MIT Engineers Unveil New Theory to Boost Wind Farm Design and Efficiency

Engineers at the US-based Massachusetts Institute of Technology (MIT) have developed an innovative theory that could significantly improve the design and operation of wind farms. This new model, which is the first comprehensive physics-based theory of rotor aerodynamics, addresses longstanding limitations in the way turbine blades and wind farms are designed and controlled.

The research, led by MIT postdoc Jaime Liew, doctoral student Kirby Heck, and Michael Howland, the Esther and Harold E. Edgerton Assistant Professor of Civil and Environmental Engineering, was published in 'Nature Communications' recently. 

For over a century, the design of wind turbines and propellers has relied on aerodynamics principles that were mathematically described in the late 19th century. However, engineers have known that these traditional formulas fail under certain conditions, particularly when turbines operate at high speeds, forces, or specific blade angles. To compensate for these deficiencies, ad hoc “correction factors” based on empirical observations were often added, leading to inaccuracies in the prediction of forces and power output.

The MIT team's new model accurately represents the airflow around rotors, even under extreme conditions. This advancement is crucial because it allows for more precise design and operation of wind turbines and wind farms. The model has potential applications beyond wind energy, including in the design of propellers for ships and aircraft, as well as hydrokinetic turbines used in tidal and river energy generation.

One of the most significant breakthroughs of the new theory is its ability to improve the control and optimisation of wind turbines in real time. Wind farm operators constantly adjust various parameters, such as the orientation, rotation speed, and blade angles of turbines, to maximise power output while maintaining safety. The new model provides a faster and more accurate way to optimise these factors, potentially leading to significant improvements in the overall efficiency and power output of wind farms. The new theory also revises the well-known Betz limit, which traditionally calculated the maximum amount of energy that could be extracted from the wind by a turbine.

The MIT model shows that it is possible to extract slightly more power than previously thought, particularly when turbines are not perfectly aligned with the incoming airflow, an everyday occurrence in wind farms. The implications of this research are far-reaching. The model, which the researchers call a 'unified momentum model,' was validated using both computational fluid dynamics and theoretical analysis. Follow-up work is currently underway, including wind tunnel and field tests, to further validate the findings.

The new theory exists as a set of mathematical formulas and is available as an open-source software package on GitHub. It is designed for rapid prototyping, control, and optimisation, positioning the wind energy field to aggressively expand capacity and reliability, essential to addressing climate change. The research was supported by the National Science Foundation and Siemens Gamesa Renewable Energy, and it promises to influence future developments in wind energy and other related fields.