How have artists and photographers helped to preserve our favorite places? Provide a unique example from our National Parks – first come first serve. Describe briefly the main biomass energy conversion technologies introduced in the class. (10%) (2) What are the primary forms of ocean energy? (10%) (3) Derive the Betz Limit in the wind power applications. (5%) Why are larger and offshore wing turbines preferred? (5%) (4) What are the main ways of hydrogen productions and storages introduced in the classes? (10%) (5) Describe the working principle of PV solar cells. (5%) Why can the efficiency be improved by the “Concentrated PV System”?(5%) (6) Describe the types of fuel cell introduced in the classes and their operating conditions and applications. (10%) (a) Draw a typical current-voltage curve for a fuel cell operating at 25 °C. Calculate the theoretical voltage and mark as a horizontal line. Label the three regions that control the fuel cell performance and give brief explanations of their causes. (b) Repeat the question for a high temperature fuel cell operating at 800 °C. (20%) Faraday constant F = 9.6485 x 104 C mol? Form of water product Temp Agf, °C kJ/mole Liquid 25 -237.2 (9)(5%) 9.2 Hong Kong has a population of 7.2 million and a land area of 1100 km? The annual average per capita primary energy consumption is 110 GJ. Would it be reasonable to expect that Hong Kong’s energy needs could be met by solar energy if the entire country’s area was covered with photovoltaic collectors? Consider an overall time average insolation of 200 W/m. costs $0.13 per 9.5 A homeowner purchases an 18% efficient photovoltaic collector with an active area of 65 cm by 80 cm for a cost of $230. If the average solar insolation is 190 W/m? (24 hour average for entire year), calculate the payback period if electricity from the public utility kWh. Note that this is exclusive of interest and the cost associated with inverters and any storage system. (11)(5%) 10.2 The construction of a wind turbine with an efficiency of 40% is planned. It is anticipated that the turbine will produce I MW in a wind of 10 m/s. What is the diameter? (12)(5%) 12.2 An ocean wave has a height of 3 m and a period of 8 s. What is the total power available from 100 m of wave front for this wave?How have artists and photographers helped to preserve our favorite places? Provide a unique example from our National Parks – first come first serve.

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