  This paper presents optimization models for electric Mobility-as-a-Service
systems, whereby electric vehicles not only provide on-demand mobility, but
also perform charging and Vehicle-to-Grid (V2G) operations to enhance the fleet
operator profitability. Specifically, we formulate the optimal fleet operation
problem as a mixed-integer linear program, with the objective combining of
operational costs and revenues generated from servicing requests and grid
electricity sales. Our cost function explicitly captures battery price and
degradation, reflecting their impact on the fleet total cost of ownership due
to additional charging and discharging activities. Simulation results for
Eindhoven, The Netherlands, show that integrating V2G activities does not
compromise the number of travel requests being served. Moreover, we emphasize
the significance of accounting for battery degradation, as the costs associated
with it can potentially outweigh the revenues stemming from V2G operations.
