Addition to Colorado Docket

Laurel Dygowski Laurel Dygowski to: Crystal Freeman 09/17/2012 07:23 AM

Can you add the following string of e-mails/attachment to the Colorado docket. It is not a public comment 

but it is supporting information. Can you title it "7/16 E-Mail from Lisa Clarke to Laurel Dygowski 

Pertaining to Fuel Switching at CENC" THanks

**** Note - New Mailing Address

Laurel Dygowski

Regional Haze Coordinator

Air Quality Planning Unit

US EPA - Region 8

1595 Wynkoop Street

Denver, CO 80202-1129

303-312-6144

----- Forwarded by Laurel Dygowski/R8/USEPA/US on 09/17/2012 07:24 AM -----

From: "Clarke, Lisa M." <Lisa.Clarke@dphe.state.co.us>

To: "Clarke, Lisa M." <Lisa.Clarke@dphe.state.co.us>, Laurel Dygowski/R8/USEPA/US@EPA

Cc: "Taipale, Curtis D." <Curtis.Taipale@dphe.state.co.us>, "Kaufman, Garry W." 

<Garry.Kaufman@dphe.state.co.us>, "King, Kirsten L." <Kirsten.King@dphe.state.co.us>, "Hea, 

Roland C." <Roland.Hea@dphe.state.co.us>, "Allison, William" 

<William.Allison@dphe.state.co.us>

Date: 07/16/2012 03:24 PM

Subject: RE: CENC 4 and 5 - fuel switching question from Laurel

Hi Laurel,

Attached is the CENC BART Cost Analysis as discussed. Again, this is a draft version of the cost analysis, 

so all of the cost alternative calculations ($/ton) for the other options may not line up with the 

submitted SIP. The cost tables are in the “CEN Alternatives – BART SO2 Avg.” and “CEN Alternatives – 

BART NOx Avg” tabs. It should be clarified that the over $25,000/ton costs are for SO2 – Boiler 4 - 

$29,985/ton and Boiler 5 - $30,945/ton. The costs for NOx are as follows: $64,102/ton (Boiler 4) and 

$82,834/ton (Boiler 5). Costs for fuel switching to natural gas are widely variable by unit and 

determined on a case-by-case basis.

I appreciate the opportunity to look at the draft portion of the notice before it goes out . Please let me 

know if you have any other questions or comments.

Thanks,

Lisa

Lisa Clarke, M.S./P.E.

Air Quality Planner/Engineer

Planning & Policy Program

Air Pollution Control Division

Colorado Department of Public Health and Environment

4300 Cherry Creek Drive South

Denver, CO 80246-1530
303-692-3117| lisa.clarke@state.co.us

 

From: Clarke, Lisa M. 

Sent: Monday, July 09, 2012 1:22 PM

To: 'Laurel Dygowski'

Cc: Taipale, Curtis D.; Kaufman, Garry W.; King, Kirsten L.; Hea, Roland C.; Allison, William

Subject: RE: CENC 4 and 5 - fuel switching question from Laurel

Laurel,

Yes, there is supporting documentation in the docket. The attached documents were originally 

provided to EPA (as well as the FWS and NPS) by Curt Taipale on August 23, 2010. Fuel switching to 

Natural Gas is mentioned on page 17 of the Technical Support Document (TSD) for CENC. The State 

conducted a preliminary analysis as described below and concluded that a complete fuel switch to 

natural gas for Units 4 and 5 was cost prohibitive, as is the case with Unit 3 at the same facility and also 

with other Colorado EGUs (such as PRPA Rawhide Unit 1). It should be noted that the cost is variable 

depending on the unit. While it is unfortunate that this conclusion is not further described in the TSD, 

all available technologies, including technically feasible alternative fuel technologies, were properly 

examined within the scope of the five-factor analysis.

The flexible BART limit established in the SIP may be accomplished through partial fuel switching and 

other operational changes to reduce emissions (see docket EPA-R08-OAR-2011-0770-0002.pdf page 260 

and EPA-R08-OAR-2011-0770-0008.pdf page 259). These changes will also result in reduced SO2 and 

PM10 emissions. CENC itself notes in the docket that fuel switching to natural gas was examined at 

both units (EPA-R08-OAR-2011-0770-0002.pdf page 264 and EPA-R08-OAR-2011-0770-0008.pdf page 

262).

Thank you,

Lisa

Lisa Clarke, M.S./P.E.

Air Quality Planner/Engineer

Planning & Policy Program

Air Pollution Control Division

Colorado Department of Public Health and Environment

4300 Cherry Creek Drive South

Denver, CO 80246-1530

303-692-3117| lisa.clarke@state.co.us

 
From: Laurel Dygowski [mailto:Dygowski.Laurel@epamail.epa.gov] 

Sent: Monday, July 02, 2012 3:37 PM

To: Clarke, Lisa M.

Cc: Taipale, Curtis D.; Kaufman, Garry W.; King, Kirsten L.; Hea, Roland C.; Allison, William

Subject: RE: CENC 4 and 5 - fuel switching question from Laurel

Was the information in the attachments included as part of the State's submittal? I do not see fuel 

switching discussed in the five factor analysis or SIP, so need to see what is actually in the record 

pertaining to this. Thanks

  Note - New Mailing Address

Laurel Dygowski

Regional Haze Coordinator

Air Quality Planning Unit

US EPA - Region 8

1595 Wynkoop Street

Denver, CO 80202-1129

303-312-6144

"Clarke, Lisa M." ---06/25/2012 09:24:54 AM---Hi Laurel, I reviewed the comment below and here is the 

Division’s response:

From: "Clarke, Lisa M." <Lisa.Clarke@dphe.state.co.us>

To: Laurel Dygowski/R8/USEPA/US@EPA

Cc: "King, Kirsten L." <Kirsten.King@dphe.state.co.us>, "Hea, Roland C." <Roland.Hea@dphe.state.co.us>, "Allison, William" 

<William.Allison@dphe.state.co.us>, "Kaufman, Garry W." <Garry.Kaufman@dphe.state.co.us>, "Taipale, Curtis D." 

<Curtis.Taipale@dphe.state.co.us>

Date: 06/25/2012 09:24 AM

Subject: RE: CENC 4 and 5 - fuel switching question from Laurel

Hi Laurel,

I reviewed the comment below and here is the Division’s response:

In determining BART for CENC Units 4 and 5, the State analyzed alternative fuel-switching scenarios. The State 

requested in a letter dated January 26, 2010 (attached) to CENC that fuel-switching needed to be examined. 

CENC responded in full on February 8, 2010 (also attached). The State subsequently examined fuel-switching to a 

number of different fuels. Boilers 4 and 5 are not capable of burning wood or other biomass types. The use of 

sludge as the primary fuel is not technically feasible due to handling and storage issues and has not been researched 

for potential pollutant reductions. Residual oil, distallate oil, ethanol, and natural gas, were reviewed as technically 

feasible options.

Residual oil would not result in pollutant reductions. Distillate oil, ethanol, and biodiesel, are extremely high cost 

fuels for boilers of this size, with prices 2-3 times the cost of natural gas, 6-7 times higher than coal (at the time of 

analysis – December 2009) and highly volatile. Using EPA’s Cost Control Manual, the State determined that the 

cost of fuel-switching to natural gas for Boilers 4 and 5 when combined with direct and indirect installation costs, is 
greater than $25,000 per ton of NOx reduced annually. A study may be needed to assess potential pipeline

changes that may need to occur to account for the increased natural gas demand which could increase costs. 

Therefore, based on the information above, the State determined that “although other alternatives achieve better 

emissions reductions, achieving lower limits through different controls was determined to not be reasonable based 

on the high cost/effectiveness ratios coupled with the low visibility improvements afforded.” 

Please let me know if you have any further questions or comments.

Thanks,

Lisa

Lisa Clarke, M.S./P.E.

Air Quality Planner/Engineer

Planning & Policy Program

Air Pollution Control Division

Colorado Department of Public Health and Environment

4300 Cherry Creek Drive South

Denver, CO 80246-1530

303-692-3117| lisa.clarke@state.co.us

From: Laurel Dygowski [mailto:Dygowski.Laurel@epamail.epa.gov] 

Sent: Thursday, June 21, 2012 7:39 AM

To: Taipale, Curtis D.

Subject: CENC 4 and 5

Hi Curt - 

We have gone through all the Colorado comments and there is one more we need your help on pertaining 

to CENC 4 and 5 (see below). Aaron looked at this and does not see a good technical reason the State (or 

EPA) did not assess fuel switching. Any thoughts? 

Comment: In determining BART for Units 4 and 5, the State failed to identify and analyze

alternative fueling scenarios that would lead to greater reductions in NOx, sulfur dioxide (“SO2

”), 

and particulate matter. The proposed rule notes, and the underlying record clearly explains, that 

Units 4 and 5 are capable of burning (and do in fact burn) fuels other than coal. In particular, the 
proposed rule states that Unit 4 can and does burn natural gas or fuel oil and that Unit 5 can and 

does burn fuel oil. Both boilers may fire ethanol or sludge from the Coors Brewery. 

Despite this, the State did not assess whether alternative fueling scenarios, such as a full or 

partial shift from coal to natural gas or fuel oil at Units 4 and 5 would represent BART. This is a 

concern because according to the CAA Title V Operating Permit for the facility, both Units 4 and 

5 could meet stronger SO2 and NOx emission rates than have been proposed by the State as 

BART. The operating permit shows that the permitted emission rates for Units 4 and 5, when 

firing natural gas and/or fuel oil, are already lower than the proposed BART emission rates. See 

Colorado Department of Public Health and Environment, Operating Permit, Trigen-Colorado Energy Corporation 

Golden Facility (Feb. 1, 2003). Attached as Exhibit 1 to the comment. Given that permitted emission rates 

are higher than actual emissions, this means that the facility is most likely capable of achieving 

far greater emission reductions under an alternative fueling scenario. Indeed for Unit 4, whether 

firing natural gas or fuel oil, both permitted SO2

 and NOx emission rates are lower than the 

proposed BART limits. For Unit 5, when firing fuel oil, the permitted SO2 emission rate is lower 

than proposed BART. Furthermore, although the permitted NOx emission rate for Unit 5 when 

firing fuel oil is higher than the proposed BART, it is based on a 3-hour average (as opposed to a 

30-day average) and even then, actual emission are likely to be lower than the proposed BART

Here, alternative fueling scenarios, such as a full or partial shift away from coal to fuels that are 

already being burned in Units 4 and 5 (including natural gas and fuel oil) both seem to

represent the “best system of continuous emission control technology” and seem entirely 

reasonable when considering the five factors required to be assessed by states when determining

BART. The State failed to analyze alternative fueling in its SIP. Alternative fueling is an 

available technology that should have been analyzed by the State given that the visibility benefits 

to Class I areas could be tremendous. Although the State purported to identify “all available 

technologies” in its BART analysis, clearly it did not identify all available technologies. 

The failure to analyze alternative fueling scenarios is especially confusing because

the State did, apparently, identify in their TSD for the CENC facility a fuel switch to natural gas 

as an available technology and in analyzing “SO2 Emissions Management” as potential BART, 

noted that an option to reduce emissions could involve a “dispatch [of] natural gas-fired 

capacity.” There is, however, no explanation in the TSD as to why “fuel switching,” or otherwise 

increased reliance on natural gas, would not constitute BART or would be contrary to the five 

factors required to be considered in establishing BART under the CAA.

The failure to analyze alternative fueling scenarios is further confusing because the

EPA’s BART guidelines indicate that alternative fueling scenarios should be analyzed by states 

when determining BART. The guidelines specifically state that “potentially applicable retrofit 

control alternatives” can include the “use of inherently lower-emitting processes/practices” or 

“combinations of inherently lower-emitting processes and add-on controls.” Appendix Y at 

Section IV.D.3. Above all, states should “identify potentially applicable retrofit technologies that 

represent the full range of demonstrated alternatives.” Id. The guidelines clearly indicate that 

inherently “lower-emitting processes,” such as alternative fueling, are squarely within the realm 

of what may be considered BART.

** ** Note - New Mailing Address
Laurel Dygowski

Regional Haze Coordinator

Air Quality Planning Unit

US EPA - Region 8

1595 Wynkoop Street

Denver, CO 80202-1129

303-312-6144(See attached file: CEN 4-Factor Questions.pdf)(See attached file: February 8,

2010 CENC Response to CDPHE.pdf) CEN BART Cost Analysis 19 July 2010.xlsx