9.3 Agricultural Equipment
Categories 1655, 1656, and 1646
9.3.1 Introduction
Categories 1655, 1656, and 1646 account for exhaust emissions (NOx, CO, PM, PM10, PM2.5, ROG, SO2, and TOG) from agricultural equipment burning gasoline and diesel fuel while engaged in farming operations.
9.3.2 Methodology
The agricultural equipment emissions are derived by California Air Resources Board (CARB) inventory staff. This significant emissions dataset, sorted by county, is published every few years and is a product of the State Implementation Plan (SIP) emissions document formally known as the California Emissions Projection Analysis Model (CEPAM) inventory. BAAQMD staff export the emissions data directly from CEPAM into the District’s Base Year inventory package. This calculation approach and collection of categories are internally termed as “CARB Source Categories”.
The current base year inventory uses the 2016 CEPAMv1.05346 to estimate emissions from “CARB Source Categories”. This version of the CEPAM derives emissions from a 2012 base year inventory and contains backcasts and forecasts from year-2000 to year-2035. All applicable regulatory and technological controls are assumed to be built into the CEPAM dataset during CARB staff’s inventory computation work. After the emissions data are exported, the inventory for CARB Source categories is taken through a quality assurance (QA) process.
9.3.3 Changes in Methodology
The current base year inventory emissions data were obtained from the CARB’s 2016 CEPAMv1.051. In comparison, the emissions in the previous inventory methodology involved area source categories derived from the CARB’s OFFROAD2007 model.
9.3.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
9.3.5 Trends
(a) Historical Emissions / History
California Air Resources Board (CARB) developed the 2007 Off-road vehicle emission inventory (OFFROAD2007) model to estimate emissions from off-road motor vehicles for all counties and air basins in California. The 2007 OFFROAD model contains a more comprehensive list of equipment from a wider range of categories compared to BAH. The OFFROAD model adds an inventory estimate for engines powered by diesel fuel, compressed natural gas (CNG), and liquid petroleum gas (LPG). The criteria and GHG emission data for farm equipment categories in the Bay Area were obtained from the CARB’s OFFROAD2007 model.
(b) Future Projections / Growth
Emissions forecasting was done by holding the year-2035 emissions data constant through and up to year-2040. For CARB Sources, emissions are forecasted by CARB staff by applying growth profiles to the base year-2012 inventory data (see above in ‘Methodology’ section).
(c) Control
In December of 1990, the CARB adopted two levels of emission standards for small off-road engines. The first phase of standards (Tier 1) was implemented in 1995347 and Tier 2 standards are scheduled for implementation in 1999. The deterioration rates for 4 stroke Tier 1 engines were derived from data supplied by engine manufacturers. Since engines meeting Tier 2 standards are not yet available, engineering judgment was used to estimate the effect of the more stringent standards.
Projected emissions include expected benefits from ARB’s Clean Diesel Regulations in 1993, Re-Formulated Gasoline Phase II and EPA’s diesel engine standards beginning 1999. These benefits were estimated using control factors developed by ARB.
9.3.6 Uncertainties
The estimated agricultural equipment emissions for Solano and Sonoma counties under District’s jurisdiction may contribute to an increased uncertainty of the Bay Area Off Road emissions.
9.3.7 Contact
Author: Michael Nguyen
Reviewer: Ariana Husain
Last Update: November 06, 2023
9.3.8 References & Footnotes
CARB. 2016. California Emissions Projection Analysis Model (CEPAM) inventory. https://www.arb.ca.gov/app/emsinv/2016ozsip/2016ozsip/fcemssumcat_2016o3sip105.php↩︎
CARB. 1995. California Exhaust Emission Standards and Test Procedures For 1995 and Later: Small Off-Road Engines. https://ww2.arb.ca.gov/sites/default/files/barcu/regact/sore/test_fin.pdf?_ga=2.97100055.962285900.1646782104-423543219.1584725377↩︎