A whole new frontier lies ahead in the field of renewable energy: airborne wind energy. This novel technology could well revolutionise electricity production. It involves the use of autonomous aircraft, which generate electricity when lifted by the wind, obviating the need for massive fixed structures. Professor Lorenzo Mario Fagiano from the Department of Electronics, Information and Bioengineering at the Politecnico di Milano guided us through this emerging technology, illustrating its advantages, outlining the challenges it faces, and stressing the leading role of the Politecnico in the research and development of cutting-edge solutions.
What is airborne wind energy?
«Airborne wind energy is a way of converting wind energy into electricity by the use of autonomous aircraft tethered to the ground by cables.
Various solutions are now either at an advanced stage of development or coming to market, with a nominal power output of about 100kW per individual system. Some solutions use flexible aircraft similar to kites or paragliders, while others use rigid-wing aircraft more like drones».

What are the benefits?
«With the use of the latest sensor technologies, automatic controls and AI systems, the aircraft harness the power of the wind to keep themselves in the air, while also generating electricity through devices located either on the ground or on the aircraft itself. There is therefore no need to construct and install expensive, high-impact structures such as the tower and rotor of a conventional wind turbine.
The overall mass of an airborne system is actually less than a tenth of the mass of an equivalent wind turbine, so the costs of construction and installation are significantly lower. In addition, the use of relatively light cables allows these systems to reach significant heights above the ground – where the wind is much stronger, resulting in greater electricity production and greater availability of the primary energy source.
Current systems are already operating at 200 to 500 metres above the ground, heights that no other types of wind generators could ever reach, and can produce up to twice as much energy per year, with the same nominal power output. The combination of lower costs and higher output could well result in cheaper electricity than that produced from any other form of generation, whether renewable or not. In addition, high-altitude wind is accessible from a greater number of sites, so this technology can easily be used in tandem with existing systems such as traditional wind and photovoltaic generation. Finally, the particular features of airborne wind energy systems make them right for installation on floating deep-sea platforms, with low costs and minimal environmental impact».
What are the main challenges?
«The principles behind this wind technology were envisioned in the late 1970s, but it was not until about 15 years ago that various research centres and enterprising companies undertook the technical development required for marketing these systems, supported by investments from public, national, European and private sources.
From a technical and scientific standpoint, the current challenges concern the development of top quality automation systems and components that can ensure high reliability and fault tolerance, as well as the development of the necessary expertise and technical solutions to be able to scale up the individual system from hundreds of kW – currently designed for small-scale applications on islands and in remote places with low energy demand – to 2-3 MW of nominal power output. This greater output is seen as a necessary condition for entering the market for large-scale electricity production.
From the commercial point of view, the current challenges concern the development of adequate regulations for these innovative systems and suitable supportive measures to encourage the rapid development of the sector and the entire value chain connected to it».
What’s the international scenario?
«Up until now, most of the research groups and developers of airborne wind systems have been within the European Union. In 2019, the Airborne Wind Europe association was set up, to create the best conditions for developing the sector. In the spring of 2024, the German Parliament approved a special preferential tariff for electricity sourced from airborne wind systems.
Studies undertaken by the industry have estimated that, with suitable support in terms of financing and regulatory procedures, airborne wind energy has the potential to make a significant contribution to the goal set by the EU and all the world’s industrialised nations of achieving climate neutral, sustainable and secure energy supplies, while also creating a whole new industrial sector with consequent economic development and growth».

What is the role of the Politecnico di Milano?
«The Politecnico di Milano is at the forefront of the research and development of airborne wind technology and is currently one of the main points of reference on the global stage. The Politecnico has been involved in projects funded by the European Union (Horizon Europe’s MERIDIONAL project, Maria Skłodowska-Curie training network), the PNRR (as part of the “NEST” Extended Partnership, the “DeepAirborne” PRIN project), the Cariplo Foundation (“NextWind” project), and public-private initiatives. Through these, researchers have been able to carry out detailed studies and subsequently develop various aspects of aerodynamics, fluid dynamics, artificial intelligence, automation, electrical conversion, and the environmental impacts related to airborne wind systems, with the active participation of three departments (DAER, DEIB, DICA).
The Politecnico di Milano is also a founding member of Airborne Wind Europe. Other academic members of the association are TU Delft (a founding member) and RWTH Aachen, with which the Politecnico di Milano has collaborative agreements such as IDEA League and ENHANCE, in addition to the University of Stuttgart, the University of Porto, the Carlos III University of Madrid, and the University of Ghent.
The Politecnico di Milano organised and hosted the ninth international conference of the sector in 2022, with about 170 delegates from all parts of the world taking part. It then confirmed its leading position in the field of scientific research at the tenth international conference, held in Madrid in April 2024, with the participation of fifteen undergraduates, PhD Candidates and professors, who explained the progress of their research».

The work of the Politecnico in the field of airborne wind energy shows it is right at the forefront of this technology. How did you develop your interest in this subject?
«After taking a Master’s Degree (equivalent to Master of Science) at the Politecnico di Torino and a brief spell working in industry, I decided to study for a PhD in Automation in 2006, and had the good fortune to encounter two lecturers, Professors Massimo Canale and Mario Milanese. They suggested I follow two lines in my research: on the one hand, the development of basic systems in the field of automatic controls, and on the other a study of this new technology, which was then known as high-altitude wind energy (or power).
My doctoral thesis was the first in this field, and attracted a certain amount of international interest and recognition, including the ENI Debut in Research Award for 2010, presented to me by President of the Italian Republic Giorgio Napolitano in a ceremony at the Quirinale.
The potential impact on the energy transition, the scientific and technical challenges, and awards for the research by myself and my colleagues, have encouraged me to pursue this field ever since then. Therefore, during the years I have worked in both academia and industry, at UC Santa Barbara, ETH Zurich, ABB Corporate Research and finally at the Politecnico di Milano, I have continued to combine the study of airborne wind power with other areas of research, always maintaining my approach of pursuing methodological and applied research in tandem. Meanwhile, a special scientific community has been created, of which our group is now an integral part».
Which areas of research would you like to develop in the future?
«For the next few years we’ll continue to concentrate mainly on airborne wind technology, with the aim of making a substantial contribution to its technical and scientific development and industrial production.
In the Safe Automation Systems laboratory (SAS-Lab), we’re also conducting research in the area of modelling, and of improving and automating complex systems, with applications in industrial fields such as aerial robotics (multicopter drones for civil use), the manufacturing and processing sectors, energy generation and distribution.
This range of topics allows us to individuate certain basic problems of significant concern, which can be investigated using mathematical methods and systems theory. One line of research we want to focus on is the development of methods to improve multiple aspects in complex systems simultaneously, for they change over time and so are difficult to predict. These studies are important not just for engineering, but also for other sectors».