首页
登录
职称英语
Complete the notes below. Write ONE WORD ONLY for each answer.Hydropowe
Complete the notes below. Write ONE WORD ONLY for each answer.Hydropowe
游客
2024-01-07
37
管理
问题
Complete the notes below.
Write ONE WORD ONLY for each answer.
Hydropower
Renewable—constant source (31) from natural hydrologic cyde
(32) —90% of hydro energy→electricity
Clean—no air or (33) pollution
(34) & curable—simple to operate
Flexible—can start
adapt quickly to meet demand→leads to (35) of power supply. [br]
Welcome to our series on renewable resources. The topic today is hydropower. As you most probably know, ’hydro’ means water—so we are talking about using water to generate electricity. Of course, there are many ways to generate electricity but hydropower is important to the community, firstly and obviously, because it’s renewable. The earth’s hydrologic cycle of constant evaporation and transpiration provides a continual supply of water from rainfall and snowmelt. The second point to consider is its efficiency. Hydropower plants are able to convert approximately 90% of the energy from the falling water into electric energy whereas many fossil-fuelled plants lose more than half of the energy content of their fuel by way of waste heat and gases. For this reason they are very efficient.
Hydropower is also clean. It doesn’t emit harmful gases that contribute to air pollution, acid rain, and global warming. No trucks, trains or pipelines are needed to bring fuel to the site and there’s no noise pollution either. Furthermore, hydropower plant machinery is fairly simple and runs at slow speeds, which makes it reliable and durable. And, hydropower units are flexible also—they have the ability to start quickly and adjust rapidly to changes in demand for electricity, thus enabling them to meet peak loads. But this also allows them to serve as reserve capacity and bring more stability to the power system overall.
The dams that provide hydroelectric power also have other uses such as navigation, flood damage reduction, water supply, recreation, irrigation and low flow augmentation but it’s not the purpose of this talk to go into those details.
How do the hydropower plants work? Well, a dam is built across a river which captures water to form a reservoir and raises the water level to create ’head’. Think of ’head’ as the vertical distance that the water falls as it passes through the dam, in other words, the difference in water level between the reservoir behind the dam and the river below. Water from the reservoir flows through an intake gate into a penstock—this is kind of a narrow channel which leads to the turbine below. The force of the water causes the turbine to rotate rapidly which, in turn, drives the generator to spin and produce electricity. The electricity is carried the long distances from the powerhouse to substations on the outskirts of cities via power lines.
Can you build a hydropower unit on any river? Well, no, just having water in a river isn’t enough. A good dam site must have enough stream flow as well as enough head. A fast flowing river on the plains is probably not suitable because a dam couldn’t be built high enough to provide the head needed for efficient production of electricity. On the other hand, dams in arid high country may have plenty of head but insufficient stream flow. The perfect spot for a hydropower plant is where the right combination of stream flow and head exists.
What about the environment? Surely the construction of large dams has an environmental impact? Well, yes it does. Certainly dams and reservoirs are built to improve the lives of people living in towns, farming communities and cities. But there must be a balance between development and preserving the natural environment. Needless to say, the natural river environment is changed which leads to changes in river ecology and aquatic habitat. Sometimes, for example, dissolved oxygen levels below dams get so low in summer that there is a negative impact on aquatic life. These levels can be improved, however, by using special aerating turbines and/or injecting oxygen directly into the stream flow. In order to protect and improve the habitat for endangered and other species of birds, fish and water life, there needs to be a thorough review of operating plans to see if a better balance can be achieved.
Hydropower plant design and operation must not only meet the needs of consumers for electricity but work hand-in-hand with agencies whose concern is for the fish and wildlife, water quality and water supply.
选项
答案
efficient
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3340805.html
相关试题推荐
Completethesummarybelow.ChooseNOMORETHANTWOWORDSfromthepassagefore
Completethesummarybelow.ChooseNOMORETHANTWOWORDSfromthepassagefore
Completethesummarybelow.ChooseNOMORETHANTWOWORDSfromthepassagefore
Completethenotesbelow.ChooseNOMORETHANONEWORDfromthepassageforeach
Completethenotesbelow.ChooseNOMORETHANONEWORDfromthepassageforeach
Completeeachsentencewiththecorrectending,A-E,below.Writethecorrectl
Completeeachsentencewiththecorrectending,A-E,below.Writethecorrectl
Lookatthefollowingstatements(Questions22-26)andlistofbooks(A-E)below.Ma
Lookatthefollowingstatements(Questions22-26)andlistofbooks(A-E)below.Ma
Lookatthefollowingstatements(Questions22-26)andlistofbooks(A-E)below.Ma
随机试题
[originaltext]Moneyfrommigrantworkersnowexceedsthecombinedtotalofall
在Excel2010公式功能区的()子功能区中,提供了数学、财务、工程等专
两条曲线分别表示氢、氧两种气体在相同温度T时分子按速率的分布,其中:曲线1、2分
风险溢价是为()投资者购买风险资产而向他们提供的一种额外的期望收益率。A、风险
火车站点A和B与初始发车站C的直线距离都等于akm,站点A在发车站C的北偏东20
2019年5月,全国12358价格监管平台受理价格举报、投诉、咨询共计37576
某机关要从赵一、钱二、孙三、李四、周五、吴六等六位同志中选拔三位同志组成团队出国
在行政程序的划分中,根据行政程序的环节可划分为( )。A.普通行政程序 B.
在灌注桩施工遇有施工深度内存在较高水头的承压力时,不宜选取下列哪种施工工艺?(
腹膜炎患者应进行手术探查的情况是( )。A.体温超过38℃ B.年龄超过60
最新回复
(
0
)