Project at a Glance

Title: Pathways Towards a Near-Zero Heavy Duty Sector

Principal Investigator / Author(s): Samuelsen, Scott

Contractor: UC Irvine

Contract Number: 16RD011

Research Program Area: Climate Change

Topic Areas: Greenhouse Gas Control, Greenhouse Gas Emissions, Mobile Sources & Fuels


Achieving California's climate and air quality goals requires significant transformation of the heavy duty sector. While electrification can help decarbonize vehicle energy demands, it may not be suitable or the least-cost option for all applications. Alternatively, biofuels can also reduce GHG emissions and provide a drop-in fuel substitute; however, they are limited in supply and may not reduce criteria pollutant emissions as much as ZEVs. This study develops long-term scenarios for least-cost uses of renewable fuel feedstocks, fuel production technologies, and powertrains for the heavy duty sector, given technology and emission constraints, to inform investments and policy development so California can achieve climate and air quality goals. Results from the techno-economic optimization show electricity and biomass-derived renewable diesel, natural gas, and hydrogen are viable pathways towards fleet mixes that can meet climate and air quality goals, but increasing ZEV adoption yields lower GHG emissions in the long-term at nearly the same cost. Additionally, constraints on biomass availability and uncertainty regarding competing demands from other sectors may require electrolytic fuel pathways play a prominent role long-term if hydrogen and renewable natural gas (RNG) meet a substantial portion of fleet fuel demands. Fleet barriers to achieving these future scenarios were investigated to create a guidance document incorporating strategies that help overcome identified constraints. The most effective policies and economic mechanisms to encourage zero and near-zero pathways are identified through analyzing existing policies and potential barriers to using advanced technologies.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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