经济学人下载:太阳能,第三种方法

In their view, three things are needed to create a workable solar-thermoelectric device. The first is to make sure that most of the sunlight which falls on it is absorbed, rather than being reflected. The second is to choose a thermoelectric material which conducts heat badly (so that different parts remain at different temperatures) but electricity well. The third is to be certain that the temperature gradient which that badly conducting material creates is not frittered away by poor design.

按他们的观点，创建一个可靠工作的太阳能热电装置有三件事要做。第一，确保更多的太阳光在装置上并被吸收，而不被发射。第二，选择一种热电效应材料，它导热不好（使在不同的部位保持不同的温度）但是导电良好。第三，要肯定的是，温度梯度要采取导热不好材料进行创建，而不要因为不良的设计而一点一滴地浪费。

The two researchers overcame these challenges through clever engineering. 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. These layers acted like the anti-reflective coatings on spectacle lenses and caused almost all the sunlight falling on the device to be absorbed.

两个研究人员通过巧妙的设计工程克服了这些挑战。第一，他们在装置的上处理和涂上铪，钼，钛氧化物层，这层物质仅有100纳米厚。这些覆盖层的作用就像眼睛镜片上的防发射层一样，因此差不多所有的照到装置上的太阳光都被吸收了。

The second desideratum, of low thermal and high electrical conductivity, was achieved by dividing the bismuth telluride into pellets a few nanometres across. That does not affect their electrical conductivity, but nanoscale particles like this are known to scatter and obstruct the passage of heat through imperfectly understood quantum-mechanical processes.

第二个所愿望之物——低热量和高导电性，是通过将整个铋碲划分成几个纳米颗粒实现的。 这样做并不影响其导电性。但是，如果完全理解量子力学过程的，这种纳米颗粒能够分散和阻挠热量通过是众所周知。

The third objective, efficient design, involved sandwiching the nanostructured bismuth telluride between two copper plates and then enclosing the upper plate (the one coated with the light-absorbing oxides) and the bismuth telluride in a vacuum. The copper plates conducted heat rapidly to and from the bismuth telluride, thus maintaining the temperature difference. The vacuum stopped the apparatus losing heat by convection.

第三个目标、高效的设计，包括三明治式的结构，纳米级碲化铋在两个铜片之间，并封闭上面的铜片（一面覆盖吸光的氧化物），碲化铋则在真空中，铜片传导热量迅速到碲化铋。因此保持了温度差，真空则阻止装置通过对流而损失热量。

The upshot was a device that converts 4.6% of incident sunlight into electricity. 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. But it is enough, Dr Chen reckons, for the process to be worth considering for mass production.

结果是装置能够将入射光的4.6%转化成电能。基于太阳能电池成功转化20%以上，由太阳能热发电机组能达到40%，甚至新一代更便宜和令人高兴德薄膜太阳能电池也达到了18—20%，和这些相比，好像没有什么伟大的。但是陈博士认为，这是不够的，该进程值得考虑大规模的生产。

He sees it, in particular, as something that could be built into the solar water-heaters that adorn the roofs of an increasing number of houses. If such heaters were covered with thermoelectric generators the sun’s rays could be put to sequential use. First, electric power would be extracted from them. Then, the exhaust heat from the bottom plate of the thermoelectric device would be used in the traditional way to warm water up. Two-for-one has always been an attractive proposition for the consumer. This kind of combined heat and power might enable more people to declare independence from the grid.

在他看来，尤其热电装置要是被建造成为装饰越来越多的房屋的屋顶太阳能热水器的一部分。 如果这种加热器都安装上能付诸连续使用太阳光热电发电机，那么首先，电能能够从中提取。 然后，从热电装置底板的排气将会用传统的方式加热温水热。 这样合二为一，总是对消费者的主张有吸引力， 这种热电联产可能会使更多的人从电网宣布独立