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NACFE Releases Emissions Report on the Messy Middle
Fort Wayne, Indiana — June 31, 2026 — The North American Council for Freight Efficiency (NACFE) has released its fourth report from Run on Less – Messy Middle, From Source to Highway: The Messy Middle Emissions Report.
This report focuses on greenhouse gas and criteria emissions based on analyzing data from the 14 trucks that participated in Run on Less – Messy Middle.
Run on Less – Messy Middle demonstrated the business of moving goods can be successfully accomplished by a variety of means. This includes creating vehicle propulsion from various energy derivatives, including fossil diesel, renewable diesel, biodiesel, electricity, fossil (conventional) natural gas, renewable natural gas, and hydrogen. Each fuel option has different characteristics from an emissions standpoint.
The report found that no longer can the environmental footprint of a heavy-duty vehicle be assessed solely by the composition of gases exiting its tailpipe. Instead, a comprehensive accounting requires a well-to-wheel perspective that integrates the well-to-tank emissions generated during energy production and distribution with the tank-to-wheel emissions produced during vehicle operation. The report used Argonne National Laboratory’s GREET model to calculate well-to-wheel emissions.
“As transportation technology rapidly evolves, so must our thinking,” says Ken North, NACFE’s emerging technologies consultant. “New energy options have emerged to efficiently move freight and power our world, it only makes sense to now evaluate the success or failure of these new technologies based on a fresh look at all emission outputs.”
The report found that as fleet operators evaluate their options for decarbonization, they are faced with a matrix of choices: clean diesel, fossil diesel, renewable natural gas, battery electric vehicles, and fuel cell electric vehicles. Each has a distinct health impact profile when analyzed from a lifecycle perspective.
“Some may see progress on emission reduction as opposition to fleet efficiency improvement,” North said. “In the end, crossing the Messy Middle will mean the achievement of both total cost of ownership efficiency gains and emission reductions. Success is not one nor the other, it’s both at the same time.”
The study team identified key findings impacting the transition of the North American heavy-duty trucking industry.
- Fuel/Energy Origin Outweigh Engine/Powertrain Technology: The carbon footprint of a truck is determined more by the origin of the fuel molecule than the metal of the engine block. For example, RNG derived from dairy waste has the potential to make a vehicle carbon-negative, regardless of the internal combustion engine’s inherent inefficiency. A BEV can only be as clean as the grid that charges it. BEV operational carbon reductions can range from 62% to more than 99% depending on whether the truck is charged on a fossil-heavy grid or a clean, nuclear/hydro-backed grid, like Northern California. California’s grid puts BEVs on par with RNG and biodiesel today.
- Alternative Fuels Achieve Diesel-Like Performance: The era of yesterday’s underpowered alternative energy truck is over. The latest 15-liter natural gas engines successfully powered 140,000-lb. loads in Canadian conditions and maintained highway speeds with triple trailers across US highways, proving they can handle the most demanding heavy-haul applications. This expanded powertrain capability brings a new reality to decarbonizing heavy haul/long distant route segments. Renewable natural gas, renewable diesel, and biodiesel are positioned to significantly reduce emissions within these segments.
- Decarbonization as a Public Health Need: The health impact from freight emissions are large and unevenly distributed. Fossil fuel emissions (diesel and coal) cost the US economy between $100 billion and $1 trillion annually in health damages, according to the US Congress’ Joint Economic Committee. Reducing emissions in populated freight corridors leads to significant reductions in negative health outcomes and healthcare cost expenditures. A transition of the oldest diesel trucks in major cities to any modern alternative (RNG, BEV, or FCEV) would yield immediate, high-value health returns.
- The Driver Impact: Drivers have as significant an impact on fuel economy and emissions reductions as do the truck technologies. Well-driven trucks on predictable, well-known routes where operations are optimized to avoid congestion and delays can achieve significantly better performance with all fuel types.
- Fleets Should Include Emissions Considerations in their Decisions: As fleets look to the many options available when considering their next truck purchases, it is important to include emissions considerations along with operational and total cost of ownership in decision making.
