Sources of Energy - Class 10th Science
Alternate & Non-Conventional Sources of Energy
Sources of Energy on which we depend today are non-renewable and getting consumed with alarming rate, this compels us to see and discover alternative or non-conventional sources of energy.
Solar Energy
Heat energy we get from sun is called Solar Energy. This heat energy can be used by developing special devices.
Solar Cooker and Solar Heater
Solar cookers and Solar water heater is used to cook food and to heat water respectively. Body of Solar cooker is made of black material as black material absorbs more heat as compared to a white or a reflecting surface under identical conditions. A mirror is fitted with the lid of solar cooker that reflects the sun rays to the cooker.
Some solar cookers are made of parabolic surface fitted with mirror, which concentrates sunlight and concentrates heat of sunlight to cook food. Heat can be reached upto 4000C in a parabolic solar cooker.
But solar cooker like devices are useful only at certain times during the day.
Solar Cells
Solar cells are device which convert solar energy into electrical energy. Solar cells are called photovoltaic cells also. A large number solar cells connected together form a solar panel that can deliver electricity for practical use.
A typical solar cell develops a voltage of 0.5 V to 1 V and can produce about 0.7W of electricity when exposed to the Sun.
Advantage of solar energy
- Solar cells have no moving parts and hence required little maintenance and work quite satisfactorily without use of any focusing device.
- Solar panels can be set up in remote and inaccessible hamlets or very sparsely inhabited areas in which laying of power transmission line may be expensive and not commercially viable.
- Solar energy produce nothing as residue and hence is very good green energy.
- Sun shines need no fuel and hence no cost for production.
Disadvantages of Solar Energy
- Silicon, which used for making solar cells, is abundant in nature but availability of special grade silicon form making solar cells is limited.
- The process of manufacturing of solar cells is very expensive as silver metal is used for interconnection of cells in the panel further adds the cost.
- Since, sun shines only in day time, hence to use of solar energy while night or in rainy seasons when sun does shines or shines very less, energy produced by solar panel is to be conserved using electric cells.
Other uses of solar energy
- Solar cells are used for many scientific and technological applications. Artificial satellites and space probes like Mars orbiters use solar cells as the main source of energy.
- Radio or wireless transmission systems or TV relay stations in remote locations use solar cell panels.
- Traffic signals, calculators and many toys are fitted with solar cells.
- Today cars are also made to use solar energy.
- In recent days a plane name Solar Impulse 2 completed its 40000 km travel for 500 hours. It has successfully completed the first fuel-free flight around the world.
- These days use of solar cells is increasing inspite of its high cost.
Energy From the Sea
Phenomenon of High tides and low tides take place at regular interval in oceans and seas. This is rise and fall of water and conserves potential energy. This energy can be converted into electrical energy.
When there is high tide, water is trapped into dams made nearby. And in the case of low tide, kinetic energy of flow of water from narrow openings of these dams is converted into electrical energy. This method harnessed energy using similar method to hydro electric energy.
However, location where such dams can be built are limited, instead of that there is potency to harness energy by this method.
Wave Energy
Due strong winds blowing across the sea, strong waves are caused in seas and oceans. Because of waves, there is continuous and rhythmic rise and fall in seas and ocean water.
Special devices are made, similar to leg operating sewing machines, to harness the energy possessed by rhythmic rise and falls of seas and ocean waves. Energy trapped in rhythmic rise and fall of water waves make the rotation of turbines attached to special devices and produce electrical energy.
Many countries, such as China, USA, etc. generate a good amount of electrical energy from wave energy.
Ocean Thermal Energy
Surface water of seas and oceans get heated due to Sun shines while water in deeper section is relatively cold. This difference of heat is harnessed into electrical energy using ocean thermal energy conversion plants.
Ammonia is a liquid which boils at low temperature. Ammonia vapour forms due to temperature difference in seas and ocean water is used to run the turbine of electric generator. The cold water from the lower part of sea water is then pumped to cool down the ammonia vapour again into liquid. This process continues and produces electricity.
Ocean thermal energy plant operates if the temperature difference between the water at the surface and water at the depth upto 2km is 200 or more.
Ocean thermal energy is very large, but efficient commercial exploitation is difficult
Geothermal Energy
Hot spots are the region of earth's crust where molten rocks are pushed upward and get trapped because of geological changes. Sometimes hot water comes in contact with those hot spots while finding outlet and are called hot springs.
Underground water gets heated and form steam when come in contact with such hot spots. The steam produced by the underground water and hot spots get trapped in rocks which is brought to turbines of electric generator is exploited to electricity.
However the cost of production of electricity using geothermal energy is too much, instead of that it is clean energy and can be exploited without burning any fuels.
Many countries like New Zealand and USA set up many number of power plants to generate electricity using geothermal energy.
Nuclear Energy
The main concept to produces electricity is to run turbines of electric generators. Nuclear fission is a process in which nucleus of radioactive elements is broken down by bombardment with low energy neutrons. In the breaking down of nucleus of radioactive elements, huge amount of energy is produced.
Heat energy produced by breaking of nucleus of radioactive elements is used to produce steam which runs the turbines of electric generator to produce electricity.
To do nuclear fission is similar to explode an atom bomb.
Disadvantage of Nuclear Energy
- Cost of set up of Nuclear Power Plant is very high.
- Fatal health problems may arise due any leak in power plants.
- Limit availability of radioactive elements.
Advantage of Nuclear Energy
- Once power plant set up, energy produced from this cost very less.
- Nuclear energy power plant can produce enough amount of electric energy to feed the increasing demand.
In India, and around the world, there are many Nuclear Power Plants in operation. Such as Kakrapar Atomic Power Station located in the state of Gujarat, Kundankulam Nuclear Power Plant, in Tamil Nadu, Madras Atomic Power Station in Kalpakkam, Tamil Nadu, Narora Atomic Power Station in Uttar Pradesh, etc. are some of the Nuclear Power Plants are in operation in India.
Environmental Consequences
Energy makes our life comfortable. We use various sources to get energy. Getting energy from different sources has their own merits and demerits. Some sources give us energy at the cost of more damaging of environment while some gives at the cost of less environmental damage. Although energy from some sources of energy are termed is termed as clean energy, but we could not develop devices to get clean energy so far. With increase in population demand of energy is increasing with leaps and bound while sources of energy are getting exhausted with alarming rate as sources on which we depend for energy today are non-renewable and limited. Scientists are trying their best to develop devices to get energy from renewable sources and alternate and new sources of energy are being discovered.
We should rethink while exploiting sources of energy as these has other dark aspects.
How Long Will an Energy Source Last Us?
Today most of our needs depend on fossil fuels, which is a non renewable energy and has limited stock as it takes millions of years to replenishment of fossil fuels. On the other hand getting energy from fossil fuels cause many problems to environment, green house effect is one of them.
Bio mass, which is also a source of energy can be replenished by planting more and more tree, so that we would never out of run of source of energy, thus bio mass is one of the alternative today. But still better and efficient devices yet to be discovered and manufactured.
We should see towards alternate and non conventional sources of energy, such as tidal energy, solar energy, etc.
If we keep our eyes open and keep developing new devices, we would never out of energy.