Chapter 7 LO11 How The Power Output From A Wind Turbine Is Affected By Air Density, Temperature And Altitude

Question 1

State the relationship between pout and air density p for a wind turbine

Answer 1

Pout is directly proportional to kp

Question 2

How does an increase in air temperature affect the density of air?

Answer 2

Molecules of gas in air have more KE and so move with a greater speed between collisions. This makes the gas expand and so the particles move further apart.

Question 3

How does a decrease in air temperature affect the density of air?

Answer 3

Molecules of gas in air have less KE and so move with smaller speeds between collisions. This makes the gas contract and so molecules move closer together.

Question 4

With a constant all year wind speed on a site in NI, would the owner of a wind turbine expect a higher output in winter or summer?

Answer 4

Higher output in winter as low temp = Higher Pout as the air has less KE and move at smaller speeds between collisions.

Question 5

What does altitude mean? Where is it measured from?

Answer 5

Altitude is how high a specific ping is above the surface of the Earth. This measurement is taken vertically upwards from the surface.

Question 6

Describe air density at low altitude. What happens to Pout at low altitude?

Answer 6

Air density is high at low altitude. There is a higher Pout value at low altitudes.

Question 7

An investor in wind farms has an option to place a wind farm at an altitude of 100m or 300m. Which should he choose if both have no obstructions and identical wind speeds?

Answer 7

He should put it at 100m as there is no point in paying for a bigger turbine if the wind speeds are the same at both altitudes . As it will cost more

Question 8

How is the power output of a wind turbine affected by Air density and Temperature

Answer 8

Lower Altitude = Higher Air Density = Higher Pout

Low Temperature = Higher Pout