What is propane?

Propane is a gas at normal temperatures and pressures but is stored under moderate pressure (150-200 psi) where it becomes a liquid. It is a clean-burning fuel, has a high energy density, and is readily available in the US. It is the 3rd most used vehicle fuel behind gasoline and diesel on the planet. (It is fairly commonplace to find light-duty propane vehicles running around European countries and in Asia.) LPG, LP-Gas, Autogas – all these are different names for propane used as a fuel. LPG stands for Liquefied Petroleum Gas.


Example fleets that use propane in TN: University of Memphis; cities of Kingsport, Knoxville, Jackson, Chattanooga & Sevierville; Great Smoky Mountains National Park; Clarksville-Montgomery County & Morgan County school buses; Groome Transportation.

Most popular propane vehicles in Tennessee: Police cars, work trucks and landscaping mowers.

Why would a fleet want to use bi-fuel propane vehicles? Bi-fuel vehicles offer the benefit of allowing the driver/vehicles to venture anywhere, anytime. Since the vehicle can operate on gasoline while away from its home operating area, the vehicle isn’t restricted to only being able to refuel at home or where they can find propane on the road.


How is it produced?

Propane is produced from liquid components recovered during natural gas processing. These components include ethane, methane, propane, and butane, as well as heavier hydrocarbons. Propane and butane, along with other gases, are also produced during crude oil refining. Approximately 85% of the propane used in the U.S. is produced in the U.S.



How is it used?

There are light-, medium- and heavy-duty vehicles that can be powered by propane. Most propane vehicles used in the U.S. today are either bi-fuel or dedicated propane, and most are converted to bi-fuel propane using conversion kits like those that ICOM North America and Alliance Autogas offer. Applications include a wide variety of vehicles like cars, pickup trucks, forklifts, transit and school buses, delivery trucks, trolleys and delivery or passenger vans. Propane is also frequently used to replace gasoline in smaller applications, such as commercial lawn equipment like zero-turn and walk-behind landscaping mowers, and is growing in use as a golf/turf applications like for mowing golf courses (these are reel-type mowers).

Light-Duty Vehicles

Light-Duty propane fleet vehicles can be purchased from authorized Ford and General Motors dealerships. See the Clean Cities Vehicle Buyer’s Guide (PDF).  (Below: Photo of the nine new propane-powered Kubota zero-turn mowers that the city of Knoxville acquired in late 2015.)
GRSM propane trucks


Heavy-Duty Vehicles

Engines and fueling systems are also available for heavy-duty vehicles, such as street sweepers and school buses. Use the Alternative Fuel and Advanced Vehicle Search to browse available models(Below: Photo of the press event and two of the 15 new propane-powered Blue Bird school buses that the Clarksville-Montgomery County Schools put into use in August 2017.)
CMCSS propane school buses


Off-road Vehicles

The use of propane in off-road vehicles has grown steadily over the last decade. Zero-turn, walk-behind and similar landscaping mowers have taken the lead with options that include OEM and low-cost conversions, and use of propane in reel-type mowers (like turf and golf courses mowers) has starting growing in the last few years. See the Clean Cities Alternative Fuel and Advanced Technology Commercial Lawn Equipment Guide (PDF).  (Below: Photo of the nine new propane-powered Kubota zero-turn mowers that the city of Knoxville acquired in late 2015. They are now the largest propane-powered mower fleet in the state of TN.)

City of Knoxville propane mowers


What are the benefits?

The Propane Green Autogas Solutions Act (“Propane GAS Act”) of 2011 offers significant economic growth, environmental and energy security benefits to the American economy, according to a study by the National Propane Gas Association. The study projects that the Propane Gas Act’s impact on jobs and the economy will be significant. The growth in propane vehicle sales and use created by the tax credits will generate an increase in economic activity that peaks at between $4 billion and $5.7 billion per year in 2016. That translates to between 30,000 and 42,000 new jobs created by 2016.

Propane is an inherently clean-burning fuel due to its lower carbon content. When used as a vehicle fuel, propane can offer life cycle greenhouse (GHG) emissions benefits over conventional fuels, depending on vehicle type, and drive cycle. In addition, using propane in place of petroleum-based fuels may reduce some tailpipe emissions.

Because propane is a low-carbon fuel, a switch to propane in these applications can result in substantial reductions of hydrocarbon, carbon monoxide, oxides of nitrogen, and greenhouse gas emissions.


What are the emissions reductions gained from propane?

Propane is non-toxic and presents no threat to soil, surface water, or groundwater. Propane has several benefits over gasoline including:

  • Potentially lower toxic, carbon dioxide (CO2), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions
  • Over the fuel’s life-cycle, propane shows greenhouse gas (GHG) emission reductions of 10%, and when derived as a by-product of natural gas production (as it is over 90% of the time), propane reduced petroleum use by 98% to 99%



Jonathan Overly of Tennessee Clean Fuels and Clarksville-Montgomery county School System Director Millard House II discuss the the system’s addition of 15 new propane school buses and the benefits.

Fleet Manager Steve Hightower and Mayor Dennis Phillips explain the success and vision of Kingsport’s propane vehicle program. Now up to 25 vehicles, they are the largest propane fleet in the state of Tennessee!



Propane Station Locator


Propane Information & Links

The Propane section on the AFDC Website – Great starting point in learning about propane opportunities and technologies.

Propane Education & Research Council (PERC)

Propane Autogas Vehicle System Companies: ICOM North America, ROUSH CleanTech, Alliance AutoGas

The Consumer Energy Center – All about propane as a transportation fuel.

Fuel Economy.gov’s propane page.


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