Take a COOL Guess – the Fun Quiz on Clean Energy.  Today’s Topic: Efficiency in Wind Turbines

Question:  In physics, the Betz Limit is the top theoretic percentage of kinetic energy that can be extracted from a moving fluid, e.g., wind.  It’s based on the fact that, if you took it all, i.e., stopped the wind dead, the oncoming wind behind it would run into what you had just stopped.  In other words, you don’t want to design a device in which the wind can’t get out of its own way.  So, having said all this, what is the Betz Limit (i.e., this theoretical top percentage)? 

Answer: Can be found at Clean Energy Answers.

Relevance:  We often encounter concepts for new wind turbine designs that claim to make huge improvements in the efficiency with which they extract energy from moving air.  Yet modern turbines already achieve 70% – 80% of this limit.  This makes it easy to spot claims that couldn’t possibly be true.