GeothermalEnergy(TPO21-1)小孩满月
Earth’s internal heat, fueled byradioactivity, provides the energy for plate tectonics, continental drift,mountain building, and earthquakes. It can also be harnesd 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 pass through asubsurface region of hot rocks (a heat rervoir) that may be hundreds orthousands of feet deep. █The water is usually naturallyoccurring groundwater that eps 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 purpo. █
By far the most abundant form ofgeothermal energy occurs at the relatively low temperatures of 80℃ to 180℃ centigrade. █Water circulated through heatrervoirs 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 undergr
ound water drawn from a heat rervoir 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.桑葚泡酒
Geothermal rervoirs with temperaturesabove 180℃ centigrade are uful 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 tho few areas where surface water eps 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 TheGeyrs, 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 becau 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 prent 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 prents 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. The waters prent 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 nnot renewable, becau in most cas the heat would be drawn out of a rervoirmuch more rapidly than it would be replaced by the very slow geologicalprocess by which heat flows through solid rock into a heat rervoir.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 prent, we canmake efficient u 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 clo to the ur 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 process describedin paragraph 1, what is the relationship between radioactivity and the steamproduced by geothermal heat?
Geothermally heated steam is producedwhen water is expod to radioactivity deep underground.
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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 rervoir of steam in subsurfacerock is produced by radioactivity, it is said to be geothermally heated.
2. The word "practical" in the passage is clost in meaning to
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米兰花plentiful
economical
familiar
3. The word "abundant" in the passage is clost in meaning to
economical
familiar
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plentiful
uful
4. According to paragraph 2, which of the following is true about heat rervoirs with a temperature in the range of 80° to 180° centigrade?
They are under international control.
They are more common than rervoirs that have a higher temperature.
Few of them produce enough heat to warm large industrial spaces.
They are ud 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 rervoirs deep inside Earth.
微信如何删好友Underground faults create spaces in which natural steam is sometimes trapped.
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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 Geyrs was in its third decade of production?
