Study: Biobased diesel use in trucks provides more emissions benefits than EVs at lower cost

A new study that evaluates several approaches to reducing greenhouse gas (GHG) and other emissions from medium- and heavy-duty vehicles from 2022-'32 finds considerable advantages with advanced-diesel technology, particularly when using renewable biofuels, as compared to an electrification strategy.

Medium- and heavy-duty trucks operating in 10 Northeastern states—Connecticut, Delaware, Massachusetts, Maryland, Maine, New Jersey, New York, Pennsylvania, Rhode Island and Vermont—that have adopted California’s low-emission (LEV) and zero-emission vehicle (ZEV) regulations were studied by Stillwater Associates for the Diesel Technology Forum. An analysis was undertaken to analyze the environmental benefits attainable from three strategies in the 2022-'32 period; electrification, accelerated fleet turnover and use of biodiesel and renewable diesel fuel.

“As we look for the best ways to reduce greenhouse gas and other emissions, this study demonstrates that accelerating fleet turnover and use of renewable and biodiesel fuels can deliver significantly more benefits (three times) that outweigh those possible from EVs in the region in the study period,” said Allen Schaeffer, executive director of the Diesel Technology Forum. “Advanced diesel technology is more effective, more affordable and, most importantly, more available than others. The urgency to implement solutions to reduce greenhouse gases from transportation and address climate change is heard on a daily basis. Transitions to new energy sources still have considerable uncertainties and longer timeframes—a decade or more—to meaningful implementation. Some solutions will be available sooner than others and at larger scale than others. Advanced-diesel technology, as well as renewable and biodiesel fuels, are key available solutions that can deliver big impacts today.”

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The considerable benefits of using low-carbon renewable biobased diesel fuels becomes clearer from this analysis. As these fuels can be used in all diesel vehicles today, fueling the diesel vehicles in the study with 100 percent renewable diesel resulted in three times more cumulative GHG reductions by 2032 than the EV scenarios. Using B20—a 20 percent blend of biodiesel with 80 percent petroleum diesel—provided about the same cumulative GHG reduction.

“All eyes seem to be focused on electrification as the best if not the only strategy for the future fuel and technology in the transportation sector,” said Gary Yowell, an automotive engineer at Stillwater Associates. “This work has illuminated that’s overly simplistic, that there are significant, less expensive and more available emissions-reduction strategies for these workhorse vehicles, which can enable greater emission reductions to be delivered more rapidly.”

Beyond GHG emissions, the research also highlighted impacts of an advanced diesel vs. electrification strategy on regional air quality as well, finding that the business-as-usual case replacing pre-2007 model-year diesel vehicles that lacked diesel particulate filters with advanced-technology diesel vehicles provided the largest particulate matter (PM) reduction. This is due to new-technology diesel engines’ 98 percent PM reductions compared to EVs’ 95 percent PM reduction, assuming power from the U.S. grid mix.

As for nitrogen-oxide (NOx) emissions, EVs have 98.5 percent lower NOX than pre-2007 diesel vehicles on a per-mile basis, and 2010 and later model-year vehicles have 79 percent less NOx emissions than a 2007 diesel model. However, when replacing a diesel medium- and heavy-duty vehicle with an EV and evaluated on an annual miles-driven basis, the NOx benefit is diminished. EVs are generally deployed on shorter routes and have a shorter range of operation than that of a comparable diesel vehicle, with about 87 percent of the mileage on a daily basis. Given this mileage difference, NOx-emission reductions for a fleet transitioning to EV will be less than the business-as-usual turnover from older-generation diesel to advanced technology with selective catalytic reduction (SCR) systems that reduce NOx by 98 percent.

On a cumulative fleet-conversion cost basis, turning over a medium- and heavy-duty fleet of 10,000 vehicles in the region over to EV carries a price tag more than three times higher than the equivalent cost for new-technology diesel vehicles. The incremental EV cost for Class 7/8 vehicles is $250,000 for the vehicle and $45,000 for charging infrastructure.

The full study can be viewed and downloaded here.

A live, virtual event will be held with the researcher at 1:00 p.m. Eastern time July 21. Register now here.