Value to Work Trucks
The number of vehicles fueled by propane (also known as “autogas”) is 270,000 in the United States alone, according to the U.S. Department of Energy. The U.S. Department of Transportation states that less than two percent of U.S. propane consumption is used for transportation, but interest is growing.
Strengths and benefits of propane include:
- Ease of refueling – On-site propane refueling stations are compact, easy to install and allow for safe and convenient refueling. Also, propane refueling stations number in the thousands across the U.S.
- Readily available supply – With well-established underground storage facilities and distribution networks, propane is the most readily available alternative internal combustion fuel used in the U.S. today.
- Relatively low environmental impact – Propane-fueled vehicles produce 30 percent to 90 percent less carbon monoxide and about half the toxins and other smog-producing emissions than gasoline engines. The total lifecycle greenhouse gas emissions for propane are 21 percent to 24 percent less than petroleum.
- High energy density – Propane is one of the highest energy density alternative fuels and has about 75 percent of the energy of an equal amount of gasoline.
Propane is a three-carbon alkane hydrocarbon gas (C3H8), which is also referred to as “liquefied petroleum gas,” “LP-gas,” “LPG,” or–when used as a fuel in internal combustion engines in vehicles–“autogas.” Propane turns into a colorless, odorless liquid when stored under pressure, but in commercial applications, an odorant—typically methyl mercaptan—is added for leak detection. Propane has numerous uses as a fuel and can be burned as a vapor or injected under pressure as a liquid fuel.
Propane is a light hydrocarbon which is a gas at atmospheric pressure, and is classified as a gaseous fuel. However, it is normally stored and handled as a liquid under pressure (typically 100 to 300PSI). At this pressure, propane becomes a liquid with an energy density 270 times greater than the gaseous form.
Propane is produced as a byproduct of two operations — natural gas processing and petroleum refining. The first operation involves the removal of butane, propane and large amounts of ethane from raw gas. In the second case, oil refineries produce propane as a byproduct of cracking petroleum into gasoline or heating oil.
Propane currently consumed in the United States is sourced from these countries:
United States – 90 percent
Canada – 7 percent
Other – 3 percent
End-use propane is distributed by major national and regional distributors as well as local suppliers nationwide. In terms of infrastructure, propane is likely the most readily available alternative internal combustion fuel used in the United States today.
Since it is primarily a byproduct of other processes, propane production cannot be easily adjusted to meet varying demands. However, large underground (salt dome) storage facilities located in Fort Saskatchewan, AB, Canada; Mont Belvieu, TX and Conway, KS can store 80 million or more barrels of propane and serve as a supply/demand buffer. Propane is distributed nationwide using pipelines. Railroad tank cars are used for delivery to areas not served by pipelines.
Propane is an approved, clean fuel listed in the 1990 Clean Air Act and the Energy Policy Act of 1992. CO2Emissions for propane are 62.7 kilograms per million BTU (Gasoline = 70.88).
Tests conducted by the U.S. Environmental Protection Agency show that propane-fueled vehicles produce 30 percent to 90 percent less carbon monoxide and about 50 percent fewer toxins and other smog-producing emissions than gasoline engines. Propane is classified as being nontoxic although it is an asphyxiant.
The development of propane as an internal combustion fuel is supported by the Propane Education and Research Council (PERC), which conducts training, research and marketing on behalf of the industry.
In addition, the Engine Fuel Advisory Committee pursues technology development to promote the use of propane as an engine fuel, which is a market accounting for about five percent of the total non-chemical propane used in the United States. The committee seeks programs that increase off-season demand through projects that encourage the development, commercialization, and marketing of propane-related engine technologies.
Propane as an Internal Combustion Fuel – A gallon of liquefied propane has about 75 percent of the energy of a gallon of gasoline, which makes it one of the highest energy density alternative fuels.
Energy density – 91,600 BTU per liquid gallon (gasoline = 125,000 BTU/gallon)
Liquefied – 4.24 pounds per gallon
Vapor – 1.5 atmospheres
Octane rating – 106 (average)
Petroleum Offsets – According to data provided by the Argonne National Labs, the use of propane as a transportation fuel will reduce U.S. petroleum consumption by approximately 98 percent compared to an equivalent gasoline-fueled vehicle.
Lifecycle Greenhouse Gas Reduction – The use of propane as an internal combustion fuel produces significantly less carbon dioxide (CO2) than the use of an equivalent amount of gasoline or diesel fuel. In addition, propane utilizes the same general production and distribution network. As a result, the total lifecycle greenhouse gas emissions for propane are 21 percent to 24 percent less than petroleum (Source: Argonne National Labs).
- Reduced greenhouse gas emissions
- Reduced engine wear and extended service intervals
- High energy density in comparison to most other alternative fuels
- Established distribution infrastructure with good availability
- Exceptionally safe – propane tanks are 20 times more puncture-resistant than gasoline tanks and propane has the lowest flammability range of all alternative fuels
- Handled as a liquid, under pressure, vehicle fueling is very rapid (similar to pumping gasoline or diesel fuel).
- Primarily domestically-sourced
- Purpose-built engines with higher compression ratios (equivalent octane rating of 106) provide improved performance and fuel economy
- Liquid injection technology eliminates freeze-up issues associated with vapor systems down to approximately -20o Fahrenheit.
To some degree, the cost of propane is tied to the cost of petroleum and natural gas and tends to be volatile. Historically, propane had an equivalent cost per gallon of approximately 60 percent of gasoline; however, in 2010 the cost increased significantly. As of January 2011, the equivalent cost per gallon (including taxes) was equal to, or higher, than gasoline at the retail level (per Clean Cities Alternative Fuel Price Report). However, when purchased in volume as autogas for fleet applications, propane still costs 30-50 percent less than gasoline (per data provided by PERC).
Lifecycle Cost Factors
- The economic factors for this fuel make it one of the simplest to adopt. If you have a home-every-night fleet, the payback is even shorter.
- Propane incurs somewhat lower conversion costs than fuels such as compressed natural gas (CNG) and liquefied natural gas (LNG), primarily due to lower storage tank costs.
- Very low infrastructure cost compared to other gaseous fuels
- Reduced vehicle maintenance costs (including fuel tanks)
- Minimal driver training costs
- Other potential factors, such as carbon credits, tax incentives, etc., will have a significant impact on the economic viability of propane as an engine fuel.
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