Project Summary
Heavy-duty vehicles, such as buses, are not only a large contributor to criteria pollutant emissions, but are also sources of emissions that are embedded within population centers. Policy efforts to address this with respect to buses are codified in regulations, such as the California Air Resources Board Innovative Clean Transit measure, with the goal of transitioning the statewide transit bus fleet by 2040 to zero emission vehicles. Multiple options exist for transitioning the urban bus fleet technology, which include but are not limited to: 1) fuel-switching to lower-carbon, cleaner burning fuels such as natural gas, 2) deployment of all-electric battery electric buses, and 3) deployment of hydrogen fuel cell buses. However, each of these options vary in their overall effectiveness in reducing different emission types over their life cycle, associated life cycle costs, ability to meet operational needs of transit agencies, and life cycle environmental footprint. In order for transit agencies to determine the cost- and environmentally-favorable pathways for transitioning urban bus fleets to reduce emissions, information regarding the life cycle greenhouse gas and criteria pollutant emissions, costs, and environmental externalities such as water resource impacts for potential urban bus technologies must be provided. This project aims to provide this insight using the following phases. The first phase will focus on acquiring life cycle inventory data for different urban bus powertrain technologies by utilizing available life cycle databases and literature studies. The second phase includes modeling of urban bus fleet operation to accurately capture operating energy needs and associated emissions in the context of powertrain characteristics and bus scheduling needs. The third phase will focus on utilizing the Brightway2 life cycle assessment framework in combination with the development of economic modeling methodologies for alternative bus powertrain deployment for performing full life cycle assessment of different urban bus powertrain options to determine per-mile greenhouse gas emission, criteria pollutant emission, cost, and environmental footprint performance.
