# Renewable energy 4 | Mechanical Engineering homework help

(All answers must have 5-7 sentences each, in own words)

1. What are the positive aspects of wind energy? Explain at least 5 of them.

2.  Identify the world’s largest three wind turbines built and their key characteristics (Location, Power, blade dia etc)

3. Write an equation to find power from a wind turbine. Explain each parameter in it.

4. What is the meaning of this equation

5. For a turbine with 160 m of wing (blade length) produces 7 MW or power. What would be the air velocity to generate this power?

6. Derive an expression for Betz limit. What is the maximum mechanical efficiency possible from a wind turbine?

7. What is the relation between ground wind speed, height, and wind speed at a certain height?

8. IF the ground wind speed is 5 m/sec. Estimate wind speed at the height of 250 m. In this case, what would be the power generated if we use a blade of 160 m.

9. Explain the terms a) lift b) drag c) solidity d) turbulence in relation to Wind turbines.

10. What are the major considerations in the design of a wind turbine (watch the video and explain how each parameter influences wind power)

11. Explain how wind energy reduces emissions from the atmosphere?

12. What are HAWT and VAWT?

13. With a small diagram, explain key components of a wind turbine.

15. What rated the power of a turbine and rated wind speed?

16. Explain the operating regimes of a wind turbine and the control strategy in each

17. Calculate the diameter for a 7.5MW wind turbine blade

18. What is the tip-speed ratio of a turbine?

19. Why do larger turbines rotate slowly (at optimum tip-speed ratio)

20. What is the connection between the tip speed ratio and the number of blades?

21. Optimally, how long would it take the 3-bladed 5 MW “monster” turbine to complete one revolution? The blade diameter is 145 m. (Assume a rated wind speed of 11 m/s.)