Strategies for Transitioning to a Low-Carbon Trucking Future: New Technologies, Fuels for the Country’s Prime Mover of Goods?

Can we reach very low carbon trucking by 2050?

The state of California is targeting an 80% reduction in greenhouse gas (GHG) emissions from 1990 levels by 2050, and recently announced its goal to reduce fossil fuel use in transportation by 40% by 2030. The U.S. federal government is also looking for new ways to reduce emissions from transport. One promising area to achieve both goals is in the tighter regulation of medium and heavy-duty trucks. A new UC Davis research study, “Strategies for Transitioning to Low-Carbon Emission Trucks in the United States,”* concludes that the trucking sector can offer significant reductions in both fuel use and greenhouse gas emissions through increased efficiency, electrification and alternative fuels. However the study cautions that achieving an 80% reduction in GHGs in the trucking sector by 2050 will be very challenging.

Anyone who drives on our major highways knows from firsthand observation: Trucks dominate freight movement in this country. Currently, trucks move 72% of the tonnage and 70% of the goods value nationwide. By 2050, truck travel is expected to increase by 80% nationally and by 50% in California.

There is no question trucks need to play an increasing role in decarbonizing transportation. The U.S. Environmental Protection Agency (EPA) has recently begun a process for tightening existing requirements for heavy-duty trucking fuel efficiency and CO2-equivalent (CO2e) reduction with its Phase 2 fuel economy standards.

Can trucks deliver deep CO2e reductions? It’s a tall order with lots of uncertainty, but our study finds that deeply reducing the carbon footprint of trucking is possible, and could be increasingly affordable over time. However, to achieve deep reductions in truck emissions will require new types of truck engines and fuels—with policies to support their adoption.

Designed for specific and varied purposes, trucks come in many shapes and sizes, including long haul tractor trailers, urban “vocational” trucks (e.g. refuse), delivery trucks, and heavy-duty pickups. Today, the majority of these trucks, no matter their size class, rely on petroleum fuel—with a small share of some segments using natural gas. By 2050, to achieve an 80% reduction in GHG, nearly all trucks in all of these segments will need to be significantly more efficient and be powered by electricity, hydrogen (via fuel cells), or very low carbon advanced biofuels. With “drop-in” biofuel (renewable diesel), trucks can continue to use conventional diesel engines.

In our paper we develop two overarching scenarios. In the first, we show a transition to “ZEV” (zero emission vehicle) trucks, in which nearly all truck sales are either fuel cell or battery electric by 2040. In this scenario, long haul trucks, which use the most fuel of any truck type, have transitioned to almost 100% fuel cell vehicles on the road by 2050. The scenario shows a ZEV sales ramp-up starting in about 2020 and reaching 30-50% market share by 2030. If this scenario were to happen, it would be one of the fastest major changes in propulsion system in the history of transportation.

A second scenario reduces the ZEV requirements and growth rates by one-half and achieves additional GHG reductions by rapidly ramping up production and use of advanced biofuels. While the transition to ZEV trucks could start later and overall looks much more manageable in this scenario, the investments in advanced biofuels production would need to accelerate dramatically over the next 10-15 years, and their feedstocks and production pathways would need to be selected very carefully to ensure that these fuels are sustainable and that they have very low life-cycle GHG impacts.

While neither of these scenarios looks easy, both appear possible and the silver lining may be that both biofuels and ZEV trucks will probably become more affordable over time. We show that taking into account a $50/ton value of CO2e, all of these propulsion systems and fuel options may become competitive with diesel fuel trucks by 2030. There is, however, considerable uncertainty – around costs, the rate that new truck technologies can be adopted, and the carbon intensity of fuels.

Strong policies will be needed to achieve these or similar sales scenarios and the emissions reductions they promise. Tighter federal fuel economy standards for trucks will certainly help to cut truck fuel consumption significantly and help offset truck travel growth. But to get to deep CO2e reductions, the rapid ramp-up pathway of ZEVs is key, and this may require strong, targeted incentives or regulations. Current policies to promote biofuels also may have to be modified to better incentivize advanced, drop-in fuels. Natural gas, leading to very-low GHG renewable natural gas, is another interesting pathway but we did not consider it in detail in this study given uncertainties in the RNG pathway that are the focus of a separate research project by UC Davis.

Ultimately, while the future for trucking looks bright, the future for achieving deep GHG reductions in the trucking sector looks challenging. This study identifies some potential avenues and trajectories, considers needed policies, and estimates some of the major costs. It also identifies areas where more research is needed, since many aspects of our trucking future are uncertain.

*“Strategies for Transitioning to Low-Carbon Emission Trucks in the United States,” a white paper from the Sustainable Transportation Energy Pathways Program at UC Davis and the National Center for Sustainable Transportation.

Read the white paper.

Read the policy brief.

View a video interview of the study’s authors.

Listen to the webinar

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