Chapter 7 LO5 Betz Limit

Question 1

Why can 100% of the winds energy never be extracted by a wind turbine

Answer 1

As there is energy lost when night velocity wind collided with the turbine

Question 2

What is the theoretical maximum limit that energy can be extracted by a wind turbine. Who established this limit?

Answer 2

59.3% of energy can be extracted from the wind due to required downstream. Albert Betz established this

Question 3

Can a turbine ever really extract this limit. Justify answer

Answer 3

No, due to the wind turbine system. Due to sound and thermal losses in a turbine. Typical efficiencies are in the region of 25% to 45%

Question 4

Define what is meant by the term Betz Limit and when applied to a wind turbine and explain how it is related to power efficiencies achievable by wind turbines in the real world

Answer 4

1)The maximum amount of the winds ke that a HAWT can convert to mechanical energy turning a rotor

2) Betz calculated this at 59.3% of the ke from the wind

3) Most modern turbines however can only convert 35% to 45% of the winds energy to electricity

4) Because of the energy losses in the gearboxes etc.