While the analysis focused on Seattle, researchers said the findings highlight a challenge that could await other cities and states with emission-cutting commitments.
The city is among the first to install inductive charging stations to power an electric bus fleet.
Two national advocacy groups are critical of how states have allocated money from the Volkswagen settlement.
Critics are worried about the number of charging stations Duke Energy would own and operate under its proposal.
The utility has been hosting webinars and meetings to promote electric school buses and funding opportunities.