Propane

 

Propane, also known as liquefied petroleum gas (LPG or LP-gas), or autogas in Europe, is a three-carbon alkane gas (C3H8).  Propane is typically stored under pressure inside a tank.  This turns the propane into a colorless, odorless liquid. As pressure is released, the liquid propane vaporizes and turns into gas that is used for combustion.  Because propane is transformed into a gaseous state before it is burned in an internal combustion engine, the engine runs more efficiently in low-speed, light-throttle conditions.[1]  

Propane-fueled vehicles have less wear and tear on their engines due to less carbon deposits in the fuel injectors.  This, in turn, is the result of cleaner burning of fuel.  Moreover, it boosts cold weather performance because it enters the engine in a gaseous state.  Propane-powered vehicles have a performance range similar to gasoline powered vehicles.  Propane has one of the highest energy densities of all alternative fuels, so propane vehicles go farther on a tank of fuel.

Additionally, propane is also an exceptionally safe fuel: propane tanks are 20 times more puncture resistant than gasoline tanks, and propane has the lowest flammability range of all alternative fuels.  Finally, propane is one of the most used alternative transportation fuel in the world. Propane vehicle technology is well established, with approximately 2,800 fueling stations located throughout the U.S.[2]

However, there are disadvantages to using propane, including the storage.  Due to its cryogenic nature, propane has limited liquid holding time in a fuel vessel.  Therefore, the fuel must be sealed in a pressure tight system at all times.[3] 

Additionally, while propane has one of the highest energy densities of all alternative fuels it still only has about 74% of the energy density of conventional gasoline.[4]  In April 2013, propane’s U.S. national average price per 1 million BTUs was $32.65 while gasoline was only $31.13.[5] Therefore, even though it has a price per gallon very comparable to gasoline, propane’s price per million BTUs is significantly higher due to its lower energy content.  This largely accounts for why less than 2% of U.S. propane consumption is used for transportation fuel and why LPG consumption has been on a steady decline from 2004-2008. [6] 



 

LPG consumption declined by 18% from 2007 to 2011.[7]

 

Finally, although propane is well established compared to other alternative fuels it is still far from being as ubiquitous as gasoline or diesel.  The 2,853 propane refueling sites across the United States seem relatively insignificant when compared to the estimated 160,000 gasoline stations in the United States. [8]

Fleet managers that want more information on the availability and costs of propane fuel on a more local level should visit the U.S. Department of Energy’s Alternative Fuels Data Center.  There fleet managers can find the DOE Alternative Fueling Station Locator[9] and the Clean Cities Alternative Fuel Price Report.[10]  Additionally, the Alternative fuel’s Data Center allows fleet managers to view their state's incentives and laws related to alternative fuel and advanced vehicle use.[11]


[1] U.S. Department of Energy, What is Propane?, http://www.afdc.energy.gov/afdc/fuels/propane_what_is.html, (May 22, 2013).

[2] U.S. Department of Energy, Propane Benefits, http://www.afdc.energy.gov/afdc/fuels/propane_benefits.html, (May 22, 2013).

[3] U.S. Department of Energy, What is Propane?, http://www.afdc.energy.gov/afdc/fuels/propane_what_is.html, (May 22, 2013).

[4] U.S. Department of Energy, Alternative Fuels Table, http://www.afdc.energy.gov/afdc/pdfs/afv_info.pdf, (May 22, 2013).

[5] U.S. Department of Energy, Alternative Fuel Price Report, http://www.afdc.energy.gov/uploads/publication/alternative_fuel_price_report_april_2013.pdf, (May 22, 2013).

[7] U.S. Energy Information Administration, Alternative Fuels Vehicle Data, http://www.eia.gov/renewable/afv/users.cfm?fs=a&uyear=2011%2c2010%2c2009%2c2008%2c2007&weightclass=ld%2cmd%2chd&ufueltype=lpg, (May 22, 2013).

[8] U.S. Department of Energy, Alternative Fueling Station Locator, http://www.afdc.energy.gov/afdc/locator/stations/, (May 22, 2013).

[9] U.S. Department of Energy, Alternative Fueling Station Locator, http://www.afdc.energy.gov/afdc/locator/stations/, (May 22, 2013).

[10] U.S. Department of Energy, Alternative Fuel Price Report, http://www.afdc.energy.gov/afdc/price_report.html, (May 22, 2013).

[11] U.S. Department of Energy, State Laws and Incentive, http://www.afdc.energy.gov/afdc/laws/state, (May 22, 2013).