Today's Environment lesson is based on the most abundant source of Energy i.e. Solar Energy. Did you know that "Every one hour the sun beams onto Earth more than enough energy to satisfy global energy needs for an entire year". Solar energy is termed as the technology which is used to harness the sun's energy and make it usable. Today, the technology produces less than only one tenth of one percent of global energy demand.
Many people across the world are familiar with so-called photo voltaic cells, or solar panels, found on things like spacecraft, rooftops, and handheld calculators. The cells are made up of semiconductor materials like those found in computer chips. When sunlight hits the cells, it knocks electrons loose from their atoms. So, as the electrons flow through the cell, they generate electricity.
Solar thermal power plants employ various techniques on a bigger scale to concentrate the sun's energy as a heat source. This heat produced, is then used to boil water to drive a steam turbine that generates electricity in much the same fashion as coal and nuclear power plants, supplying electricity for thousands of people across the globe.
In one of the techniques, long troughs of U-shaped mirrors focus sunlight on a pipe of oil that runs through the middle. The hot oil then boils water for electricity generation. Another technique uses moveable mirrors to focus the sun's rays on a collector tower, where a receiver sits. Molten salt flowing through the receiver is heated to run a generator.
Rest other solar technologies are passive. For example, big windows placed on the sunny side of a building allow sunlight to heat-absorbent materials on the floor and walls. These surfaces in turn release the heat at night to keep the building warm. Similarly, the absorbent plates on a roof can heat liquid in tubes that supply a house with hot water.
Solar energy is lauded as an inexhaustible and the most abundant fuel source that is pollution and often noise free and this technology is also versatile. For example, solar cells generate energy for far-out places like satellites in Earth orbit and cabins deep in the Rocky Mountains as easily as they can power downtown buildings and futuristic cars.
But a disadvantage of solar energy is that it doesn't work at night without a storage device such as a battery, and cloudy weather can make the technology unreliable during the day. Another major drawback of the Solar Technologies is that they are not easily affordable in price and they require a lot of land area to collect the sun's energy at rates useful to lots of people.
Nevertheless, despite the drawbacks, solar energy use has surged at about 20 percent a year over the past 15 years, thanks to rapidly falling prices and gains in efficiency. Japan, Germany, and the United States are major markets for solar cells. With tax incentives, solar electricity can often pay for itself in five to ten years.
Source: National Geographic
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