. Sustainable Energy Sources
| Sustainable ener gy, specifically renewable energy or green energy, is an energy source which |
| can be replenished, that is essentially inexhaustible. Sustainable sources of energy include solar, |
| wind, water, biomass and geothermal. Non renewable energy sources include coal, oil and |
| The Generation of Electricity from Water |
| Explain the generation of electricity from water |
| Energy sources are areas of origin of a particular kind of energy. There are two types of sources |
| These are the energy sources, which can be turned into use again after being |
| used. Example sun, water, wind and fossils. |
| These are the energy sources, which cannot be turned into use again. |
| Examples: oil, natural gas and char coal. |
| Sustainable sources of energy: |
| This refers to natural resources that are used in the production of |
| electricity without destroying the environment. These include: |
| refers to the energy obtained from running water by use of turbines and |
| generators. This energy is called hydr oelectric power. |
| Hydroelectric Power (H.E.P): |
| This is electricity produced by running water.Hydroelectric |
| power stations provide about 20% of the world’s electricity. In Tanzania, hydroelectric power |
| stations/plants are found at Mtera, Kidatu and Nyumba ya Mungu. |
| Production of hydroelectric power |
| First, a dam is built to trap running water. This is usually in a valley where there is an existing |
| lake. Water is allowed to flow through tunnels in the dam, where they turn turbines, which in |
| The generator then produces electricity from water energy. Force of moving water thus turns the |
| generators. Hydroelectric Power plants have no fuel costs and gives off no waste. |
| The dam constructed is made much thicker at the bottom than at the top because the |
| pressure of water increases with depth. |
| Hydro electricity produces no waste products. |
| The Importance of Water Energy |
| Explain the importance of water energy |
| Water energy has the following importance. |
| The energy is virtually available |
| It is environmental friendly |
| It is more reliable than other sources like wind |
| Electricity can be generated constantly |
| The energy increases power very quickly |
| Application of energy from water |
| In Industries - to drive machine parts |
| Lighting purposes for example in homes |
| In health facilities i.e. runs incubators and freezers. |
| A Model of Hydro-electric Power Plant |
| Construct a model of Hydro-electric power plant |
| A model of Hydro-electric power plant |
| Solar energyrefers to the energy obtained from the sun by the use of solar cells. |
| The Sun as a Source of Energy |
| Explain the sun as a source of energy |
| We consume energy in dozens of forms. |
| Yet virtually all of the ener gy we use originates in the |
| power of the atom. Nuclear reactions ener gize stars, including our Sun. The ener gy we capture |
| for use on Earth comes largely from the Sun or f rom nuclear forces local to our own planet. |
| Sunlight is by far the predominant source, and it contains a surprisingly large amount of energy. |
| On average, even after passing through hundreds of kilometers of air on a clear day, solar |
| radiation reaches Earth with more than enough energy in a single square meter to illuminate five |
| 60-watt lightbulbs if all the sunlight could be captured and converted toelectricity. |
| The Conversion of Solar Energy to Electric Energy |
| Explain the conversion of Solar energy to electric Energy |
| The energy produced by the sun is more than we need. Solar energy can be converted to |
| electricity by using solar cells or photo voltaic cells. The main surface of solar panel is dull |
| black. This enhances the absorption rate of the radiant energy from the sun. |
| Applications of solar energy |
| Solar energy has been harnessed by mankind and put to several uses. Below are some of the |
| applications of solar energy: |
| It is used in electric appliances such as television and radios |
| Spaceship satellites use solar cells |
| Some torches, cars and calculators are powered by solar cells |
| Drying of clothes and far m (food) products. |
| Heating water using a solar hot water system |
| Though solar cells are expensive, they are very useful in remote and sunny areas. |
| Construct a model of solar panel |
| Wind as a Source of Energy |
| Explain wind as a source of energy |
| Wind energy ref ers to the energy obtained from wind.It can be converted into |
| electricity.Babylonians and Chinese used wind energy as a source of energy to pump water for |
| irrigation 4000 years ago. |
| Wind energy can be converted into electricity by building a tall tower with a large propeller on |
| When wind blows, it rotates the propeller, which causes the attached generators to produce |
| : for more electricity to be produced, mor e properties are needed. |
| Construct a model of a Wind Mill |
| A Wind Mill in Daily Life |
| Apply Wind Mill in daily life |
| Application of wind energy |
| For centuries, people have been using the power of the wind to move ships, boats and pump |
| Today, enormous wind energy is used to turn generators that facilitate the production of power. |
| As windmills are efficient, very large turbines are required to providing the much-needed power. |
| Disadvantages of wind energy |
| Wind energy is not reliable |
| The wind turbines are noisy and can spoil the landscape. |
| Large windy sites are required |
| Sea Wave as a Source of Energy |
| Explain sea wave as a source of energy |
| The concept of sea water: |
| Sea water around the world is continually moving. The wind causes |
| ocean waves as it blows across the sea. These waves are powerful sources of energy. This can be |
| used to drive generators. |
| Tides by definition are the rising and falling of the ocean flow. Tides are |
| produced by the gravitational pull of the moon and to some extent the sun. The change of water |
| levels that the tides produce can be used as an energy source. |
| The concept of wave energy: |
| There are several methods of getting energy from waves. |
| The occurrence of waves in a swimming pool: |
| Air is blown in and out of the chamber beside |
| the pool; this makes the water bob up and down, causing waves. |
| The Conversion of Sea Wave Energy to Electric Energy |
| Explain the conversion of sea wave energy to electric energy |
| Electricity can also be generated from tides. As tide rises, water is allowed to enter the upper |
| basin in the dam. Once the high tide has passed, the water on the upper basin is made to flow |
| back to the lower basin through turbines in the barrage. The turbine turns generators, which |
| convert seawater into electricity. |
| is the energy obtained from running water by use of turbine and generators |
| Is the energy obtained from the series of swells of sea water. |
| Geothermal as a Source of Energy |
| Explain Geothermal as a source of energy |
| The word “geothermal” means “Heat”, so geothermal energy is the energy generated by the flow |
| of heat from the earth’s surface. It is the energy associated with areas of frequent earthquakes |
| and high volcanic activity. |
| Areas like Kilimanjaro and Oldonyo in Tanzaia; and Rift valley in Kenya are geologically well |
| structured to produce efficient geothermal system. The hot spring can cause rocks to be hotter |
| than the earth’s surface. Thermal energy is obtained from radioactive materials that naturally |
| The energy produced can be used in: |
| The Conversion of Geothermal Energy to Electric Energy |
| Explain the conversion of Geothermal energy to electric energy |
| Energy is obtained in the earth’s interior; it is necessary to drill through rocks. This creates vents |
| where pipes are laid to bring the steam from the hot zone to the earth’s surface. |
| Once the steam has risen to the surface, it is directed into turbines. The steam drives turbines, |
| which again are used to drive electric generators that produce electricity. |
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