Research Projects

Project at a Glance

Project Status: complete

Title: Determination of usage patterns and emissions for propane/LPG in California

Principal Investigator / Author(s): Sullivan, Michael

Contractor: Freeman, Sullivan, & Co. and Systems Applications International

Contract Number: A032-092

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels


The purpose of this study was to determine the usage patterns of liquified Petroleum Gas (LPG) and to estimate propane emissions resulting from LPG transfer operations for the entire state of California, and then for each of its counties and Air Basins. The importance of this study is that this is the first attempt to quantify LPG transfer emissions for California. No similar estimates exist in any prior government-sponsored or private industry research.

Freeman, Sullivan & Co. (FSC) and Systems Applications International (SAI) estimated state-wide propane emissions in three ways: by analyzing data collected through a telephone survey of businesses using LPG in California, by extracting information from existing data bases, and by using information provided by the Western Uquid Gas Association (WLGA) and the National Petroleum Gas Association (NPGA). These data and information contributed to the formulation of an emissions model which was used to calculate propane emissions for six significant LPG use-categories:

* Agricultural,
* Commercial,
* Engine Fuel Applications: Industrial,
* Residential, and
* LPG Distributors.

Usage patterns and related emissions were then estimated for each of the 58 counties and the 14 Air Basins in the state.

Results of this study concluded that the total estimated emissions for 1991 due to LPG transfers to be 1,131 tons per year (3.11 tons per day). The source distribution of this total amount among the six LPG-use categories is: industrial users, 456.3 tons per year; engine fuel use, 214.1 tons per year; residential use, 198.7 tons per year; distributors, 180.2 tons per year; agricultural use, 42.3 tons per year; and commercial use, 39.9 tons per year. The Air Basins with the largest emissions were South Coast at 345.5 tons per year (30.5% of total). San Francisco at 209.9 tons (18.6% of total). San Joaquin Valley at 146.9 tons (13% of total). and Southeast Desert at 144.9 tons per year (10.2% of total). The other Air Basins accounted for 314.4 tons per year (27.7% of total).

The 1,131 tons per year represents approximately 464,000 gallons of LPG This is 0.064% of the 722 million gallons of LPG transferred in California last year.

These emissions should be viewed in light of propane's relatively low ozone forming ability (compared to other organic emissions) and the fact that there is virtually no likelihood of human toxic effects in outdoor atmospheric concentrations.

Outage / bleeder vapor value emissions were found to have as much significance as filling line disconnect emissions. It is recommended that when filling LPG containers, safe alternatives which do not rely on the outage / bleeder valve should be used.


For questions regarding research reports, contact: Heather Choi at (916) 322-3893

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