5.4 Other Waste Management
Category 53
5.4.1 Introduction
Category 53 accounts for PM and TOG emissions from miscellaneous industrial and commercial waste management facilities. The operations and facilities included in this category are recycling and transfer stations, hazardous waste, waste management at chemical plants, marine terminals etc.
The focus of Category 53 is mostly process-related emissions of PM and TOG . Emissions for this category are obtained from point source data only, as contained in the District’s internal permitting system. Greenhouse gas emissions, namely carbon dioxide (CO2) was also calculated for this category.
5.4.2 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 53 is considered a point source category and follows the above methodology for emissions estimates. The PM2.5/PM and the PM10/PM ratios applied to this category 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, PM speciation ratios used by other regional air quality agencies, and other relevant literature. These ratios are not necessarily consistent with the latest speciation profiles developed by CARB141 or the US Environmental Protection Agency142. For Category 53, PM2.5 constitutes 92.5% of total PM and PM10 constitutes 96% of total PM. The Air District staff routinely review speciation profiles and may update ratios as needed for improving emissions estimates.
5.4.3 Changes in Methodology
No changes in methodology were made in this version of the base year emissions inventory as compared to the previous version.
5.4.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
This category primarily accounts for PM emissions. Total PM emissions from this category have ranged between 200 to 400 tons/year in the past twenty years making it a reasonably important source of PM.
5.4.5 Trends
(a) Historical Emissions / History
Historical emissions for point sources 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 permitting database which is queried to retrieve 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.
PM emissions peaked in the late-1990s and have decreased gradually over the years. In general, emissions have remained steady and averaged around 200-250 tons/year in the last decade. No significant change in throughputs, emission factors or regulation-driven control factors are observed in the historical emission trends.
(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 this 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 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 are 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 Governments143, fixed-percentage growth assumptions consistent with historical emissions data trends, and specific growth profiles derived using relevant regional or sub-national data sources. For this category, future projections are based on a California-specific greenhouse gas industrial growth profile developed in the mid-2010s by researchers at Lawrence Berkeley National Laboratory144. This growth profile takes into account both adopted and in-legislature emission reduction mandates, policies and targets.
5.4.6 Uncertainties
The main uncertainty in estimating emissions for this category is that the emission factors used for calculating PM emissions have mostly remained unchanged since the mid-1990s, and no controls have been placed on these operations. These estimates may be based on outdated emission factors. At present, there is no validation of these estimates using source testing. The overall magnitude of PM emissions from this category is reasonably large so improvements to emission factors would be useful.
5.4.7 Contact
Author: Abhinav Guha
Reviewers: Tan M. Dinh and Yuan Du
Last Update: November 06, 2023
5.4.8 References & Footnotes
CARB. 2022. PMSIZE. https://ww2.arb.ca.gov/speciation-profiles-used-carb-modeling↩︎
USEPA. 2022. SPECIATE. https://www.epa.gov/air-emissions-modeling/speciate↩︎
ABAG. 2017. Plan Bay Area 2040. http://2040.planbayarea.org/files/2020-02/Final_Plan_Bay_Area_2040.pdf↩︎
CALGAPS. 2015. Energy Policy. https://doi.org/10.1016/j.enpol.2014.12.024↩︎