Ground-generation airborne wind energy design space exploration

Abstract. While some Airborne Wind Energy System (AWES) companies aim at small-scale, temporary or remote off-grid markets, others aim to integrate utility-scale, multi-megawatt AWES into the electricity grid. This study investigates the scaling effects of single-wing, ground-generation AWESs from small to large-scale systems, subject to realistic 10-minute, onshore and offshore wind conditions derived from the numerical mesoscale weather research and forecasting (WRF) model. To reduce computational cost, wind velocity profiles are grouped into k = 10 clusters using k-means clustering. Three representative profiles from each cluster are implemented into a nonlinear AWES optimal control model, to determine power-optimal trajectories, system dynamics, as well as instantaneous and cycle-average power. We compare the performance of three different aircraft masses and two sets of nonlinear aerodynamic coefficients for each aircraft size, with wing areas ranging from 10 m2 to 150 m2. We predict size and weight-dependent, optimal AWES power curves, annual energy production (AEP) and capacity factor (cf). Tether impacts, such as power losses associated with tether drag and the tether contribution to total system mass are quantified. Furthermore, we estimate a minimum average cycle-average lift to weight ratio, above which ground-generation AWES can operate, to explore the viable AWES mass budget.