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OAR Box 1787 

Prepped by Ollie Stewart 

Document Number: 

96) ll-C-54 

Docket Number: 

A-90-37 

Printed 11/4/2008 10:22:20 AM Sheet 96 of 147 
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

February 15, 1994 

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^"01998 jjilj Mr. Roger L. Swingle 

Manager, Environmental Programs 

Solar Turbines Incorporated 

P.O. Box 85376 

San Diego, California 92186-5376 " * * iE*»^ 

Dear Mr. Swingle: 

This is in response to your February 2, 1994 letter 

transmitting a study, commissioned by Solar Turbines and 

conducted by Sierra Research, entitled "Comparison of Emissions 

from Gas Turbines and Alternative Power Generation Options." The 

study claims that dry low nitrogen oxides turbines without 

selective catalytic reduction provide a greater overall 

environmental benefit than other project alternatives, such as 

internal combustion engines or electric motors. 

As you point out, the 1990 Clean Air Act (CAA) Amendments 

made numerous statutory changes to both Part C (Prevention of 

Significant Deterioration) and D (Plan Requirements for 

Nonattainment Areas) of the CAA. The EPA is revising the new 

source review (NSR) regulations to reflect these statutory 

changes. In your letter, you particularly note the NSR 

alternative siting analysis which is required prior to the 

issuance of a permit to construct a major source in a 

nonattainment area. This analysis must consider alternative 

sites, sizes, production processes, and environmental control 

techniques for the proposed source, and demonstrate that benefits 

of the proposed source significantly outweigh the environmental 

and social costs imposed as a result of its location, 

construction, or modification. In its upcoming rulemaking 

package, EPA will be addressing this analysis. The information 

provided by your study will be taken into consideration during 

the development of the rulemaking. 

If you have additional questions on the Part C and D 

rulemaking package, please contact Mike Sewell of my staff at 

(919) 541-0873. 

David Solomon, Chief 

New Source Review Section 

Permits Programs Branch 
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Solar Turbines Incorporated cf^^.v!,,.^ ^ . ^ 

'vi.&TJL 

P.O. Box 85376 

San Diego. CA 92186-5376 

Tel (6191544-5000 

Fax 16191544-5825 

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SolarTurbines 

A Caterpillar Company 

February 2, 1994 

Mr. David Solomon, MD -15 

U.S. EPA 

Office of Air Quality Planning 

Research Triangle Park, NC 27711 

Dear Mr. Solomon: 

A recently completed study by Sierra Research, a nationally recognized environmental 

consulting firm, has concluded that gas turbines using dry, low NOx (DLN) combustion 

technology produce fewer nitrogen oxides (NOx) per unit of power than either 

reciprocating engines or fossil-fueled utility plants associated with electric motors. 

Entitled "Comparison of Emissions from Gas Turbines and Alternative Power Generation 

Options," the study was commissioned by Solar Turbines Incorporated, a San Diego, 

California manufacturer of small to medium size stationary gas turbines used by industries 

in nearly 80 nations. The study also indicates that NOx emissions from combustion 

turbines with DLN technology generally are lower than those produced by electric utility 

generating plants. 

Solar feels that the attached report further supports the need for New Source Reform, 

especially when permitting within a non-attainment area. 

Solar Turbines commissioned the study in order to examine the environmental 

"opportunity cost" represented by the EPA's current permitting policy for non-attainment 

areas. It has been our observation that in some cases where permitting agencies have 

taken an absolute, unwavering position that new or modified projects in non-attainment 

areas must resort to the maximum degree of "end-of-pipe" emissions control, they might 

be contributing to a deterioration in air quality; certainly, not their intent. 

In non-attainment areas, air boards are requiring owners of new small gas turbines to 

meet NOx limits of 9 ppm or lower in order to get an operating permit. Because such 

stringent levels can be met only with end-of-pipe controls like Selective Catalytic 

Reduction (SCR), when customers come face-to-face with the high costs of SCR, they 

usually select other alternatives-like reciprocating engines or electric motors-which, as 

the report reflects, are less generally environmentally beneficial. 

The Clean Air Act Amendments of 1990 require permitting authorities to consider not only 

alternative sites for projects, but also alternative processes. We believe that the 
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environmental community will agree with our recommendation that this requirement, which 

is expected to be incorporated in the proposed new NSR regulations due to be published 

in the Federal Register by as early as mid-1994, will recognize the findings of Sierra's 

study, i.e., that dry low NOx turbines without SCR provide a greater overall environmental 

benefit than the alternatives. 

In regard to many regions of the country, it is important to point out that although the use 

of gas turbines most likely would displace electricity generated by coal-fired sources, the 

study assumed that all the states in those regions would adopt extremely low Reasonably 

Available Control Technology (RACT) levels for coal-fired utility boilers. The Northeast 

States for Coordinated Air Use Management (NESCAUM) has recommended adoption 

of very stringent RACT levels; however, none of those states has yet proposed imposing 

such severe levels in their pending RACT rules. Even if such low levels were adopted 

without being contested, which we feel is unlikely, the displacement of coal-fired 

emissions by natural gas-fired turbines definitely would reduce emissions of sulfur dioxide 

(S02) and carbon dioxide (C02). The attached study concentrated on NOx and made no 

attempt to consider other air pollutants. 

Sincerely, 

^'7 /tM-u^L-..•% ftk 

Roger L. Swingle 

Manager, Environmental Programs 

Encl - Sierra Research Report 
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c Report No. SR93-12-01 

Comparison of Emissions 

from Gas Turbines and 

Alternative Power 

Generation Options 

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prepared for: 

Solar Turbines Incorporated 

December 1, 1993 

prepared by: 

Sierra Research, Inc. 

1801 J Street 

Sacramento, California 95814 

(916)444-6666 

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