4.17 Flexible & Rigid Discs Manufacturing
Category 44
4.17.1 Introduction
Category 44 accounts for reactive organic compound (ROG) emissions from computer discs manufacturing plants. Manufactured discs are flat, circular plastic film contained in a non-rigid envelope (flexible), or a non-flexible plate (rigid), with a magnetic coating on which digital information can be stored. Manufacturing processes include coating, mixing operations, coating line, and polishing. Organic solvents are used in these operations and emissions from volatile organic compounds are reported in this category.
4.17.2 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 44 is considered a point source category and follows the above methodology for emissions estimates. District Regulation 8 Rule 38 - Flexible and Rigid Disc Manufacturing 101 pertaining to disc coating, polishing and coating mixing operations requirements became effective in January 1987. Currently, the estimated overall control from the manufacture of flexible and rigid magnetic data storage discs rule is approximately 81%.
The total organic gas (TOG) emissions from the Flexible & Rigid Discs Manufacturing category are considered all reactive organic gas (ROG). The ROG:TOG ratio is equal to 1.
4.17.3 Changes in Methodology
There are no changes to methodology for Flexible & Rigid Discs Manufacturing (Category 44).
4.17.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
4.17.5 Trends
(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.
The historical growth profile was based on a combination of permitted emissions data and the Association of Bay Area Government’s (ABAG’s) 2009 Information Employment growth profile.
(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
Projections of emissions to 2040 are assumed to be constant starting from 2020 as the trends for the Flexible & Rigid Discs Manufacturing category.
4.17.6 Uncertainties
According to International Data Corporation (IDC), the computer hard drive industry continue to see demand for data storage capacity. This demand for Flexible & Rigid Discs may lead to uncertainties of emission projections.
4.17.7 Contact
Author: Michael Nguyen
Reviewer: Ariana Husain
Last Update: November 06, 2023
4.17.8 References & Footnotes
BAAQMD. 1995. BAAQMD Regulation 8 Rule 38 - Flexible and Rigid Disc Manufacturing, https://www.baaqmd.gov/~/media/dotgov/files/rules/reg-8-rule-38-flexible-and-rigid-disc-manufacturing/documents/rg0838.pdf?la=en&rev=a9a079aa9ba448bfae8265ac28ca9dff↩︎