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Propane

Background

Propane has been used as a vehicle fuel worldwide for decades. Also known as liquefied petroleum gas (LPG), propane is a domestically produced, well-established, clean-burning, high-energy alternative fuel that can power light, medium and heavy-duty propane vehicles.

Propane is produced as a by-product of natural gas processing and crude oil refining. It accounts for about 2% of the energy used in the U.S., and of that, less than 2% is used for transportation fuel. Propane is relied upon in rural areas where natural gas is unavailable, and is mainly used for home and water heating, cooking and refrigerating food, clothes drying, powering farm and industrial equipment, and drying corn.

How it Works

Propane is a three-carbon alkane gas (C3H8). It is stored under pressure inside a tank and turns into a colorless, odorless liquid. As pressure is released, the liquid propane vaporizes and turns into gas that is used for combustion.

There are two types of propane vehicles: dedicated and bi-fuel. Dedicated propane vehicles run only on propane. Bi-fuel propane vehicles have two separate fueling systems that enable the vehicle to use either propane or gasoline. There are also two types of fuel injection systems: vapor injection and liquid propane injection. In both types, propane is stored as a liquid in a relatively low-pressure tank.

Propane vehicles work much like gasoline-powered vehicles with spark-ignited engines. In vapor injected systems, liquid propane travels along a fuel line into the engine compartment. The supply of propane to the engine is controlled by a regulator or vaporizer, which converts the liquid propane to a vapor. The vapor is fed to a mixer located near the intake manifold, where it is metered and mixed with filtered air before being drawn into the combustion chamber where it is burned to produce power. Liquid propane injection engines do not vaporize the propane. Instead, it is injected into the combustion chamber in liquid form.

Availability

Development of new light, medium and heavy-duty propane vehicles has surged for fleets in recent years, resulting in a variety of models available today. Fleets and consumers also have the option of economically, safely and reliably converting existing gasoline or diesel vehicles for propane operation using qualified system retrofitters. 

There are more than 270,000 on-road propane vehicles in the U.S. today, many of which are used in fleet applications, such as police cars, shuttles and school buses.

Cost

The average price for propane fuel nationwide in 2013 was $2.73, which is about $0.92 cheaper than gasoline. However, because propane has about 25% less energy (BTUs) per volume, it takes more fuel to drive the same distance. The result is a fairly comparable cost per mile between propane and gasoline.

Incentives

There are a variety of Federal, State and local propane incentives. To search by zip code, visit our Incentives page.

Fueling

While there are thousands of propane fueling stations in the U.S., fueling infrastructure is still limited enough that fleets may need to install their own propane stations. Fleets can also work with local propane marketers to establish the fueling infrastructure.

Performance

A propane vehicle's power, acceleration, and cruising speed are similar to those of gasoline-powered vehicles. The driving range for dedicated and bi-fuel vehicles is also comparable to that of gasoline vehicles.

Benefits

Using propane as a vehicle fuel increases energy security, provides convenience and performance benefits and improves public health.

In 2010, 49% of the petroleum consumed in the U.S. was imported - two thirds of which was used to fuel vehicles in the form of gasoline or diesel. The majority of propane is produced in the U.S., which contributes to fuel diversity and reduced dependence on foreign oil.

Propane has a high octane rating and excellent properties for spark-ignited internal combustion engines. It is non-toxic, nonpoisonous and presents no threat to soil, surface water, or groundwater. Compared with gasoline and diesel vehicles, propane vehicles can produce lower amounts of some harmful air pollutants and greenhouse gases. Well to wheels, propane use reduces greenhouse gas emissions by nearly 10%, and when derived as a by-product of natural gas production, petroleum use is reduced by 98%.

Propane's clean burning characteristics allow the engine to have increased service life. In fact, lower maintenance costs are a prime reason behind propane's popularity for high-mileage vehicles. Propane's high octane and low-carbon and oil-contamination characteristics have resulted in greater engine life than conventional gasoline vehicles (up to two times). Since the fuel's mixture of propane and air is completely gaseous, there are fewer cold start problems associated with liquid fuel.

Safety

Propane vehicles must meet the same safety standards as gasoline vehicles and have passed rigorous crash testing. In addition, propane has a narrow flammability range, and its tanks are 20 times more puncture-resistant than gasoline tanks.

Additional Resources

 

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This document was printed from DriveClean.ca.gov.