Volume 24, number 3, December 2010

Natural gas: A fuel for the future

In this era of environmental questions being raised about the transport sector, natural gas for vehicles is changing the landscape when it comes to transporting goods and heavy trucking.

The most recent natural gas engine technologies can effectively and efficiently replace diesel fuel for trucks. In fact, there are technologies adapted to Class 7 and 8 trucks. These are distinguished by their gross vehicle weight rating (GVWR). For exam­ple, a garbage truck is a Class 7 with a GVWR between 11,794 kg and 14,969 kg. A huge truck with a GVWR above 14,969 kg is a Class 8. Since natural gas is the cleanest fuel, the reduction in GHGs associated with this option varies between 16% and 26% and it may play an important role in helping achieve the objectives set by the Québec government. Also, the use of natural gas as a fuel can result in financial and rates savings of up to 40% compared with diesel.

Here, Gaz Métro Transport Solutions presents an overview of this solution for the future to the search for an alternative to the use of gasoline in the transport sector.

Operation of natural gas engines

Since natural gas takes up more space than diesel, it has to be carried on board vehicles in a compressed (CNG) or liquefied (LNG) state. There are two types of engines that work on natural gas: spark-ignited engines and compression-fired engines.

The natural gas spark-ignited engines manufactured by Cummins-Westport operate in the same way as standard gasoline engines. They meet the new EPA 2010 standards without requiring either a urea injection system or a particulate filter.

EPA standards are the U.S. standards regulating pollutants emitted by vehicles.


The natural gas compression-fired engines manufactured by Cummins-Westport are as efficient as diesel engines since they use the same high-pressure auto-ignition phenomenon. Ignition continues by the injection of natural gas into the engine cylinder, where combustion has already begun. Natural gas combustion significantly reduces GHGs while maintaining diesel-like power and torque.


Natural gas compression-fired
engines manufactured
by Cummins Westport

Availability of natural gas

Given specialized facilities, CNG can be available anywhere where natural gas is already present. In Québec, there is only one liquefaction plant. LNG therefore has to be transported by cryogenic tankers.


Natural gas for vehicles is neither subject to the 4¢/L Federal excise tax nor the Québec 17.2¢/L tax on diesel fuels. Also, the provincial government is offering a grant and taxation measures to reduce the additional cost of the vehicle.

Lastly, thanks to the cleaner combustion properties of natural gas, operating and maintenance costs are lower than for standard vehicles.

Below is a simulation based on the projected consumption of two types of truck fleets:

Fleet A

  • 10 CNG garbage trucks
  • Annual consumption: 35,000 L per truck
  • Consumption: 65 L/100 km
  • Cost of diesel fuel: $1/L
  • Additional cost: $26,000 per truck

Fleet B

  • 25 LNG Class 8 trucks
  • Annual consumption: 70,000 L per truck
  • Consumption: 50 L/100 km
  • Cost of diesel fuel: $1/L
  • Additional cost: $75,000 per truck

Solutions for the future

The economic analysis in the following table shows the potential savings and GHG reductions in two scenarios for natural gas for vehicles. For some years, the price of diesel has been higher than that of natural gas and it has fluctuated a lot over time. The savings also vary depending on the complexity of the facilities (number of refuelling stations, capacity of LNG tanks, etc.). Since the investment for LNG projects is higher, the payback period is a little longer.

The use of natural gas as a fuel for fleets of heavy trucks represents a viable economic alternative and can result in significant reductions in GHG emissions in a sector that produces 40% of the emissions in Québec.

Scenario 10 CNG garbage trucks 25 LNG Class 8 trucks
Annual consumption of diesel (L) 350,000 ($1/L) 1,750,000 ($1/L)
Annual cost of fuel ($) 350,000 1,750,000
Additional cost of natural gas trucks ($) 260,000 1,875,000
Grants and taxation measures 78,000 700,000
Actual additional cost of trucks ($) 182,000 1,175,000
Savings (%) 20% 30% 40% 20% 25% 30%
Unit cost of natural gas ($/m3) 0.8 0.7 0.6 0.8 0.75 0.7
Annual cost of natural gas ($) 311,111 272,222 233,333 1,400,000 1,312,000 1,225,000
Savings ($) 38,889 77,778 116,667 350,000 437,500 525,000
Paback periode (years) 4.58 2.34 1.56 3.35 2.69 2.24
Kilometrage (km) 538,462 3,500,000
GHG emissions of a typical diesel truck (g/km) 2,581 1,365
GHGs reduced by use of natural gas % 20% 26%
g/km 516 354.9
Total (tonnes) 278 1 242.15
Jean-François Gauthier, Technical Advisor
Martin Blanchet, Eng.
Gaz Métro Transport Solutions