  This paper examines the marginal value of mobile energy storage, i.e., energy
storage units that can be efficiently relocated to other locations in the power
network. In particular, we formulate and analyze the joint problem for
operating the power grid and a fleet of mobile storage units. We use two
different storage models: rapid storage, which disregards travel time and power
constraints, and general storage, which incorporates them. By explicitly
connecting the marginal value of mobile storage to locational marginal prices
(LMPs), we propose efficient algorithms that only use LMPs and transportation
costs to optimize the relocation trajectories of the mobile storage units.
Furthermore, we provide examples and conditions under which the marginal value
of mobile storage is strictly higher, equal to, or strictly lower than the sum
of marginal value of corresponding stationary storage units and wires. We also
propose faster algorithms to approximate the optimal operation and relocation
for our general mobile storage model, and illustrate our results with
simulations of an passenger EV and a heavy-duty electric truck in the PJM
territory.
