经济学人89:利用太阳能发电的第三种方法

 　　Science and Technology Solar power The third way

　　科技 太阳能 利用太阳能发电的第三种方法

　　A new method of making electricity from sunlight has just been tested

　　一种新的利用太阳能发电的方法刚刚得到测试

　　AT THE moment, there are two reliable ways to make electricity from sunlight.

　　目前，利用阳光发电的可靠方法有两种。

　　You can use a panel of solar cells to create the current directly, by liberating¹ electrons from a semiconducting material such as silicon².

　　你可以使用一块太阳能电池板从硅等半导体材料中释放电子来直接制造电流。

　　Or you can concentrate the sun's rays using mirrors, boil water with them, and employ the steam to drive a generator³.

　　也可以用镜子集中太阳光线，利用它们烧开水，利用蒸汽驱动发电机。

　　Both work. But both are expensive.

　　这两种方式都能进行也都很昂贵。

　　Gang Chen of the Massachusetts Institute of Technology and Zhifeng Ren of Boston College therefore propose, in a paper in Nature Materials, an alternative.

　　为此，麻省理工学院的陈刚和波士顿大学的任志峰在《自然-材料》杂志上刊登的一篇论文中提出了另一种方式。

　　They suggest that a phenomenon called the thermoelectric effect might be used instead—and they have built a prototype to show that the idea is practical.

　　他们提出可以利用一种名为热电效应的现象——而且还建立了一个模型来证明这个想法的可行性。

　　Thermoelectric devices are not new.

　　热电器件并不是什么新鲜事。

　　They are used, for example, to capture waste heat from car engines.

　　比如它们被用来捕捉从汽车引擎排出的废热。

　　They work because certain materials, such as bismuth telluride, generate an electrical potential difference within themselves if one part is hotter than another.

　　它们之所以能起作用是因为某些材料，比如碲化铋，如果其中一部分比另一部分热，内部就会产生电位差。

　　That can be used to drive a current through an external circuit.

　　通过外部电路就可以利用这一点来导通电流。

　　The reason thermoelectric materials have not, in the past, been applied⁴ successfully to the question of solar power is that to get a worthwhile current you have to have a significant temperature difference. (200oC is considered a good starting point.)

　　为什么在过去热电材料没能成功地应用到太阳能上呢，这是因为如果要获得有价值的电流必须有巨大的温度差。（200摄氏度被视为合适的起点。）

　　In a car engine, that is easy.

　　汽车引擎里很容易达到这个温度差。

　　For sunlight, however, it means concentrating the heat in some way. And if you are going to the trouble of building mirrors to do that, you might as well go down the steam-generation route, which is a much more efficient way of producing electricity.

　　但是对于阳光来说，这意味着通过某种方式集中热量，而如果你费尽力气用一堆镜子达到这个温度差，你很可能走回蒸汽发动的老套路上了，那是一种效率更高的发电方式。

　　If the heat concentration could be done without all the paraphernalia⁵ of mirrors, though, thermoelectricity's inefficiency⁶ would be offset⁷ by the cheapness of the kit⁸.

　　倘若能集中热量而不需要使用镜子的复杂步骤，虽然热电效率不高，但设备的廉价却可以弥补这点。

　　And that is the direction in which Dr Chen and Dr Ren hope they are heading.

　　而陈博士和任博士希望他们可以朝这个方向努力。

　　In their view, three things are needed to create a workable solar-thermoelectric device.

　　他们认为创造一种可行的太阳能热电设备需要具备三个条件。

　　The first is to make sure that most of the sunlight which falls on it is absorbed, rather than being reflected.

　　第一是确保大多数射入该设备的阳光被吸收而不是被反射回去了。

　　The second is to choose a thermoelectric material which conducts heat badly (so that different parts remain at different temperatures) but electricity well.

　　第二是选择的热电材料的导热性差（这样不同部分就能保持不同的温度）但是导电性良好。

　　The third is to be certain that the temperature gradient which that badly conducting material creates is not frittered away by poor design.

　　第三是确保那种导热性差的材料产生的温度变化率不因为设计缺陷而白白浪费。

　　The two researchers overcame these challenges through clever engineering.

　　两位研究者经由巧妙的工程技术克服了上述挑战。

　　The first they dealt with by coating the top of the device with oxides of hafnium, molybdenum and titanium, in layers about 100 nanometres thick.

　　他们在设备顶上盖上了大概100纳米厚的二氧化铪、氧化钼和氧化钛的混合物。

　　These layers acted like the anti-reflective coatings on spectacle lenses and caused almost all the sunlight falling on the device to be absorbed.

　　它们的作用类似玻璃眼镜上面防反射的覆盖层，使所有落到设备上的阳光都被吸收。这样第一个问题就解决了。

　　The second desideratum, of low thermal⁹ and high electrical conductivity, was achieved by dividing the bismuth telluride into pellets a few nanometres across.

　　低导热性和高导电性则通过把碲化铋分成几纳米的粒状物来实现。

　　That does not affect their electrical conductivity, but nanoscale particles like this are known to scatter¹⁰ and obstruct¹¹ the passage of heat through imperfectly understood quantum-mechanical processes.

　　它们的导电性不会因此受到影响，但是人们知道像这样的纳米级颗粒会分散开来并通过人们还尚未完全理解的量子力学过程阻碍热量通道。

　　The third objective, efficient design, involved sandwiching the nanostructured bismuth telluride between two copper¹² plates and then enclosing the upper plate (the one coated with the light-absorbing oxides) and the bismuth telluride in a vacuum.

　　第三个目标是高效的设计，它涉及到把纳米级的碲化铋夹在两片铜薄片之间然后把位于上方的薄片（这个薄片被覆盖上了吸收光线的氧化物）和碲化铋封入一个真空内。

　　The copper plates conducted heat rapidly to and from the bismuth telluride, thus maintaining the temperature difference.

　　铜片可以把热量迅速地传递到碲化铋上或从碲化铋上导出，这样就能保持气温差。

　　The vacuum stopped the apparatus¹³ losing heat by convection.

　　容器防止该设备通过对流失去热量。

　　The upshot was a device that converts 4.6% of incident sunlight into electricity.

　　结果就是这样一个可以把射入阳光的4.6%转化为电能的设备。

　　That is not great compared with the 20% and more achieved by a silicon-based solar cell, the 40% managed by a solar-thermal turbine, or even the 18-20% of one of the new generation of cheap and cheerful thin-film solar cells.

　　以硅晶为基础的太阳能电池的转化率为20%甚至以上，太阳能热力涡轮的为40%，就连一种新一代价廉物美的薄膜太阳能电池的转化率也能达到18%-20%，与它们相比，4.6%并不可观。

　　But it is enough, Dr Chen reckons, for the process to be worth considering for mass production.

　　但是陈博士认为这已经足够了，值得考虑对该设备进行大规模生产。

　　He sees it, in particular, as something that could be built into the solar water-heaters that adorn¹⁴ the roofs of an increasing number of houses.

　　他特别指出该设备可以安装到越来越多的房屋顶上装有的太阳能热水器上去。

　　If such heaters were covered with thermoelectric generators¹⁵ the sun's rays could be put to sequential use.

　　如果这样的热水器配上热电发动机，那么太阳光就可以被连续使用。

　　First, electric power would be extracted from them.

　　首先，从它们身上可以获取电能。

　　Then, the exhaust heat from the bottom plate of the thermoelectric device would be used in the traditional way to warm water up.

　　其次，从热电设备中位于底部的薄片中出来的排气可以用于传统方式来加热水。

　　Two-for-one has always been an attractive proposition for the consumer.

　　对消费者来说，二合一总是很有吸引力的建议。

　　This kind of combined heat and power might enable more people to declare independence from the grid¹⁶.

　　这种结合热力和电力的方式可以让更多人摆脱输电网。

1 liberating   

解放，释放( liberate的现在分词 )

参考例句：

• Revolution means liberating the productive forces. 革命就是为了解放生产力。
• They had already taken on their shoulders the burden of reforming society and liberating mankind. 甚至在这些集会聚谈中，他们就已经夸大地把改革社会、解放人群的责任放在自己的肩头了。 来自汉英文学 - 家（1-26） - 家（1-26）

2 silicon   

n.硅(旧名矽)

参考例句：

• This company pioneered the use of silicon chip.这家公司开创了使用硅片的方法。
• A chip is a piece of silicon about the size of a postage stamp.芯片就是一枚邮票大小的硅片。

3 generator   

n.发电机，发生器

参考例句：

• All the while the giant generator poured out its power.巨大的发电机一刻不停地发出电力。
• This is an alternating current generator.这是一台交流发电机。

4 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

5 paraphernalia   

n.装备；随身用品

参考例句：

• Can you move all your paraphernalia out of the way?你可以把所有的随身物品移开吗？
• All my fishing paraphernalia is in the car.我的鱼具都在汽车里。

6 inefficiency   

n.无效率，无能；无效率事例

参考例句：

• Conflict between management and workers makes for inefficiency in the workplace. 资方与工人之间的冲突使得工厂生产效率很低。 来自《简明英汉词典》
• This type of inefficiency arises because workers and management are ill-equipped. 出现此种低效率是因为工人与管理层都能力不足。 来自《简明英汉词典》

7 offset   

n.分支，补偿；v.抵消，补偿

参考例句：

• Their wage increases would be offset by higher prices.他们增加的工资会被物价上涨所抵消。
• He put up his prices to offset the increased cost of materials.他提高了售价以补偿材料成本的增加。

8 kit   

n.用具包，成套工具；随身携带物

参考例句：

• The kit consisted of about twenty cosmetic items.整套工具包括大约20种化妆用品。
• The captain wants to inspect your kit.船长想检查你的行装。

9 thermal   

adj.热的，由热造成的；保暖的

参考例句：

• They will build another thermal power station.他们要另外建一座热能发电站。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

10 scatter   

vt.撒，驱散，散开；散布/播；vi.分散，消散

参考例句：

• You pile everything up and scatter things around.你把东西乱堆乱放。
• Small villages scatter at the foot of the mountain.村庄零零落落地散布在山脚下。

11 obstruct   

v.阻隔，阻塞(道路、通道等)；n.阻碍物，障碍物

参考例句：

• He became still more dissatisfied with it and secretly did everything in his power to obstruct it.他对此更不满意，尽在暗里使绊子。
• The fallen trees obstruct the road.倒下的树将路堵住了。

12 copper   

n.铜；铜币；铜器；adj.铜(制)的；(紫)铜色的

参考例句：

• The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
• Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。

13 apparatus   

n.装置，器械；器具，设备

参考例句：

• The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。
• They had a very refined apparatus.他们有一套非常精良的设备。

14 adorn   

vt.使美化，装饰

参考例句：

• She loved to adorn herself with finery.她喜欢穿戴华丽的服饰。
• His watercolour designs adorn a wide range of books.他的水彩设计使许多图书大为生色。

15 generators   

n.发电机，发生器( generator的名词复数 )；电力公司

参考例句：

• The factory's emergency generators were used during the power cut. 工厂应急发电机在停电期间用上了。
• Power can be fed from wind generators into the electricity grid system. 电力可以从风力发电机流入输电网。 来自《简明英汉词典》

16 grid   

n.高压输电线路网；地图坐标方格；格栅

参考例句：

• In this application,the carrier is used to encapsulate the grid.在这种情况下，要用载体把格栅密封起来。
• Modern gauges consist of metal foil in the form of a grid.现代应变仪则由网格形式的金属片组成。