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Carriers that need to reduce their carbon footprint from diesel or gasoline have several alternative fuels to choose from besides battery electric. Compressed natural gas (CNG) and renewable natural gas (RNG) are increasingly used in commercial vehicles, from work trucks to over-the-road Class 8 semi-trucks.
Scope
CNG and RNG considerations apply to all motor carriers, shippers, and receivers that need to reduce their carbon footprint.
Regulatory citations
- None
Key definitions
- Compressed natural gas (CNG): A non-renewable fossil fuel extracted through wells in subsurface rock formations. CNG is produced by compressing natural gas to less than one percent of its volume at standard atmospheric pressure. To provide adequate driving range, CNG is stored onboard a vehicle in a compressed gaseous state at a pressure of up to 3,600 pounds per square inch.
- Renewable natural gas (RNG): A gaseous byproduct of the decomposition of organic matter such as landfill waste, cow manure, and wastewater processed to purity standards. RNG is fully interchangeable with conventional natural gas and can be used when compressed or liquified in natural gas vehicles. Also referred to as biomethane.
Summary of requirements
Fleets cannot risk widespread service interruptions because an inappropriate fuel was selected. Yet, the choice must be cost-effective.
Greenhouse gas (GHG) emissions requirements from states or the Environmental Protection Agency (EPA) and available state or federal incentives are factors for deciding which alternative fuel vehicle will work for a fleet. After emissions deadlines pass, penalties are possible, and incentives expire.
To understand the fleet impact by state, see the current emissions regulations and incentives on this DOE website: https://afdc.energy.gov/laws/
Below is a summary of the emissions reduction toward meeting greenhouse gas (GHG) requirements, along with positives and negatives of each.
Alternative fuel | Emissions Impact | Positives | Negatives |
CNG | 10 percent lower carbon dioxide (CO2) emissions than diesel | - Widespread availability - Relatively low cost Similar fuel efficiency and performance to gasoline or diesel engines - Can be used in dual-fuel engines - Can convert gasoline or diesel vehicles to CNG -No particulate filter issues or cost | - Need liquified natural gas (LNG) or more storage tanks to increase range - Limited fueling infrastructure - Possible facility modifications for fueling and to meet fire, electrical, mechanical, building and other safety codes for natural gas |
RNG | Negative carbon intensity* due to harmful methane removal | - Relatively low cost - Widespread availability in CA - Reliable powertrains - Growing in use - Interchangeable with CNG in vehicles and distribution channels | - 60 percent of supply is in California - Possible facility modifications for fueling and to meet fire, electrical, mechanical, building and other safety codes for natural gas |