Sources of Energy - Class 10th Science
Hydro Power Plant
Kinetic energy of running water or potential energy of water at a height is another source of energy.
Hydro Power Plants convert kinetic energy of flowing water or potential energy of water at a height into mechanical energy and mechanical energy so produced in converted into electrical energy.
Electricity produced from Hydro Power Plants, big and high rise dams are constructed on the river. High rise dam store river water in reservoir by obstructs the flow of water. Because of obstruction, i.e. dam, water level rises and in this process kinetic energy of flowing water gets transformed into potential energy.
Water from high level in dam is carried to the turbine installed at the bottom of dam through pipes. Water falling from very high, makes turbine run. Electric generator attached with turbine, converts mechanical energy of turbine into electrical energy. Energy so produced is transmitted through electric wires to different places.
Water in the reservoir refilled each time when rains, thus hydro power is a renewable source of energy.
Problems associated with Hydro Electric Power
- To draw hydro electricity, dam is must which can be constructed in a limited number of places. Dams are constructed preferably in hilly areas, so that hill can be act as natural boundaries for reservoir.
- In the construction of dam, larges of agriculture land and human habitations are got submerged, resulting in displacement of large human population.
- In the reservoir, many trees are submerged, which destroyed large eco-systems.
- Vegetations submerged because of water in the dams, rot under anaerobic conditions and give rise to the large amounts of methane which make green house effect worsen.
- Because of displacement and rehabilitation of people of the catchment area of dam, in recent years, Government had to face many problems while construction of Tehri Dam on the river Ganga and Sardar Sarovar project on the river of Narmada.
Advantages of Hydro Electric Power
- In hydro electric power, electricity can be generated continuously once dam is constructed.
- Hydro electric power does not use water at all, water returned to its origin.
- Hydro electric power does not create any pollution to environment.
- Dams constructed for hydro electric power station has sluice gates, which can be closed as per requirement.
- After construction of dams water can be used for other purposes also, such as for irrigation, for drinking, etc. apart from production of electricity.
- Hydro power plants produce clean energy.
Improvements in the Technology for using Conventional Sources of Energy
To increase efficiency of conventional sources of energy technology to use them must be improved. By improving technology, fuel will produce less pollution and can work more per unit volume.
Bio Mass
Fuels come from plant and animal produces are called Bio Mass, for example fire wood, cow dung, etc. Fire wood has been used from ancient time for getting energy along with cow dung. Even today in many areas, especially in rural areas, fire wood and cow-dung are still in use. However, burning of fire wood and cow dung do not produce much heat and these fuels produce a lot of smoke when they burn, so technologies are being improved to improve the efficiency of these fuels.
Charcoal
Charcoal is a type of fuel. Charcoal burns without flames and is comparatively smokeless and has higher heat generation efficiency. Charcoal is formed when wood is burnt in a limited supply of oxygen, water and volatile materials present in it get removed and the charcoal is left behind as the residue.
Bio Gas
Bio gas is formed by the decomposition in absence of oxygen of cow dung, various plant materials like the residue after harvesting the crops, vegetable waste and sewage, etc. Bio gas is popularly known as 'Gobar Gas' because starting material of formation of bio gas is mainly cow dung.
Bio gas is an excellent fuel. Bio gas contains up to 75% of methane. Bio gas burns without smoke and leaves no residue like ash in wood, charcoal and coal burning.
Bio-Gas Plant:
In bio gas plant, slurry of cow-dung and other waste materials of plant are put in a sealed chamber. In the sealed chamber anaerobic micro organisms that do not require oxygen decompose or break down complex compound of cow dung slurry. In few days gases like methane, carbon dioxide, hydrogen and hydrogen sulphide are produced after the completion of decomposition process. The bio gas so produced is stored in a tank and is drawn through pipes for use.
Bio gas so produced is used for lightning, cooking, etc. The slurry left behind is removed periodically. The residue, i.e. slurry left behind is rich in nitrogen and phosphorous, which is used as manure.
The large scale utilization of bio waste and sewage material provides a safe and efficient method of waste disposal besides supplying of energy and manure.
Wind Energy
Air movement and blow of wind happens because of unequal heating of land mass and water bodies. Conversion of Kinetic energy of wind into mechanical energy and finally into electrical energy is called wind energy.
In ancient times also, Kinetic Energy of wind was harnessed by windmills, such as in water lifting pump, in grinding of grains, etc.
Today, wind mills are used to generate electricity. A windmill has structure similar to a large electric fan that erected at some height on a rigid support.
In wind mills the rotary motion of blades is used to turn the turbine of the electric generator. But, output of one windmill is very small and cannot use for commercial purpose, so a series of windmills are established to coupled together to get electricity at commercial scale.
Wind energy is an environment friendly and efficient source of renewable energy as it requires no expense on fuel to produce electricity.
Limitation or Disadvantage of Wind Energy
- To established wind energy farms, only those places are required where wind blows for greater part of the year.
- Wind speed should also be more than 15 km/h to maintain the required speed of turbine to generate electricity.
- Back up facilities should be required to conserve electricity produced for use when there is no required wind.
- For generation of 1 MW of electricity, about 2 hectares of land is required, this make the cost of establishment very high.
- Tower and blades are exposed the vagaries of nature, like rain, sun, storm and cyclone, etc. thus it needs a high level of maintenance.
Country of Winds: Denmark
In the country of Denmark about more than 25% of required electricity is generated by wind energy farms. So, Denmark is known as Country of Winds. India lies at fifth rank in the world in terms of wind energy production.