Abstract. While modern wind turbines have become by far the largest rotating
machines on Earth with further upscaling planned for the future, a renewed
interest in small wind turbines (SWTs) is fostering energy transition and smart
grid development. Small machines have traditionally not received the same
level of aerodynamic refinement as their larger counterparts, resulting in
lower efficiency, lower capacity factors, and therefore a higher cost of
energy. In an effort to reduce this gap, research programs are developing
worldwide. With this background, the scope of the present study is 2-fold.
In the first part of this paper, an overview of the current status of the
technology is presented in terms of technical maturity, diffusion, and cost.
The second part of the study proposes five grand challenges that are thought
to be key to fostering the development of small wind turbine technology in
the near future, i.e. (1) improving energy conversion of modern SWTs through
better design and control, especially in the case of turbulent wind; (2)
better predicting long-term turbine performance with limited resource
measurements and proving reliability; (3) improving the economic viability of
small wind energy; (4) facilitating the contribution of SWTs to the energy
demand and electrical system integration; (5) fostering engagement, social
acceptance, and deployment for global distributed wind markets. To tackle
these challenges, a series of unknowns and gaps are first identified and
discussed. Based on them, improvement areas are suggested, for which 10 key
enabling actions are finally proposed.