MOUNT VERNON — Many people may not know the liquid petroleum gas used by homeowners to heat their homes can also be used as fuel for car and truck gasoline engines. There are quite a few trucks on the road fueled with LPG, or LP gas, as it is sometimes called.
LP gas is being promoted as an alternative fuel source for gasoline-powered engines, by the industry and through the 1992 Energy Policy Act passed by Congress. The purpose of the act is to decrease the use of foreign oil and encouraging use of domestically produced alternative fuels for national security. Anxious to promote alternate fuels, the government has provided tax breaks to users.
Proponents say there are four reasons to use LP gas for motor fuels. One is, it is “green,” and causes less air pollution than gasoline. Two, it is a much cleaner fuel and does not contaminate engine oil, and leaves practically no carbon deposits on valves and in the combustion chamber. The third reason is that LP gas is produced in the United States and fourth, it is cheaper — now about 2.25 cents per gallon — than gasoline. In addition, say proponents, because LP gas burns cleaner, engine wear is reduced.
The reduction in emissions is pretty dramatic according to Orange County, Calif., Transit Authority. Its fleet of buses show an 87 percent decrease in total hydrocarbons, 50 percent of nitrogen oxides and 40 percent lower in particulate matter emission.
Use of LP gas as a fuel for engines has been around since the middle 1950s, and has gradually increased over the years. But with crude oil becoming increasingly scarce and pricey, alternative fuels have taken on a new urgency.
Sixty percent of LP gas is produced from natural gas, where it is “stripped,” or refined, from the natural gas as it comes from wells. The other 40 percent is extracted from crude oil produced in the United States.
Typical users of propane are fleets of vehicles, such as a city’s cars and trucks, bus fleets or taxicab fleets. Proponents say a central refueling station makes fleet use practical. LP gas-fueled cars are widespread in Europe, especially in England.
If propane use is to become widespread, refueling stations need to be easy to install. Bob Wise, a local distributor of LP gas, said the cost of installing a propane refueling station is about one third the cost of setting up a gasoline station. A tank to hold the LP gas, refueling pumps and meters to measure the flow is all that is needed.
According to Wise, there are two refueling stations in Knox County, one in Fredericktown, the other in Apple Valley. Expanding the use of LP gas depends on the availability of refueling stations. It is not necessary, he said, to redesign current gasoline engines to use LP gas.
LP gas is refined from natural gas; it is turned into a liquid by compressing it. A container of LP gas sitting in open air would return to a gas, so it is confined to a tank to keep it in a liquid state.
At 44 degrees below zero Fahrenheit, there is no pressure in a tank. At zero degrees there is 25 pounds of gas pressure, and at 70 degrees, 125 pounds of pressure. LP gas tanks are specially designed to hold that type of pressure.
Feeding LP gas to the engine is done by running the liquid into a converter that is warmed by engine heat, and turning the liquid back to a gas. Then the gas, mixed with air, is drawn into the engine.
Now, CleanFuel USA has developed fuel injection for LP gas. The injection system was developed by the German company Siemens and Walbro, and adapted for use on General Motors’ medium-duty, gasoline-powered trucks. CleanFuel USA emphasizes the simple design of three major component assemblies: The fuel tank assembly made to hold LP gas under pressure; tow injectgor fuel rail and injector assemblies; and flow control wiring harness. The setup uses orginal equipment power train control wiring harness.
It works exactly like the fuel injection on current gasoline engines. Designed for LP gas, the injectors inject the liquid, which instantly turns to gas in the intake manifold. A side benefit from the use of LPgas is the octane rating is 105 versus 87 octane for regular unleaded gasoline. This increases horsepower by a small amount.
When GM receives an order for a propane-powered truck, it is taken from the assembly line to a department that installs the LP gas injection system. Needing another LP gas delivery truck, Wise chose one of the GM conversions on the 8.1 liter V-8 gasoline engines. The truck is now in service, and Wise said the LP gas delivers the same fuel mileage as his diesel-powered truck — five miles per gallon. A drive in the truck gives no indication as to the kind of fuel powering the it.
The Ford Motor Co. has entered the field with LP gas and LP gas conversion for the 5.4 liter V-8 engine that powers the F-150 pickup.The conversion is made by Roush Industries, a Livonia, Mich., firm involved in racing and high performance Ford cars.
