Official 36 Set 2

纠错
  • Q1
  • Q2
  • Q3
  • Q4
  • Q5
  • Q6
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Potential Energy Source - Helium-3

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What is the lecture mainly about?
  • A. The role of fossil fuels as an energy source in the future

  • B. Reasons for research into alternative energy sources

  • C. The feasibility of using a potential energy source

  • D. Causes of probable future energy problems

显示答案 正确答案: C

我的笔记 编辑笔记

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    NARRATOR:Listen to part of a lecture in an environmental science class.

    MALE PROFESSOR:Now last week, when we discussed the serious energy challenges we're going to face as the world's population continues to grow and we place more stress on our finite supply of fossil fuels- especially natural gas and oil- well, maybe it's not all doom and gloom.In a number of areas, scientists are "thinking outside the box" and trying to come up with unusual, uh, novel solutions to the energy question.Not that a positive outcome is inevitable by any means, but...Well, let's take a look at one of these creative ideas, involving the gas helium-3.

    Helium-3 is an isotope of helium that has tremendous potential for use in practical energy applications.Remember, ah, an isotope is a form of a chemical element that has the same number of protons in its atomic nucleus but a different number of neutrons.The most common isotope of helium on Earth is helium-4, which does not have any known or potential uses as an energy source.Helium-3, in comparison, is extremely rare; there isn't very much of it on Earth, plus the, uh- well the main source of helium-3 in our solar system is solar wind- a stream of lethal radiation and particles pouring off of the Sun- and Earth's magnetic field fortunately prevents that wind from reaching us.So why is helium-3 so exciting?

    Well, it seems a sure bet that helium-3 is available in abundant quantities on the Moon.Since the Moon doesn't have a magnetic field, the solar wind must have been depositing helium-3 there for billions of years; in fact, Apollo astronauts have already discovered it in the Moon's dust.Some estimates hold that there may be over a million tons of helium-3 buried on the lunar surface.And one ton is more than enough energy for a city of ten million people for a whole year.So you can see, this would certainly solve most of our energy problems.

    But how could this be possible?Well, we think helium-3 would have to be used in nuclear fusion reactors.Keep in mind that a nuclear fusion reactor is completely different from our existing nuclear fission reactors.Basically, a nuclear plant powered by nuclear fission derives its energy from the splitting of atoms, while a plant based on nuclear fusion utilizes the energy produced when atoms are fused together.Fusion is the same nuclear reaction that fuels stars, which as you know, produce almost unfathomable amounts of energy.Researchers have identified two isotopes of hydrogen as the most promising fuel sources for fusion power plants.However, there is a real drawback- they both produce a large amount of radioactive material in a fusion reaction.But helium-3 fusion produces no radioactive material.In fact, one proponent stated you could safely build a helium-3 power plant in the middle of a city!A clean, safe source of power.Almost sounds too good to be true, doesn't it?

    Well, of course this is all very theoretical, and there are issues that have to be addressed.For one thing, we still haven't created a single nuclear fusion plant, despite decades of research and development.An often-heard joke about fusion is that a nuclear fusion plant has been "just decades away" from being created for several decades now.Nuclear fusion research is still ongoing, strong as ever in fact.But we still don't have a full scale fusion plant to point to.

    And there's a rather big logistical problem as well: how to get the helium-3 off the Moon.Digging the stuff up is challenging because the distribution of helium-3 is so diffuse across the lunar surface.One estimate is that you'd need to heat a million tons of lunar soil to about 800 degrees Celsius to yield about 70 tons of helium-3 gas.It's kind of like digging out a crater with a spoon to find a single nugget of gold.Kind of ridiculous, right?There's a camp that believes it'll take more energy to extract helium-3 gas than the gas itself would provide.

    So there are concerns.But given the lure of the possibilities and the pressing nature of our energy difficulties, it's possible that helium-3 could be a significant driver of future exploration of the Moon.And it certainly could ease the pressure on the demand for fossil fuels- if and when the numerous challenges-and not just the ones we've talked about- are solved.

  • 旁白:请听一段环境科学课的节选片段。

    教授:上个星期,当我们讨论到我们将要面对的严峻的能源挑战时,随着世界人口的持续增长,我们对有限的化石燃料施加了更多压力—尤其是天然气和石油,但也许这并不全是灾难和黑暗。在很多领域,科学家在努力跳出定式思维,试着去想出不寻常的、新颖的解决能源问题的方案。并不是说好的结果是无论如何都不可避免的,但是...让我们来看看其中一个有创意的想法,关于一种气体——氦3。

    氦3是一种氦气的同位素,它在实际的能源应用上有巨大的潜力。记得吗,同位素是一种化学元素的形式,原子核中有相同的质子数但中子数不同。地球上最常见的氦气的同位素是氦4,作为能源,氦4没有任何已知或潜在的应用。相比之下,氦-3极为罕见;地球上的氦-3的主要来源是太阳风——一股致命的辐射和从太阳下倾泻而出的粒子流——地球的磁场幸运地阻止了风的到达。所以为什么氦3这么另人激动呢?

    看起来已经确定氦3在月球上储备充足。因为月球没有磁场,太阳风带来的氦3肯定已经在月球上积累了上十亿年,实际上,阿波罗号的宇航员已经在月球的尘埃中发现了氦3。一些人估计,在月球地表下可能埋着一百亿吨的氦3。一吨氦3足够给一座千万人的城市供能一年。所以你看,这可以解决大部分的能源问题。

    但是具体要怎么使这个设想变为可能呢?我们认为氦3会被用在核聚变反应堆里。记住,核聚变反应堆和核裂变反应堆有很大不同。一般来说核工厂是靠着核裂变,也就是原子分裂的过程来产能的,然而一个靠着核聚变的核反应堆是利用原子聚合在一起时放出的能量。核聚变也是恒星产能的方式之一,像你所知道的,可以产生超级大量的能源。研究者已经确定了两种氢气的同位素作为核聚变工厂可以使用的最被看好的能源来源。然而,事情遭遇了一些不妙,它们都会在聚变过程中产生放射性物质。但是氦3并不会产生放射性物质。实际上,有一个支持者甚至说就是把氦3聚变工厂建在市中心,也是安全的。一个清洁安全的能源听起来太好,以至于不真实,不是吗?

    当然了,这都是很理论化的,还有几件事我们需要强调一下。第一件事,我们也还不能创造出一个单一的核聚变工厂,尽管经过了几十年的研究和发展,我们经常能听到一个这样的笑话,还有短短几十年又几十年我们就可以创造出来核聚变工厂啦。核聚变的研究还在继续,实际上研究力度与以往一样强但是我们还是造不出全规模的核聚变工厂。

    另一个问题是,还存有一个巨大的逻辑问题,我们要怎么从月球上获得氦3呢?直接挖掘是很困难的,因为月球上氦3分布太分散了。有人估计说,你需要加热一百万吨月球上的土到800摄氏度来生产大约70吨的氦3气体。这就好像是一个人手持一把勺子,翻遍整个陨石坑来找一块小金子。听起来有点荒诞,对吗?有一个阵营的人认为,提取氦3所需要的能量比其能产生的能量还要多。

    所以这就有顾虑了,但是考虑到这种可能性带来的诱惑以及越来越紧迫的能源危机,氮3就可能成为以后探索月球的重要驱动力。它当然可以减轻人类对于化石燃料的需求,如果真的可以被用作能源而不是仅仅留作谈资的话,能源问题就可以解决了

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    题型分析:主旨题

    原文定位:

    Now last week, when we discussed the serious energy challenges we’re going to face as the world’s population continues to grow and we place more stress on our finite supply of fossil fuels—especially natural gas and oil—well, maybe it’s not all doom and gloom. In a number of areas, scientists are “thinking outside the box” and trying to come up with unusual, uh, novel solutions to the energy question. Not that a positive outcome is inevitable by any means, but…Well, let’s take a look at one of these creative ideas, involving the gas helium-3.

    选项分析:

    原文提及能源问题, 且提到最近科学家们发现了一种新的不寻常能源可以解决能源问题,选项C 符合题意,故选项C正确。

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