1. Alternative sources of energy

2. Contents 1.How the renewable energy work? 2.Hydroelectric power 3.Tidal energy 4.Geothermal energy 5.Wind power

3. 1. How the renewable energy work? Renewable energy effectively utilizes ( 利用 ) natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished ( 補充 ). Renewable energy technologies range from solar power, wind power, and hydroelectricity to biomass and biofuels for transportation.

4. 2.Hydroelectric energy Introduction -Using of moving water(kinetic energy)  generate electricity Channeled down a pipe and turns a turbine at the bottom Turbine spins. It drives a generator and generates electricity. Location 1.natural waterfalls-heavy rainfall and mountainous ground 2. no natural waterfalls -hold the water back with a dam ( 水霸 )

5. Advantages 1.Clean 2.Renewable 3.Elimination of the cost of fuel Disadvantages 1.Lead to scouring of river beds and loss of riverbanks 2.Change aquatic faunal populations 3.Historically and culturally important sites can be flooded and lost

6. 3.Tidal energy Introduction -The tide moves a huge amount of water twice each day, and harnessing it could provide a great deal of energy It is not easy to convert the energy into useful electrical power.

7. How it works -A huge dam (called a "barrage") is built across a river estuary. When the tide goes in and out, the water flows through tunnels in the dam. -The ebb and flow of the tides can be used to turn a turbine, or it can be used to push air through a pipe, which then turns a turbine.. -Then, the turbine generates electricity.

8. Advantages -Doesn't cause pollution, -Doesn't need fuel -Renewable -It produces electricity reliably. -Not expensive to maintain. -Tides are totally predictable. Disadvantages -Very expensive to build. -Only generate electricity twice a day. -Affect wildlife habitats and farming areas. -Very limited choice of suitable sites.

9. 4.Geothermal energy Introduction -Geothermal power is energy generated by heat stored beneath the Earth's surface. In the geothermal energy,cold water is pumped into the underground.The cold water is heated by hot rock and steam is produced.The steam drives turbines( 渦輪 ) to generate electricity.

10. Advantages -Clean and safe for the surrounding environment -It is sustainable -Unaffected by changing weather conditions -It is extremely price competitive in some areas -Reduces reliance on fossil fuels and their inherent price unpredictability -Long lasting

11. Disadvantages - Difficult to find suitable sites to build the plant -Emit carbon dioxide,nitric oxide, which cause air Pollution -High building cost

12. 5.Wind power What Is Wind Power?

13. The most common design of modern wind turbines( 渦輪 ).

14. Advantages -Plentiful( 充足的 ) -Renewable -do not need water to generate electricity. -Clean -reduces toxic atmospheric and greenhouse gases emission -Mitigates( 緩和 ) the negative effects of energy use -no long-term effects on climate or local environment left for future generations.

15. Disadvantages -kill some bird and bat species -Wind does not always blow -Windmills may be damaged -eyesore -Less land

16. List of team members Ale Manta 5C (1) Chow Kit Shan 5C (4) Mak Chu Lan 5C (11) Tang Man Ki 5C (13) Tae Ka Man 5C (16)