Detailed data were collected on diesel and BE fuel options for both transit and school buses. A Life Cycle Assessment (LCA) methodology that utilized a wheel-to-wheel (WTW) approach was used to assess the relevant downstream and upstream impacts of V2G service over a 12 year study period (2015 - 2027).

• Downstream impacts ("on-site" impacts, quantified as tailpipe and tire & brake wear (TBW) related emissions) were gathered from the emission data for diesel transit and school buses from the Environmental Protection Agency’s (EPA) widely utilized MOVES Tool.
• Upstream impacts ("off-site" impacts, emissions from petroleum refineries and the applicable power generation and supply sectors) analysis results were gathered from Argonne National Laboratory's GREET Model.

Findings

• BE transit buses using the V2G system can eliminate 1000 metric tons of CO2-equivalent GHG emissions on average over the lifetime of the system, and BE school buses can eliminate more than 1,400 metric tons over a lifetime.
• Using V2G technology can also eliminate the air emissions caused by combustion power plants (which are not environmentally efficient) when accommodating high electricity demand fluctuations. The V2G system can provide enough electricity back to the grid to reduce the mean air externality value of transit BE buses by $13,000 and school BE buses by $18,300 (a net benefit).
• Life cycle cost results indicate that although BE buses require two or three times higher initial costs compared to diesel bus types, overall net costs are less than diesel bus ownership for BE buses (see below table)