Power to Propane -- Part I

LCT Magazine
Posted on May 12, 2008

PROPANE IS SANE: The trend toward greener vehicles likely will grow, but the bar for admission will rise as well. Not every vehicle billed as green should be pursued as an option. For example, ethanol vehicles are a flop, and for multiple reasons already cited on this blog, likely will fail in the future. But one category worth a serious look is propane vehicles. Following is a basic primer on propane vehicles and their potential for future use in chauffeured transportation:

FAQs from the U.S. Department of Energy

What is a converted vehicle?
A converted vehicle is originally designed to run on gasoline, but has been altered to perform on an alternative fuel. Generically, they are known as bi-fuel vehicles. The two most common fuels used in vehicle conversion are compresses natural gas (CNG) and liquefied petroleum gas (LPG or propane).

What do conversions cost?

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.

The cost for each vehicle conversion at Premiere Transportation Group was $3,850.

How long has propane been used in vehicles? And, what about bi-fuel vehicles?

Propane has been used in vehicles since the 1920s. It is considered an alternative fuel under the Energy Policy Act of 1992 and qualifies for alternative fuel vehicle tax incentives.

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.

What about acceleration, driving range, etc.?

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.

Why has propane become popular?

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.

Related Topics: Driving Green

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