Cost Minimization for Charging Electric Bus Fleets


Recent attention for reduced carbon emissions has
pushed transit authorities to adopt battery electric buses (BEBs).
One challenge experienced by BEB users is extended charge
times, which create logistical challenges and may force BEBs
to charge when energy is more expensive. Furthermore, BEB
charging leads to high power demands, which can significantly
increase monthly power costs and may push electrical infrastruc-
ture beyond its present capacity, requiring expensive upgrades.
This work presents a novel method for minimizing the monthly
cost of BEB charging while meeting bus route constraints. This
method extends previous work by incorporating a more novel
cost model, effects from uncontrolled loads, differences between
daytime and overnight charging, and variable rate charging.
A graph-based network-flow framework, represented by a
mixed integer linear program, encodes the charging action space,
physical bus constraints, and battery state of charge dynamics.
Results for three scenarios are considered: uncontested charging,
which uses equal numbers of buses and chargers, contested
charging, which has more buses than chargers, and variable
charge rates. Among other findings, we show that BEBs can
be added to the fleet without raising the peak power demand
for only the cost of the energy, suggesting that conversion to
electrified transit is possible without upgrading power delivery

See publication:
This publication pertains to:
Charging Stations
Publication Authors:
  • Daniel Mortensen
  • Jake Gunther
  • Greg Droge
  • Justin Whitaker
It appeared in:
Peer-reviewed technical journal
Battery Electric Buses, Cost Minimization, Multi-Rate Charging, Mixed Integer Linear Program