Eco-conscious design evaluation of Airborne Wind Energy Systems using Life Cycle Assessment

Presentation by Adrien Guillore, Technical University of Munich, during the mini-symposium "Airborne Wind Energy" at the Wind Energy Science Conference, Glasgow, 23-26 May 2023. https://www.wesc2023.eu/

Airborne Wind Energy (AWE) is a promising, rising, clean and affordable renewable energy technology. Specifically, one of the main promising assets of AWES is their potentially very low Climate Change impact (expressed in gCO2/kWh) since they can get rid of highly material-intensive systems like the tower.

Past work at TUM has been conducted to develop automated procedures capable of assessing, through the Life Cycle Assessment (LCA) methodology, the Climate Change impact of conventional wind energy systems (e.g. wind turbines) [1,2,3]. Specifically, the greenhouse gas emissions of these systems are estimated throughout their lifetime considering, among others, manufacturing, installation, maintenance and decommissioning. This metric, alongside the most conventionally used Levelized Cost of Energy (LCOE), has also been integrated within automated design tools.

The focus of this present work is to extend the tool to AWES, specifically to assess the environmental impact of the fly-gen rigid-wing drag power kite prototype developed by the company Kitekraft GmbH [4]. This study aims to analyze and quantify the potential reduction of greenhouse gas emissions that can be obtained with this new technology. The tool consists of various sub-models that estimate the masses of several system components (e.g., kite, motors, tether, ground station, foundations, etc.) based on design parameters and the expected energy production. Finally, the LCA sub-model translates the related material consumption and activities (from cradle to gate) to the overall life-cycle Climate Change impact. The so-defined Impact Of Energy (IOE, measured in gCO2eq/kWh) is finally assessed.

The tool has been applied to specific kite sizes defined by their installed powers of 5kW, 100kW and 500kW. Lower IOE are observed compared to conventional wind turbines, with decreasing IOE observed for increasing kite size, thus revealing a potentially huge benefit in upscaling the technology from the prototype. Furthermore, the environmental impact can be broken down into related life stages, with the material extraction and components manufacturing being responsible for the major part of the impact. Further assessment, performed at the components and materials level, identifies the ground station as the system with the highest impact. which allows us to analyze future design opportunities to minimize it. These preliminary results will be used to improve confidence in the kite mass scaling laws (physic-based laws having to be refined). The tool will be applied for continuous design optimizations of the system.