3.2 Energy from water LO’s: Describe the construction of a wind turbine. Describe how waves can be used to generate electricity. Describe the type of power station that uses water running down hill to generate electricity. Explain how tides can be used to generate electricity 4-6 4-6 4-6 6-8 Keywords Wind turbine hydroelectric Tidal scheme MW Cost per MW Starter Show clip 2 ‘How Hydroelectricity works’ Main Activity Work through the PPT ‘energy from water’ Answer Q 1, 2, 3. from AQA Physics text BK p39 Plenary Discuss answers form text book questions Or PHYS FDN ‘Generating electricity with water’ Homework: Kerboodle Follow up section of Wind and wave power

Q1a. Renewable energy resources can never be used up because they are always being replenished by natural processes. Q1b. i) Tidal power does not need energy from the sun ( gravitational attraction of Moon and sun create tides) Q1b. ii) Wind power does not need water, but it is unreliable.

Q2a (i) n x 2 MW = 2000 MW n = 2000 MW 2 MW n = 1000 Mountain areas Estuaries Coastline Hilly or coastal n km x 20 MW = 500 MW km n = 500 20 ANS = 25km = 25 Q2a (ii)

Q3a. A tidal power scheme is very expensive to build because: * construction occurs under water with strong tidal flows * materials must be highly resistant to corrosion and be very strong * the length of a tidal scheme is much longer than a hydroelectric dam. Q3b(i) The resource with the lowest total cost per MW is the hydroelectric scheme. (ii) Hydroelectic schemes need a large dam to collect a large reservoir of water. Steep sided valleys in mountain regions are often the most economical locations. A constant supply of water is also required.

Q4a. A pumped storage scheme: * pumps water up to a top reservoir when electricity is cheap ( at night) * water flows though turbines when electricity is required (at peak times). Q4b. Main benefit of a pumped storage scheme: * start up time is very rapid * energy is stored until required * renewable resource – provided pumps can be run from a renewable supply.