November 8, 2011 

Mr. Gerardo Rios 

Chief, Permits Office 

USEPA Region IX 

75 Hawthorne Street 

San Francisco, CA 94105 

Subject: Pio Pico Energy Center PSD Permit Application 

 BACT for Cooling System 

 

Dear Mr. Rios: 

As requested by EPA in emails from Roger Kohn to Steve Hill dated October 12, 2011, 

and November 3, 2011, and a telephone conversation between Roger Kohn and Steve 

Hill on November 3, 2011, we are submitting clarifying information on behalf of Pio Pico 

Energy Center, LLC. 

October 12, 2011 Email 

In the application, PPEC proposes the use of a high efficiency drift eliminator for 

particulate BACT for the cooling towers, and a drift rate of 0.001% or less (see pages 

4.52 and App-1.94). Please note that the drift rate in our proposed Palmdale permit is 

one half this rate. We need PPEC to evaluate this higher level of control for its project 

as part of the top down BACT analysis. Also, in the top down analysis, PPEC should 

provide the equivalent hourly emission rate and concentration of measured TDS, as these 

values are needed to propose enforceable particulate permit conditions limiting 

emissions. Please submit a revised top down particulate BACT analysis for the cooling 

tower with this additional information.

Response: 

The cooling tower at Palmdale is a large (130,000 gpm circulation rate) evaporative 

cooler. It is sized to condense the steam from the steam turbine in this combined cycle 

power plant. 

The cooling system used by PPEC is not a cooling tower, it is a partial dry cooling 

system comprised of two components: a dry cooling component that provides necessary 

cooling most of the time and has zero emissions; and a small (7,000 gpm circulation rate) 

wet cooling component that supplements the dry cooling component when ambient 

temperatures are too high for the dry cooling system to function effectively. The PPEC 

cooling system is sized to provide intercooling for the simple-cycle turbines, and is much 

smaller than a system designed for condensing steam from a combined cycle unit. 

As demonstrated in the BACT analysis submitted with the reformatted PSD permit 

application, the PPEC cooling system is a different basic technology with inherently 

sierra 

research

1801 J Street 

Sacramento, CA 95811 

Tel: (916) 444-6666 

Fax: (916) 444-8373

Ann Arbor, MI 

Tel: (734) 761-6666 

Fax: (734) 761-6755 
Gerardo Rios -2- November 8, 2011 

lower emissions than the cooling technology approved in the Palmdale permit. Because 

it is much smaller, and because it is not a recirculating water cooling tower, the PPEC 

cooling system is a different class/category of source than the Palmdale cooling tower. 

The BACT analysis also documents that the drift rates achievable in large evaporative 

coolers have not been demonstrated in, and are not applicable to, much smaller units such 

as the PPEC system. 

We have contacted the vendor to determine whether a guarantee of 0.0005% drift is 

available, and if so, at what price. Based on information provided by the cooling system 

vendor, the estimated incremental cost of control would be: 

Capital cost ($) $2.1 MM 

Annualized capital cost ($/yr, 0.11 recovery factor) $231,000 

Operating cost ($/yr) -- 

Total incremental cost ($/yr) $231,000 

Emission reductions (TPY PM/PM10/PM2.5) = 1.4 TPY – 0.7 TPY = 0.7 TPY 

Cost effectiveness = ($231,000/yr)/(0.7 TPY) = $330,000/ton 

The TDS levels for the wet cooling component are provided in the PSD application at 

page PSD-4.29. The hourly emission rate from the cooling tower is provided in the PSD 

application at page PSD –App-1.53. 

October 12, 2011 Email 

Can you tell me at what temperature the PPEC SCR units will start to be effective, and at 

what temperature the units will be fully effective? 

Response: 

The SCR inlet flue gas temperature must be equal to or above the limit temperature of 

570 degrees F before ammonia may be injected. This is also the temperature at which the 

SCR unit will be capable of achieving the emission limits. There will be a time delay of 

a few minutes while the SCR catalyst is saturated with ammonia, but there no difference 

between the two temperatures. Maximum allowable gas temperature into the SCR 

catalyst is 870 degrees F. 

The turbines will be in compliance with NOx limits for normal operations immediately 

after the end of the startup period (i.e., the NOx concentration and mass emission rate for 

the first hourly average after the end of the startup period will meet the applicable limits). 

October 12, 2011 telephone conversation 

Please confirm that PPEC will use only PUC-quality natural gas in the turbines.

 

Response: 

PPEC will use only PUC-quality natural gas in the turbines. 
Gerardo Rios -3- November 8, 2011 

If you have any questions regarding this application, please contact the applicant’s 

representative David Jenkins at (317) 431-1004, or Gary Rubenstein or me at (916) 444-

6666. 

Sincerely, 

Steve Hill 

cc: John McKinsey, Stoel Rives LLP 

David Jenkins, Apex Power Group 

 Steve Moore, SDAPCD