The energetical potential of solar energy is great, by nowadays calculations it’s approximately 1,57*10^18 Watt peak a year. The science that studies the methods of collecting and transformation of solar energy to another kinds of energy is solar energetic.
There are several priorities of transformation and usage of solar energy. The first one is transformation of solar energy into heat and using of it for heating buildings, air conditioning, heating or distillation of water.
The basis of such generators of heat energy is plane solar collector that allows transforming solar energy to the energy of heat with a temperature of 160-180 F. It looks like a metallic frame with special pipes or it’s a plane box-like device that let pass the air, water or special liquids. This collector is put into heat isolation cover, with the exception of it’s working part that is subjected to the sunrays. A 9 ft. sqr. collector gives up to 20 gallons of hot water (150-170 F) per day. This solar water heats have a lot of perspectives to be used in remote desert areas or in the areas with a big number of sunny days. The prime cost of the hot water produced by the solar heaters is much lower than one produced by electric boiler or gas boiler. It doesn’t require any fuel and doesn’t pollute the environment. So the advantages of using solar water heaters are obvious.
The second priority of using solar energy is transformation of it into electricity. If to cover a silicon crystal with a thin, pure for light layer of metal, than the photons stream, while passing through a metal layer, will release free electrons from the crystal of silicon. Those electrons will start to concentrate in the metal layer. This will cause a potential difference between crystal and a metal layer. If to connect thousands of such crystals in series or in parallel (to increase voltage and current), we’ll get a solar battery that produces direct current.
Also there exists another trend of using solar energy for electricity production, which is similar to the heat power plant. It assumes using of glass pipes cover by the semiconductor layer from inside. Such pipe will let pass the sunrays but still collects 80% of them. Sunrays are collected into a narrow beam of light with a help of conversion lens. Then this heat is transmitted to the pipe that is inside of the glass pipe and it heats the working pipe up to 1000 F, which is more than enough to melt metallic natrium, that melt near 197 F. Incandescent heat conductor is transmitting to the underground reservoirs, where the heat collected for the solar energy makes salt to melt. The heat energy form the salt is transmitted to water pipes, where the water boils and then the energy of water steam is used as a moving energy for electric current generators.
The transformation of solar energy into another types of energy doesn’t bring any visible pollution to the environment, which makes it very beneficial. Other ways of electricity production are tightly connected with the pollution of environment. 80-85 percent of energy used by man is got by burning fuel (oil, gas, different kinds of bio resources). Even so that thee portion of heat power plants is decreasing now, still lots of countries use it as a primary source for getting energy (75% power plants in China and nearly 40% of power plants in Russia use oil, coal and gas). Heat power plants produces 50% of carbonic gas, 35% sulphur and nitrogen oxides released into atmosphere and nearly the same amount of dust. Recent researches also show that heat power plants twice more pollute the environment with radiation contamination than do nuclear power plants.
The influence of the hydroelectric power stations on the environment is also a subject of concern, because it’s connected with alienation of big territories for transformation of them into reservoirs. Hydroelectric power stations break the ecological aqua systems, more over they are quite often begin to silt and become ineffective in some 50-100 years. In the dry areas evaporation from the surface of water reservoirs is dozen times higher than evaporation from the surface of the land.
Nuclear energetics has been seen recently is one of the most promising trends in the electricity production that united cheap energy produced (one pound of radioactive fuel substitutes two million tons of coal) and a small influence on the environment. But the tragedy that happened on the power plant in Chernobyl, Ukraine proved that nuclear energy has a high potential risk.
The exploitation of solar energy can be useful in many ways. First by substituting the fuel that is used on heat power stations it reduces the air and environment pollution, it reduces the usage of oil and other fuel that can be used in more important purposes, by substituting nuclear fuel it reduces the radiation threat, and at the same time solar energy generators can make us more secure, by reducing the dependence upon uninterrupted fuel supply.
But still there are many obstacles that prevent mass spreading of solar energy usage. One of the most obvious is low intensiveness of solar radiation even in the sunny weather. Another obstacle is high initial price of solar energy generators.
The primary value for making a plane collector solar heater is 1000$ per 1 Watt peak. First looking, it may seem that because of the high price solar energy generators are not competitive with traditional electric power plants, where this index is low as 100$ per 1Watt peak. Even small diesel generators are not so costly. But if to include the fuel price to the coast of each kilowatt than this comparison won’t be so striking. Even it’s thought that solar generators are cheaper in the technical exploitation and lifetime is longer than that of tradition sources of electric energy. The calculations show that the price of the electric energy produced by solar generators can be reduced in future to .05-.01$ per kilowatt, and for solar water heater approximately to .02$ per kilowatt.
To be more specific in costs of solar electric systems lets refer to International Energy Agency data: “The type of system defines the components you need for a solar system and therefore the costs. The overall system prices for grid-connected systems vary between 7.8 and 24.0 USD/Watt peak. The price range for solar systems not connected to the grid is 5.5 to 25.2 USD/Watt peak.” But still there even more disadvantages of solar electric systems. First one is that they can be used locally, because the direct current produced by solar systems is effective for transmission on long distances (not more than 70 miles). In addition if to refer to MySolar; information on solar energy and solar systems says:
No comments:
Post a Comment