What Is A Dam Used For
A dam is a barrier constructed to hold water back and raise its level. Hydro-power and pumped-storage hydroelectricity are often used together with dams to generate electricity. A dam can also be used to collect water or else to store water.
Dams make money by generating electricity which in turn is sold to the public. Electricity comes about when the flowing water is changed into mechanical energy by a hydraulic turbine.
A generator works on the concept that when a magnet is moved past a conductor, it causes electricity to flow. This was discovered by Faraday. Loops of wire wound around stacks of magnetic steel laminations cause electromagnets to be made in a large generator. These are mounted on the perimeter of the rotor and are called field poles where the rotor is attached to the turbine shaft, and turns at a constant speed. When the rotor rotates, it makes the field poles (the electromagnets) move past the conductors mounted in the stator. This, in turn, causes electricity to flow and a voltage is developed at the generator output terminals.
Demand for electricity is constantly changing. Demand goes up and down. There is more demand for electricity during the day than there is at night especially in offices, businesses and factories. In summer there is a huge demand for electricity to run air conditioners mainly during the day but not so much during the night.
Water is kept in reserve by means of pumped storage where the water which has already been pumped is kept in store for when it is required. This water is stored at a time when the demand is low e.g. the middle of the night. The water is then allowed to flow back through the turbine-generators at times when demand is high and a heavy load is placed on the system.
The reservoir stores power in the form of water just like a battery does, storing water when the demand is low to be able to use when there is a high demand. Hydroelectric generating units can start up quickly and adjust themselves without loss of time which gives an advantage to this system of pumped storage. They are able to operate efficiently no matter how long they are being used for. Construction costs of pumped storage reservoirs are considerably low because they are generally small when compared to conventional hydropower facilities.
