CNG Is Clean

Natural gas vehicles can have a direct, positive impact on America’s air quality and environment – today. NGVs in urban environments are a solution for meeting EPA non-attainment measures and improving local air quality.

Emissions Reduction in Real Numbers

Natural gas vehicles improve air quality through the following dramatic reductions in emissions:

• Reduces carbon dioxide (CO₂) emissions by 20%-30%
• Reduces carbon monoxide (CO) emissions by 70%-90%
• Reduces nitrogen oxide (NOx) emissions by 75%-95%
• Reduction of up to 90% of particle matter (PM) emissions
• Reduces volatile organic compound (VOCs) emissions by 89%

Source: NGVAmerica/DOE/EPA

Energy efficiency of various alternative fuels
(Click on the graph below to enlarge.)

Source: The Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET) Model 1.8b

Total Energy consumption of select alternative fuels
British Thermal Unit (BTU)/Mile
(Click on the graph below to enlarge.)

Source: The Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET) Model 1.8b

In addition, alternative fuel vehicles such as CNGs produce little or no evaporative emissions (i.e. fumes) during fueling and use. In gasoline vehicles, evaporative and fueling emissions can account for at least 50% of a vehicle's total hydrocarbon emissions.

Per unit of energy, natural gas contains less carbon than any other fossil fuel, and thus produces lower carbon dioxide (CO₂) emissions per vehicle mile traveled. While CNG vehicles do emit methane, another principle greenhouse gas, any increase in methane emissions is more than offset by a substantial reduction in CO₂ emissions compared to other fuels.

A recent study done on behalf of the California Energy Commission concludes that CNG vehicles produce up to 29% less greenhouse gas emissions than comparable gasoline vehicles and up to 22% less than comparable diesel vehicles.

Some vehicle fuels use water in processing their raw elements for usable energy. For example, although ethanol is billed as an environmentally friendly fuel, some forms of processing involve using large amounts of water to refine it into energy. Natural gas uses far less water when it is processed, versus other transportation fuels.

Water intensity of transportation fuels
(Click on the graph below to enlarge.)

The bottom line is that natural gas-powered vehicles are dramatically better for the environment than gasoline-powered vehicles.

Source: NGVC.org: Environmental Benefits of Natural Gas Vehicles. 

“Vehicles (such as the Honda NGV) with a SULEV, PZEV or AT PZEV emissions rating emit only two pounds of hydrocarbons over 100,000 miles of driving – that's equivalent to spilling a pint of gasoline.”

- DriveClean.ca.gov