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Enengy or Solar Enegry
Energy means the power which works and drives machines. All living things (including humans) rely on the sun as a source of energy. Coal, petroleum and natural gas are energy sources available today because organisms in the past captured sunlight energy and stored it in the complex organic molecules that made up their bodies, which were then compressed and concentrated. With the development of society, a large number of energy sources have been used,such as coal, petroleum, natural gas, geothermal energy, nuclear fission power, nuclear fusion power, solar energy and Hydrogen gas. however, under the circumstances, the quantity of energy source is limited. unlimited usage of energy source results in energy crisis.
At present, most of the energy consumed by humans is produced from fossil fuels. The greatest recoverable fossil is in the form of coal and lignite. Although global coal resources are enomous and potentially can satisfy energy needs for a century or two, their utilization is limited by environmental disruption from mining and emissions of carbon dioxide and sulfur dioxide. These would become intolerable long before coal resources were exhausted. Only a small percentage of coal and lignite has been utilized to date, whereas much of the recoverable petroleum and natural gas has already been consumed. Petroleum has several characteristics that make it superior to coal as a source of energy. Its extraction causes less environmental damage than coal mining. It is a more concentrated source of energy than coal, and it burns with less pollution, and it can be moved easily through pipes. These characteristics make it an ideal fuel for automobiles.
Since first commercial oil well in 1859, somewhat more than 100 million barrels of oil have been produced in the United States, most of which are producted in recent years. In 1990 the world petroleum consumption was at a rate of about 65 million barrels per day. Projected use of petroleum and natural gas indicates rapid depletion. Alaskan oil can help the petroleum supply only temporarily. Peak world petroleum resources production will be reached within a few years.
Since the first "energy crisis" of 1973-1974, some specific measures have been taken. However, the several-fold increase in crude oil prices since 1973 has extacted a toll. In the U.S. and other industrialized nations, the economy has been plagued by inflation, recession, unemployment, and obsolescence of industrial equipment. The economy of some petroleum-deficient developing countries have been devastated by energy prices.
Energy crisis is accompanied by worldwide shortages of some foods and minerals, followed in some cases by surpluses, such as the surplus wheat resulting from increased planting and a copper surplus resulting from the efforts of copper-producing nations to acpuire foreign currency by copper export.
As it’s known to all,the availability and cost of energy has become dominant factors in society today. Obviously, solving the "energy crisis" makes good sense. Many schemes has been proposed for conserving present energy resources and developing new ones. It is always possible to use less energy in any process. Therefore, energy engineer is created and develop rapidly . The first goal of energy engineer is to determine the methods by which energy utilization is reduced but the output remains the same, or even increases.The second goal is to determine which methods of using less energy are cost effective.
Conventional engineering techniques are used to evaluated the mechanisms of energy use. Economic considerations are of equal importance and life cycle cost and saving techniques are used to determine cost-effective measures. The evaluation focuses on those uses which are significant in the overall picture and attempts to determine those technical measures that can reduce usage and save money.
Meanwhile, looking for ideal energy sources is also very important to solve energy crisis. The recipe for an ideal energy source calls for one that is unlimited in supply, widely available, and inexpensive; it should not add to the earth's total heat burden or produce chemical air and water pollutants. Solar energy fulfills all of these criteria. Solar energy does not add excess heat to that which must be radiated from the earth. On a global basis, utilization of only a small fraction of solar energy reaching the earth could provide for all energy needs.
Solar energy is unlimited in supply, but its exploitation and utilization are limited owing to the limitation of technology and conditions. Solar energy utilization needs an enormous amount of land, and there are economic and environmental problems related to the use of even a fraction of this amount of land for solar energy collection. Certainly, many residents of Arizona would not be pleased at having so much of the state devoted to solar collectors, and some environmental groups would protest the resultant shading of rattlesnake habitat.
Solar power cells for the direct conversion of sunlight to electricity have been developed and are widely used for energy in space vehicles. With present technology, however, they remain too expensive for large-scale generation of electricity. Therefore, most schemes for the utilization of solar power depend upon the collection of thermal energy, followed by conversion to electrical energy. The simplest design is a steam electric generating unit focusing sunlight on a steam-generating bioler. Parabolic refkectors can be used to focus sunlight on pipes containing heat-transporting fluids. Selective coatings on these pipes can be used so that only a small percentage of incident energy is reradiated from the pipes.
Silicon photovoltaic cells mainly in the absorption of solar light energy emitted by silicon photocell is mainly extracted from the sand by the development of Bell Labs. Solar energy is the interior or the sunspot on the surface of the sun continuous process of nuclear fusion reactions produce energy. Earth's orbit on the average solar radiation intensity for 1367w / ㎡. Circumference of the Earth's equator to 40000km, and thus calculated the Earth's energy can be obtained 173000TW. At sea level standard for peak intensity 1kw/m2, a point on the Earth's surface 24h of the annual average radiation intensity 0.20kw / ㎡, which is equivalent to have 102000TW energy.
Human rely on these energy to survive, including all other forms of renewable energy (except for geothermal energy resources), although the total amount of solar energy resources is the human equivalent of the energy used by ten thousand times, but low energy density of solar energy, and it varies with place and time,this is a major problem that the development and utilization of solar energy facing. These features will make solar energy in the integrated energy system of the role of subjectcertain restrictions.
The use of solar cells, through the photoelectric conversion to solar energy conversion, is included in electricity, the use of solar water heaters, the use of solar heat hot water and use water for power generation, using solar energy for desalination. Now, the use of solar energy is not very popular, the use of solar power costs are high there, the problem of low conversion efficiency, but for satellite solar cells to provide energy has been applied.
Although the Earth's atmosphere solar radiation to the total energy only 22 billionths of a radiation energy, it has been as high as 173,000 TW, that is to say a second exposure to the sun's energy on Earth is equivalent to five million tons of coal. such as coal, oil, natural gas, etc.are some kinds of solar energy from ancient times, so the broad sense of solar energy is very large,while the narrow sense is limited to solar radiation of solar light thermal, photovoltaic and photochemical conversion of the directly.
Solar energy is first time but also renewable energy. It is rich in resources,it can be used free of charge, and without transportation, without any pollution to the environment, creating a new life for mankind ,making social and human energy step into a era of saving energy and reducing pollution.
Solar cells have to respond to a light and convert solar energy to power the device. Photovoltaic effect can produce many kinds of materials, such as: single crystal silicon, polycrystalline silicon, amorphous silicon, gallium arsenide, copper indium selenium.The principle of power generation of them are nearly the same.Now take the crystal for example to describe the process of light generation. P-type crystalline silicon available after phosphorus-doped N-type silicon, the formation of P-N junction.
When the surface is under solar light, part of the photons are absorbed by silicon material,then photon energy transfer to the silicon atom, electronic transitions have taken place, as a free-electron concentration in the PN junction formed on both sides of the potential difference, when the external circuit connected under the effects of the voltage, there will be a current flowing through the external circuit and produce a certain amount of output power. The substance of this process are: photon energy into electrical energy conversion process.
"Si" is one of the planet's abundance of storage materials. Since the 19th century, scientists have discovered the properties of crystalline silicon semiconductor, it almost changed everything, even human’s thoughts,at end of the 20th century. It can be seen evrywhere in our life, "silicon" figure and role of crystalline silicon solar cells is the formation of the past 15 years the fastest growing industry. Production process can be divided into five steps: a, purification process b, the process of pulling rod c, slicing the process of d, the process of system battery e, the course package.
能源与太阳能
能源就是能够用于工作和驱动机器的能量。所有的生物（包括人类）都是依靠阳光作为能量的来源。煤、石油和天然气都是可以利用的能源，这些能源都是过去的生物体在太阳光能源的作用下生成复杂的存储这些能源有机分子结构经过长时间的压缩集中后生成的。大量的能源已经被使用，如煤炭、石油、天然气、地热资源、核聚变能源、核裂变能源、太阳能和氢气等。然而，在这种情况下，由于许多能够产生能量的资源是不可再生的，大量的使用这些能源可能会引起能源危机。
目前，人类的能源消耗主要体现在燃料资源的消耗上。现在的固体状能源主要是煤炭，目前已知的加上潜藏的煤炭储量最多可使用一到两个世纪，而且煤炭的开采和使用会破坏环境并且产生大量的二氧化碳与二氧化硫。当煤炭资源用尽前这些影响将会越来越恶劣。煤炭在能源的利用方面的比例已经越来越低，而石油和天然气正在被大量的使用着。作为能源，石油比煤炭有更大的优势。其开采地比煤炭更为集中因此对环境的破坏要少，其燃烧产生的污染物要比煤炭少，而且石油可以很容易的通过管道进行运输。同时这些优势使石油成为理想的汽车燃料。
自从1859年第一个商业油田的建成以来，美国已经生产了超过100万桶石油，其中大部分是在最近几年生产的。1990年全世界约消耗了65万桶石油。石油与天然气资源在迅速的消耗着，阿拉斯加出产的石油只能暂时缓解石油的供应危机。世界石油的生产将在几年之内达到最高值。
自从1973～1974年的第一次“能源危机”以来，已经出现了一些具体的措施。然而，自1973年以来，原油的价格已经提高了若干倍。美国和其他工业化国家一直受到通货膨胀、经济衰退、大批的失业和工业设备的过时的困扰。一些石油不足的发展中国家由于能源价格的关系其经济已经遭到破坏。
在能源危机的同时，世界范围内还有一些食品和矿产资源的短缺，其次一些物品的生产则出现过剩，如小麦和铜的生产过剩，一些铜生产国将铜以铜币的形式出口。
众所周知，能源的供应和成本已经成为当今社会的一个主要的话题。很显然，解决“能源危机”是非常有意义的。目前已经有许多节约能源和发展新能源的计划被提出来。在任何领域节约能源都是可行的。因而，能源工程师这个职业产生并迅速发展起来。能源工程师的第一个提议是想办法减少能源的消耗同时保证产量不变甚至有所提高，第二个提议是寻找降低能源成本的方法。
传统的工程技术被用来评估能源利用的技术。周期成本与用于节省资金的方法与经济利益同等重要。评价的重点是整个大局中的重要性和减少浪费和使用的资金的方法。
同时，寻找更为理想的能源是非常重要的。解决能源危机的一种理想的能源的要求应该是无限的供应、能够被广泛的使用、价格低廉、而且其使用后不会添加地球的总热量的负担或者不会产生化学空气和水污染物的排放。太阳能满足这些标准，其产生的多余的热量会从地球辐射出去。而且利用照射到地球的一小部分太阳能就能够提供地球所需的能源。
太阳能的供应是无限的，但是由于技术和条件的限制，其开发和利用是有限的。太阳能的利用需要大量的土地，还有经济和环境方面的要求，而且这一部分土地上太阳能的收集也只能达到一小部分。当然，亚利桑那州的许多居民渴不喜欢国家大力发展太阳能的收集，而且一些环保组织也因为太阳能的收集对响尾蛇的生活习性等产生的影响而抗议太阳能收集装置的实行。
太阳能电池能够将太阳能直接转化为电能，而且已经广泛应用于空间飞行器能源的提供。然而，以目前的技术水平如果应用于大规模发电其代价于昂贵。因此，目前大多数太阳能发电方式仍旧是首先将太阳能转化为热能，然后再将热能转化为电能。这种方式目前最简单的设计是蒸汽发电装置，收集到的太阳能通过管道中的载热气体进行输送。这种管道使用涂层能够使运输过程中的入射能量只有很少部分的流失。
使用太阳电池，通过光电转换把太阳光中包含的能量转化为电能，使用太阳能热水器，利用太阳光的热量加热水，并利用热水发电，利用太阳能进行海水淡化。现在，太阳能的利用还不很普及，利用太阳能发电还存在成本高、转换效率低的问题，但是太阳电池在为人造卫星提供能源方面得到了应用。
主要是硅光电池在吸收太阳所发射出来的光能，硅光电池主要是从沙子里提炼出来的，由贝尔实验室开发。太阳能是太阳内部或者表面的黑子连续不断的核聚变反应过程产生的能量。地球轨道上的平均太阳辐射强度为1367w/㎡。地球赤道的周长为40000km，从而可计算出，地球获得的能量可达173000TW。在海平面上的标准峰值强度为1kw/m2，地球表面某一点24h的年平均辐射强度为0.20kw/㎡，相当于有102000TW 的能量，人类依赖这些能量维持生存，其中包括所有其他形式的可再生能源（地热能资源除外），虽然太阳能资源总量相当于现在人类所利用的能源的一万多倍，但太阳能的能量密度低，而且它因地而异，因时而变，这是开发利用太阳能面临的主要问题。太阳能的这些特点会使它在整个综合能源体系中的作用受到一定的限制。
尽管太阳辐射到地球大气层的能量仅为其总辐射能量的22亿分之一，但已高达173,000TW，也就是说太阳每秒钟照射到地球上的能量就相当于500万吨煤。地球上的风能、水能、海洋温差能、波浪能和生物质能以及部分潮汐能都是来源于太阳；即使是地球上的化石燃料（如煤、石油、天然气等）从根本上说也是远古以来贮存下来的太阳能，所以广义的太阳能所包括的范围非常大，狭义的太阳能则限于太阳辐射能的光热、光电和光化学的直接转换。
太阳能既是一次能源，又是可再生能源。它资源丰富，既可免费使用，又无需运输，对环境无任何污染。为人类创造了一种新的生活形态，使社会及人类进入一个节约能源减少污染的时代。
太阳电池是一对光有响应并能将光能转换成电力的器件。能产生光伏效应的材料有许多种，如：单晶硅，多晶硅，非晶硅，砷化镓，硒铟铜等。它们的发电原理基本相同，现以晶体为例描述光发电过程。P型晶体硅经过掺杂磷可得N型硅，形成P－N结。
当光线照射太阳电池表面时，一部分光子被硅材料吸收；光子的能量传递给了硅原子，使电子发生了跃迁，成为自由电子在P-N结两侧集聚形成了电位差，当外部接通电路时，在该电压的作用下，将会有电流流过外部电路产生一定的输出功率。这个过程的的实质是：光子能量转换成电能的过程。
“硅”是我们这个星球上储藏最丰量的材料之一。自从19世纪科学家们发现了晶体硅的半导体特性后，它几乎改变了一切，甚至人类的思维，20世纪末．我们的生活中处处可见“硅”的身影和作用，晶体硅太阳电池是近15年来形成产业化最快。生产过程大致可分为五个步骤：a、提纯过程 b、拉棒过程 c、切片过程 d、制电池过程 e、封装过程。