首页
登录
职称英语
The need for solar electricity is clear, it is safe, ecologically sound, eff
The need for solar electricity is clear, it is safe, ecologically sound, eff
游客
2025-04-21
25
管理
问题
The need for solar electricity is clear, it is safe, ecologically sound, efficient, continuously available, and is has no moving parts. The basic problem with the use of solar photovoltaic devices is economics, but until recently very little progress has been made toward the development of low-cost photovoltaic devices. The larger part of research funding has been devoted to study of single-crystal silicon solar cells, despite the evidence, including that of the leading manufacturers of crystalline silicon, that the technique holds little promise. The reason for this pattern is understandable and historical. Crystalline silicon is the active element in the very successful semiconductor industry, and virtually all of the solid state devices contain silicon transistors and diodes. Crystalline silicon, however, is particularly unsuitable to terrestrial solar cells.
Crystalline silicon solar cells work well and are successfully used in the space program, where cost is not an issue. While single crystal silicon has been proven in extraterrestrial use with efficiencies as high as 18 percent, and other more expensive and scarce materials such as gallium arsenide can have even higher efficiencies, costs must be reduced by a factor of more than 100 to make them practical for commercial use. Beside the fact that the starting crystalline silicon is expensive, 95 percent of it is wasted and does not appear in the final device. Recently, there have been some imaginative attempts to make polycrystalline and ribbon silicon, which are lower in cost than high-quality single crystals. But to date the efficiencies of these apparently lower-cost arrays have been unacceptably small. Moreover, these materials are cheaper only because of the introduction of disordering in crystalline semiconductors, and disorder degrades the efficiency of crystalline solar cells.
This dilemma can be avoided hy preparing completely disordered or amorphous materials. Amorphous materials have disordered atomic structure as compared to crystalline materials. That is, they have only short-range order rather than the long-range periodicity of crystals. The advantages of amorphous solar cells are impressive. Whereas crystals can be grown as wafers about four inches in diameter, amorphous materials can be grown over large areas in a single process. Whereas crystalline silicon must be made 200 microns thick to absorb a sufficient, amount of sunlight for efficient energy conversion, only I micron of the proper amorphous materials is necessary. Crystalline silicon solar cells cost in excess of $100 per square foot, but amorphous films can be created at a cost of about 50 per square foot.
Although many scientists were aware of the very low cost of amorphous solar cells, they felt that they could never be manufactured with the efficiencies necessary to contribute significantly to the demand for electric power. This was based on a misconception about the feature which determines efficiency. For example, it is not the conductivity of the material in the dark which is relevant, but only the photoconductivity, that is the conductivity in the presence of sunlight. Already, solar cells with efficiencies well above 6 percent have been developed using amorphous materials, and further research will doubtless find even less costly amorphous materials with higher efficiencies. [br] The tone of the passage can best be described as ______.
选项
A、analytical and optimistic
B、biased and unprofessional
C、critical and discouraged
D、tentative and inconclusive
答案
A
解析
选A是因为文中采用了大量的数据(有整数,有百分比),并且最后一段的最后三行表明了作者乐观的态度。
转载请注明原文地址:https://tihaiku.com/zcyy/4046884.html
相关试题推荐
Theneedforsolarelectricityisclear,itissafe,ecologicallysound,eff
Theneedforsolarelectricityisclear,itissafe,ecologicallysound,eff
Theneedforsolarelectricityisclear,itissafe,ecologicallysound,eff
Theneedforsolarelectricityisclear,itissafe,ecologicallysound,eff
Theneedforsolarelectricityisclear,itissafe,ecologicallysound,eff
Thepeoplewereannoyedbythe______supplyofelectricityandwaterinsummer.A、
Plasticsarethebestinsulatorofelectricity,rubber______itclosely.A、followi
Investmentinthepublicsector,suchaselectricity,irrigation,quarrying,
Investmentinthepublicsector,suchaselectricity,irrigation,quarrying,
Thefailureofelectricityputallthecomputersintheregionoutof______.A、wo
随机试题
Thereisnodenyingthatstudentsshouldlearnsomethingabouthowcomputers
Thewomanwantstoknowfromthemanthat[originaltext]W:Hey,Robert!Iwasli
小儿急性淋巴细胞性白血病中以下列哪一亚型多见A.早期前B细胞型 B.普通B细胞
证券公司编造虚假信息,扰乱证券、期货交易市场,造成严重后果的,()A.处5年以
支气管哮喘宜选用A.罗布麻叶 B.地龙 C.蜈蚣 D.羚羊角 E.天麻
按污染物排放的空间分,在距地面一定高度上排放污染物的污染源称为( )。A.空中
在委托开发合同中,除合同另有约定外,委托开发完成的发明创造,申请专利的权利属于:
泥板书舍作为一种学校出现在()。A.古印度 B.古巴比伦 C.古埃及 D
反收购管理层防卫策略有()。A:毒丸策略 B:金降落伞策略 C:银降落伞策
工程网络计划工期优化的基本方法是:在不改变网络计划中各项工作逻辑关系的前提下,通
最新回复
(
0
)