经济学人下载:太阳能,第三种方法

Solar power
太阳能

The third way
第三种方法

A new method of making electricity from sunlight has just been tested
一种从太阳光得到能源的新方法正在尝试

AT THE moment, there are two reliable ways to make electricity from sunlight. You can use a panel of solar cells to create the current directly, by liberating electrons from a semiconducting material such as silicon. Or you can concentrate the sun’s rays using mirrors, boil water with them, and employ the steam to drive a generator.

到现在为止，已经有两种可行的办法从太阳光获取能量。你能够使用太阳能电池板直接获取电流，它是通过从像硅这样的半导体材料释放电子而实现的。或者你也能使用镜子聚集太阳光线来煮沸水而产生蒸汽来推动发电机运转。

Both work. But both are expensive. Gang Chen of the Massachusetts Institute of Technology and Zhifeng Ren of Boston College therefore propose, in a paper in Nature Materials, an alternative. 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.

这两种方法都能工作，但是都很昂贵。因此，麻省理工技术学院的陈刚和波士顿学院的任智丰在《自然材料》上发表论文建议用其他方法替代，他们认为，这种称为热电效应的现象可能被使用，而且他们已经建立了一个原型，证明这个想法是可行的。

Thermoelectric devices are not new. They are used, for example, to capture waste heat from car engines. They work because certain materials, such as bismuth telluride, generate an electrical potential difference within themselves if one part is hotter than another. That can be used to drive a current through an external circuit.

热电效应装置不是什么新东西。例如，它们已经被用来捕获汽车发动机的余热。他们能工作是因为像碲化铋这样的材料，如果在他们的一端比另一端热，那么内部会产生一个电势差，这可用于驱动外部电路中通过的电流。

The reason thermoelectric materials have not, in the past, been applied successfully to the question of solar power is that to get a worthwhile current you have to have a significant temperature difference. (200??C is considered a good starting point.) In a car engine, that is easy. 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. If the heat concentration could be done without all the paraphernalia of mirrors, though, thermoelectricity’s inefficiency would be offset by the cheapness of the kit. And that is the direction in which Dr Chen and Dr Ren hope they are heading.

在过去，热电效应材料没有成功的应用到解决太阳能的问题的原因是你必须大的温差才能得到一个有用的电流（200℃被认为是一个开始）。在一个汽车发动机内是很容易的，但是对太阳光那意味着要采取一些办法来积聚热量。如果你要建设镜子麻烦做到这一点，那么你又会回到蒸汽时代的老路，那是产生电力的有效办法。如果在没有镜子装置的情况下能够聚集热量，那么热电效应的无效性将会通过便宜的装置来弥补。那是方向，陈博士和任博士也希望他们正向前行。