3.2 Resins
Category 24
3.2.1 Introduction
Category 24 accounts for organic emissions from operations performed at resin manufacturing facilities.
Resin is a semi-solid, water insoluble organic material with little or no tendency to crystallize under standard temperature and atmospheric conditions. Resins are the basic components of plastics and other surface coating formulations. Equipment used in the operations and manufacturing of resins include resin reactor vessels and thinning/blending tanks. The manufacturing of resins produces mostly organic emissions.
3.2.2 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 24 is considered a point source category and follows the above methodology for emissions estimates. For this category, emissions have increased due to increasing demand from related industries, such as plastics and coating manufacturers. To limit and reduce emissions from this category, District’s Regulation 8, Rule 36 11, was adopted in June 1984 and place limits the emissions of precursor organic compounds from resin manufacturing operations.
3.2.3 Changes in Methodology
There are no changes in the methodology to estimate emissions in the current base year inventory as compared to the previous base year inventory (year 2011).
3.2.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
3.2.5 Trends
Activities/throughputs have increased due to increasing demand from related industries, such as plastics and coating manufacturers.
(a) Historical Emissions / History
Historical emissions for point source emissions 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.
As previously mentioned, historical emission has significantly decrease since the adoption of District Regulation 8, Rule 36 1, which limits precursor organic compound emissions from resin manufacturing operations.
(b) Future Projections / Growth
Forecasting of point source emissions 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 the current base year 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 past or 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 a given category or a group of related categories, future emissions estimates were developed using a growth profile based on data available from a handful of resources. These resources include employment- and population-based growth projections generated by the Association of Bay Area Governments12, fixed-percentage growth assumptions consistent with historical emissions data trends, and specific growth profiles derived using relevant regional or sub-national data sources (e.g. county-specific wine production data from the Wine Institute for wine fermentation categories, California crude oil distillation capacity data from the Energy Information Administration for refinery categories, and California Energy Commission natural gas usage projection data for residential and commercial natural gas combustion categories). For this category(s), projections to year 2040 were based on growth profile generated by California Air Resources Board (ARB) for Chemical Manufacturing which shows a growth between 2-3 percent per annum.
3.2.6 Uncertainties
Throughputs for this category are reported by facility via permit system requirement on a year by year basis and are assumed to reflect the most current data available at the time. Throughput data that are taken based on source test is considered the most accurate, followed by engineering calculations such as mass/material balance, and then published data via literature such as AP-42. The emission factor is estimated using historical data and could change or be improved as new data is published.
3.2.7 Contact
Author: Tan Dinh
Reviewer: Abhinav Guha, Yuan Du
Last Update: November 06, 2023
3.2.8 References & Footnotes
BAAQMD. 1984. Reg 8-36. https://www.baaqmd.gov/rules-and-compliance/rules/reg-8-rule-36-resin-manufacturing↩︎
Plan Bay Area 2040. ABAG 2017. http://2040.planbayarea.org/files/2020-02/Final_Plan_Bay_Area_2040.pdf↩︎