Реферат: Энергетические ресурсы
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<span New Century Schoolbook",«serif»"> What is energy.
<span New Century Schoolbook",«serif»"> Everything in the universe is either energy or matter. For us humans,energy is the means for doing work. Picking up a book, watching TV or launchinga Space Shuttle all needs energy. Without it there would be no life, for alllife uses energy.
<span New Century Schoolbook",«serif»"> Energy, so far as we are concerned, comes from only two sources: the Sunand the decay of radioactive elements inside the Earth. The Sun radiates itswarmth out to all the planets, but ours happens to be about the right distanceaway to be able to support Life. In fact, Life seems to control the temperatureof the planet like a thermostat.
<span New Century Schoolbook",«serif»"> But what about oil, gas or coal, which also come from inside the Earth?They were formed because of the energy from ancient sunshine from millions ofyears ago driving life on Earth. These have formed 'fossil fuels' or'non-renewable' energy sources.
<span New Century Schoolbook",«serif»"> Energy is the power that we use to do things, whether it is thinkingabout building a ship or actually building it. Building it needs large amountsof energy to power blast furnaces to make the steel, mills to roll it andelectricity to weld it to form the ship's structure. That ship, when built, hasengines, which push it through the water. Most energy is not available to us ina usable form. We have to convert it into another form to make it work for us.
<span New Century Schoolbook",«serif»"> Here are two examples:
<span Times New Roman",«serif»;color:windowtext"><img src="/cache/referats/7453/image002.gif" v:shapes="_x0000_i1025">
<span New Century Schoolbook",«serif»">Afast-flowing river is full of energy we can't use. If you dam it and installturbines, you get electricity.<span Times New Roman",«serif»;color:windowtext"><img src="/cache/referats/7453/image002.gif" v:shapes="_x0000_i1026">
<span New Century Schoolbook",«serif»">Coalis just black rock with one odd property… it burns. If you burn it, you canwarm your home, cook food or raise steam in a boiler — to make electricity.<span New Century Schoolbook",«serif»"> Life needs energy. Life's energy is self-perpetuating only so long asthere is sunshine. Plants can convert it and store it for their next generation(as in potato tubers, groundnuts, rice or peas). Animals eat the plants or eachother, die and decompose, freeing nutrients for plants again. It is asustainable cycle. For hundreds of thousands of years, humans have merely beena part of this cycle. Then we got clever and discovered that we could useenergy other than from our own muscles to do work for us.
<span New Century Schoolbook",«serif»"> First we discovered that wind could drive our ships and water couldpower our mills. Later, we found that coal could make heat and steam formachinery. Then came oil and gas and nuclear power, all needed in increasinglylarge amounts to fuel our endless appetite for being comfortable and doingthings with as little effort as possible. So we heat our homes, schools andworkplaces in the winter. In the richer countries, most people have a car (orseveral) so that they can travel about. Transport guzzles huge amounts ofenergy — all so that we can have goods and services when we want them.
Kinds ofenergy resources.
<span New Century Schoolbook",«serif»">Almost all of the energy we usecomes from non-renewable sources.
<span New Century Schoolbook",«serif»">All non-renewable energysources create pollution, in part due to their extraction from the crust of ourplanet but mainly from their burning. Only two types exist: the fossil fuels(coal, oil and natural gas) and nuclear fuels (uranium, plutonium and, for thefuture, unusual types — isotopes — of hydrogen such as deuterium and tritium).
<span New Century Schoolbook",«serif»"> Fossil fuels areuseful to us only because they liberate heat energy when we burn the carbonthey contain. «Burning» — combustion — is really oxidation; makingcarbon and oxygen combine to liberate heat. Unfortunately for us, the principalbyproduct is carbon dioxide, CO2. Most scientists believe that thisis an important contributor to global warming. The heat from coal, gas and oilwe can use either directly or indirectly to raise steam in boilers and generateelectricity using steam turbines to drive generators. By contrast, properlymanaged nuclear fuels liberate no pollution to the atmosphere at all. Accidentsare rare in the nuclear power industry but when they occur, their potential forlong-lasting damage is horrific. The disaster at Chernobyl on April 26, 1986was by far the world's worst nuclear accident.
<span New Century Schoolbook",«serif»"> Phytoplanktonare tiny floating plants called algae. The commonest are golden or browncolored <span New Century Schoolbook",«serif»; mso-bidi-font-family:Arial;font-style:normal">diatoms
and <span New Century Schoolbook",«serif»;mso-bidi-font-family:Arial; font-style:normal">din flagellates. Zooplankton are tiny animals,which eat the phytoplankton but are themselves the main food for fish and somewhales. Oil (petroleum) and natural gas formed by complex decay processes frommicroscopic life forms called phytoplankton (<span New Century Schoolbook",«serif»; mso-bidi-font-family:Arial;font-style:normal">phyto=plant) whichfloated in the world's oceans millions of years ago. Just like today'sphytoplankton, they harnessed the Sun to photosynthesis and store energy. Whenthese myriads of tiny floating plants died, they sank to the sea floor andbecame mixed with muds from distant rivers, and were gradually buried. Overimmense periods of time, the soft sediments became ever more deeply buried andslowly hardened into rocks. Heat from the Earth's interior and the weight ofthe overlying rocks gradually changed the energy-containing substances in theaccumulated plants into hydrocarbon liquids and gases. Hydrocarbons are simplemolecules made up of carbon and hydrogen atoms joined together in chains or inrings. These molecules, being light and mobile, migrated upwards through therocks but eventually became trapped beneath impermeable rock structures in theEarth's crust. The oil and gas companies around the world know how to findthese trapped reservoirs and release their contents by drilling holes intothem. As everyone knows, crude oil and gas from these deposits form the basisfor the world's largest energy industry: oil and gas. Much oil and gasproduction now comes from underneath the seabed. As the technology forextraction continues to advance, production becomes possible from deeper anddeeper waters. This means that new oil and gas fields will continue to be foundfor some years yet so the early forecasts of oil running dry have proved to bewrong. But we know that the supplies are limited. We also know that every dropof oil we burn adds to the monumental environment problems we already have bypumping gases like carbon dioxide (CO<span New Century Schoolbook",«serif»">2<span New Century Schoolbook",«serif»">)into the atmosphere. Many scientists worry that this continual release of CO<span New Century Schoolbook",«serif»">2<span New Century Schoolbook",«serif»">is an important cause of global warming. <img src="/cache/referats/7453/image003.gif" vspace=«10» v:shapes="_x0000_i1027"><span New Century Schoolbook",«serif»">
<span New Century Schoolbook",«serif»">Nuclear power taps the ultimatesource of energy, which powers the universe, and its myriads of stars like ourSun. It exploits the famous E=mc2 [e1] equation, which shows that matter, canchange into energy. Nuclear engineers deliberately arrange to «split»certain atoms — this is called nuclear fission. When this happens, some mattergets destroyed — liberating huge amounts of energy. This energy mostly ends upas heat from which you can make steam to drive turbines and generators, and makeelectricity in power stations. In the Sun, atoms of hydrogen fuse to createhelium and liberate the seemingly endless stream of energy we call sunlight.Without this solar fusion reactor 150 million kilometers away, our home planetwould be a frigid lifeless world. Scientists hope to reproduce this fusionreaction in a controlled way to yield almost unlimited energy supplies with farfewer radioactive waste problems. So far, they've only managed the uncontrolledreactions… hydrogen bombs. The discovery ofnuclear reactions is a wonderful example of the neutrality or indifference ofscience. Like so many other discoveries, humans for good or for ill couldexploit nuclear reactions. The pressures of war caused the ill to be developedfirst but out of that development came an industry, which now provides 22% ofelectricity supply in the OECD countries. In France, it provides 73%; in the UK23% and 17% in the USA. And whilst it's true that the two nuclear bombs used inanger on Japan killed and maimed hundreds of thousands, they have some way togo to catch up with the hundreds of millions of people who've lost their livesbecause of ordinary bombs, high-explosive shells, bullets and mines. Many claimthat the very existence of nuclear weapons has prevented major conflict sinceWorld War 2. But what really scares people — and rightly so — is that modernnuclear weapons could destroy the entire planet… if they're ever used inanger again. So now, there are forces -like the World Court Project — afoot tomake their possession and use illegal throughout the world. On the other hand,many countries view with disgust the idea that the nuclear «haves»should keep their weapons whilst making sure that the «have nots»don't get any; a kind of nuclear imperialism. This is a good reason for makingall such weapons illegal. Otherwise, proliferation is a worry, particularlysince the break-up of the Soviet Union, which has inadvertently made weapons-gradematerials available on the international black market. Sooner or later,extremists will accumulate enough of this to build a crude device, which couldeasily be carried by a vehicle, driven into a major city and detonated. Theprospects are frightening. As in any industry, accidents happen. Seriousaccidents can mean the spreading of dangerous radioactivity into theenvironment. Several serious accidents have occurred, as everyone knows.Several other less well-known accidents associated with the race to buildnuclear weapons occurred in the former Soviet Union, causing the contaminationof hundreds of square kilometers of land. <span New Century Schoolbook",«serif»">Renewablesources — Renewable energy sources have long been energy's Cinderella. Today,wind power is finally coming into its own. Denmark, already employing 12,000people in its wind industry, intends wind power to produce half its totalelectricity needs by 2030. Several major wave power projects are now underwayand solar energy is booming in Germany, the western USA and, in a smaller way,in remoter parts of the South. Equally important in cold climates is the designof buildings to capture 'passive' energy and retain it through insulation.Other minor renewables include geothermal power in volcanically activecountries like Iceland, while tidal barrages remain a possibility in the UK andeastern Canada.<span New Century Schoolbook",«serif»">People use some kinds of renewablesources.
<span New Century Schoolbook",«serif»"><span New Century Schoolbook",«serif»"> At first, it is wind energy. We have been harnessing the wind's energyfor hundreds of years. From old Holland to farms in the United States,windmills have been used for pumping water or grinding grain. Today, thewindmill's modern equivalent – a wind turbine – can use the wind's energy togenerate electricity. Wind turbines, like windmills, are mounted on atower to capture the most energy. At 100 feet (30 meters) or more aboveground,they can take advantage of the faster and less turbulent wind. Turbines catchthe wind's energy with their propeller-like blades. Usually, two or threeblades are mounted on a shaft to form a rotor. A blade acts much like anairplane wing. When the wind blows, a pocket of low-pressure air forms on thedownwind side of the blade. The low-pressure air pocket then pulls the bladetoward it, causing the rotor to turn. This is called lift. The force of thelift is actually much stronger than the wind's force against the front side ofthe blade, which is called drag. The combination of lift and drag causes therotor to spin like a propeller, and the turning shaft spins a generator to makeelectricity. Wind turbines can be used as stand-alone applications, or they canbe connected to a utility power grid or even combined with a photovoltaic(solar cell) system. Stand-alone wind turbines are typically used for waterpumping or communications. However, homeowners or farmers in windy areas canalso use wind turbines as a way to cut their electric bills. For utility-scalesources of wind energy, a large number of wind turbines are usually built closetogether to form a wind plant. Several electricity providers today use windplants to supply power to their customers.
<span New Century Schoolbook",«serif»; color:black">At second, it is bio energy. We have used bio energy – the energy from biomass (organic matter) – for thousands of years, ever since people started burning wood to cook food or to keep warm. And today, wood is still our largest biomass resource for bio energy. But many other sources of biomass can now be used for bio energy, including plants, residues from agriculture or forestry, and the organic component of municipal and industrial wastes. Even the fumes from landfills can be used as an energy source.<span New Century Schoolbook",«serif»">The use of bio energy has the potential to greatly reduce our greenhouse gas emissions. Bio energy generates about the same amount of carbon dioxide as fossil fuels, but every time a new plant grows, carbon dioxide is actually removed from the atmosphere. The net emission of carbon dioxide will be zero as long as plants continue to be replenished for bio energy purposes. These energy crops, such as fast-growing trees and grasses, are called bio energy feedstocks. The use of bio energy feedstocks can also help increase profits for the agricultural industry.
Ithink, that it is very important to use sun energy. The Sun is the center ofour solar system and the source of life on the planet earth. Moreover, aspetroleum continues to pollute and destroy the earth, what better way than tolook to the Sun for a solution?
<span New Century Schoolbook",«serif»">Theearth and either being used or simply bouncing off are always capturing theheat from the Sun. Solar technology utilizes this heat energy and converts itto electrical energy, which is then fed into the power grid for users. That,albeit, is not all. One of the benefits of solar energy is its ability to beused widely and in specialized situations. For instance, «Small systemscan be installed on the roofs of homes to heat water for domestic use.Moderate-size systems can supply hot water, steam, and hot air to schools,hospitals, businesses, and industries. Large solar thermal electricinstallations can generate electricity in quantities comparable to thosegenerated in intermediate-size utility generating plants (that is, 100 to 200megawatts [MW] of electricity).»
<span New Century Schoolbook",«serif»">Onemyth about solar power is that it requires large areas of land in order to bedeemed useful. One example of this falsity is «Solar collectors coveringless than half of Nevada could supply all of the United States' energyneeds.» While that seems like a lot of land, that area divided my 50states and spread out could almost go unnoticed. One of solar powers biggestadvantages is cost. For 1% of the construction cost on a building, solar panelsinstalled could save up to 50% on heating bills. In addition, at a moreconsumer level, a resident of a home could save almost $500 within just thefirst year of installation. As an added bonus, the savings are likely toincrease over the years due largely to increase in electrical bills. Thus, asolar heating system is capable of paying for itself in less than 10 years. Theanswer to the energy crisis the world is seeing could be to simply return tothat with we depends on already, the Sun.
<span New Century Schoolbook",«serif»"> Flowing water creates energy that can becaptured and turned into electricity. This is called hydropower. The mostcommon type of hydropower plant uses a dam on a river to store water in a reservoir.Water released from the reservoir flows through a turbine, spinning it, whichin turn activates a generator to produce electricity. But hydropower doesn'tnecessarily require a large dam. Some hydropower plants just use a small canalto channel the river water through a turbine. Another type of hydropower plant– called a pumped storage plant – can even store power. The power is sent froma power grid into the electric generators. The generators then spin theturbines backward, which causes the turbines to pump water from a river orlower reservoir to an upper reservoir, where the power is stored. To use thepower, the water is released from the upper reservoir back down into the riveror lower reservoir. This spins the turbines forward, activating the generatorsto produce electricity.
The ocean can produce two types of energy: thermal energy from the sun'sheat, and mechanical energy from the tides and waves. Oceans cover more than70% of Earth's surface, making them the world's largest solar collectors. Thesun's heat warms the surface water a lot more than the deep ocean water, andthis temperature difference creates thermal energy. Just a small portion of theheat trapped in the ocean could power the world. Ocean thermal energy is usedfor many applications, including electricity generation. Ocean mechanicalenergy is quite different from ocean thermal energy. Even though the sunaffects all ocean activity, tides are driven primarily by the gravitationalpull of the moon, and waves are driven primarily by the winds. As a result,tides and waves are intermittent sources of energy, while ocean thermal energyis fairly constant. Also, unlike thermal energy, the electricity conversion ofboth tidal and wave energy usually involves mechanical devices. A barrage (dam)is typically used to convert tidal energy into electricity by forcing the waterthrough turbines, activating a generator. For wave energy conversion, there arethree basic systems: channel systems that funnel the waves into reservoirs; floatsystems that drive hydraulic pumps; and oscillating water column systems thatuse the waves to compress air within a container. The mechanical power createdfrom these systems either directly activates a generator or transfers to aworking fluid, water, or air, which then drives a turbine/generator.
Conclusion.
<span New Century Schoolbook",«serif»">Thus, humanity uses many kinds ofenergy: renewable and non-renewable. To make sure we have plenty of energy inthe future, it's up to all of us to use energy wisely. We must all conserveenergy and use it efficiently. It also up to those of you who will want tocreate the new energy technologies of the future. One of you might be anotherAlbert Einstein and find a new source of energy. It's up to all of us. Thefuture is ours but we need energy to get there.
<span New Century Schoolbook",«serif»"> The world has changed dramatically over the last 200 years, thankslargely to fossil fuels – coal, oil and natural gas. These have provided uswith cheap and convenient energy, which we use to heat and cool our homes andto run our cars, appliances and industries. But there has been a cost. No cityin the world is immune from the polluting effects of fossil fuels, and theycontribute vast quantities of greenhouse gases to the atmosphere, somethingthat many scientists believe causes global warming.
<span New Century Schoolbook",«serif»">So,in the last few decades, scientists have been looking for ways to produceenergy without adverse side effects. Promising renewable energy sources such aswind, direct solar and biomass are dealt with in other Nova topics (see linksat the end of this page). Now we'll have a look at hot dry rocks, waves andhydrogen. It may be some years before these energy sources make a big impactbut they illustrate the diversity of options that are available.