| 成本应该说是关键 |
| 送交者: 道友 2010月09月29日22:34:50 于 [世界股票论坛] 发送悄悄话 |
| 回 答: 道长, 光漏斗太阳能电池也只是一种方法。。。 由 eachus 于 2010-09-29 19:36:56 |
|
那段话 “发明了一种收集量是传统光伏电池100倍的光漏斗”,国内记者翻译不一定准确，英文原文附在下面。老道的理解是那句话不是说光电转换效率提高了100倍，而是把光聚焦了100倍。太阳能光电池有几种，其中有聚光的有不聚光的，你说的传统的是不聚光的，其问题是太阳能密度很低，在中午直射时每平方米能量不过1千瓦，早晚斜着时能量密度就更低了，现在也有用反射镜将太阳光聚集后再用高效太阳能电池将其转化为电能，多节太阳能电池的效率可以达到50%以上，远高于传统太阳能电池，但多节太阳能电池的单位面积成本也比传统太阳能电池贵得多，可是如果聚光100倍的话，那么多节太阳能电池的面积只需传统太阳能电池的百分之一，所以虽然其单位面积成本高，但因面积小，所以总成本不见得比传统太阳能电池高。三类太阳能电池如下图所示。
 问题是现有的反射镜集光需对准太阳，这个带来了高机械成本，光漏斗的概念便是要解决这个问题，让光照在某些纤维上，这些纤维自动把光导向某一点，把高效光电池放在那点上就可以把光能高效转化为电能。 能源的使用的选择跟成本有关，如果有比太阳能便宜的能量，在那种能量使用完以前，太阳能在经济上难以普及，现在有些报道说太阳能很便宜，其实是指那些低效太阳能电池，这些电池名义上是便宜，但需要占大量的地，如果地皮不要钱的话，还要考虑这些电池的维护清理，那也是要钱的，所以综合成本其实要比吹的高很多。现在太阳能电池基本上只有在政府补贴下才能生产，而政府补贴不是稳定的，政策一变太阳能及多晶硅价格就会大跌。所以现有的太阳能技术都是不成熟技术，老美是把重点放在研发上，希望研发成功在推广，而中国政府研发不下功夫，忙着推动不成熟产品的生产，造成多晶硅短期不足，价格飞涨，所以生产多晶硅的太阳能类股如TSL等在涨，但真正生产太阳能电池的如STP等却不怎么动。 MIT’s Solar Funnel Concentrates Solar Energy 100 Times
A group of chemical engineers at MIT have devised a way to collect solar energy 100 times more concentrated than a traditional photovoltaic cell. If their ’solar funnel’ venture proves to be a success, it could drastically alter how solar energy is collected in the future — there will no longer be a need for massive solar arrays or extensive space to generate significant and sufficient amounts of power. The engineers’ research has determined that carbon nanotubes – hollow tubes made up of carbon atoms — will be the primary instrument in capturing and focusing light energy, allowing for not just smaller, but more powerful solar arrays.  
In the Sept. 12 online edition of the journal Nature Materials, Michael Strano, the Charles and Hilda Roddey Associate Professor of Chemical Engineering and leader of the research team said, “Instead of having your whole roof be a photovoltaic cell, you could have little spots that were tiny photovoltaic cells, with antennas that would drive photons into them.” Their work is being funded by a National Science Foundation Career Award, a Sloan Fellowship, the MIT-Dupont Alliance and the Korea Research Foundation. The antenna itself is incredibly small – it consists of a fibrous rope about 10 micrometers (millionths of a meter) long and four micrometers thick, containing about 30 million carbon nanotubes. The prototype made by Strano’s team consisted of a fiber made of two layers of nanotubes, each with different electrical properties. When a photon strikes the surface of the solar funnel, it excites an electron to a higher energy level, which is specific to the material. The relationship between the energized electron and the hole it leaves behind is called an exciton, and the difference in energy levels between the hole and the electron is known as the bandgap. The inner layer of the antenna contains nanotubes with a small bandgap, and nanotubes in the outer layer have a higher bandgap. Excitons like to flow from high to low energy, and in the solar funnel’s case means they can flow from the outer layer to the inner layer where they can exist in a lower energy state. When light strikes the antenna, all of the excitons flow to the center of the antenna where they are concentrated and the photons are converted to an electrical current. Like with all solar cells however, its efficiency depends on the materials utilized for the electrode. Read more: MIT's Solar Funnel Concentrates Solar Energy 100 Times | Inhabitat - Green Design Will Save the World
Strano’s team is the first to construct nanotube fibers in which the properties of different layers can be controlled — an achievement made possible by recent advances in separating nanotubes with different properties. It is not just the higher rate of concentrated energy that makes the solar funnels a breakthrough — by utilizing carbon nanotubes, solar cells can be constructed at a lower-cost than traditional silicon-based solar cells. While the cost of carbon nanotubes was once prohibitive, it has come down in recent years as chemical companies build up their manufacturing capacity. “At some point in the near future, carbon nanotubes will likely be sold for pennies per pound, as polymers are sold,” says Strano. “With this cost, the addition to a solar cell might be negligible compared to the fabrication and raw material cost of the cell itself, just as coatings and polymer components are small parts of the cost of a photovoltaic cell.” In theory, with this new technology, not only could the solar funnels be used to generate power, but they could be used in applications where light needs to be concentrated — such as telescopes or night-vision goggles. The design behind the solar funnel is quite innovative, by capturing the light in a tube, Strano’s solar funnel, also know as an nanotube antenna, boosts the number of photons that can be transformed into energy, but in a similar process to that of tradition solar cells. Strano’s team is now reportedly working on ways to minimize the energy lost as excitons flow through the fiber, as well as new antennas that would lose only 1 percent of the energy they absorb versus the standard 13 percent. |
|
|
 |
||||
|
 |
| 实用资讯 | |