6.25 Miscellaneous Organic Evaporation
Category 282
6.25.1 Introduction
Category 282 accounts for organic gas (TOG and ROG) emissions from miscellaneous sources. Emissions from various types of equipment that are not defined in other categories and therefore designated as “other” or “miscellaneous” are combined to make up the emissions in this category.
6.25.2 Methodology
Point Sources are operations that emit air pollution into the atmosphere at a fixed location within a facility, for which the Air District has issued a permit to operate, e.g. refinery cooling towers. These could also be a collection of similar equipment / sources located across multiple facilities, e.g. reciprocating engines.
During the permit to operate (PTO) issuance process, the BAAQMD collects information from the operating facility and/or determines from published literature, e.g. EPA’s AP-42, characteristics of a source including maximum throughput, emission factors for emitted pollutants, and control factors associated with downstream abatement devices. These characteristics are then stored for future use in the BAAQMD’s internal database. Facilities that hold a permit to operate are required to renew this permit periodically (this period varies based on facility and source type). Upon renewal, the facilities are requested to provide any updates to source characteristics as well as the source throughput for the last 12 months. This throughput, in combination with the emission factors and controls factors stored in the internal database, are used to estimate annual emissions at the source level. These source level emissions are then sorted and aggregated into categories.
Further speciation and quality assurance of emissions are performed as a part of the inventory process. The BAAQMD staff also perform a systematic crosswalk between CEPAM’s source category classification (Emission Inventory Code - EICs) and the District’s source category classification (category identification number - cat_ids), which ensures consistency in the annual emissions reporting process (CEIDARS) to California Air Resources Board. The last part of the inventory development process includes forecasting and back casting, and aggregation into sub-sectors and sectors for documentation purposes. For those years where no data is available, emissions data are backcasted to year-1990, as well as forecasted to year-2040 using either interpolation or another mathematical approach (see Trends section). Finally, emissions trends spanning from year 1990-2040 for each category and pollutant are evaluated for anomalies that are then investigated and addressed.
Category 282 is considered a point source category and follows the above methodology for emissions estimates.
The ROG/TOG ratios applied to this category or this group of related categories are based on an Air District internal speciation profile. Multiple data sources have been used for developing speciation profiles, such as Air District-approved source tests, TOG speciation ratios used by other regional air quality agencies, and relevant literature including latest speciation profiles developed by CARB264 and the US Environmental Protection Agency265. For this category or group of categories, ROG constitutes 70% of TOG. Further assessment and improvement of ROG/ TOG speciation profiles has been planned in future inventory updates.
6.25.3 Changes in Methodology
No changes in methodology were made in this version of the base year emissions inventory.
6.25.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
6.25.5 Trends
Sources in this category may be subject to Rule 8-4266. The purpose of this Rule is to "limit emissions of volatile organic compounds from the use of solvents and surface coatings in any operation other than those specified by other Rules of the Regulation 8. Originally passed in 1980, this rule has been amended several times—the latest being in 2002 regarding surface preparation standards.
Starting from 1998, organic emissions remain fairly consistent with slight decreases and increases from year to year.
(a) Historical Emissions / History
Historical emissions for category 282 are derived from source-specific throughputs provided by the permitted facility, compiled/reported emission factors, and regulation-based control factors. This information is archived in the BAAQMD’s internal database which is queried to retrieve the data for historical and current years. Interpolation techniques to account for missing data are used when necessary, this is the case for years 1991-1992.
(b) Future Projections / Growth
Forecasting of emissions for category 282 is done based on calculations as shown in the equation below using recently updated growth profiles and a base year of 2020. The growth profiles for this inventory have been verified and updated to represent the most likely surrogate for growing emissions for a given category up to year 2040. Forecasting for point source emissions includes impact of in-place regulations, but does not include estimation of controls that will theoretically be implemented as part of future policy emission targets or proposed regulation and legislation.
\[ \text{PE} = \text{Gr} * \text{Ci} * \text{Ei} \]
\(PE\) = projected emissions of pollutant i in a future year
\(Gr\) = growth rate by economic profile of industry or population
\(Ci\) = control factor of pollutant i based on adopted rules and regulations
\(Ei\) = base year emissions of pollutant i
For category 282, emissions are grown from year 2020 to 2040 using the 2017 ABAG growth profile for Manufacturing and Wholesale Employment267.
6.25.6 Uncertainties
The emissions for point source category 282 are estimated based on either factors derived from literature or source testing. Uncertainty in emissions are directly linked to the percent (%) error associated with the specific emission factors applied to any single source. In general, the emissions for sources in category 282 are based on the VOC content for the organic solution being evaporated as stated on the Safety Data Sheet which is considered a well tested and accurate source.
6.25.7 Contact
Author: Ariana Husain
Reviewer: Michael Nguyen
Last Update: November 06, 2023
6.25.8 References & Footnotes
CARB. 2022.ORGPROF. https://ww2.arb.ca.gov/speciation-profiles-used-carb-modeling↩︎
U.S. Environmental Protection Agency (EPA). 2022. SPECIATE.https://www.epa.gov/air-emissions-modeling/speciate↩︎
BAAQMD. 2002. Regulation 8, Rule 4 - General Solvent and Surface Coating Operations. https://www.baaqmd.gov/rules-and-compliance/rules/reg-8-rule-4-general-solvent-and-surface-coating-operations↩︎
Association of Bay Area Governments (ABAG). Forecasts and Projections. [accessed 2023 Feb 22]. https://abag.ca.gov/our-work/land-use/forecasts-projections↩︎