Propane also known as liquefied petroleum gas (LPG), has been used in vehicles since the 1920s. However today, most propane vehicles are conversions from gasoline vehicles. Dedicated propane vehicles are designed to run only on propane; bi-fuel propane vehicles have two separate fueling systems that enable the vehicle to use either propane or gasoline.
Propane vehicle power, acceleration, and cruising speed are similar to those of gasoline-powered vehicles. The driving range for bi-fuel vehicles is comparable to that of gasoline vehicles. The range of dedicated gas-injection propane vehicles is generally less than gasoline vehicles because of the 25% lower energy content of propane and lower efficiency of gas-injection propane fuel systems. Extra storage tanks can increase range, but the additional weight displaces payload capacity. Liquid Propane Injection engines, introduced in 2006, promise to deliver fuel economy more comparable to gasoline systems.
Lower maintenance costs are a prime reason behind propane's popularity for use in delivery trucks, taxis, and buses. Propane's high octane rating (104 to 112 compared with 87 to 92 for gasoline) and low carbon and oil contamination characteristics have resulted in documented engine life of up to two times that of gasoline engines. Because the fuel mixture (propane and air) is completely gaseous, cold start problems associated with liquid fuel are eliminated.
Compared with vehicles fueled with conventional diesel and gasoline, propane vehicles can produce significantly lower amounts of harmful emissions. Another benefit of propane vehicles is increasing U.S. energy security.
No light-duty propane vehicles are available for sale by automotive original equipment manufacturers (OEMs). However, Roush Industries converts Ford F150 pickup trucks to dedicated propane fuel use to meet OEM-like standards and has plans to convert F250 and F350 pickups to propane use. Propane engines and fueling systems are also available for medium- and heavy-duty vehicles such as school buses and street sweepers, including some from OEMs.
Conversions in the United States require U.S. Environmental Protection Agency (EPA) approval and a licensed propane conversion technician. See the AFDC Conversions page.
The average cost of conversion of a light-duty vehicle from gasoline to dedicated propane fuel ranges from $4,000 to $12,000. The upfront costs to convert fleet vehicles to propane can be offset by lower operating and maintenance costs over the lifespan of the vehicles. Conversion to a dedicated propane or bi-fuel propane vehicle can be attractive when fueling infrastructure is in place and volume fuel discounts are available. The payback period depends on the average distance traveled by these fleet vehicles. Fleet vehicles typically are high-mileage, high fuel consumption vehicles operating in a limited area, so the payback period on propane fleet vehicles can be very reasonable. |
