Two new studies offer signs that this could be changing quickly. One offers a new way to produce solar cells more cheaply and sa

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问题     Two new studies offer signs that this could be changing quickly. One offers a new way to produce solar cells more cheaply and safely than current methods. The other indicates that concentrating solar power, which uses the sun’ s energy to heat up a liquid that drives a turbine, could supply "a substantial amount of current energy demand."
    In a study released Wednesday in journal Nature, University of Liverpool’s Jon Major and several other researchers announced that they had found that magnesium chloride, which is used in making tofu, bath salts and applied to roads in the winter could replace cadmium chloride in the making of second-generation, thin-film solar cells.
    Speaking in a teleconference from Copenhagen, Major said magnesium chloride, which is extracted from seawater, would cost $0,001 per gram compared to $0.3 for cadmium chloride. It would also eliminate the challenges and expense of handling cadmium chloride, a highly toxic compound that requires elaborate safety measures to protect workers during its manufacture and a special disposal process when panels are no longer needed.
    "So what we have done without any loss of efficiency is to replace expensive and highly toxic material with one that is completely benign and much lower in cost in the process," Major said. "This offers a great cost benefit for production of these kinds of solar cells and could help make a step change in the production of them." The solar market is currently dominated by panels made with silicon. In a bid to make solar more competitive, there is growing interest from companies like First Solar in developing solar cells using cadmium telluride, which is more efficient and more flexible so it could be applied many more surfaces including windows. To make these cadmium telluride cells, a thin layer of cadmium chloride is applied to the solar cell, and then heated up in a furnace. This is considered the activation process, Major said, helping to boost a cell’s efficiency from around 1 percent to as much as 20 percent. In a bid to find a safer alternative, Major and his team first looked at sodium chloride, but found the efficiency was about half of cadmium chloride. Another option was difluoro chloromethane but that has been linked to ozone depletion and its use has been restricted by international agreements.
    They then turned to magnesium chloride and found that it was just as efficient as comparable and could be applied without any expensive safety equipment.
    Major said magnesium chloride isn’t being used at the moment, but was hopeful it "would be taken up by research and hopefully by industry once this work is publicized."
    Steve Krum, the director of corporate communications for First Solar, would only say cadmium chloride remains "critical part" of its production process and that it was not a "major cost driver in our manufacturing process."
The best title of the passage may be______.

选项 A、How to Make Solar Cells
B、The Future of Solar Power
C、Magnesium Chloride is to Make Solar Cells
D、Magnesium Chloride Replaced Cadmium Chloride

答案C

解析 主旨题。本文主要介绍了氯化镁制造太阳能电池的优点——廉价、清洁、高效,有望取代昂贵而有剧毒的氯化镉。成为新一代太阳能电池的生产材料。C项意为氯化镁将用来制造太阳能电池,准确地概括了文章主旨大意。因此最为贴切。A项和B项偏离主旨,D项太片面,没有提及文章主题“太阳能电池”,故不正确。
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