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October 12, 2021   |   Diesel Technology Forum

Policy Insider

“Best” Technology Choices? How Diesel Comes Out on Top of Natural Gas and Electric

The next best short-term option for meeting ultra-low NOx requirements is diesel.

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Diesel, natural gas, and electric heavy-duty vehicles can all be designed to limit tailpipe NOx emissions to ultra-low levels required by California’s soon-to-be finalized omnibus rule.



Which fuel is best for meeting the nation’s heavy-duty trucking needs? Electric, natural gas or diesel? New policies setting future ultra-low emissions standards for nitrogen oxides for heavy-duty vehicles have been adopted in California and are expected to be announced early in 2022 by U.S. EPA. The rules don’t dictate which fuels can be used – diesel, natural gas and electric are all possible – only that the technology complies with the standards. Other policies are advancing the introduction of zero emission vehicles like electric and hydrogen.

In a recent briefing the International Council on Clean Transportation (www.theicct.org) explored these new standards where they compared the capabilities of these three powertrain types in meeting an ultra-low NOx standard across four key areas: feasibility, cost, health impacts and climate impacts. They concluded that the outcomes for each (type of fuel/technology) are not the same. 

ICCT concludes: “Diesel, natural gas, and electric heavy-duty vehicles can all be designed to limit tailpipe NOx emissions to ultra-low levels required by California’s soon-to-be finalized omnibus rule. The costs to do so are similar on a total cost of ownership basis. Of the three technologies, electric vehicles have the lowest overall health and climate impacts, and it is crucial that regulations be put in place to support a transition to 100% electric HDVs as soon as possible. However, it is unlikely to be possible to transition to a 100% electric HDV fleet within the time frame of the regulation (2027).

“In this case, the next best short-term option for meeting ultra-low NOx requirements is diesel. Diesel is a better alternative in the immediate term than natural gas for three main reasons: (1) adoption of natural gas vehicles would require significant investment in new infrastructure that could slow the transition away from fossil fuels; (2) the overall health impacts from natural gas due to high emissions of unregulated pollutants (ammonia and ultrafine PM) are significant; and (3) once fugitive methane emissions are factored in, natural gas heavy vehicles are on average more harmful to the climate than heavy-duty diesel vehicles.”

The briefing highlights the challenges and merits of each fuel type:

This insight from ICCT demonstrates the importance of carefully evaluating technologies and how they will meet the needs of the short term and long term.



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Key Contact

Allen Schaeffer
Executive Director
aschaeffer@dieselforum.org
301-668-7230

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