimpfer

Subject: Reid Gardner Question

Hi, Mike,

As we discussed this afternoon, here are the two questions for which we need written responses. I know 

you went over your responses on the phone, but if you could provide them in writing for our records, that 

would be great. I will call you tomorrow regarding the other topic that we discussed to provide NDEP 

with more information. Thanks so much,

Colleen

1. What is the technical, unit-specific explanation for the difference in the ROFA/Rotamix level of 

performance of Unit 3 in relation to Units 1 and 2? 

2. Are you aware of which coal sources Nevada Energy purchases its fuel for Reid Gardner from?

Colleen W. McKaughan

Associate Director, Air Division

USEPA, Region 9

(520) 498-0118
This document responds to questions from EPA regarding two issues: 

1. What is the technical, unit-specific explanation for the difference in the ROFA with Rotamix 

level of performance of Unit 3 in relation to Units 1 and 2? 

It is important to point out that the boiler design of Unit 3 is different than Units 1 & 2. Unit 3 is a 

Balanced Draft-Negative Pressure boiler and Units 1 & 2 are Forced Draft-Positive Pressure boilers. 

When evaluating control systems, the design of the boiler must be taken into account. For example, in a 

Negative Pressure boiler, the unit may experience ‘air in’ leakage within the furnace because air tends to 

be drawn into it - whereas in a Positive Pressure boiler environment, excess air intrusion is less likely to 

occur. 

To arrive at the level of performance for all three units, first we took the highest two consecutive years 

from the acid rain data for 2001 through 2007 and averaged them for each unit. That gave us a number 

in lb/mmbtu for each unit’s performance. We then applied the percentage reduction for each 

technology that the utility provided to NDEP. In the case of ROFA with Rotamix, it was 57.7% for Unit 1, 

59% for Unit 2 and 38.3% for Unit 3. 

Thus, we calculated the emission limit as follows: 

• Unit 1: 0.462 MMBtu (from years 2002 and 2003) x 57.7%=0.267 lb/ MMBtu reduction; 

• Unit 2: 0.456 MMBtu (from years 2002 and 2003) x 59.0%=0.269 lb/ MMBtu reduction; 

• Unit 3: 0.451 MMBtu (from years 2001 and 2002) x 38.3%=0.173 lb/ MMBtu reduction. 

Subtracting the reduction from the actual emissions for the average of the two highest consecutive 

years arrived at the following: 

• Unit 1: .462-.267 =0.195 lb/ MMBtu (rounded up to 0.20) 

• Unit 2: .456-.269=0.187 lb/ MMBtu (rounded up to 0.20) 

• Unit 3: .451-.173=0.278 lb/ MMBtu (rounded up to 0.28) 

Some comments have been made regarding whether the emission limit for Unit 3 is too high in 

comparison to the actual current NOx emission rates from the three units. The table below shows the 

comparison of the baseline emission rates to the rates for 2009 through 2011. 

Table 1 

Reid Gardner 

Unit 

NDEP NOx BART 

(lb/MMBtu, annual average)

NDEP BART 

Baseline 

(lb/MMBtu)

Acid Rain NOx

(lb/MMBtu)

2009 2010 2011

#1 0.20 0.462 (‘02-‘03) 0.31 0.27 0.25

#2 0.20 0.466 (‘02-‘03) 0.33 0.29 0.25

#3 0.28 0.451 (‘01-‘02) 0.26 0.23 0.20
A look at how the units have been operating over the last ten years explains why Unit 3’s emissions are 

currently lower than the proposed BART limit. Figures 1 through 3 present the total energy produced (in 

megawatts) from 2002 through 2010. Load data for 2011 is not yet available from the Acid Rain 

database. As the below three figures represent, there has been a relatively significant decrease in 

overall energy production from all three BART units since the baseline time frame. 

Figure 1 – Unit #1 

Figure 2 – Unit #2 
In addition to the overall reduction in energy production, it is informative to look at the way the units 

have been operated. Figures 4 through 6 present the energy production as a function of operational 

load for Units 1 through 3. 

Figure 3 – Unit #3
Figure 2 – Unit #1 Changes in Load 

Figure 3– Unit #2 Changes in Load 
Figure 4 – Unit #3 Changes in Load 

As can be seen from Figures 4 through 6, the base-load operating condition for all three units has 

declined significantly. For instance, the Unit 3 base load operating condition fell by roughly 50% 

between 2008 and 2011. Even more significant base load operating reductions were observed for Units 

#1 and #2. 

When the units operate at higher load capacities and spend more time at base load operating 

conditions, higher boiler operating temperatures result in greater amounts of NOx emissions. Reid 

Gardner’s base load operating conditions have decreased since about 2008, which appears upon first 

glance that the NOx emissions are reduced. However, when viewing the NOx emissions in context with 

the downturn of Nevada’s economy, the recent addition of combined cycle gas fired units to the NV 

Energy system, and the lower price of natural gas, there is currently less demand and less need to 

operate Reid Gardner at base load conditions. However, because all of those circumstances can 

fluctuate and it is expected that Nevada’s economy will eventually recover, neither NDEP nor NV Energy 

proposed to limit the capacity factor during the control costs review to require NV Energy to decrease its 

base load operations of Reid Gardner. Therefore, NDEP does not believe that it is appropriate to use 

recent emissions data to represent normal or typical operations from which to base control technology 

emission reductions. Rather, emission reductions should be considered from the NDEP identified 

emission baselines in Table 1, above. 

2. From which coal sources is NV Energy purchasing its fuel for Reid Gardner? 

To answer your question regarding the source of coal for Reid Gardner, the below table shows from 

where the coal has been sourced during the last five years. 

Table 2 
It should be noted that the Wyoming based coal is about 1% nitrogen based where the Utah/Colorado 

coal is about 1.7% nitrogen content. The facility has increased usage of lower nitrogen based fuel which 

will result in slightly lower NOx emission rate, the predominant decrease in NOx emissions is due to the 

decrease in load described above. 

Year Utah/Colo Wyoming

2007 100 0

2008 100 0 

2009 90 10 

2010 65 35

2011 55 45