Grasping the impact of emission factors: this article provides a list of sources for foundry emission factors and shows if new factors could affect whether a foundry is considered a "major" source.
While this new knowledge is important, it has raised several issues regarding the use of emission factors in the regulatory, permitting and compliance arenas.
What is an Emission Factor?
Simply put, an emission factor is a number that lets foundries predict their emissions based on some unit of production. For example, a typical factor for emissions from melting operations would be expressed in lb of a pollutant per ton of metal melted. Maximum emission levels are estimated in order to establish the applicability of various regulatory and permitting programs and to predict compliance with various emission standards.
Ideally, an emission factor would provide an accurate estimate of emissions prior to the construction of a source, and the measured value after construction would be equal to or somewhat less than the factor used. In other words, what is assumed on the front end of the process has to be true on the back end when emissions may actually be measured for compliance purposes.
Most emission factors are general, covering a broad range of process types and conditions. Factors that may significantly over-predict emissions may cause a source to meet the requirements of a more restrictive permitting program than is actually required. Factors that significantly under-predict may result in an enforcement action and a re-evaluation of permitting and regulatory requirements after the source is built. The need for accurate unit specific emission factors may require more complex emission factors in the future and better research into the factors which actually affect emissions.
For example, a factor now may only be based on the general production throughput. In the future, factors may need to be tailored for the type of material processed, process operating parameters, variations of speed or flow rate, temperature, and the presence and levels of secondary materials.
The use of emission factors is of particular importance in the various air permitting programs, especially in determining the applicability of the Federal Prevention of Significant Deterioration (PSD) or Emission Offset permitting programs. The applicability of these programs is based on whether a source is major and/or whether the modification to the source is major.
Sources undergoing Title V permit reviews now are having their entire permitting history reviewed, specifically to determine whether past modifications should have gone through the PSD or Emission Offset process when they were originally permitted and constructed. These reviews are done using currently available emission factors, which may not have been available when the source was originally permitted.
EPA has made it a priority to identify sources that have "avoided" PSD review. If a determination is made that PSD review was required, then enforcement of fines could be levied and Best Available Control Technology (BACT) must be applied based on today's technology.
New emissions factors also could affect whether a source is "major" and therefore subject to the Title V air operating permit program, or they could alter the emission limitations under a Federally Enforceable State Operating Permit (FESOP). Sources that chose to use the FESOP programs accepted permit conditions designed to ensure they were not major sources under the Title V permit program. Since much of the information on the level of Hazardous Air Pollutant (HAP) emissions from foundry processes has been developed since 1997, sources may need to re-evaluate whether their FESOP permit has adequate limits to ensure that emissions are limited to less than major source thresholds for HAPs. Changing emission factors could also affect the applicability of federal compliance monitoring requirements, which apply to individual process units that are determined to be "major."
In addition to regulatory and permitting issues, sources should reevaluate their compliance status based on new emission factors. A compliance certification submitted with a Title V permit application or under a Title V permit may have been based on an old emission factor. The certification may have been different if the newer factors had been used. In addition, many Title V permits will require emission source tests to prove compliance with applicable limits.
Sources of Foundry Emission Factors
Information on emission factors can be found in several places. Many state regulatory agencies specify the use of EPA's "Compilation of Air Pollutant Emission Factors," which is commonly referred to as AP-42. In addition to AP-42, EPA also publishes databases called AIRS and FIRE, which have factors that supplement the AP-42 factors. Unfortunately, inconsistencies exist in these Federal databases, and often the quality of information supporting the emission factors is poor, resulting in recently published articles and research papers, or from stack testing results on similar emission units.
A considerable body of new emission information for a variety of foundry processes has been developed from research programs, and accumulated source test data from around the country. These new sources of emissions data provide more accurate information that can be used in estimating emissions, but also raise new questions regarding the variability of emissions and the influence of various process parameters that can affect actual emissions and the influence of various process parameters that can affect actual emissions. Some of the newer sources of foundry emissions data include the following:
* the Casting Emission Reduction Program (CERP) has been testing HAP emissions from foundry products and processes for the past five years (see sidebar above);
* the AFS Environmental, Health and Safety Div. committees and the Casting Industry Suppliers Assn. (CISA) have jointly published the "Gold Book" on Form R Reporting of Binder Chemicals Used in Foundries (2nd Edition). This publication lists release rates for SARA reportable chemicals from commonly used binder systems during mold and coremaking and storage;
* the AFS Air Quality Committee (10-E) has compiled "screening" HAP emission factors and a guidance document to assist foundries in developing a preliminary estimate of HAP emissions;
* the Ohio Cast Metals Assn. (OGMA) commissioned a study jointly funded by OGMA and AFS to determine VOC emissions from phenolic urethane binder systems in coremaking and storage. The results of this study were published in "Control of VOCs: Following Ohio's Lead," December 2002, MODERN CASTING.
Knowledge often brings with it a new set of challenges. To meet these challenges, it is recommended that the following evaluations be made. First, Identify whether there are new emission factors available that differ from ones used in past regulatory and permitting activities. If so, re-evaluate your actual and potential emissions using the new information. If appropriate, use one or more factors to establish a range of estimates.
Then, using these revised emission estimates, reevaluate the applicability of Title V, MACT, PSD, etc. If it appears that the new factors change applicability determinations, or compliance determinations, the accuracy of the new emission factors for your specific process should be carefully evaluated. This evaluation may even require emissions testing to establish an accurate estimate for your particular source.
As our knowledge of emissions continues to expand, the foundry industry will be talking about emission factors, emission estimates and their relationship to regulatory programs for years to come. Ultimately, the environment and industry will best be served by accurate, complete emission factors and reasonable policies from government agencies to assimilate the changes resulting form this information.
For More Information
"Practical Solutions to Casting and Shakeout Emissions Control," M. Bedwell and P. Sheehan, MODERN CASTING, December2000, p.32-35.
HAP Testing in Gray Iron
The Casting Emission Reduction Program (CERP) was established in 1994 to evaluate ways to reduce air emissions from foundry processes so that the metalcasting industry can continue to deliver quality products while meeting the new Clean Air Act Standards. CERP is operated under a Cooperative Research and Development Agreement (CRADA) between the U.S. Dept. of Defense, U.S. Army's Industrial Ecology Center and the U.S. Council for Automotive Research (USCAR). Associated members include the U.S. EPA, the California Air Resources Board (CARB), AFS and the Casting Industry Suppliers Assn. (CISA).
Foundry operations face many environmental and competitive challenges in today's regulated society. The 1990 Clean Air Act Amendments contained a set of mandates that includes the Maximum Achievable Control Technology (MACT) requirements. The overall MACT rulemaking process has brought a requirement to more accurately identify and quantify foundry HAP emissions. CERP has been working with all the major foundry suppliers to develop baseline emission levels for current products and processes and compare "lower emitting" product emissions and relative productivity and quality impacts to those baselines.
Data from CERP Mexico testing and U.S. EPA indicates that HAPs coming from melting operations are approximately 8% of the total RAPs from a foundry (Fig. 1), with coremaking and pouring, cooling and shakeout (PCS) HAP emissions representing the remaining 92%. A large portion of major foundries that have control devices on their PCS stacks use dry baghouses to capture the particulate off these operations. Testing at CERP indicates that dry dust collection on pouring, cooling and shakeout has little effect on the organic HAP emissions.
The CERP program has been testing new foundry products that could reduce HAP emissions up to 50% on certain processes with little capital expenditure. Quality and productivity impacts of new materials also must he considered but the opportunity for major emission reduction exists. All major foundry suppliers have been working with CERP and are continuing to develop improved low emission products. These suppliers have the detailed test information and the technical assistance needed to help foundries select lower emitting products and push them into operation without major problems.
CERP continues to evaluate materials and foundry processes that will help reduce foundries' effects on the environment. The organization plans on expanding its research to support the sustainment of the metalcasting industry--By George R. Crandell, Steven M. Knight and Clifford R. Glowacki, Technikon L.L.C.
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About the Authors
Thomas R. Rarick is the senior vice president at Keramida, Inc., Indianapolis. George R. Crandall is the vice president of operations tar Technikon L.L.C., McClellan, California.
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|Author:||Crandell, George R.|
|Date:||Jun 1, 2003|
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