Renewable Energy
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.
14. What are the advantages and disadvantages of VAWT
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.)
22. List 5 advantages and 5 disadvantages of wind turbines
Major financial support is provided under communist governments. Theoretically this is a beneficial policy, but realistically it isn’t as beneficial as it is intended to be. At least 20 percent of Soviets lived in poverty compared to 14 percent of Americans in 1988 (Fein, 1989). The average Soviet only has to dedicate 6 percent of their income to paying rent, whereas Americans dedicate 26 percent of their income to living expenses (Fein, 1989). The Soviets denounced the existence of poverty in their country up until Gorbachev’s leadership, and instead claimed that poverty was only brought on by capitalism. The large number of people who were experiencing economic hardships sought for change in the USSR. Despite Soviet officials claiming that the poverty was caused by laziness, many believe that poverty was brought on by the economic state of the USSR. The economy under Gorbachev suffered immensely, causing over 20 million people to live impoverished lives (Fein, 1989). The communist Soviet Union crumbled soon afterward.
A defining factor of a capitalist economy is its economic freedom. The five most economically free nations are Hong Kong, Singapore, New Zealand, Switzerland, and Australia according to the Index of Economic Freedom (2018). Hong Kong is a part of China, yet the only things the Chinese government controls in Hong Kong is foreign relations and the military. The population grew in Hong Kong from 600, 000 to 6 million in fifty years (Friedman, 1998). This population growth was due to people fleeing from the communist state of China to Hong Kong. A major downside to reduced economic freedoms, is the reduced political freedom that typically comes with it. Both issues have gradually diminished in China since the height of their communist reign. It’s evident that people prefer freedom over control from the fact that people fled from their controlling to country, to a free country.