Wind Energy

1. What is the formula for power in the wind?

• P = ρ A v²

• P = ρ v³

• P = 0.5 ρ v²

• P = 0.5 ρ A v³

2. What is the Betz limit?

• 50%

• 59.3%

• 70%

• 42%

What does the tip-speed ratio (TSR) represent?

• Ratio of wind speed to blade speed

• Ratio of blade tip speed to wind speed

• Ratio of wind power to mechanical power

• Ratio of rotor speed to air density

Which formula correctly expresses the tip-speed ratio (TSR)?

• λ = v / (ωR)

• λ = (ωR) / v

• λ = R / (ωv)

• λ = ω / (vR)

Calculate the power in the wind for a turbine with v = 10 m/s, ρ = 1.225 kg/m³, R = 40 m.

• 3.08 MW

• 30.8 MW

• 15.4 MW

• 50.2 MW

What is the formula for capacity factor (CF)?

• CF = Power output / Wind speed

• CF = Rated capacity / Actual output

• CF = Area / Power output

• CF = Actual annual energy output / (Rated capacity × Time)

A 2 MW turbine produces 5,000 MWh in a year. What is its capacity factor?

• 25.0%

• 28.5%

• 35.0%

• 15.8%

What is the effect of increasing tower height on wind turbine performance?

• Decreases rotor efficiency

• Increases captured wind speed and energy output

• Reduces power by lowering air density

• Has no significant impact

If a turbine extracts 12 MW from 30.8 MW available, what is its power coefficient (Cp)?

• 0.25

• 0.30

• 0.39

• 0.59

What does a wind turbine power curve show?

• Turbine output versus air density

• Turbine output versus wind speed

• Turbine efficiency versus height

• Turbine noise versus speed