1. Using a dam (hydroelectric)

2. How does it work? The theory is to build a dam on a large river that has a large drop in elevation. The dam stores large amount of water behind it in the reservoir. From Reservoir it goes through the intake and goes to the turbine. When the water passes through the turbine the generator produces power and the power goes through power lines. The intake it allow to the water goes in and it doesn’t allow to rocks, wood, sand and dead animals to go in. So it wouldn’t have problem. The turbine it produces power by the movement of the water. When the water falls into the turbine the turbine blades starts to spin and produces power. So that’s why we need a large drop in elevation so the water can fall into the Turbine Blades.

3. Is it reliable or not? The hydroelectric dam is only reliable in the large river when there is a large drop in elevation. So that the dam can storage water and then produces electricity. However, if you don’t build the dam in a correct place it won’t be reliable because it won’t produce a lot of power. Map Where is most used

4. Cost CountryAnnual hydroelectric production (TWh)TWh Installed capacity (GW)GW Capacity factor % of total capacity China 585.2196.790.3722.25 Canada 369.588.9740.5961.12 Brazil 363.869.0800.5685.56 USA 250.679.5110.425.74 Russia 167.045.0000.4217.64 Japan 69.227.2290.377.21 Sweden 65.516.2090.4644.34

5. Effects in environment Hydropower is considered to be a clean, renewable source of energy, using a very low level of greenhouse gases when compared to fossil fuels. In benefit is that the power is generally available on request since the flow of water can be controlled. Using hydroelectric power also has disadvantages. Dams can block fish passage to spawning grounds or to the ocean, although many plants now have measures in place to help reduce this impact. The diversion of water can impact stream flow, or even cause a river channel to dry out. Hydroelectric plants can also have an impact on water quality by lowering the amount of dissolved oxygen in the water

6. Bibliography http://ga.water.usgs.gov/edu/hyhowworks.html http://www.enviroliteracy.org/article.php/59.html http://www.en.wikipedia.org/hydroelectric.html