How energy is converted
Basic Types
There are two basic types of solar energy converters, thermal collectors as well as photovoltaic collectors, use absorption to capture the sun’s energy.
The Thermal Process
The thermal collectors absorb the light coming from the sun and concentrate it to heat a transfer fluid to a very high temperature. The hot heat transfer fluid generates steam that drives the power conversion to produce electricity.
The Photovoltaic Process
Photovoltaic cells, also called PV cells, convert sunlight directly to electricity. Photovoltaic means light electricity. They are made from semiconductors, with the most common types being made from silicon. As light strikes the cell a portion of it is absorbed in the semiconductor. The energy breaks free electrons that flow in a certain direction because of the electric fields produced by the PV cell. This energy is channeled off to be used externally where it is needed.
Other types of solar energy converters
When higher temperatures are needed, the use of concentrating solar conductors is necessary. They use large reflective surfaces that concentrate the energy onto a smaller surface that then absorbs the light.
Parabolic dish
Parabolic trough
Frensel lens
Central Receiver System
Solar Source
The sun’s light is used in many ways. We can convert its energy to produce heat, light, hot water, electricity, etc. for homes, businesses and industries. Solar panels are used in a variety of ways from heating a pool, to powering a calculator. They can be found on the rooftops of houses, on the face of a wrist watch, and even on the tops of emergency phones located on the sides of highways.
Different parts of the world can collect more or less solar energy depending upon location, climate, and what type of area it is. For example a desert will be able to capture more energy from the suns rays than a forest could. The figure below highlights the highest regions that are able to retain the most solar energy.
The largest solar energy generating plant is located at Kramer Junction, California. It can produce a maximum of 354 Mega Watts of energy, which is used to power the greater Los Angeles area.
Solar Energy Efficiency
Solar energy is one of the cleanest and safest ways to produce energy. Unlike the ordinary energy sources it does not give off waste that pollutes the environment, it doesn’t deplete natural resources, and it does not cause global warming. It is a quiet and self contained source that is used in a myriad of ways. It can be used for lighting small appliances in homes, or powering irrigation systems on farms, and can even provide the energy needed to run an industrial plant. Unlike coal it is not expensive to buy, in fact its free, and not expected to run out any time soon. Every gigawatt hour of solar generated electricity can save 1,000 tons of carbon monoxide from reaching the atmosphere.
A Parabolic dish concentrates the solar radiation to a single point. A tube or other heat transferring device is connected to that point where it is then transferred to a gas.
A Parabolic trough concentrates the sun’s radiation onto a line that contains heating fluid inside, which is then channeled out for use.
A Fresnel lens concentrator uses refraction not reflection to capture solar energy.
A Central receiver system contains a large area of independently movable mirrors and a receiver located on top of a tower. The mirrors move on angles to reflect the light onto the receiver a the top of the tower. The receiver at the top of the tower is connected to tubes or other heat channeling device.
A Fresnel lens concentrator uses refraction not reflection to capture solar energy.
Immediately outside the Earth’s atmosphere the sun’s energy is available at 1,367 watts per square meter facing towards the sun.
One of nine generating systems located at Kramer Junction.
Although it may be less efficient and more expensive, there are no side effects that are harmful to the environment. Because of the extremely high price of oil, researchers are trying to develop cheaper and more efficient ways of harnessing the sun’s energy. From The late 1980s to the late 1990s the demand for solar energy increased 290 percent. The government is also trying to encourage the use of solar power and has increased its budget almost tenfold in the last decade to 400 million dollars going to fund solar energy research.
The problem with solar energy is its cost. It is not mass produced like the other convention forms of energy. However the department of energy estimates that about 17 miles of solar absorption plates (PV cells, parabolic dishes, etc) would be needed in each state to supply it with enough energy. If we use the 5 million acres of no longer used land in the United State’s cities, than we could have enough energy to supply 90% of the electric demand in the whole country.
Solar energy continues to be developed and researched extensively today because of the harmful effects that the other power sources cause. It is one of the fastest growing energy suppliers and it can only grow larger. Other alternatives are running out, or are to dangerous the atmosphere, so the answer is solar energy.