Browse our Frequently Asked Questions section to learn more about natural gas vehicles for your fleet.

LNG (Liquefied Natural Gas)

Q1: Why does natural gas need to be liquefied (LNG) for vehicle use and how does LNG compare to CNG?

A1: Natural gas has less energy by volume compared to liquid fuels. To get sufficient vehicle range, natural gas must be either compressed (CNG) or liquefied (LNG). A megajoule is a unit of energy. The following table shows how the energy content compares for a litre of diesel, LNG, and CNG.  One litre of diesel fuel has the same energy as 1.7 litres of LNG.

  • Diesel            36.0 megajoules per litre
  • LNG               21.0 megajoules per litre
  • CNG              7.5 megajoules per litre

Q2: What are the basic properties of LNG?

A2: LNG is natural gas that has been condensed into a liquid by cooling it to -162°C (-260°F). At atmospheric pressure, LNG occupies only 1/600 the volume of natural gas in ambient vapour form. Since it must be kept at such cold temperatures, LNG is stored in double-wall, vacuum-insulated pressure vessels. LNG fuel systems typically are only used with heavy-duty vehicles requiring greater driving range.

Q3: What is the difference between saturated and unsaturated LNG?

A3: The difference between saturated and unsaturated LNG is fuel temperature. Saturated LNG is warmer which results in a higher tank pressure (approximately 120 pounds per square inch). Vehicles equipped with Cummins Westport engines require saturated LNG as there is no fuel pump involved. Vehicles equipped with Westport Innovations HD engine system can operate on either saturated or unsaturated LNG, although vehicle range is better using the unsaturated form. The Westport system includes a fuel pump in the fuel storage tank.

Q4: What is LNG boil-off and can it be prevented?

A4: As LNG warms up, it changes from a liquid to a gas. This phase change is called “boil off” and it increases pressure in the fuel tank. The vehicle fuel system is designed to handle a certain amount of boil off by capturing it and returning it to the fuel storage tank. If an LNG vehicle is left to sit for more than 3-4 days, the rate of boil off will exceed the vehicle’s system to capture it. In this case, the boil off will  vent to atmosphere through a pressure-controlled vent valve. Venting natural gas is not desirable from either an economic or environmental standpoint. Fleets need to consider their vehicle usage patterns when  considering LNG as a fuel option.

Approvals & Certification

Q1: What approvals are required for natural gas vehicles?

A1: Factory-built natural gas vehicles must meet the same safety and emissions requirements as diesel or gasoline vehicles. Transport Canada has authority over all new vehicles sold in Canada. The provinces  have jurisdiction over aftermarket conversions. At present, there are no specific provincial requirements that must be met for aftermarket conversions.

Q2: What approvals are required for natural gas refueling stations?

A2: Natural gas refueling stations are approved at the provincial level. The provincial Authority Having Jurisdiction for fuels and for pressure vessels and electrical installations is responsible for reviewing and approving stations.

Pressure piping systems used for both compressed natural gas (CNG) and liquefied natural gas (LNG) refueling stations must be registered and approved by each province. A Canadian Registration Number (CRN) must be secured for each pressure component.

Equipment manufacturers and technical expertise can work with fleets and station owners to secure CRNs and to get the appropriate permits and required site inspections to ensure local compliance.

Q3: How is a new LNG station approved when Canada does not yet have its own LNG station code?

A3: Canada is developing an LNG station code within the scope of the CSA Z276 Liquefied Natural Gas Production, Storage & Handling. This new code is expected to be complete by Fall 2013. In the interim, provincial Authorities Having Jurisdiction will rely on other existing LNG station codes to review and approve station designs and installations. For the three LNG stations built in Canada to date, local Authorities relied primarily on the American LNG station code, NFPA 52 Vehicular Gaseous Fuel Systems Code, for station approval.

Q4: Who can I contact for assistance with securing vehicle or station approvals?

A4: Vehicle approvals will be handled by your local truck dealer or bus supplier. For refueling station approvals, contact your local natural gas distribution company or search our online directory under “Fuel Providers” or “Technical Experts” to locate someone who can assist.

Q5: When do the fuel tanks on a natural gas vehicle have to be inspected or re-certified?

A5: Factory-built natural gas vehicles now come with fuel storage cylinders that are designed to last the life of the vehicle, so there is no need for period re-certification. As with any other vehicle, though, a natural gas vehicle’s fuel system should be inspected periodically as part of a program of regular maintenance. Natural gas fuel tanks should always be inspected by qualified personnel following a  motor vehicle accident.

Canada does not have any regulations requiring inspection at set intervals. In the U.S., there is a  requirement (FMVSS 304) specifying that fuel storage tanks be visually inspected after a motor vehicle accident or at least every 36 months or 36,000 miles (60,000 km), whichever comes first.

Q6: Do refueling stations require periodic approvals or re-certification?

A6: Natural gas fuelling facilities require routine maintenance and basic system inspection on at least a monthly basis carried out by a qualified technician. There are also certain components that require re-certification at least every five years, such as pressure relief valves and certain types of CNG storage tanks. These components must be removed, retested, and re-stamped prior to going back into service.

At public refueling stations, fuel dispensers must be tested annually by Measurement Canada to ensure they comply with legal requirements for fuel sales. This testing is done with a mobile apparatus at the station site.

CNG (Compressed Natural Gas)

Q1: Why does natural gas need to be compressed (CNG) for vehicle use and how does CNG compare to liquefied natural gas (LNG)?

A1:  Natural gas has less energy by volume compared to liquid fuels. To get enough vehicle range, natural gas must be either compressed (CNG) or liquefied (LNG). A megajoule is a unit of energy. The following table shows how the energy content compares for a litre of diesel, LNG, and CNG.

  • Diesel            36.0 megajoules per litre
  • LNG               21.0 megajoules per litre
  • CNG              7.5 megajoules per litre

Q2: What pressure is CNG dispensed at in Canada?

A2: CNG is dispensed at either 3,000 pounds per square inch (psi) or 3,600 psi in Canada. Canadian codes require that public stations dispense CNG at 3,000 psi. Private fleet stations can dispense CNG at 3,600 psi. All CNG refueling stations in the United States dispense fuel at 3,600 psi.

Work is underway in Canada to harmonize fill pressures with the United States, so that eventually all stations in Canada including public stations can dispense fuel at 3,600 psi. At 3,600 psi, CNG occupies only 1/300 of the volume of natural gas in ambient vapour form.

Codes, Standards & Regulations

Q1: Does Canada have codes and standards for compressed natural gas (CNG) vehicles and refueling stations?

A1: Yes. Canada was an early leader in developing codes and standards for CNG vehicles, stations, and components. Canada has well-established CNG vehicle and station codes:

  • CSA B108 – Natural Gas Fuelling Station Installation Code
  • CSA B109 – Natural Gas for Vehicles Installation Code

The Canadian Standards Association recently re-established the Committees that oversee these codes. Work is underway to review and ensure that both codes are up-to-date.

Q2: Does Canada have codes and standards for liquefied natural gas (LNG) vehicles and refueling stations?

A2: As liquefied natural gas (LNG) vehicles and stations are new to the Canadian market, Canada does not yet have codes for LNG vehicles and refueling stations. Industry and government are working to close these gaps starting with developing an LNG refueling station code. By Fall 2013, it is expected that Canada will have an LNG refueling station code which will be added as an amendment to Canada’s existing industrial LNG code, CSA Z276 – Liquefied Natural Gas Production, Handling & Storage.

The development of an LNG vehicle code is currently under review by the CSA B109 Committee.

Q3: How are natural gas vehicles identified on the road and by emergency first responders?

A3: Natural gas vehicles have a diamond-shaped decals indicating there is a compressed natural gas (CNG) fuel system or a liquefied natural gas (LNG) fuel system on the vehicle. Highway tractors that use the Westport Innovations engine system have both CNG and LNG diamond decals since the fuel is stored as LNG and is vapourized to CNG or gaseous form before it is delivered to the engine.

Environmental Benefits

Q1: Is natural gas better for the environment?

A1: Yes. Natural gas is the cleanest burning fossil fuel. On a well-to-wheels or total lifecycle basis, factory-built natural gas vehicles reduce greenhouse gases by 20-25%. A highway tractor driven 120,000 kilometers per year produces 35 tonnes less  of greenhouse gas emissions compared to its diesel counterpart.

Q2: Isn’t natural gas itself a greenhouse gas?

A2: Yes. Natural gas is primarily made up of methane (CH4) which is a greenhouse gas. The 20-25% well-to-wheels greenhouse gas benefit for medium and heavy natural gas vehicles includes the impact of any increase in methane. In fact, Natural Resources Canada’s GHGenius model which is used across Canada to determine the greenhouse gas benefits of a range of fuel and vehicle technology options, incorporates three greenhouse gases in all calculations – carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Emissions of each of these three gases is calculated on a weighted average basis in GHGenius based on their global warming potential as determined by the International Panel on Climate Change.

Q3: With improvements in diesel technology, aren’t diesel vehicles now just as “clean” as natural gas vehicles?

A3: Natural gas and diesel vehicles meet the same tailpipe emissions standards. ..

Q4: Is it true that natural gas vehicles are quieter than diesel vehicles?

A4: Yes. The noise from one idling diesel truck is comparable to the noise from 10 idling natural gas trucks. This lower noise level can provide benefits for drivers who spend their days behind the wheel of a truck or bus.

Q5: How does shale gas affect the greenhouse gas benefits of natural gas vehicle use?

A5: Greenhouse gas emissions from natural gas production are a relatively small part of the well-to-wheels greenhouse gas emissions. Natural gas production represents less than 10% of the total greenhouse gas footprint from natural gas vehicle use. It is true that the carbon dioxide (CO2) content of shale gas can vary considerably by deposit. In Canada, the approximate range of CO2 content in shale gas is less than 1 up to 12%. Since some shale gas contains more CO2 than conventional gas, mitigation methods will need to be developed for high-CO2 shale formations.

Made in Canada

Q1: Is it true that the first natural gas transit bus in the world was developed in Canada?

A1: Yes. Hamilton Street Railway based in Hamilton, Ontario, partnered with the natural gas vehicle industry and with the federal and provincial governments to develop the first natural gas transit buses in the world in the mid-1980s. This led to 1st generation natural gas engine technology which was used by many transits in Ontario including Grand River, Burlington, Toronto, London, Cornwall, and Mississauga. Today’s 4th generation engine technology has significantly improved in terms of power, performance, fuel efficiency, and reliability.

Q2: Which Canadian companies are involved in the supply of natural gas vehicles and stations?

A2:  There are many leading natural gas vehicle and station equipment suppliers based in Canada. The following table shows where these companies are located and what products they produce.

Q3: Is it true that Canadian companies are the North American market leaders in the area of supplying natural gas engines for trucks and buses?

A3: Yes. Vancouver-based Westport Innovations and its joint venture company, Cummins Westport which is also based in Vancouver, supply natural gas engine systems to more than 20 different North American truck and bus manufacturers. All of the leading truck and bus manufacturers such as, for example, Peterbilt, Freightliner, Navistar, Mack, Volvo, and Kenworth for trucks, integrate engines from Canadian suppliers into their vehicles at the factory level.

Natural Gas

Q1: Where does natural gas come from?

A1: Natural gas is a clean-burning fuel  found in abundance in Canada as a mixture of gases in porous rock formations. Natural gas is formed from marine organisms buried millions of years ago. It can be found in the same formations as oil or coal.

Natural gas is primarily made up of methane (CH4), but can also contain other hydrocarbons, moisture, and impurities. It is extracted from the ground, processed to remove impurities, and compressed to be stored and transported by pipeline. After processing, Canadian natural gas typically has a methane content of more than 95%. Natural gas represents about one-third of all energy used in Canada and is delivered to more than 6 million homes.

Q2: What is biogas?

A2: Biogas is a naturally occurring gas that is produced from organic decomposition. Biogas  is produced from waste sources at landfills and in wastewater treatment plants and anaerobic digesters.  It consists of methane (

Q3: What is shale gas?

A3: Shale gas is natural gas that is attached to organic matter or is contained in thin, porous silt or sand beds in shale formations. Shale is one of the most common sedimentary rocks and is mainly composed of clay and fragments of other minerals such as quartz and calcite. Shale formations normally have low permeability meaning there is limited ability for the gas to flow easily through the shale formation. They normally require advanced drilling techniques including horizontal drilling and multi-stage hydraulic fracturing to produce the shale gas. Shale gas is a form of unconventional natural gas.

Q4: How much natural gas is there?

A4: North America has huge amounts of proved natural gas reserves and resources. Canada is the world’s 3rd largest natural gas producer at 5.4 trillion cubic feet per year. Recent estimates put the global reserve of natural at 100 years at current demand levels.

Q5: What is the significance of shale and other unconventional natural gas resources in North America?

A5: Not long ago, energy analysts projected that natural gas production in North America would decline steadily for the foreseeable future. Large scale natural gas import terminals were proposed in several locations in Canada. Due to technological advances, shale and other unconventional natural gas resources can be cost-effectively extracted. This development is referred to by North American energy market analysts as an “energy game changer”  and governments and industry are exploring new and expanded opportunities for this low carbon resource.

Natural Gas Compared to Propane

Q1: What is the difference between natural gas and propane?

A1: Natural gas and propane are both fossil fuels. Natural gas is lighter than air, so in the event of a leak,  it will disperse upwards and not pool on the ground. By comparison,  propane is heavier than air and would normally pool in low spots in the event of a leak. Both fuels have unique properties that need to be considered for fleets considering their use.

Q2: How do natural gas and propane vehicles compare?

A2:  Propane-fueled vehicles require different fuel tanks, as propane is stored under much lower pressure and is stored as a liquid. In order to combust, liquid propane must undergo a phase change into a gas. This can be challenging in cold-weather conditions because propane tends to remain a liquid when it’s very cold. Compressed natural gas does not have to undergo a phase change to combust.


Q1: Are natural gas vehicles more dangerous if they are involved in an accident?

A1: All fuel usage involves some risk. CNG and LNG tanks are designed to withstand extreme pressures and potential impacts.  These tanks are made of very durable materials that have been subjected to a range of tests and requirements. If a CNG or LNG tank were to rupture, natural gas is lighter than air and the fuel would disperse quickly .

Q2: Is natural gas volatile and dangerous?

A2: Natural gas is a combustible hydrocarbon, but is no more volatile than other petroleum fuels such as gasoline, diesel, or propane. As with all fuels, responsible storage, transfer, fueling, and use is the best way to avoid spills or leaks and ensure public and worker safety.

Q3: Can natural gas vehicles be parked in underground parking garages?

A3: Natural gas vehicles can be safely parked in properly designed underground parking garages. Natural gas is lighter than air, so in the event of a leak,  the natural gas will disperse upwards and be removed by the garage’s ventilation system. By comparison,  propane is heavier than air and would normally pool in low spots in the event of a leak.  The policies of individual parking garages and building operators as well as  local regulations may vary.  Some buildings prohibit natural gas vehicle parking as they do propane vehicle parking.

Q4: Can I a natural gas vehicle be driven through a tunnel or taken on a ferry?

A4: Yes. It is good to check with your local ferry operator as to any special restrictions they may have, but in general there are no restrictions on taking a natural gas vehicle on a ferry.


Q1: Is refueling with natural gas slower than with diesel?

A1: No. Fast fill CNG stations and LNG stations dispense fuel at rates comparable to diesel and gasoline. Fast fill CNG stations have large compressors as well has high pressure fuel storage tanks to support rapid vehicle refueling. LNG stations have large diameter refueling hoses and pumps capable of high speed vehicle refueling.

Time fill CNG are based on overnight refueling for return-to-base fleets. These stations allow vehicles to be plugged in overnight at the fleet owner’s site. Time fill stations are less expensive than fast fill stations and they can eliminate vehicle lineups at the end of shifts for refueling.

Q2: How is natural gas delivered for CNG and LNG refueling stations?

A2: A CNG refueling station relies on natural gas delivery via the underground natural gas pipeline network. In the same way that natural gas is delivered to a home, a natural gas service line to the refueling station property can be connected to a CNG system that will compress, store, and dispense the natural gas as vehicle fuel.

By comparison, LNG is delivered by tanker truck and stored in an insulated, above-ground vessel at the station. LNG is delivered to the vehicle using a fuel dispenser that includes a cryogenic pump to move the LNG into the insulated storage tank on the vehicle. In order to set up an LNG station, there must be a source of LNG within a reasonable distance to truck the fuel to the station. LNG cannot be transported by pipeline due to its cryogenic nature.

Q3: When will LNG refueling stations be available along major truck corridors in Canada for highway tractor fleets?

A3: LNG fueling station networks will  be established in response to market demand in Canada. Investments in natural gas liquefaction facilities are required to bring LNG into the trucking market. Canada has existing utility LNG facilities in British Columbia (2), Ontario, and Québec and these facilities can be used to provide LNG to early fleet adopters. Shell Canada is also building Canada’s first non-utility LNG production facility west of Calgary. By the end of 2013, this facility will be supply Canada’s first three commercial cardlock truckstops with LNG. The LNG will be available at Shell Flying J stations in Calgary, Red Deer, and Edmonton.

Q4: Who can provide periodic maintenance services for CNG and LNG refueling stations?

A4: Only qualified and authorized personnel should perform maintenance on CNG or LNG refueling stations to ensure proper operation and system safety. In many cases, fleets can access training from equipment suppliers in order to maintain their own refueling station. CNG and LNG station suppliers can also provide qualified field service personnel capable of providing any level of service.  Station maintenance training courses are also offered in the U.S. through NGVi.

In many cases, CNG and LNG station systems are computer controlled and can be set up with remote monitoring systems for 24/7 monitoring via the Internet or by modem connection.

Q5: Where are there public refueling stations in Canada?

A5: There are 42 public CNG refueling stations in Canada located in Alberta, British Columbia, Ontario, and Saskatchewan. Canada’s first three commercial LNG stations for trucks will open in Alberta in 2012.

Q6: Is there a way to provide public access to a private refueling stations?

A6: There are many examples where private fleets have set up public access to their refueling station. ATCO Gas has allowed public access to its private station in Lethbridge, Alberta, for example for many years. The challenge typically relates to access for traffic flow. Private fuelling sites are often arranged within a secure yard that cannot allow public traffic access. A separate “outside the fence” public access dispenser is one approach that has been successfully used in the U.S.  In addition to technical and access issues, private station owners must confirm that zoning allows for the public fuel sales.

Q7: How can I know if my existing refuelling facility could accommodate natural gas?

A7: With planning for CNG or LNG, there is a need for space for equipment and storage vessels. Changes to site traffic patterns should also be considered. It is recommended that a knowledgeable expert be engaged to help review and determine site-specific  requirements and feasibility. Factors such as space availability, site services (gas pressure and electrical supply), soil type, height restrictions, noise levels, and even wind patterns need to be considered.

Q8: What is a “mother-daughter” CNG station?

A8: For locations not serviced by a natural gas distribution network but within range of a distribution system, CNG can be transported in a bulk CNG trailer. The trailers are filled at a CNG bulk-filling station and transported by truck to one or more vehicle refueling stations. This is called a virtual pipeline or a “mother-daughter” system. These types of stations are commonly used in countries such as Thailand and Colombia where the natural gas distribution system is not as extensive as it is in Canada.

Q9: Are there any community impacts with natural gas refueling stations?

A9: Compressors for CNG stations are installed in sound-attenuated enclosures which help to reduce noise. As with any commercial installation, natural gas refueling stations must comply with all applicable local regulations and bylaws. LNG stations include spill containment structures in the event of a tank rupture. In all cases, local zoning and property use requirements must be met as would be the case for a diesel refueling station. There is no risk of soil or water contamination with a natural gas refueling station as natural gas, whether CNG or LNG, is lighter than air and less dense than water and will dissipate in the event of a fuel spill.


Q1: Is any special training required to refuel a natural gas vehicle?

A1: For CNG vehicles, there is no special training required. All public CNG refueling stations offer the fuel on a self-serve basis. The dispenser nozzle needs to be connected to the vehicle’s receptacle and “locked down” before fuel will flow to the vehicle. There is no risk of spills and no fumes emitted during refueling.

For LNG vehicles, basic training and personal protective equipment (face shield, gloves, apron) are required. LNG is a cryogenic fuel and there is a risk of frostbite as well as inhaling cold vapours. There are also different dispenser types and procedures for grounding and managing pressure between the station and vehicle tank.

Vehicle Maintenance

Q1: Are natural gas vehicles more expensive to maintain?

A1: Natural gas vehicles have similar maintenance costs compared to diesel vehicles. The maintenance interval is typically the same, although the maintenance tasks may be different. For example, vehicles equipped with the Cummins Westport 8.9 litre spark-ignited engine will require spark plug changes at recommended intervals.

Q2: Where can I get my mechanics trained to perform routine service work on natural gas vehicles?

A2: Both Westport Innovations and Cummins Westport offer training for their natural gas engine systems. With this training, a service technician can perform routine vehicle maintenance tasks that do not involve the natural gas fuel system. For natural gas fuel systems training, programs are currently being developed in Canada and are expected to be available in 2013.

In the interim, Ontario-based fleets can contact Centennial College regarding their Internal Combustion Alternative Fuel Technician (Natural Gas) course. The 1.5 day course is open to trained automotive service technicians. In the U.S., NGVi offers a range of training programs including ones related to CNG vehicle servicing.

Q3: Can my local truck dealer service natural gas trucks?

A3:  Many dealers across Canada are gearing up to be able to service natural gas trucks. This involves training service personnel, modifying facilities so that they are safe for natural gas use, and educating all staff regarding natural gas and how it compares to diesel as a vehicle fuel. Please contact your local dealer for more information regarding their natural gas vehicle-related services.

Vehicle Performance

Q1: Do natural gas vehicles have less power compared to diesel vehicles?

A1: No. Current generation, factory-built natural gas vehicles incorporate engine technologies that  provide power, torque, and performance that is similar to a diesel vehicle technologies. As natural gas is a newer alternative, there are not yet as many engines and factory-built vehicles to choose from as there are with diesel, so fleets need to ensure that available natural gas vehicle options are suitable for their particular fleet application and duty cycle.

Q2: Are natural gas trucks and buses as fuel efficient as diesel trucks and buses?

A2: Natural gas vehicles have significantly improved in terms of fuel efficiency over the past decade. Highway tractors with Westport Innovations’ HD engine system match the efficiency of diesel tractors on an energy equivalency basis. Trucks, buses, and tractors with Cummins Westport’s 8.9 litre or 11.9 litre engine come within 12% of the efficiency of their diesel counterparts and there is no need for diesel exhaust fluid.

Q3: What kind of driving range do natural gas trucks and buses have?

A3: In general, vehicle range issues should not be a major barrier to natural gas adoption for most types of urban, return-to-base and regional corridor fleets. There are numerous options for onboard fuel storage that allow adequate driving range to meet the driving needs of many types of fleets. Fuel storage can be tailored to daily driving needs.