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

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

admin2014-12-26  31
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 word "benign"(Line 2, Para. 4)may be replaced by______.
选项 A、sweet
B、humane
C、nontoxic
D、amiable
答案C
解析 推断题。第三段讲到氯化镁远低于氯化镉，接着继续讲到氯化镁的优点，即It would also eliminate the challenges and expense of handling cadmium chloride．ahighly toxic compound that requires elaborate safety measures to protect workers…(此外，它还能够消除处理氯化镉的挑战和费用——氯化镉是一种剧毒化合物．需要复杂的安全措施来保护生产工人……)，由此可知氯化镁是一种无毒的物质，而第四段第一句提及的正是氯化镁的优点，与benign并列的是much lower cost。因此可推知，benign在此处意为“无毒的”(nontoxic)。
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