Power optimized battery swap and recharge strategies for electric aircraft operations

Abstract

Electric propulsion for commuter air transportation is becoming promising because of significant strides in battery specific energy and motor specific power. Energy storage and rapid battery recharge remain nonetheless challenging owing to the significant energy and power requirements of even small aircraft. By modifying algorithms developed in the field of scheduling theory, we propose power optimized and power-investment optimized strategies for electric aircraft battery swaps and recharges. Several aspects are considered: electric energy expenditures, capital expenditures, and flight schedule integrity. The first strategy optimizes the swaps and recharges to minimize the peak-power draw from the grid and to reduce electric energy expenditures. The second strategy optimizes the swaps and recharges to minimize electricity expenditures and capital expenditures associated with battery and charger procurement. In both cases, the optimization is decomposed into two simpler problems. The first is a recharge schedule feasibility analysis given a number of chargers and batteries, which is based on a network flow representation of the battery swap and recharge. The second is a recharge schedule generation given a number of chargers and batteries. Both strategies are applied to the operations of two commuter airlines and are contrasted with a benchmark non-optimized power-as-needed strategy. Promising results are obtained with up to 61% reduction in peak-power draw and up to 25% reduction in electricity costs.