求一篇水能源介绍 英语文章 讲 2—-3分钟 求一篇能讲2——3分钟的故事
Energy is the capacity to do work and transfer heat. Work is performed when an object or substance is moved over some distance. Energy is needed to carry out processes, such as boiling water or burning candles. Energy is also the heat that flows from a hot object or substance to a cold one, when they come in contact. A clear example of this is the fact that water heats up when you put in a water boiler device.
Energy has many forms, such as light, heat, electricity, chemical energy (stored in chemical bonds) and mechanical energy (moving matter, such as flowing water).
自己摘选点就行，帅哥
All energy forms are divided up between two main kinds of energy. The first main kind of energy is kinetic energy, the energy of motion and action. Heat is a total of kinetic energy of atoms, ions or molecules. When these chemical compounds are in motion due to kinetic energy they will warm up. You cannot always detect heat that originates from kinetic energy, because sometimes the heat of a substance can rise without an additional rise in temperature. The second main kind of energy is potential energy, energy that is stored and potentially available for use. Before potential energy can be used it is transferred into kinetic energy. An example of an object containing merely potential energy is a dice that you hold in your hand. When you throw the dice the potential energy is transferred into kinetic energy and this will cause the movement.
Does water contain energy?
Water, like many substances, contains two kinds of energy. The first kind of energy is called kinetic energy. This is energy that is used during the execution of processes, such as movement. Because of kinetic energy water can flow and waves can exist.
But water can also contain potential energy. This is energy that is stored in the water. Stored, but not used. This energy can become useful when water starts to flow. It will be transferred to kinetic energy and this will cause movement.
Can energy be generated through water?
When water flows or falls, energy can be generated. The generation of energy through water is usually carried out in large water power plants, with a number of process steps and the use of several devices, such as turbines and generators. The energy in water can be used to produce electricity.
What is hydroelectric power?
Hydroelectric power is electricity that is supplied by generating energy from falling or streaming water. Hydroelectric power is a so-called renewable energy source. This means that the source, which provides the energy, can be renewed. This is because, unlike non-renewable energy sources such as crude oil, we will not run out of water fully. It can be renewed after we have used it for energy generation.
What are the benefits and drawbacks of hydroelectric power?
There are several benefits to the use of hydropower. Hydropower has a moderate to high amount of useful energy and fairly low operating and maintenance costs. Hydroelectric power plants emit very little heat-trapping carbon dioxide and other air pollutants during operation. They have live spans of two to ten times those of coal and nuclear plants.
The dams that are used in the power plants help prevent flooding and supply a regulated flow of irrigation water to the areas below the dam.
However, there are some drawbacks to the use of hydroelectric power. A hydroelectric power plant takes up a lot of space and this may cause animal habitats to go lost. Large-scale projects can threaten recreational activities and disrupt the flows of rivers. Due to the presence of dams and reservoirs, fish may not be able to swim to sea and aquatic life may decrease in the area of the hydroelectric power plant.
How is energy generated in a hydroelectric power plant?
A hydroelectric power plant consists of a high dam that is built across a large river to create a reservoir, and a station where the process of energy conversion to electricity takes place.
The first step in the generation of energy in a hydropower plant is the collection of run-off of seasonal rain and snow in lakes, streams and rivers, during the hydrological cycle. The run-off flows to dams downstream. The water falls through a dam, into the hydropower plant and turns a large wheel called a turbine. The turbine converts the energy of falling water into mechanical energy to drive the generator. It turns a shaft, which rotates a number of magnets in the generator. When the magnets pass copper coils a magnetic field is created, which aids the production of electricity. Step-up transformers will than increase the voltage of the electricity, to levels needed for the journey to communities. After this process has taken place electricity is transferred to the communities through transmission lines and the water is released back into the lakes, streams or rivers. This is entirely not harmful, because no pollutants are added to the water while it flows through the hydropower plant.
How much of the world's electricity is supplied by hydroelectric power?
Hydroelectric power supplies about 20% of the world's electricity, and 6% of its total commercial energy.
This is an indication of the total electricity supply by hydroelectric power in several different countries:
- 99% in Norway
- 75% in New Zealand
- 50% in developing countries
- 25% in China
- 13% in the USA
Can we produce electricity from tides and waves?
Production of electricity from waves and tides is an option today. About twice a day in high as well as low tides, water flows in and out of coasts and estuaries. This water can spin turbines, in order to produce electricity. But analysts have been taking a closer look at this form of energy supply and they believe that tidal power can only make a tiny contribution to the world's energy supply, because of the few suitable sites, the high construction costs and the risk of equipment destruction by saltwater corrosion. However, there are a few areas with the right conditions to produce tidal power. France and Canada own the largest tidal energy facilities right now.
Is production of electricity from heat stored in water possible?
Several countries believe that energy can be produced from ocean thermal gradients. They have been evaluating the use of the large thermal differences of tropical oceans for the production of energy. With the thermal heat in the water they want to produce steam that can spin turbines, for the production of electricity. The thermal energy in the oceans would be converted in conversion plants, which would be anchored to the bottom of the ocean. The technology of energy production from heat stored in water has not yet been applied, as it is still in the research phase. Analysts believe that this technology will not have enough economic value to compete with other energy production technologies.
An alternative that may have economic value is the solar pond. By trapping sunlight in a freshwater pond the water will warm up, which causes steam production. This steam is trapped and used to spin turbines for electricity production. The principle is the same as electricity production from thermal energy in oceans, however, the technology is much simpler and it has moderate construction and operating costs.
Read more: http://www.lenntech.com/water-energy-faq.htm#ixzz1FKpfikIE
求一篇能讲2——3分钟的故事~
革命故事两则
《水缸的秘密 》
瑞金沙洲坝的杨大娘是红军家属。大儿子参加红军以后，家里少了一个劳动力，里里外外什么事都要她自己操心。
1933年7月的一个傍晚，杨大娘浇完菜园，回家准备挑水做饭。她刚拿起扁担，却发现水缸里的水满满的。大娘奇怪了：前天水缸满，昨天水缸满，今天水缸又满了。这是怎么回事？她问小儿子：“小发仔，下午你挑水了吗？”
11岁的小发仔把头摇得拨浪鼓似的，说：“我没挑。”
杨大娘越想越觉得奇怪，就跑到田头问代耕队长：“我屋里那口水缸，天天都满满的。是你派人给我家挑水了吧？”
“没有啊，”代耕队长也感到奇怪，将信将疑地问，“真有这样的事？”
正说着，上屋的二婶也提着菜蓝子走过来搭话：“是啊，我屋里的水缸也是干了又会满，满得都快要溢出来 了，不知道是谁在做好事。”
代耕队长把斗笠往头上一扣，笑笑说：“毛主席主张调查研究，你们该去调查调查呀！”
杨大娘和二婶觉得这话有理，俩人商量了一阵，就各自回家了。
第二天，杨大娘擦桌子、洗衣服，不到下午，满满一缸水就用完了。她故意不去挑，也不下地干活，早早拿起一双鞋底，坐在门口，和二婶你一针我一线地纳起鞋底来。她俩鞋线扯得嗦嗦响，纳好鞋底又上鞋帮，四只耳朵听动静，两双眼睛观八方，边做针线活，边搞起“调查”来。但是等了半天，也没有半点儿动静，她俩心里纳闷极了。
太阳离西山只有两竿高的时候，杨大娘忽然听见屋里的后门响了，接着又听到水桶铁钩碰撞的声音。她俩惊喜地互相丢了个眼色，不约而同地喊了出来：“这回捉到了！”说着站起身就往屋里跑。
杨大娘刚进门，差点跟一个挑着水桶的人撞个满怀。她抬头一看，见这人身材高大魁梧，穿一身红军制服，正冲着她和二婶笑。望着他那双明亮的大眼睛，她觉得很面熟，但是又记不起在什么地方见过。二婶一下就认出来了：“呀，这不是毛主席吗！”
二婶拉着毛主席坐下，杨大娘赶忙端上一碗茶，说：“毛主席，你来沙洲坝不久，可处处爱护体贴老百姓，叫我们怎么感谢你呀！”
毛主席喝着茶，和两位红军家属聊起家常来，问她们：生活有没有困难？代耕队耕的田满意不满意？房子漏雨不漏雨？小孩子在列宁小学的功课好不好？一直谈到天擦黑，毛主席又要去挑水，非要把水缸挑满不可。杨大娘拗不过，只好答应了。
毛主席为杨大娘和二婶家挑水的事，很快就在村里传开了。
《一块银元 》
三千多名战士驻扎一个村，吃饭吃菜成了一件大事。刚开始，由于地主老财造谣惑众，加上村民对红军并不了解，许多人弃家躲避，来不及逃的人关门闭户，筹集粮菜一时陷入了困境。朱德军长严明纪律，让战士挨家挨户做思想工作。一天，两名战士到村南一户人家，大门紧锁，听说已逃到外村亲戚家中。只见其家门口有一个南瓜大架棚，十分旺盛，棚上挂着两个黄艳艳的大南瓜，小战士心想：人家又不在，怎么个买呢?太个子战士说：“把两个南瓜割下，我写一张纸条，钱以后送来。”说完割下南瓜，写了一张字条“买两个南瓜，以后付钱。一～红军”．放在架上回去了。有一天晚饭，朱德吃到香酥的南瓜饭后，询问谁买的瓜真是好吃时，他才知道南瓜没有付钱。他让人叫来那二位战士，从背包里带出一块银元，语气严肃地说：“人不在，也不能白吃呀。”说完要二位战士去还钱，两位战士原以为办了一件好事，却受到首长的批评，顿时面面相觑，等他们回过神来时，早已站在身旁的排长对他们耳语了一番，这时他俩才兴冲冲地走了。
再说红军进村后，帮助村民打扫庭院、挑水劈柴。一位大爷病了，还派医生为他诊治……一桩桩军爱民的好事在村里传颂着。村民们消除了误解，事实戳穿了地主们造谣中伤的阴谋，外逃的村民回来了，村子里家家户户敞开大门，争相帮红军做事，有送粮送菜的，有送儿子来帮丁当兵的，真是军民鱼水一家亲啊。又说村南那户种南瓜的村民叫陈亮，他携妻带儿回到家里，一切依然如故，十分高兴。只是棚上两个南瓜不见，他心里想：家在就好，两个南瓜算是让贼偷了罢，也不把它当回事，在村民会上他无意说了这事，没想到那二个战士又狠狠挨了一顿批，可他们心里不服气哪。
一天，陈亮的妻子上棚割南瓜叶准备煮了喂猪，不经意间看见被割走的一个南瓜蒂上用红布扎着一个小包，他拿下来一看，里面包着一个金闪闪的银元，还有一张小纸条，可他不识字，急忙拿到村里给丈夫看，只见字条写着：“老乡：买2个瓜送上一块银元。一一红军’’村里人顿时都聚拢过来，有的窃窃私语。陈亮顿时面红耳赤，捶胸顿足，大声说：“我好糊涂啊，原以为南瓜被贼偷了，没想到红军大哥纪律严明，买东西付钱，一银元可买好多南瓜呀。”说完他拉着郭夫爷一起找朱军长，一是把银元还了，二是要向两位战士赔罪。朱德军长激动地对他们说：“这是红军应该做的。银元你留着，至于赔罪由我来吧。”回到家里，陈亮倾其所有，把鸡蛋、鸭蛋和鸡鸭装满箩筐，上面用红纸写着“拥军爱民”，一家三口人高高兴兴担着慰问品走向美魁堂，听说红军走的前一天，他还特地屠杀大肥猪前去慰劳。
一石激起千层浪。陈亮的“银元故事”在村里传遍了，拥军爱民在福鼎在横口成了时尚，蔚然成风。后来，一位诗人以此为题材写了一首《南瓜蒂上长白银》的诗还在省里获奖，而一位画家以此为题材的国画也得了奖。从此，拥军爱民的优良风尚在福鼎在横口在永春代代相传，永远相传。
你可以选择一篇~~~
一篇很励志的 很简单 2 3 分钟吧
Rome was not built in a day,No pains,no gains.There're so many various things like these sayings.All these show us that the success couldn't be gained without any efforts. As we know,the success comes after the efforts and the time.Firstly,to accomplish one thing,we must learn the aims.Secondly,we should draw up the relevant plan to realize our aim.Thirdly,we must try hard to accomplish the plan.It's undeniable that we may meet many problems which may not be thought at the beginning,such as the new conditions and the sudden changes in the process.At last,we may find to do one thing is more difficult than to think it.We must defeat ourselves-the main and the strongest enemy of ours.To some extent,it's the decisive factor that the length of the time we could persist in. In spite of the difficulties,we must gain our aims for we may enjoy the pleasur of success.The joy and happiness couldn't be replaced by the other things. Rome Was Not Built in a Day,are you ready to welcome the new challenges in the future-?
--------- 邵奎摘！
罗马不是一天建立的，不付出就没有收获，世界上有很多像这样的谚语，这些谚语都是告诉我们不努力就不会有回报。 我们都知道，成功要经得起努力和时间的考验。首先要完成一件事，我们应该知道我们的目标，其次，我们应制定与其相关的计划来实现我们的目标，第三我们应尽我们最大的努力来完成他。不可否认我们可能在此过程遇到很多我们最初没想到的问题，例如：突发的状况和计划的改变。我们会发现要完成一件事情要比我们想象的难。我们必须击败我们最大的敌人就是我们自己。要完成一件事的决定性因素一定程度上是我们愿意在它身上所付出的时间。 此过程汇中尽管有困难，但是也有付出过程所带来的乐趣。这种欢乐和幸福是不能够被其他事情而代替的。 罗马不是一天建立的，你准备好迎接未来对你的挑战了吗？
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