Hydroelectric power plants capture the energy of flowing water to generate electricity. The most common type uses a dam to store water in a reservoir, then water released through turbines spins a generator. Dams are expensive to build and can cause environmental issues like flooding habitat, but hydro provides renewable energy without pollution. Hydroelectric power works best where there is abundant water, steep valleys to build dams, and nearby demand for electricity.

1. Hydroelectric Power

2. What is it? Flowing water creates energy that can be captured and turned into electricity. This is hydroelectric power

3. The most common type of hydroelectric power plant uses a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity…this can be seen in the following diagram.

4. Diagram of an HEP Dam

6. Advantages Fuel is not burned so there is minimal pollution and no waste is produced Water to run the power plant is provided free by nature It's renewable - rainfall renews the water in the reservoir, so the fuel is almost always there Dams built to store water for HEP production can also reduce risks of flooding and water shortages .

7. Disadvantages Dams are expensive to build Dams and unsightly pylons in highland valleys cause visual pollution . Possibility of dam collapsing Large areas of farmland and wildlife habitats may have to be flooded forcing people and animals to move. Silt previously spread out over farmland will be deposited in the reservoir Decaying vegetation in flooded area can release methane and carbon dioxide

8. So Why Don’t We Use More? Mainly because you need lots of water and a lot of land where you can build a dam and reservoir, which all takes a LOT of money, time, and construction. Ecological Effects:. Run-of-the-River plants can impact the mobility of fish and other river life.

9. Nearby industrial and domestic demand provide the necessary high head of water Steep upland gradients or former waterfall Cheap land, sparsely populated Impermeable rock – water does not soak through Narrow valleys are ideal for dam construction and water storage Upland areas where narrow valleys with strong and impermeable rock Large and regular rainfall Relief rainfall ( > 1500mm pa) Low rates of evaporation provides a constant supply of water Found mainly in the north and west of the UK in upland areas REASON HEP REQUIREMENTS

10. CASE STUDY - Cruachan Scotland Cruachan is situated on the western side of Scotland in the Grampian mountains. Rainfall is over 2,500mm per annum and is evenly distributed throughout the year. Reservoir is kept at a high level and there is always enough water to turn the turbines. High cloud cover means there is little water loss by evaporation . The impermeable slate rock in the area gives a high surface run off to fill the reservoir with water and means the water does not soak away through the rocks. A corrie on the side of Ben Cruachan acts as a reservoir . Corrie is dammed by a concrete barrage 316m long and 46m high Steep U-shaped valley provides a head height of 364m to the machine hall. This supplies the energy to generate the electricity Only 75km away there is a high demand for electricity in Glasgow and a surface transmission line takes the electricity to urban area.

11. Exam Questions 1998 Q4b Describe and give reasons for the distribution of the HEP stations shown in Fig. 11

12. 2001 H Q 1e Using fig. 21 and 2b and your own knowledge, explain the distribution of HEP stations in Britain