The use of natural gas as a vehicle fuel provides environmental benefits. Greenhouse gas emissions are reduced on a total lifecycle or well-to-wheels basis by 15% to 25% below diesel vehicles. While emissions from diesel vehicles have decreased in response to tightening emissions standards, these improvements relate to air pollutants. To date, there has been no reduction in greenhouse gas emissions from diesel vehicles as a result of tightening emissions standards.
New heavy vehicle standards that come into effect in Canada and the United States for model year 2016 vehicles will, for the first time, regulate greenhouse gas emissions. Natural gas trucks and buses will comply with these standards and can help position fleets for longer term compliance due to the lower greenhouse gas emission profile of natural gas as a transportation fuel.
Natural gas-powered vehicles also emit fewer air pollutants. Smog-related emissions of sulphur dioxide (SO?) and non-methane hydrocarbons (NmHC) are reduced. During vehicle refueling, there are no evaporative emissions because the connection between the fuel dispenser and the vehicle creates a sealed system.
Natural gas vehicles are quieter than diesel vehicles. The noise from one diesel bus idling equals the noise from ten idling natural gas buses. Lower noise levels benefit fleets, communities, and drivers who spend their days behind the wheel.
Natural gas use does not pose any risk to soil or groundwater because it is lighter than air and will rise into the atmosphere if released. In the event of a motor vehicle accident involving a fire, natural gas fuel storage systems on vehicles are designed to release fuel from the storage tanks, so as to minimize risk to vehicle occupants and to the public. As natural gas is primarily made up of methane which is, itself, a greenhouse gas, it is important to minimize any natural gas releases to the atmosphere.