What ways can people utilize solar energy?
What are the advantages of solar energy?What ways can people utilize solar energy?
There are several methods through which to harness solar energy and here are four of them:
| Focusing Collectors: | There are three basic components of a focusing collector: heliostats, the moveable mirrors used to track the sun for the greatest efficiency; a parabolic collector that collects and reflects the solar energy from the heliostats to a single centre point; and a receiver that utilizes the concentrated energy at that centre point. A focusing collector can provide a temperature as high as 4000 o C. The high temperature is ideal for a solar furnace that provides contaminant-free environments for research and industrial use. Focusing collectors can also be used to generate solar electricity. The heliostats can focus the energy to a boiler (also known as a central receiver) that turns water into steam which then moves a generator.1 |
| Flat Plate Collectors: | An absorber plate, a glass or plastic plate, an array of pipes and insulation are the basic components of a flat plate collector. The absorber plate is basically a plate of black coated metal (commonly steel, aluminum or copper) used to trap the solar radiation and turn it into heat. The transparent plate, usually constructed of glass or plastic, is put on top of the absorber plate to preserve the heat. Then, a series of pipes are put between the plates with cold water passing through them. The hot water is then used to provide heating. These collectors take less space than focusing collectors and they are comparatively cheaper although they cannot provide as much heat. Therefore, flat plate collectors can be used in households or schools in such applications as swimming pool heating.2 |
| Solar Distillation: | The concept of solar distillation is simple. Sea water is put in shallow ditches or tanks with two slanted transparent plates placed on top of the roof of a house. Solar energy heats the water and evaporates it. The transparent plates, made of glass or plastic, collect and turn the water vapor into liquid water as the vapor condenses. The ducts along the sides of the unit then collect the fresh water to a main reservoir. Solar distillation is actually very similar to flat plate collectors except that, instead of heat, distilled water is the end product. Salt can also be "produced" during this process (for it is the by-product of distilled sea water). This may be seen as another advantage of solar distillation.3 |
| Solar Electricity: | There are two ways of generating electricity from solar energy. One of them uses focusing collectors as mentioned above.4 The other method uses photovoltaic cells. These cells are made up of thin pieces of semiconductors, such as crystalline silicon and gallium arsenide. These semiconductors convert solar radiation directly into electricity.5 |
What are the advantages of solar energy?
Solar energy is cost effective in terms of fuel
(because no fuel is required) and its price would not be affected by the supply
and demand of fuels. Solar energy is also pollution free. In addition, as solar
energy does not use fuel, it also eliminates the problems that arise during
the recovery, transportation and storage of fuels.
Why is solar energy
not very popular?
Generally, the initial cost is the main disadvantage of solar energy. All the methods (except for flat plate collectors) of solar energy mentioned require large space to achieve average efficiency. Therefore, the cost of solar energy increases. The efficiency of generating solar energy also relates to the location of the sun, but it can be improved by installing heliostats like those used in focusing collectors. Air pollution and weather can reduce the productivity of the power plants. Solar electricity by photovoltaic cells is particularly expensive because of the semi-conducting materials. It is estimated that the cost for this kind of solar electricity at least doubles the cost of conventional electricity, which makes it rather an inefficient alternative. Nocturnal down-times are another set back.6
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