Usually alternating current (AC) transmission suffers lower losses than direct current (DC), and thus, AC became the industry standard. Some people, however, question that standard because over long distances high-voltage DC lines suffer lower losses than AC. Not only does that make them better in their own right, but employing them would allow electricity grids to be restructured in ways that would make wind power more attractive. That would reduce the need for new conventional (and polluting) power stations.

Wind power has some problems. You don't always get it where you want it and you don't always get it when you want it. The question of where the wind is blowing would no longer matter because it is almost always blowing somewhere. If it were windy in Spain but not in Ireland, current would flow in one direction. Dealing with when the wind blows is a subtler issue. For instance, an important part of Dr Schmid's continental grid is the branch to Norway. It is not that Norway is a huge consumer. Rather, the country is well supplied with hydroelectric plants. These are one of the few ways that energy from transient sources like the wind can be stored in grid-filling quantities. The power is used to pump water up into the reservoirs that feed the hydroelectric turbines. That way it is on tap when needed. The capacity of Norway's reservoirs is so large, according to Dr Schmid, that should the wind drop all over Europe—which does happen on rare occasions—the hydro plants could spring into action and fill in the gap for up to four weeks.

Put like this, a Europe-wide grid seems an obvious idea. That it has not yet been built is because AC power lines would lose too much power over such large distances. Hence the renewed interest in DC. Dr Schmid calculates that a DC grid of the sort he envisages would allow wind to supply at least 30% of the power needed in Europe. Moreover, it could do so reliably—and that means wind power could be used for what is known in the jargon as base-load power supply.

Though wind power has its opponents, too, its environmental virtues might be enough to swing things in its favour if it were also reliable. Indeed, a group of Norwegian companies have already started building high-voltage DC lines between Scandinavia, the Netherlands and Germany, though these are intended as much to sell the country's power as to accumulate other people's. And Airtricity—an Irish wind-power company—plans even more of them. It proposes what it calls a Supergrid. This would link offshore wind farms in the Atlantic Ocean and the Irish, North and Baltic seas with customers throughout northern Europe.

注（1）：本文选自Economist, 07/28/2007

注（2）：本文习题命题模仿对象为2004年真题Text 3。

1． By saying “make them better in their own right” (Line 3-4, Paragraph 1), the author means _______.

  [A] realize the right of DC

    [B] make DC suffer lower losses

    [C] make DC more useful than AC

    [D] make better use of DC to transfer power

2． By “current would flow in one direction” (Line 4, Paragraph 1), the author is actually referring to _______.

  [A] current flows from Spain to Ireland

    [B] current flows from Ireland to Spain

    [C] current flows from Ireland to other places

    [D] current flows from Spain to other places

3． How will consumers think of a DC electricity grid?

  [A] Useless

    [B] Feasible

    [C] Troublesome

    [D] Comfortable

4． Why does Dr Schmid's continental grid locate in Norway?

  [A] To make use of the country’s capacity of reservoirs

    [B] To make use of the country’s rich wind power.

    [C] It is simply Dr Schmid’s personal preference.

    [D] Because traditional power plants in Norway cannot meet cosumers’ demand.

5． Which of the following is TRUE according to the passage?

    [A] Wind power has won universal support.

    [B] Companies hesitate to invest in wind power.

    [C] The prospect of wind power so far seems very positive.

    [D] Wind farms on oceans can supply power demand of the whole Europe in the future.

篇章剖析

    本文是一篇科技说明文，主要说明了风能发电的优势和可行性。第一段通过比较说明直流电和交流点来引出风能发电的话题；第二段分析了风能发电存在的一些限制及其解决办法；第三段和第四段则说明了在欧洲建设新型电网的前景。

词汇注释

alternating current 交流电       turbine [`tE:bin] n. 涡轮

direct current 直流电            envisage [in`vizidV] v. 正视

voltage [`vEJltidV] n. 电压, 伏特数  jargon [`dVB:gEn] n. 行话

electricity grid 电网              Scandinavia[9skAndi`neivjE]斯堪的纳维亚(半岛)

subtle [`sQtl] adj. 微妙的, 精细     offshore [`CfFC:] adj. 向海面吹的, 离岸的

难句突破

Not only does that make them better in their own right, but employing them would allow electricity grids to be restructured in ways that would make wind power more attractive.

主体句式  Not only does that make them better, but employing them would allow electricity grids to…

结构分析  这个句子是一个相对比较复杂的not only, but also 结构。前半句中的not only 后面跟的句子按照语法规律需要倒装，后半句but also 结构中省略了also这个词，这也语法上也是允许的，且后半句的主句是一个现在分词结构，后面的in ways之后跟的是一个定语从句。

句子译文  这不仅能有利于电流的传送，而且通过使用高压直流电缆，人们可以对电网进行改造，从而更加有利于风能发电。

题目分析

1．D. 语义题。根据文章第一段，由于高压直流电缆损失的电量比交流电缆少，因此通过这个方法能够更加充分地利用直流电来传输电能，因此答案为D。

2．A. 语义题。文章第二段指出风在什么地方吹不是一个大的问题，因此如果西班牙有风而爱尔兰没有风，那么只要把电流从西班牙往爱尔兰方向传送就可以了。

3．B. 推理题。文章第三段指出，建设直流电电网可以节约在传输过程中浪费的电能，因此对于消费者来说这一方案是切实可行的。

4．A. 推理题。文章第二段后半部分描述了史密德博士设计的大陆电网，其中指出选择挪威的原因不是因为这个国家缺乏足够的电能，而是这里有足够多的水库可以用来储存电能。

5．C. 细节题。各个题支的细节均可以在文章最后一段中找到对应信息。其中提到了欧洲多家能源公司已经在计划建设传输风能的直流电缆，充分说明了风能利用的前景非常好。

参考译文

    一般来说，交流电传输比直流电传输损失的电量要少，因此，交流电成为了工业上的标准。但是一些人却在质疑这个标准，因为从远距离传输来看，高压直流电缆损失的电量比交流电缆少。这不仅能有利于电流的传送，而且通过使用高压直流电缆，人们可以对电网进行改造，从而更加有利于风能发电。如此一来，对于新建更多传统（也是污染的）发电站的需求就会减少。

    风能发电存在一些问题。风能不是随处都在、也非随时可得。但是现在风向问题现在已经得到解决，因为风总是在向着某个方向吹。如果现在西班牙多风而爱尔兰却无风，那么电流就会朝一个方向传送。但是，风在什么时候吹则是一个更加微妙的问题。比如说，史密德博士设计的大陆电网的重要一部分就位于挪威。但这并不是因为挪威消费很多的电能。相反，原因是这个国家到处都是水电站。利用水电站是可以把如风能等稍纵即逝的资源大量储存起来的方式之一。通过使用这些风能，人们可以把水往上抽到水库中推动水电涡轮。水电站以这个方式就可以随时把水抽上来。史密德博士认为挪威水库容量如此之大，以至于如果欧洲所有的地方都不刮风了—这种现象确实偶尔会发生—挪威的水电站仍然可以继续运转并供应整个欧洲的用电量达四周之久。

    如果情况真是这样的话，那么建设一个跨欧洲的电网是势在必行的了。此前没有进行该项目建设是因为交流电缆在进行如此远距离传输的时候会损失大量的电能。而现在人们开始在思考用直流电缆来实现这一设想。史密德博士估计，他设想的这种直流电缆能够使风能满足全欧洲至少30%的用电需求。此外，这样做也非常可靠—这意味着从术语上说，风能可以被称为是基本负荷型电能供应。

    尽管对于风力发电也有反对者，但是如果风能可靠的话，那么其清洁环保的特点足以赢得广泛的支持。实际上，一些挪威的公司已经开始在斯堪的纳维亚、荷兰和德国之间建设高压直流电缆，尽管他们的目的在于通过销售本国的能源来赚钱。此外，一家爱尔兰风能公司Airtricity则计划比挪威的公司们做的更多。该公司提出了一个所谓的超级电网的概念，该电网能够将大西洋、爱尔兰海、北海和波罗的海上的风能电厂与整个北欧的消费者们连接起来。