Wind energy and water energy
What is wind?
Air in motion due to natural forces is called wind. High speed wind has a lot of energy. It can uproot trees and even destroy buildings. Wind possesses Kinetic energy by virtue of its motion. This kinetic energy can be utilised to do work, say by making sail boats and wind mills. Man used sail-boats to undertake long journeys on water and to move heavy loads. Windmills were used to grind corn and wheat and pump water from the wells. Nowadays wind energy is also used to generate electricity.
Thus kinetic energy of wind can be used in the following ways
1. To power sail boats
2. To drive wind mills
3. To generate electricity
4. For flying gliders
5. For aeroplanes, to manipulate upward and downward motion.
Advantages of wind energy are:
1. Wind power is freely available in nature
2. No transportation of fuel is required.
3. It is non polluting.
4. It is an inexhaustible source of energy.
Disadvantages of wind energy :
1. Wind is not available at all times, at all places
2. Sometimes stormy winds may flow, sometimes no winds
- i.e. it is not dependable and is inconsistent.
A sail boat uses the kinetic energy of wind to sail. For sailing ordinary boats, man has to use his muscular energy for rowing. In a sail boat the kinetic energy of wind does this work.
A sail boat is propelled forward by wind energy (rather than by muscular energy ). The wind does this job. The limitation of a simple-sail boat is that it can move only in the direction of the wind. Later on man learnt to overcome this limitation by using two sails instead of one and by attaching them to a stemming device called the rudder. The two sails are held at a suitable angle to each other. One of the sails diverts the wind and the other moves the boat. By adjusting the angle between the two sails the boat can be moved in the desired direction.
A windmill is a machine which operates by wind energy. The kinetic energy of the moving blades is utilised in the windmill. A windmill is used for operating a water pump to draw water from under the ground. The motion of the blades is passed on to the pump rod. The rod moves up and down, pumping out the underground water. It is said the windmill was invented in China in the 12th Century.
A large number of windmills have been installed in various places to do different jobs such as drawing under ground water, moving heavy loads, grinding corn and wheat, etc.
USING WIND GENERATORS TO PRODUCE ELECTRICITY
The potential for using wind to generate electricity is huge. Modern wind generators are very different from the old windmills. They are giant propellers with 2 or 3 blades called rotors, mounted on top of tall towers of steel or concrete. The rotors turn a shaft which drives an electric generator. The size of the blades and the height of the tower determine how much electricity the machine can generate. Wind generators do not need stormy weather. They are designed to operate at moderate wind speeds. However, it is better to have a steady output over a wide range of wind speeds than to be able to take advantage of a few really strong gusts.
Countries like Britain have built very large wind generators, where one generator can generate enough electricity for a locality.
1. No transportation of fuel
2. Lesser installation times
3. Lesser manpower required to run the plant
4. Lesser Maintenance is required
5. It is non-polluting
1. Wind is inconsistent and not dependable
2. The rotor blades must sweep out large areas to generate
a worthwhile amount of energy.
3. Hurricanes and tornadoes cause damage.
Moving water contains a lot of energy that can be used to drive machines. The energy possessed by flowing water is due to its motion and this kinetic energy can be utilised by man
- To rotate the blade of a water wheel
- To produce electricity in hydro power stations.
1. Water wheel :
The energy of water is used to rotate the blades of a water wheel. The motion of the water wheel can be conveyed to other connected parts and be used
- To pump water
- To grind corn (in flour mills)
2. Hydroelectricity :
Water is stored in reservoirs behind a dam. This stored water possesses a very large amount of potential energy. The water is made to fall through pipes on water wheels called turbines and thus turn the turbine. The turbine rotates the armature of the generator and produces electricity. Hydro electric power stations are cheap to run because their fuel (water) is free.
Advantages of water energy
1. It is available abundantly and is free
2. It is an inexhaustible and renewable source of energy
3. It is non-polluting.
Limitations of water energy
1. Flowing water may not be found everywhere.
1. Tidal power is the energy generated by sea waves known as tides.
2. Tidal power stations are built as part of a dam across a river's mouth where the tides cause a large movement of water
3. Channels in the dam allow water to pass through when the tides rise and flow back when the tides fall
4. The water flow turns the turbines in the channels which operate generators which in turn produce electricity.
5. The main disadvantage in this kind of energy is that it can generate energy only at certain times.