Модуль 4 - Modal Verbs (1096808), страница 5
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The country hasat least 25 active volcanoes and many hot springs and geysers.Geothermal ElectricityHot water or steam from below ground can also be used to make electricity in a geothermal powerplant.17In California, there are 14 areas where we use geothermal energy to make electricity. The redareas on the map show where there are known geothermal areas. Some are not used yet becausethe resource is too small, too isolated or the water temperatures are not hot enough to makeelectricity.The main spots are:•••••The Geysers area north of San FranciscoIn the northwest corner of the state near Lassen Volcanic National ParkIn the Mammoth Lakes area - the site of a huge ancient volcanoIn the Coso Hot Springs area in Inyo CountyIn the Imperial Valley in Southern California.Some of the areas have so much steam and hot water that it can be used to generate electricity.Holes are drilled into the ground and pipes lowered into the hot water, like a drinking straw in asoda.
The hot steam or water comes up through these pipes from below ground.You can see the pipes running in front of the geothermal power plant in the picture. This powerplant is Geysers Unit # 18 located in the Geysers Geothermal area of California.A geothermal power plant is like in a regular power plant except that no fuel is burned to heatwater into steam. The steam or hot water in a geothermal power plant is heated by the earth. Itgoes into a special turbine.
The turbine blades spin and the shaft from the turbine is connected to agenerator to make electricity. The steam then gets cooled off in a cooling tower.The white "smoke" rising from the plants in the photograph above is not smoke. It is steam givenoff in the cooling process. The cooled water can then be pumped back below ground to bereheated by the earth.Here's a cut-away showing the inside of the power plant.
The hot water flows into turbine and outof the turbine. The turn turns the generator, and the electricity goes out to the transformer and thento the huge transmission wires that link the power plants to our homes, school and businesses.California's geothermal power plants produce about one-half of the world's geothermallygenerated electricity. The geothermal power plants produce enough electricity for about twomillion homes.Geothermal / Ground Source Heat PumpsThough it gets much hotter as we go deep below ground, the upper layer of the earth close to thesurface is not very hot.Almost everywhere across the entire planet, the upper 10 feet below ground level stays the sametemperature, between 50 and 60 degrees Fahrenheit (10 and 16 degrees C). If you've ever been ina basement of a building or in a cavern below ground, the temperature of the area is almost alwayscool.A geothermal or ground source heat pump system can use that constant temperature to heat or coola building.
Pipes are buried in the ground near the building. Inside these pipes a fluid, like theantifreeze in a car radiator, is circulated.In winter, heat from the warmer ground goes through the heat exchanger of a heat pump, whichsends warm air into the home or business. During hot weather, the process is reversed. Hot airfrom inside the building goes through the heat exchanger and the heat is passed into the relativelycooler ground. Heat removed during the summer can also be used to heat water.2. Hydro Power18When it rains in hills and mountains, the water becomes streams and rivers that run down to theocean. The moving or falling water can be used to do work.
Energy, you'll remember is the abilityto do work. So moving water, which has kinetic energy, can be used to make electricity.For hundreds of years, moving water was used to turn wooden wheels that were attached togrinding wheels to grind (or mill) flour or corn.
These were called grist mills or water mills.Inthe year1086,the Domesday Book was written. The multi-volume books are very large. Hand-written on thepages of the books are lists of all properties, homes, stores and other things in England. TheDomesday Book listed 5,624 waterwheel-driven mills in England south of the Trent River. Thatwas about one mill for each 400 people.Water can either go over the top of the wheel like in the photograph on the left, or the wheel canbe placed in the moving river.
The flow of the river then turns the wheel at the bottom like in themoving graphic on the right.Today, moving water can also be used to make electricity.Hydro means water. Hydro-electric means making electricity from water power.Hydroelectric power uses the kinetic energy of moving water to make electricity. Dams can bebuilt to stop the flow of a river. Water behind a dam often forms a reservoir Like the picture ofShasta Dam in Northern California pictured on the right. Dams are also built across larger riversbut no reservoir is made. The river is simply sent through a hydroelectric power plant orpowerhouse.
You can see this in the picture of The Dalles Dam on the Columbia River along theborder of Oregon and Washington State.Hydro is one of the largest producers of electricity in the United States. Water power suppliesabout 10 percent of the entire electricity that we use.
In states with high mountains and lots ofrivers, even more electricity if made by hydro power. In California, for example, about 15 percentof all the electricity comes from hydroelectric.The state of Washington leads the nation in hydroelectricity. The Grand Coulee, Chief Joseph andJohn Day dams are three of six major dams on the Columbia River. About 87 percent of theelectricity made in Washington state is produced by hydroelectric facilities. Some of thatelectricity is exported from the state and used in other states.How a Hydro Dam WorksThe water behind the dam flows through the intake and into a pipe called a penstock. The waterpushes against blades in a turbine, causing them to turn. The turbine is similar to the kind used in apower plant that we learned about in Chapter 6.
But instead of using steam to turn the turbine,water is used.19The turbine spins a generator to produce electricity. The electricity can then travel over longdistance electric lines to your home, to your school, to factories and businesses.Hydro power today can be found in the mountainous areas of states where there are lakes andreservoirs and along rivers.3. Nuclear Energy – Fission and FusionAnother major form of energy is nuclear energy, the energy that is trapped inside each atom. Oneof the laws of the universe is that matter and energy can't be created nor destroyed. But they canbe changed in form.Matter can be changed into energy. The world's most famous scientist, Albert Einstein, createdthe mathematical formula that explains this.
It is:This equation says:E [energy] equals m [mass] times c2 [c stands for the velocity or the speed oflight. c2 means c times c, or the speed of light raised to the second power — or c-squared.]You can listen to Einstein's voice explaining this at:www.aip.org/history/einstein/voice1.htmPlease note that some web browser software may not show an exponent (raising something to apower, a mathematical expression) on the Internet.
Normally c-squared is shown with a smaller"2" placed above and to the right of the c.20Scientists used Einstein's famous equation as the key to unlock atomic energy and also createatomic bombs.The ancient Greeks said the smallest part of nature is an atom. But they did not know 2,000 yearsago about nature's even smaller parts.As we have already learned , atoms are made up of smaller particles -- a nucleus of protons andneutrons, surrounded by electrons which swirl around the nucleus much like the earth revolvesaround the sun.Nuclear FissionAn atom's nucleus can be split apart. When this is done, a tremendous amount of energy isreleased.
The energy is both heat and light energy. Einstein said that a very small amount ofmatter contains a very LARGE amount of energy. This energy, when let out slowly, can beharnessed to generate electricity. When it is let out all at once, it can make a tremendous explosionin an atomic bomb.A nuclear power plant (like Diablo Canyon Nuclear Plant shown below) uses uranium as a "fuel."Uranium is an element that is dug out of the ground many places around the world. It is processedinto tiny pellets that are loaded into very long rods that are put into the power plant's reactor.The word fission means to split apart. Inside the reactor of an atomic power plant, uranium atomsare split apart in a controlled chain reaction.In a chain reaction, particles released by the splitting of the atom go off and strike other uraniumatoms splitting those.
Those particles given off split still other atoms in a chain reaction. In nuclearpower plants, control rods are used to keep the splitting regulated so it doesn't go too fast.If the reaction is not controlled, you could have an atomic bomb. But in atomic bombs, almostpure pieces of the element Uranium-235 or Plutonium, of a precise mass and shape, must bebrought together and held together, with great force.
These conditions are not present in a nuclearreactor.The reaction also creates radioactive material. This material could hurt people if released, so it iskept in a solid form. The very strong concrete dome in the picture is designed to keep this materialinside if an accident happens.This chain reaction gives off heat energy. This heat energy is used to boil water in the core of thereactor. So, instead of burning a fuel, nuclear power plants use the chain reaction of atomssplitting to change the energy of atoms into heat energy.21Power plant drawing courtesy Nuclear InstituteThis water from around the nuclear core is sent toanother section of the power plant.
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