What is propane?
Propane is composed of three carbon and eight hydrogen atoms (C3H8). It naturally occurs with petroleum deposits and the associated natural gas that accumulates in subterranean reservoirs made of porous layers of sandstone and carbonate rock. LPG (liquefied petroleum gas) is mostly propane with small amounts of other C3 and C4 hydrocarbons.
Propane has many uses as a fuel. A gas at room temperature, it is easily liquefied and stored in pressure cylinders for both fixed and mobile applications. Propane is a byproduct of the natural gas processing and crude oil refining industries. In Canada, about 85 to 90 percent of propane comes from natural gas processing; the rest from crude oil refining. Canada is the world’s fourth-largest propane producer: 171.7 million barrels per day (2015). Over half is used domestically with the remainder being exported to the U.S. Propane is distributed by pipeline, railcar and bulk trucks and trailers. Hubs are locations where product flows are transferred. Major Canadian hubs include Edmonton and Sarnia.
What are the benefits of propane?
Propane burns more cleanly than gasoline or diesel fuel. On a per unit energy use basis, propane produces fewer greenhouse gas emissions that contribute to climate change. The use of propane as an alternative fuel in factory-built vehicles can reduce greenhouse gas emissions by 20 – 25 percent in light-duty vehicles on a life-cycle (well-to-wheel) basis (compared with gasoline).
Propane also contains fewer toxic pollutants. For example, because propane has extremely low sulphur content, it does not produce significant amounts of sulphur oxides, which can contribute to acid rain and smog. Furthermore, propane is a pressurized fuel that must be contained within a sealed system, right up to the time it enters your vehicle, so it is less likely to escape into the soil or water through careless handling, spills or evaporation.
Societal and economic
All the propane available in Canada is produced by Canadian sources, bringing economic benefits to Canadians. As well, propane as a vehicle fuel is widely available throughout urban and rural Canada.
Where is propane used?
Transportation fuel is one (6 percent) of its many applications. Feedstock for chemical production represents 10 percent of use. It also serves as a lower-cost heating fuel in rural and remote areas where natural gas is unavailable. With propane’s many applications, production, storage, and bulk distribution capabilities are well established.
Most propane-powered vehicles can refuel at existing retail sites that sell propane in small volumes, for example for barbecue tanks. The infrastructure needed to dispense propane is very similar to equipment for gasoline and diesel refueling. Pumps may need upgrading to provide faster fueling.
The availability of new light- and medium-duty propane vehicles has surged in recent years, especially for fleet use: vehicles can be sourced from an original equipment manufacturer, or conventional vehicles can be retrofitted. OEM delivered light-duty propane vehicles can cost several thousand dollars more than comparable gasoline vehicles. The average conversion cost for a fleet vehicle is $5,800 installed. A vehicle can be converted to run on propane alone, or to run on either propane or gasoline. Equipment to convert vehicles is readily available, from the facilities who are also certified to install and service them. British Columbia, Alberta and Ontario have the largest auto propane markets in Canada.
Fuel and refuelling
Propane is dispensed in the same way as conventional gasoline, takes about the same amount of time to refuel and is sold in litres. Also, because propane weighs less than gasoline, propane tanks can be made larger without affecting vehicle acceleration.
Propane costs less per litre than gasoline and offers comparable range to conventional fuel. It has a higher-octane rating than gasoline (104 to 112 vs. with 87 to 92). This, combined with its low carbon and low oil-contamination characteristics, delivers improved engine life. Although its lower energy density results in lower fuel economy, its better price per litre can quickly generate 20 to 40 percent savings in cents-per-km driven.
There are about 900 retail fuel outlets across the country, with a higher concentration in, Alberta, Ontario and Quebec. Many of these are operated by the major gasoline retailers, and it is usually easy to find stations that sell propane, even in smaller towns. A list of refuelling stations across Canada is available on NRCan’s Electric Charging and Alternative Fuelling Stations Locator.
Safety and performance
Propane has a good safety record as a transportation fuel, thanks to national and provincial/territorial standards for safety and handling that require staff training and certification of equipment installers and refuelling sites. Like gasoline, propane is highly combustible, but it has two safety advantages over gasoline: it must be present in higher concentrations in the air before it will ignite, and it requires a much higher temperature than gasoline to ignite.
In its liquid form, propane is colourless and non-toxic, but it will displace air and oxygen and can become an asphyxiant. An odorant is added to permit detection in the case of a leak. The odorant smells “skunky” or like a rotten egg. It is added in concentrations that can be noticeably smelled at one fifth of the lower combustion limit.
Refuelling a propane vehicle is relatively simple, but it is important to be aware of some safety precautions. The tank must be filled to only 80 percent of its capacity because liquid propane expands and contracts with changes in temperature. Conversions made before 1991 may not have automatic stop-fill valves in the vehicle tank.
It is important to wear protective gloves when refuelling the vehicle because liquid propane exiting the spit valve can cause frostbite.
Federal, provincial and territorial regulations spell out the safe design, manufacture, testing and installation of propane vehicles.
There is usually no significant difference in performance between propane and gasoline vehicles. Gasoline vehicles that are converted to propane with some after-market systems may experience a slight drop in the maximum horsepower of the vehicle under a wide-open throttle. This does not occur with liquid propane injection.
Propane is a naturally high-octane fuel. Manufacturers of propane vehicles can optimize the engine for propane by increasing its compression ratio, which improves thermal efficiency and leads to better fuel economy.
Propane-powered vehicles reportedly have less carbon build-up. Many fleets report a reduction in maintenance costs or an increase in the life of vehicles that operate on propane, but this is difficult to quantify.