2024 APES Unit 6 Progress Check: FRQ

2024 APES Unit 6 Progress Check: FRQ (a)(i) Describe one advantage of using hydroelectric power plants over using coal-fired power plants. -Hydroelectric power plants use renewable energy, making them more sustainable than coal-fired power plants. -There are no/fewer air pollutants (such as CO2 ) generated from hydroelectric power. -Since hydroelectric power produces less air pollution, there will be a reduction in photochemical smog and acid rain. -There will be no environmental disturbance/habitat loss caused by coal mining. -Hydroelectric dams create reservoirs, which can be used for · recreation and tourism · flood control · drinking water · wildlife habitat -There are no fuel costs for generating hydroelectric power. After initial construction, the energy cost is relatively low. (a)(ii) Describe one potential disadvantage of hydroelectric power plants. disrupt fish migration/fish migration routes. -Hydroelectric dams can trap sediments, which can lead to coastal erosion. -Hydroelectric dams can -Hydroelectric dams can change the flow regime of a river/can disrupt original river habitat/can lead to changes in flora and fauna in the river ecosystem. -Terrestrial habitats/agricultural areas/human populations can be displaced by the construction of the reservoir. (b)(i) Propose a different renewable resource to use that would be a realistic solution to generating electricity without using fossil fuels or hydroelectric power in a grassland ecosystem. -Solar energy/PV cells -Biomass burning/ethanol production -Wind energy/wind turbines (b)(ii) Justify the solution proposed in (b)(i) by explaining a potential advantage of using a different renewable resource to generate electricity. (c) One recent cost analysis report indicates that electricity from hydroelectric power can be produced for about $0.05 per kWh , while electricity from conventional coal-fired power plants can be produced for an average of about $0.11 per kWh . Calculate the percent change in the cost of electricity for a typical house resulting from a switch between conventional coal-fired power plants to hydroelectric power. Show your work. Work: ($0.05 per kWh - $0.11 per kWh)/$0.11 per kWh×100=(−$0.06 per kWh)/$0.11 per kWh×100 Answer: -55% There will be a 55% savings by switching to hydroelectric power. (d) In a typical coal-fired power plant, 2,460kWh of electricity can be produced per ton of coal burned. Calculate how many tons of coal would have to be burned in a typical coal-fired power plant to provide the electricity for a typical house in the United States for a year. Show your work. 1.09×104 kWh/1 year×1 ton of coal/2.46×103 kWh Answer: The coal-fired power plant would need to burn 4.43 tons of coal per year Work: (e) The world's largest hydroelectric power plant is the 22.5 gigawatt (GW) Three Gorges Dam in China. It produces about 90TWh of electricity each year. If a hydroelectric plant with the same capacity as the Three Gorges Dam was built in the United States, calculate how many houses such a plant would be able to provide the electricity for in a year. Show your work. Work: 9x10 TWH/1 year x 1x10^9 kwh/1 TWH x 1 house/1.09 x 10^4 kwh/year