GeothermalEnergy(TPO21-1)
Earth’s internal heat, fueled byradioactivity, provides the energy for plate tectonics, continental drift,mountain building, and earthquakes. It can also be harnessed to drive electricgenerators and heat homes. Geothermal energy becomes available in a practica form whenunderground heat is transferred by water that is heated as it passes through asubsurface region of hot rocks (a heat reservoir) that may be hundreds orthousands of feet deep. █The water is usually naturallyoccurring groundwater that seeps down along fractures in the rock; lesstypically, the water is artificially introduced by being pumped down from thesurface. █The water is brought to thesurface, as a liquid or steam, through holes drilled for the purpose. █
By far the most abundant form ofgeothermal energy occurs at the relatively low temperatures of 80℃ to 180℃ centigrade. █Water circulated through heatreservoirs in this temperature range is able to extract enough heat to warmresidential, commercial, and industrial spaces. More than 20,000 apartments inFrance are now heated by warm underground water drawn from a heat reservoir ina geologic structure near Paris called the Paris Basin. Iceland sits on avolcanic structure known as the Mid-Atlantic Ridge. Reykjavik, the capital ofIceland, is entirely heated by geothermal energy derived from volcanic heat.
Geothermal reservoirs with temperaturesabove 180℃ centigrade are useful for generatingelectricity. They occur primarily in regions of recent volcanic activity ashot, dry rock; natural hot water; or natural steam. The latter two sources arelimited to those few areas where surface water seeps down through undergroundfaults or fractures to reach deep rocks heated née the recent activity ofmolten rock material. The world’s largest supply of natural steam occurs at TheGeysers, 120 kilometers north of San Francisco, California. In the 1990s enoughelectricity to meet about half the needs of San Francisco was being generatedthere. This facility was then in its third decade of production and wasbeginning to show signs of decline, perhaps because of over development. By thelate 1990s some 70 geothermal electric-generating plants were in operation in California,Utah, Nevada, and Hawaii, generating enough power to supply about a millionpeople. Eighteen countries now generate electricity using geothermal heat.
Extracting heat from very hot, dryrocks present a more difficult problem: the rocks must be fractured to permitthe circulation of water, and the water must be provided arterially. The rocksare fractured by water pumped down at very high pressures. Experiments areunder way to develop technologies for exploiting this resource.
Like most other energy sources,geothermal energy presents some environmental problems. The surface of theground can sink if hot groundwater is withdrawn without being replaced. Inaddition, water heated geothermal can contain salts and toxic materialsdissolved from the hot rock. These waters present a disposal problem if theyare not returned to the ground from which they were removed.
The contribution of geothermal energyto the world’s energy future is difficult to estimate. Geothermal energy is in a sensenot renewable, because in most cases the heat would be drawn out of a reservoirmuch more rapidly than it would be replaced by the very slow geologicalprocesses by which heat flows through solid rock into a heat reservoir.However, in many places (for example, California, Hawaii, the Philippines,Japan, Mexico, the rift valleys of Africa) the resource is potentially so largethat its future will depend on the
economics of production. At present, we canmake efficient use of only naturally occurring hot water or steam deposits.Although the potential is enormous, it is likely that in the near futuregeothermal energy can make important local contributions only where theresource is close to the user and the economics are favorable, as they are inCalifornia, New Zealand, and Iceland. Geothermal energy probably will not makelarge-scale contributions to the world energy budget until well into thetwenty-first century, if ever.
1. According to the processes describedin paragraph 1, what is the relationship between radioactivity and the steamproduced by geothermal heat?
Geothermally heated steam is producedwhen water is exposed to radioactivity deep underground.
When water is introduced into holesdrilled thousands of feet in the ground, it becomes radioactive and turns tosteam.
Radioactivity heats Earth's interiorrock, which in turn can heat water to the point it becomes steam.
When a reservoir of steam in subsurfacerock is produced by radioactivity, it is said to be geothermally heated.
2. The word "practical" in the passage is closest in meaning to
usable
plentiful
economical
familiar
3. The word "abundant" in the passage is closest in meaning to
economical
familiar
plentiful
useful
4. According to paragraph 2, which of the following is true about heat reservoirs with a temperature in the range of 80° to 180° centigrade?
They are under international control.
They are more common than reservoirs that have a higher temperature.
Few of them produce enough heat to warm large industrial spaces.
They are used to generate electricity.
5. According to paragraph 3, what is the connection between underground faults and naturally occurring steam?
Underground faults enable the heat from molten-rock material to escape upward to regions where it can heat surface water enough to produce steam.
Underground faults are created by steam that is produced in geothermal reservoirs deep inside Earth.
Underground faults create spaces in which natural steam is sometimes trapped.
Underground faults allow surface water to reach deep rocks that are hot enough to turn it into steam.
6. In paragraph 3, why does the author mention that in the 1990s The Geysers was in its third decade of production?
To provide the historical context of the geothermal production of electricity in the United States
To imply that The Geysers was the first geothermal site to be put into production in California
To help explain the signs of decline shown by The Geysers
To explain why 70 new geothermal sites were put into electricity production in the late 1990s
7. Which of the following can be inferred from paragraphs 2 and 3 about geothermal reservoirs?
Volcanic heat is associated only with geothermal reservoirs that have a temperature over 180° centigrade.
More countries produce power from geothermal reservoirs than use them for heating buildings.
Most geothermal reservoirs are suitable for producing electricity.
A higher geothermal reservoir temperature is needed to generate electricity than is needed to heat homes.
8. According to paragraph 4, extracting heat from very hot, dry rocks is difficult in part because
the underground rock must be fractured before heat can be removed from it
the water above the rock is under very high pressure
the rock breaks apart when water is pumped into it
the water circulated through the rock must be much cooler than the rock itself
9. The word "exploiting" in the passage is closest in meaning to
locating
increasing
making use of
estimating the size of
10. How is the problem that the surface may sink related to the problem that water heated geothermally may contain toxic materials?
Both problems could be solved by returning groundwater that is removed from an underground heat reservoir back to the reservoir after heat is extracted from it.
The problem of sinking is more difficult to solve than is the problem of toxic materials. Land at the surface sinks because the rock beneath the surface is weakened when salts and toxic materials are removed from it in the process of extracting geothermal energy. Both problems are caused by the fact that the hot groundwater in a heat reservoir
dissolves the rock, which weakens the rock and makes the water toxic with salt.
11. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
Heat flows through solid rock very slowly, so it takes a very long time for geological processes to produce a reservoir of geothermal energy.
Geothermal energy is not renewable because heat flows very slowly through solid rock into or out of a heat reservoir.
The heat quickly removed from a heat reservoir is replaced so slowly by geological processes that geothermal energy is not practically speaking, renewable.
In most cases, heat travels into a heat reservoir so slowfy that it is a much quicker process to remove the heat from a reservoir than to replace it.
12. In paragraph 6, the author implies that in California, Hawaii, the Philippines, Japan, Mexico, and the rift valleys of Africa the potential size of the geothermal resource is so large that
it might be economically worth developing these sites even though geothermal energy is not renewable
these sites will be the first geothermal energy sites to be developed witb new technology these sites are likely to make a large-scale contribution to the world energy budget in the twenty-first century
it does not matter whether they have naturally occurring deposits of hot water or steam
13．Look at the foursquares [█] that indicate where the followingsentence could be added to the passage. In either case,the heated water will usually be under considerable pressure, and so may have atemperature that is well above its sea-level boiling point of 100°centigrade.Where would the sentence best fit? Click on asquare to add the sentence to the passage.
█
█
█
█
14．Directions: An introductory sentence for a brief summary ofthe passage is provided below. Complete the summary by selecting the THERRanswer choices that express the most important ideas in the passage.Somesentences do not belong in the summary because they express ideas that are notpresented in the passage or are minor ideas in the passage. This question is worth 2 points.Heat reservoirs in the form of hot rock farbeneath Earth's surface are a potential source of usable geothermal energy.·Heat reservoirs with a temperature from 80° to 180° centigrade can be used, as in France and Iceland, to heat buildings.
·A number of countries now use geothermal reservoirs that contain water or steam above 180° centigrade to generate electricity.
·Most heat reservoirs with a temperature above 180° centigrade cannot be used for energy because they are usually too close to recent volcanic activity.
·The sinking of land above heat reservoirs and other environmental problems arise when water is pumped into a heat reservoir under high pressure.
·Experiments are under way to determine if geothermally heated waters could be used as a source of certain minerals that have been dissolved out of hot rocks deep within Earth. ·A number of issues, including how to extract heat from reservoirs that do not have a natural supply of water, will significantly limit the use of geothermal energy for the foreseeable future.
答案解析：
1. 细节题，问radioactivity和steam的关系，所以找双关键词，分别定位至本段第一句和最后一句，第一句说radioactivity提供了地球的内热，最后一句说水变成蒸汽到达地表，水受热才能蒸汽，而这份热量是geothermal energy提供的，这就是二者的关系，所以答案是C。A的水暴露在radioactive underground时候steam产生没说；B水变成radioactive没说；D的radioactivity产生蒸汽更不靠谱
2. practical实际的，可用的，答案是A的usable，此题简单，B的plentiful大量C的economical 节省和D的familiar熟悉完全不对
3. abundant大量的，充足的，所以答案是C的plentiful，我怀疑这个题的选项是不是跟上一道题弄混了，待定。不过C肯定是对的。此题也较简单，其他答案完全不沾边，不会的各位最好认真背单词了
4. 以80到180度做关键词定位至第一句，说最丰富的geothermal energy是在80到180度范围内的，所以同义替换是B的more common than higher temperature。A的international control原文没说；C与本段第二句说反；D在本段没提，但下一段说高于180度的可以用来发电，所以D说反了
5. 又是一个问两者关系的题，找双关键词，定位至第三句，说natural hot water和natural steam 仅存在于那些地点，地表水通过fault或者fracture渗到地下，碰到被加热的blabla，答案明显是D。A说fault使heat跑上来，和原文的方向说反了，原文是水跑下去；B说steam创造了fault完全不靠谱；C的steam被trap原文没说
6. 修辞目的题，先读例子所在句，只是细节，按照常规应该往前看，但前一句已经在上题看过，与答案无关，所以往下看，而且看下一句另外一个原因是因为代词this，下句说G经历了30年的运作，已经显示衰败迹象，可能是因为过度开发，所以答案是C，A和B的内容原文没提；D本身也是个细节
7. 此题用排除法更快，A与第二段首句说反，错；第二段只是说geothermal energy可以用来加热building，没说most，B错；C和D都可以从两段的首句看出来，第二段说最多的是在80到180度，第三段说发电需要180度以上，所以发电比别的温度高，D对，C说反
8. 整个问题做关键词定位至第一句，说从hot, dry rock抽热量是特别难的，必须先fracture rock，水也要人工引入，所以答案是A。D没说，B和C原文确实有说，但没有回答为什么难，也就是那种答非所问选项，所以也不对
9. exploit开发，利用，剥削压榨，所以C的making use of正确。原文说人们正在实践新的技术来怎么样这种资源，B很显然不对，资源如果想加就加那就好了；A定位和D估计数量都太初级了，而且现在的技术就可以定位和算储量，明显不应该是under way
10.又是一个问两者关系的题，本来应该找双关键词，但这段实在太短，找关键词还不如读完，快速扫完之后发现这两件事情都是由于开采地下水引起的问题，而且最后一句说如果不把地下水补充回去就会有问题，所以答案是A。两个问题之间是并列关系，既没有比较也没有因果，所以B和C都不对；D的dissolved溶解原文没说，也不对
11.原句的结构是geothermal energy是不renewable的，因为blabla，所以前面的结果一定要有，A和D排除；原句的原因中有一个比较，说draw out比replace的快，C重现了这个比较，B没有，所以正确答案是C
12.修辞目的题，先读细节所在句，说在这些资源如此充足的地方，资源的利用前景取决于economies of production生产经济，四个答案中只有A提到了开采是否划算的问题，所以答案是A。B和D原文直接没说；C跑到最后一句去了，跟例子也没什么关系，注意倒数第二句MS也有例子，但是题目问的不是那个
13.这道题有一个过渡点就够了，in either case说明正确插入点之前必须有两种情况，直接确定B，因为之前有usually和less typically两种情况
14.Heat选项对应原文第二段，正确；注意不要因为温度和国家把这个选项当成细节，即使当成细节，也可以凭其他选项都不对的排除法解决
Most heat选项与原文第三段首句说反，不选
Experiments选项MS对应原文第四段最后一句，但原文说的是利用热能，不是矿物，所以这个选项不选
A number of countries选项对应原文第三段首句，正确；注意不要因为温度把这个选项当成细节
The sinking选项不知所云，好像有语法错误，不知道是不是我的TPO版本问题，但即使这个选项语法没问题，说的也应该是第五段的细节，或者是干脆没说，所以不选
A number of issues选项对应原文第六段，正确