6.7 Gasoline Truck Transport
Categories 1600, 1601, and 1602
6.7.1 Introduction
Categories 1600, 1601, and 1602 account for organic emissions (TOG and ROG) from Gasoline truck transport losses. Gasoline truck transit losses are similar in many ways to breathing losses associated with petroleum storage. The gasoline is transferred by tank trucks from refineries and bulk plants for delivery to end user outlets. Emissions depend on the vapor tightness of the tank, the pressure relief valve settings, the pressure in the tank at the start of the trip, the vapor pressure of fuel being transported, and the degree of fuel vapor saturation of space in the tank. Categories 1600, 1601, and 1602 account for total emissions from the above actions. Category 1600 accounts for emissions from the Cargo Tank, Category 1601 accounts for emissions for losses from the return vapor hoses during the loading of gasoline, 1601 accounts for losses from the main hoses during loading of gasoline.
6.7.2 Methodology
These categories accounts for the organic emissions occurring in transit while transporting fuel by tank trucks. Emissions from gasoline cargo tanks include the fugitive emissions and emissions from maintenance. The emission points are from pressure-related fugitive (category 1600, Cargo Tank) emissions from the cargo tank fittings and valves, vapor hoses (category 1601, Loading-Return Vapor Hoses) after loading into the underground tank, and wetted wall emissions from the product (category 1602, Loading-Main Hoses).
Pressure-related fugitive (category 1600, Cargo Tank) emissions are volatile organic vapors leaking from fittings, valves and other connecting points in the vapor collection system on a cargo tank. Pressure inside the cargo tank is caused by solar and reflective heat gains. Due to these heat gains, vapors inside the cargo tank expand and exert pressure to the tank walls, fittings and valves.
Emissions from the vapor hose (category 1601, Loading-Return Vapor Hoses) are a result of vapors trapped inside the hose after product delivery to the underground tank. Some vapors condense inside the hose. When the hose is disconnected from the underground tank and truck fittings, the vapors and condensed vapor inside the hose are emitted into the ambient air.
Emissions from the product hoses (category 1602, Loading-Main Hoses) are a result of residual product clinging to the walls of the hoses. Residual liquid, inside the hose, vaporizes into the ambient air resulting in emissions.
These categories are considered area source categories since they cover facilities / emission sources that are not directly permitted by the District, and hence not systematically cataloged. Emissions for area source categories are determined using the formula:
Current Year Emissions = Base Year Emission X Growth Profile, and,
Base Year Emission = Throughput X Control Factor X Emission Factor
where,
- throughput or activity data for applicable base year(s) is determined using a top-down approach (e.g. state-, national-level data);
- emission factor is derived from general literature, specific literature and reports, and/or source testing results provided by Air District staff;
- control factor (if applicable) is determined by District and state rules and regulations in effect;
- and, historical backcasting and forecasting of emissions is based on growth profiles as outlined in the Trends section of this chapter
More details on throughput, county distribution, emission factors and controls is provided in the following subsections.
(a) Activity Data / Throughput
The estimates of gasoline consumption in the Bay Area were obtained from California Energy Commission (CEC) , California Annual Retail Fuel Outlet Report Results 177 report.
(b) County Distribution / Fractions
County annual gasoline fuel consumption distributed into the Bay Area counties were based on CEC California Annual Retail Fuel Outlet Report County breakdown. The gasoline consumption throughput for Solano and Sonoma counties is apportioned based upon CEC’s throughput and CARB’s county estimated emissions.
(c) Emission Factors
This methodology is presently based on CARB’s methodology 178. TOG emission factors are listed below:
- Pressure-Related (category 1600) Losses: 0.588 lbs per 1000 gallons,
- Vapor Hose (category 1601) Losses: 0.024 lbs per 1000 gallons,
- Product Hose (category 1602) Losses: 0.133 lbs per 1000 gallons.
(d) Control Factors
These Gasoline Truck Transport categories had been originally developed by CARB. There are no specific CARB regulations to control emissions from these categories.
(e) Speciation
The total organic gas (TOG) emissions from these three Gasoline Truck Transport categories are considered all reactive organic gas (ROG). The ROG:TOG ratio is equal to 1.
6.7.3 Changes in Methodology
No major changes in methodology were made in this version of the base year emissions inventory. The base year estimates of gasoline consumption (Annual throughput) for these Gasoline Truck Transport categories were obtained from CEC.
6.7.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
6.7.5 Trends
(a) Historical Emissions/History
Prior to Base Year 1999, taxable gasoline sales for California obtained from the Board of Equalization were assumed to distribute to all gasoline filling stations. Gasoline consumption in 2007 reached record levels. However, the gasoline consumption decreased slightly during the economic recession in 2008-2010. Base Year 2011 gasoline consumption in the Bay Area was based on the California State Board of Equalization, Fuel Taxes Statistics & Reports and Caltrans Transportation Planning Support Information System (TPSIS). These estimates were made by adjustments of Gasoline Dispensing Facility sales, population, number of registered vehicles, and the number of drivers’ license. In 2012, California Air Resources Board (CARB) updated the emission factors for gasoline storage, transfer operations from cargo tank trucks, fuel containers, and gasoline-powered equipment.
(b) Future Projections/ Growth
Projections are based on CARB’s EMission FACtor (EMFAC) model, EMFAC2021 179, which includes estimates of gasoline consumption in the Bay Area.
Due to the coronavirus pandemic impact on the economy, gasoline consumption dropped significantly in 2020. With the new requirements of the California Executive order 180 to phase out gasoline powered cars and passenger trucks by 2035, the GDF categories’ emissions are expected to be further reduced for forecasted emission years.
6.7.6 Uncertainties
The gasoline consumption estimates for Solano and Sonoma counties could also contribute to an increased uncertainty of the Bay Area gasoline consumption.
6.7.7 Contact
Author: Minh Nguyen
Reviewer: Ariana Husain
Last Update: November 06, 2023
6.7.8 References & Footnotes
CEC. 2021. California Annual Retail Fuel Outlet Report Results (CEC-A15), https://www.energy.ca.gov/data-reports/energy-almanac/transportation-energy/california-retail-fuel-outlet-annual-reporting↩︎
CARB. 2003. Petroleum Production and Marketing Methodologies - Petroleum Marketing, Section 4.11-Gasoline Cargo Tanks, https://ww3.arb.ca.gov/ei/areasrc/onehtm/one4-11.htm↩︎
CARB. 2022. EMFAC2021 emissions inventories of onroad mobile sources in California: https://arb.ca.gov/emfac/↩︎
CA Executive order. 2020. Governor Newsom Announces California Will Phase Out Gasoline-Powered Cars & Drastically Reduce Demand for Fossil Fuel in California’s Fight Against Climate Change, https://www.gov.ca.gov/2020/09/23/governor-newsom-announces-california-will-phase-out-gasoline-powered-cars-drastically-reduce-demand-for-fossil-fuel-in-californias-fight-against-climate-change/ ↩︎