Researchers analyzed variations in estimated life cycle costs under both a full-funding case and a common scenario with 80 percent external funding.
Pittsburgh, Pennsylvania, United States
Life cycle ownership cost and environmental externality of alternative fuel options for transit buses
Summary Information
Researchers used characteristics of the operations and 736-bus fleet of the Port Authority of Allegheny County (PAAC) to estimate life-cycle costs associated with several alternative fuel options for transit buses. The analysis considered the following variations for a 40-foot and a 60-foot transit bus:
- Conventional bus powered by either diesel or a biodiesel blend (B20 or B100)
- Diesel hybrid-electric bus
- Sparking-ignition bus powered by Compressed Natural Gas (CNG) or Liquefied Natural Gas (LNG)
- Battery electric bus (BEB) (rapid or slow charging)
Estimates were made for life cycle ownership that included costs for buses and infrastructure, and costs associated with environmental externalities attributable to greenhouse gases (GHGs) and criteria air pollutants (CAPs) emitted during the life cycle of bus operation. Two funding scenarios were modeled: a common 80 percent external / 20 percent local; and a 100 percent agency funded scenario.
METHODOLOGY
Ownership costs included vehicle and supporting infrastructure costs and annualized operating and maintenance costs. Estimation of life cycle external costs included both global factors and consideration of local parameters such as regional electricity sourcing and emission impacts on health. Various parameters such as mileage, fueling infrastructure costs, fuel and electricity unit costs were included in sensitivity analyses.
FINDINGS
Under the funding assumption where the transit agency pays 100 percent of the purchase cost, nearly all alternative fuel options led to higher estimated life cycle ownership and external costs than conventional diesel.
When external funding was available to pay for 80 percent of vehicle purchase expenditures (which is common for U.S. transit agencies) BEBs were estimated to have 17-23 percent lower life cycle costs in terms of agency ownership, and environmental and health costs as compared to diesel. Furthermore, BEBs’ advantages were robust to changes in operation and economic assumptions when external funding was available. BEBs were able to reduce criteria air pollutant (CAP) emissions significantly in Pittsburgh’s hotspot areas, where existing bus fleets contributed to one percent of particulate matter emissions from mobile sources.
Life cycle ownership cost and environmental externality of alternative fuel options for transit buses
Volume 57, December 2017
