All About Solar Energy
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All About Solar Energy

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Good information about solar energy.

Good information about solar energy.

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All About Solar Energy All About Solar Energy Document Transcript

  • ==== ====For complete information on everything solar, and to learn more about solar energy, visithttp://solar-panel-s.com/2011/12/about-solar-energy==== ====Learning About Solar Energy From the Dept of Energy: Its a bit cloudyInterest in solar energy as an energy source rises and sets along with the tax credits that fuel itsgrowth. Because I am essentially a kid at heart, I visited the Energy Kids Page of the EnergyInformation Administration to learn more.The Energy Information Administration (EIA), created by Congress in 1977, is a statistical agencyof the U.S. Department of Energy. "Our mission is to provide policy-neutral data, forecasts, andanalyses to promote sound policy making, efficient markets, and public understanding regardingenergy and its interaction with the economy and the environment."The Energy Kids Page starts off in a friendly manner in a way that even I could understand:The sun has produced energy for billions of years. Solar energy is the suns rays (solar radiation)that reach the earth.Some of this solar energy is converted to heat, which is used to heat water and building interiors.So far, so good.Solar energy can be converted to electricity in two ways:Photovoltaic (PV devices) or "solar cells" - change sunlight directly into electricity. PV systems areoften used in remote locations that are not connected to the electric grid. They are also used topower watches, calculators, and lighted road signs.Solar Power Plants - indirectly generate electricity when the heat from solar thermal collectors isused to heat a fluid which produces steam that is used to power generator. Out of the 15 knownsolar electric generating units operating in the United States at the end of 2006, 10 of these are inCalifornia, and 5 in Arizona. No statistics are being collected on solar plants that produce less than1 megawatt of electricity, so there may be smaller solar plants in a number of other states.With childlike wonder, I pressed further, wanting to learn how energy-efficient, renewable solarenergy can help reduce fossil-fuel-generated electricity (half of which comes from burning coal,which in turn creates the 104 tons of mercury annually we have the pleasure of breathing,drinking, and eating).
  • So I dug into the Photovoltaic Section. Without warning or proper disclosure, The Energy KidsPage sent me back to college for my PhD in electronics. (Guys: Seriously, do you really think yourKid Page is kid-friendly?!)With quick googling, I found an online university and enrolled, studied night and day for four entireweeks, got my PhD, and now am delighted to give you this kid-friendly explanation of solar energy.Well shine a light on photovoltaic energy and the three types of solar power plants.Photovoltaic EnergyPhotovoltaic energy is the conversion of sunlight into electricity. A photovoltaic cell, commonlycalled a solar cell or PV, is the technology used to convert solar energy directly into electricalpower. The solar cell is a nonmechanical device usually made from silicon alloys.Sunlight has photons. Photons have energy. The solar cell gets slammed by photons and absorbssome of them. Others bounce right off like basketballs or pass through like ghosts.The absorbedphotons knock electrons out of place. Electrons are the stuff that electricity is made of. Theelectrons bubble up to the surface of the solar cell.This movement to the surface creates animbalance. When you hook up a wire from the solar cell to an outside battery, you create a paththat the electrons will follow.That flow into the battery is electricity.A single photovoltaic cell will power your calculator and your curiosity, but not much more. At 1 or2 watts, you need hook up a bunch together to get some real juice flowing. This is called an array,and can include as many cells as you can afford. Definitely a case of the more you spend, themore you save.Dont Stick It Where The Sun Dont ShineSunlight is constant - the clouds and fog are not. Climate conditions significantly effect the amountof solar energy received by a photovoltaic array and, in turn, its performance. Most currenttechnology photovoltaic modules are about 10 percent efficient in converting sunlight. Furtherresearch is being conducted to raise this efficiency to 20 percent.AC/DC: ConversionThe battery collects direct current (DC). You need alternate current (AC) flowing through your lightfixtures. Solid state devices called inverters convert DC power to AC. Problem solved.Photovoltaic Energy Recap: photovoltaic or solar cells absorb the slings and arrows of outrageousphotons from the Sun, which shove electrons to the surface of the cells, where you store them byhaving them flow through a wire into a battery. You break out your inverter to make that batteryenergy usable. But at 10% efficiency, they suck big time in consistently poorly lit areas, such asSweden during November to January when theyre nearly blacked out and lighting their way withseal blubber candles and Ikea accent lamps.Next up, kids (and Ill keep it friendly):
  • Solar Thermal Power PlantsSolar thermal power plants use the suns rays to heat a fluid, which is put into water and turns itinto steam. The steam propels a turbine that powers a conventional generator that createselectricity. Solar thermal power generation works essentially the same as generation from fossilfuels except that instead of using steam produced from the combustion of fossil fuels, the steam isproduced by the heat collected from sunlight. Solar thermal technologies use concentratorsystems due to the high temperatures needed to heat the fluid.In short, they replace fossil fuels with solar energy to run turbines which create electricity.The three main types of solar-thermal power systems are:parabolic troughssolar dish, andsolar power towerParabolic TroughsThe most common type of solar plant, the parabolic trough is used in the largest solar powerfacility in the world located in the Mojave Desert at Kramer Junction, California. This facility hasoperated since the 1980s and accounts for the majority of solar electricity produced by the electricpower sector today.A parabola is U-shaped. The parabolic trough is like a magnifying glass: it takes sunlight andfocuses it on a spot to heat it up. That spot is on a tower, surrounded by all the parabolic troughs.It heats the spot up to 400 degrees Celsius. The parabola can follow the Suns movement duringthe day in order to get the most sunlight.The spot that is heated up is filled with fluid. This fluid flows to heat up water and create steam.The steam propels a turbine that powers a conventional generator that creates electricity. The fluidcools down a bit and is returned to the spot on the tower to be reheated to 400 degrees.The plant is usually designed to operate at full rated power using solar energy alone, givensufficient solar energy. However, all plants are hybrid solar/fossil plants that have a fossil-firedcapability that can be used to supplement the solar output during periods of low solar energy. Thisdefeats the purposes of generating renewable energy, but I guess the scientists know what theyredoing.Solar DishesA solar dish/engine system utilizes concentrating solar collectors that track the sun on two axes,concentrating the energy at the focal point of the dish (the box-like thing sticking out from thecenter of it) because it is always pointed at the sun.The solar dishs concentration ratio is much higher that the solar trough, typically over 2,000, with
  • a working fluid temperature over 750 degrees Celsius. The power-generating equipment used witha solar dish can be mounted at the focal point of the dish, making it well suited for remoteoperations or, as with the parabolic trough, the energy may be collected from a number ofinstallations and converted to electricity at a central point.The engine in a solar dish/engine system converts heat to mechanical power by compressing theworking fluid when it is cold, heating the compressed working fluid, and then expanding the fluidthrough a turbine or with a piston to produce work. The engine is coupled to an electric generatorto convert the mechanical power to electric power.Solar Power TowerA solar power tower or central receiver generates electricity from sunlight by focusingconcentrated solar energy on a tower-mounted heat exchanger (receiver).This system uses hundreds to thousands of flat sun-tracking mirrors called heliostats to reflect andconcentrate the suns energy onto a central receiver tower. The energy can be concentrated asmuch as 1,500 times that of the energy coming in from the sun. Energy losses from thermal-energy transport are minimized as solar energy is being directly transferred by reflection from theheliostats to a single receiver, rather than being moved through a transfer medium to one centrallocation, as with parabolic troughs. Power towers must be large to be economical. This is apromising technology for large-scale grid-connected power plants. Though power towers are in theearly stages of development compared with parabolic trough technology, a number of test facilitieshave been constructed around the world.What We Learned TodayWe learned that solar energy can be used to heat water and interiors.Next, we learned that solar energy can be converted to electricity using photovoltaic cells andsolar thermal power plants. The photovoltaic cells take in photons, which shove aside electrons.The electrons, seeking a new home, journey in mass across a wire to their new land calledBattery. Solar thermal power plants work by focusing sunlight to heat a fluid, and that fluid turnswater into steam, which runs a turbine, and that turbine is the engine to run an electric generator.And most important, we learned that, no matter what you label something, such as being designedfor kids, that does not make it so. I think we need to call in the Department of Commerce toenforce the Truth-in-Labeling Act with the Department of Energys Energy Kids Page, one of themost kid-unfriendly websites known as mankind. And Im going downtown right now to file a claimfor reimbursement of my expensive online tuition for the PhD I had to get just to understand thisEnergy Kids Page.And now I would like to offer you free access to powerful info on energy efficiency thats easy toread and cuts through all this "green" information clutter -- so you can literally start making positivechanges today.
  • You can access it now by going to: [http://www.a19.com/pub/articles]From Cinnamon Alvarez: Founder, A19 -- woman-owned green manufacturer of hand-madeceramic lighting fixturesArticle Source:http://EzineArticles.com/?expert=Cinnamon_Alvarez==== ====For complete information on everything solar, and to learn more about solar energy, visithttp://solar-panel-s.com/2011/12/about-solar-energy==== ====