NOTE: The Activity Guide titled "ALTERNATIVE FUELS - WHAT ARE THEY?" must be completed before using this guide.

To understand Liquified Petroleum Gas (LPG) as optional fuel and the technological effects of LPG as an alternative fuel.

The students will learn LPG's effects as an alternative fuel with respect to:

1. vehicle fuel economy,
2. the environment, and
3. technical changes in the vehicle.

Historically, propane has been used as a motor fuel by tens of thousands of fleet users, agricultural machinery, and materials handling equipment for over eighty years. Propane (LPG) powers innumerable school buses, taxis, police cruisers, forks lifts, farm tractors, as well as "zamboni" vehicles to dress hockey rink ice.

Several factors affect the use and selection of any fuel. Of particular importance are engine design, net energy per pound, net energy per gallon and the fuel's sulphur content. Present design internal combustion (IC) engines run on liquid fuels. For an engine designed for gasoline to run on LPG, significant modifications are needed. If an engine is dual fueled, more weight is added to the vehicle (approximately 350 - 400 pounds) and cargo / passenger space is sacrificed (up to 20 cu. ft. of space under the hood and in the trunk) for fuel tanks.

These dual fueled vehicles are known as hybrid demonstration vehicles to expose the public to LPG gas vehicles by demonstrating how LPG performs in a standard engine. The agricultural and industrial sectors have used LPG in tractors and forklifts for years. Many school buses presently operate on LPG. These LPG vehicles are usually "dedicated," that is, they are not dual fueled. While LPG presently accounts for about 1% of the U.S. transportation industry's energy usage, serious impediments prohibit it from widespread usage. It is heavier than air; therefore, if leaks occur it collects near the ground as a vaporized liquid and thus fire and explosion hazards exist. Underground tunnels prohibit LPG vehicles, although its ignition temperature is 900°F compared to 120°F for gasoline. LPG is significantly heavier than gasoline and has little or no CO and CO2 emissions advantage over gasoline although sulphur-based acid-type pollutants are somewhat reduced. LPG powered vehicles emit higher levels of NOx emissions.

Most laboratory tests give LPG an emission advantage over gasoline in emitted unburned hydrocarbons. LPG is mostly made from by-products of oil refining. It's limited in availability and is kept artificially cheap as a result. This has been accomplished by the plastics industry since they use considerable quantities of propane as feed stock. If propane were more widely used as an alternative fuel, then its price would surely rise. LPG prevents premature engine wear, doesn't contaminate engine oil, and is a higher octane fuel than gasoline.

Several manufacturers offer LPG powered vehicles. Other manufacturers have licensed and marketed retrofit "kits" to convert gasoline engines to operate on LPG as well as gasoline (dual fueled) or to operate solely on LPG. Some lift truck manufacturers offer an LPG option in production. Photographs 1 through 4 show how a late model fuel injected engine may be converted to dual fueled. Number 1 shows an under hood view; photograph 2 shows that the main conversion components are the fuel line lock, the expansion/pressure regulator, and the mixing control; photograph 3 shows the tank connections with the safety cover removed (for illustration purposes only); and photograph 4 shows the fuel fill connection.

Photograph 1

Photograph 2

Photograph 3

Photograph 4

Dual fuel conversion kits are controversial. According to Stuart R. Perkins, Director of Engineering for Chrysler of Canada, "with the same emission control equipment, conversions will deteriorate emission results. Worse yet, in dual-fuel conversions, the emissions from the engine when operating on gasoline are also worse."1 Many automotive engineers believe that emissions problems and slightly reduced fuel economy problems could be overcome by totally redesigning the engine for LPG. However, this could be a costly gamble. LPG and all alternative fuels must compete with gasoline for market share. With a spotty fuel distribution infrastructure and little real or perceived advantages other than a presently lower price, the motoring public is not likely to switch from gasoline, the product they know can deliver what they expect. Presently, Canada has over 5,000 auto propane refueling stations. Many of these use pumps that look and operate like the gasoline pump. Canada's average propane price per gasoline equivalent gallon is 30-50% less than gasoline. Presently, propane prices fluctuate from summer to winter seasons.

1. Use the chart on the next page to determine what type of vehicles are available in your area which use gasoline or LPG. Determine what type of vehicles are available powered only by LPG.

2. Determine if LPG conversion systems are available in your area.

3. For each LPG vehicle or LPG conversion system, determine each of the following:
a. LPG associated extra cost for a new vehicle; cost (materials and labor) to install the system;

b. maintenance requirements or changes if any;

c. changed operational characteristics for drivers;

d. number of available fueling stations in immediate area;

e. cost for fuel compared to pure standard gasoline.

Type of Vehicle Type of System Fuel System
Type of
can be used
and Labor)
Cost of Fuel







LPG: $ _______________________________

STANDARD GASOLINE:$_________________________

Directions: Indicate whether the statements below are true or false. If the statement is false, explain why it is false.

1. LPG and CNG are the same fuel but they are distributed differently.

2. A dual fueled LPG/gasoline vehicle will gain more dead weight and lose trunk/cargo space.

3. LPG powered vehicles should produce less unburned hydrocarbons and tailpipe emissions than a comparable gasoline powered vehicle.

4. Conversion to propane from gasoline is not possible for a computer controlled fuel injected engine.

5. Which of these hinder wide public use of propane?
a. unstable price
b. unfamiliar looking refueling stations
c. low fuel cost
d. hard, cold starting problems
e. both "a" and "b"

Propane, Butane, LPG? While propane and butane are slightly different, both are considered LPG. LPG has been used for years by industry, agriculture, and fleets. Many automotive technicians support LPG as a good, clean, safe fuel. Engine wear is minimized, crankcase oil becomes less polluted, and there is little perceptible loss of engine power on throttle response. This guide gives students a look at an old fuel that is now getting a second chance as an alternative fuel.

1. False. LPG is usually a by-product of refinery oil. It may also be made from natural gas.
2. True.
3. True.
4. False. The photos described such a conversion.
5. E. Both an unstable price and unfamiliar looking refueling stations and procedures inhibit many consumers from considering propane as an alternative fuel.

1LP Gas Alternative Fuel Symposium Proceedings. National Propane Gas Association,December, 1992.

New Transportation Fuels, American Petroleum Institute, Washington, D.C.-1991. Special Issue Department, Public Affairs Group, _______.

The Automobile. Earth Day, 1990, Fact Sheet, Stanford, CA. 1990.

Gordon, Deborah, Steering A New Course: Transportation, Energy, and the Environment. A Report by the Union of Concerned Scientists, Cambridge, MA 1991.

Motor - Vehicle Fuel Efficiency and Global Warming. Union of Concerned Scientists Briefing Paper: Cambridge, MA. 1991.

Duffy, James E., editor and Howard Bud Smith. Auto Fuel Systems. Goodheart Wilcox Co., South Holland, Illinois. 1987.

Scharff, Robert. Complete Fuel Systems and Emission Control. Delmar Publishers, Inc., Albany, NY. 1989.

Bata, Reda M. Ethanol and Methanol Blends with Gasoline; an Experimental Approach to Engine Performance and Emission. Unpublished Dissertation. 1985.

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