Disproving and Rederiving the Betz Law Through Theoretical and Experimental Methods
Chloe Chen
West Point Grey Academy
Floor Location : M 078 D

The Betz Law is currently one of the most recognized and often-cited theories regarding wind power. It assumes that all the turbine�s harnessed energy comes from the wind�s kinetic energy, and calculates that we can harness at best 59% of the wind�s kinetic energy, regardless of surroundings or conditions. These assumptions and formulas have become the basis of nearly all calculations for wind turbine efficiency and design for the past century. However, after thoroughly studying Betz Law�s derivation, I realized that many of its fundamental assumptions are illogical (the details of which I will go into in my report). Rather than all the turbine�s energy being derived from the wind�s kinetic energy, I proposed that there is another form of energy in wind power called pressure energy (a form of potential energy), and that wind power contains different proportions of kinetic and pressure energy depending on the surrounding circumstances. In my project, then, I first proved that the Betz Law is theoretically incorrect by finding problems in its derivation, then I derived a more realistic formula to describe wind turbine behaviour based on the concept of pressure energy. Finally, I used experiments to disprove Betz Law�s predictions, as well as to confirm the assumptions of my own theory. The data from the experiments supported my predictions, and provided evidence that my new wind power model is indeed more accurate than Betz Law�s model. These results are significant, and the idea that wind power is not derived entirely from kinetic energy could be revolutionary in the wind turbine industry. In the short term, this new understanding of pressure power could help us choose more suitable designs and locations for wind turbines to maximize their output, making energy a more viable option as a renewable resource. Ultimately, a more efficient way of harnessing wind power may be constructed based on my new model to better utilize the pressure power in wind.