1. Natural sources of energy

2. There are a lot of natural sources of energy such as: - water energy - wind energy - light energy - geothermal energy They are safe for our environment. They can help us. With them we can make our world healthier!

3. Water enegry

4. Water is a natural source of energy which is available almost everywhere in the world. It's nothing special that it is used as an ecological source of energy. In the beginning, it powered water mills and steam engines, and now it is used in hydroelectric power stations.

5. There are two kinds of hydroelectric power stations – run-of-the-river station which produces electrical energy, and the pumped-storage stations which store energy supplied by different sources. Tidal power station is a form of hydropower that converts the energy of tides into useful forms of power, mainly electricity.

6. Unfortunately, a method of using water energy is not totally harmless for our environment. The big power stations, which produce large amounts of electric energy are built on dams so the level of water rises.

7. Wind energy

8. For many years people have used the power of wind. At the beginning it was used to move boats and ships or windmills in sawmills. Now, the most popular kinds of using wind power are the wind power stations. They use wind turbines to change kinetic energy into electrical power. The advantage of this kind of obtaining power is ecological "purity".

9. Solar energy

10. The fact that the sun produces heat the mankind knew from the beginning. Recently however, people have begun to use solar energy to produce electricity. Throughout almost the whole twentieth century people invented, constructed and rationalized solar panels (collectors) – the devices to enable the processing of sunlight into electricity and storage produced energy.

11. Currently, solar thermal collectors have become very popular so they ceased to be seen as the most unconventional source of energy. Obtained energy can be used for lighting, heating, and even as a fuel for electric vehicles. Interestingly, solar thermal collectors work even on cloudy days because even if the amount of sunlight entering the atmosphere is so large, it can provide energy through solar collectors. The only downside are the high prices of the collectors - including all of the necessary accessories needed for the proper functioning of the collectors. They are really expensive.

12. Geothermal energy

13. Geothermal energy is stored in rocks, soil and fluids contained in the rock crevices. Its main carriers are water and steam, heated by the hot interior of the Earth. It is used primarily in power plants and geothermal power plants. The most popular kind of using is for heating buildings by heat pumps, pumping hot water from the cooler sites and premises to the warmer ones. This technology is a bit risky - geothermal waters contain harmful substances, so their mining can contaminate groundwater.

14. Although the current method of using natural sources of energy leaves a lot to be desired, this is the direction which the industries of many countries should follow related to the generation and use of electricity and heat - that is, virtually all of them. Natural resources such as coal, petroleum, natural gas, wood will eventually wear out, while the natural resources like water, wind, sun and heat from the core of the Earth are inexhaustible, continue to renew and with the use of sufficiently advanced technology they may prove to be completely harmless to the environment.

15. Thank you for your attention! By Group 6