, ·- , ... 

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INSTITUTE OF 

CLEAN 

AIR 

COMPANIES 

Memorandum 

March 18, 2009 

1730 M Street NW 

Suite 206 

Washington, DC 20036-5603 

Telephone 202.457.0911 

Fax 202.331.1388 

David C. Foerter, Executive Director 

Email: dfoerter(@icac.com 

Chad S. Whiteman, Deputy Director 

Email: cwhiteman@icac.com 

TO: Walt Stevenson, U.S. Environmental Protection Agency, OAQPS 

FROM: Chad Whiteman, Deputy Director, Institute of Clean Air Companies 

SUBJECT: Selective Non-Catalytic Reduction Technology Costs for Industrial Sources 

The Institute of Clean Air Companies (ICAC) is the national trade association of companies that 

supply air pollution emission control and monitoring technologies for electric power plants and 

other stationary sources. ICAC represents more than ninety of the leading manufacturers providing 

emissions control solutions for affected industries as well as employment opportunities across the 

u.s. 

The following memo provides a brief description of the selective non-catalytic reduction (SNCR) 

technology and some real-world cost information for various industrial sector applications. The 

SNCR technology is a post combustion emissions control technology that uses a chemical process 

for removing NOx from flue gas. In the SNCR process, a reagent, typically urea or anhydrous 

gaseous ammonia, is injected into the hot flue gas, and reacts with the NOx, converting it to nitrogen 

gas and water vapor. No catalyst is required for this process. Instead, it is driven by the high 

temperatures normally found in combustion sources. SNCR is "selective" in that the reagent reacts 

primarily with NOx. 

The principal components of the SNCR system are the reagent storage and injection system, which 

includes tanks, pumps, injectors, distribution modules, and associated controls. The combustion 

unit acts as the reactor chamber simplifying the SNCR process. The reagent is generally injected 

within the boiler superheater and reheater radiant and convective regions, where the combustion gas 

temperature is at the required temperature range. The number of injection ports and location is 

determined by flue gas flow and temperature profiles. 

Selective non-catalytic reduction technology was first applied commercially in 1974 and has been 

installed on approximately 400 applications worldwide. Applications include utility boilers and a 

broad range of industrial applications including installations on the following: wood-fired boilers, 

coal-fired boilers, co-generation boilers, pulp and paper, steel industry, refmery process units, 

process heaters, cement kilns, municipal waste combustors, glass melting furnaces, hazardous waste 
incinerators, and other combustion sources. A cross-section of the various industrial sector 

deployment experiences was taken in order to develop the following cost data. 

ICAC identified 126 SNCR installations on Municipal Waste Combustors in the United States and 

Europe in ICAC's February 2008 whitepaper titled, "Selective Non-Catalytic Reduction for 

Controlling NOx Emissions." These installations include more than 50 SNCR installations on 

municipal waste combustors in the United States. For the SNCR systems installed in the U.S., the 

percent NOx emission reduction ranges between 25 to 72 percent with the average being 42 percent 

NOx reduction. 

The primary regulatory drivers for NOx reductions from these SNCR systems are command-andcontrol programs that mandate a specific NOx limit in their operating permit. There is no incentive 

to reduce NOx emissions beyond the permitted limit due to potential increases in operating costs 

from the injection of additional reagent or added capital equipment costs to improve the SNCR 

system performance. If market-based regulatory programs were implemented for these municipal 

waste combustors, there would be additional incentives to increase the NOx reduction performance 

where proven to be cost effective. 

In Figure 1, the installed cost of more than fifty different SNCR installations was compiled in order 

to compare the installed costs for various sizes of industrial applications. The installed cost of the 

equipment is expressed in dollars per unit size ($/mmBtu/hr) and is plotted against the boiler gross 

heat input (mmBtu/hr), which indicates the unit size. The installed cost represents the cost of all of 

the capital equipment plus the cost of installing the equipment at the end-user site. The operation 

and maintenance costs are not included in the capital equipment cost but are largely made up of the 

cost of the reagent. A logarithmic best-fit curve was applied to the data to develop the dashed line. 

As demonstrated by the data, the capital costs for SNCR technology are low due to the small 

amount of capital equipment required. Similar to most technology applications, SNCR technology 

becomes progressively more cost effective the larger the boiler size. The cost curve indicates that 

units less than 75 mmBtu have higher relative capital costs even though the SNCR technology is a 

low capital cost technology. 
Figure 1. Actual SNCR Installed Capital Costs on Industrial Sources 

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In Figure 2, the cost effectiveness of more than fifty SNCR applications for NOx reductions on 

industrial sources is compared for vanous unit sizes. The cost effectiveness of SNCR is expressed 

in dollars per ton ofNOx removed and is plotted against the boiler heat rate (mmBtu/hr), which 

indicates the unit size. The cost effectiveness numbers consider both the installed costs (capital 

equipment, installation expenses, and annual O&M costs) compared to the incremental reduction of 

NOx from the baseline NOx emissions for each given unit for the year. The cost effectiveness for 

both a~ual operation and ozone season operation (May 1st - September 30th) were plotted. A 

logarithmic best-fit curve was applied to both the annual and ozone season costs and is represented 

by the dashed lines in Figure 2. 

As demonstrated by the data, SNCR technology is more cost effective when operated year round 

due to the increase in the NOx reduced over a longer operating period. Similar to most technology 

applications, SNCR technology becomes progressively more cost effective the larger the boiler size. 

The cost curve for the fifty applications analyzed indicates that the majority of the ozone season 

applications have cost effectiveness values less than $4000/ton even for smaller units. An even 

greater percentage of the applications have cost effectiveness values less than $3000/ton for annual 

operation of the SNCR technology. 
Figure 2. Actual SNCR Cost Effectiveness for NOx Reductions on Industrial Applications 

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As the above cost curves indicate, SNCR technology is a proven technology that can be cost 

effectively applied to a wide range of industrial applications. The technology has emerged as a co t 

effective solution for small and large unit size applications due to the low capital cost of the 

installed equipment.