Airborne wind energy (AWE) systems harness wind power using devices flying in controlled patterns, with two main concepts: onboard power generation in the 'drag mode' and ground-based generation in the 'pumping cycle'. Quasi-steady state models (QSM) efficiently predict parameters like tether force and kite velocity for smaller AWE systems but the neglect of inertial forces leads to inaccuracies for bigger systems. Various formulations of quasi-steadiness exist in AWE literature, but their validity limits remain poorly understood. This research presents a theoretical framework specifically tailored to crosswind tethered flight dynamics, which is used to obtain a consistent definition of quasi-steadiness and to quantify the validity of this assumption, through extensive solution space analysis. The study finds that QSM provides reasonable accuracy for time-averaged quantities but fails to predict other aspects such as amplitude or phase. Limitations arise from the use of a steady aerodynamic model and assumptions of a rigid tether.

The WaveWings project seeks to harness the synergetic potential of Airborne Wind Energy Systems (AWES) and Wave Energy Converters (WEC) to create a 1 GW deep-offshore renewable energy farm, contributing to the European Union’s net-zero 2050 goals. This report details the design process and outcomes of integrating a Leading-Edge Inflatable (LEI) kite system with a point absorber wave energy converter (WEC). The LEI kite and point absorber generate 2.3 MW and 150 kW of power, respectively. Key trade-offs and design choices were made in selecting the kite, launch system, WEC, and anchoring mechanisms to optimize performance and sustainability. Sustainable design strategies are implemented to reduce the Levelised Cost Of Electricity (LCOE) and Global Warming Potential (GWP). The integration of the airborne and wave energy systems was optimized through simulations to maximize energy absorption and respect synergy requirements. Market and financial analyses indicated that WaveWings project can be competitive on the west coast of Ireland.