太阳能 Solar Energy

从太阳接电
莫哈未沙漠一个晴朗的11月清晨，太阳才刚以寒冷的粉红色霞光碰触到麦卡洛山脉的山顶。在山脉的后面，一轮满月则在拉斯韦加斯10亿瓦的强光中沉沉落下。内华达太阳能一号发电厂还在沉睡，但一天的工作即将展开。
令人难以想象的是，发电厂竟然可以这么美观：100公顷和缓弯曲的镜子排列成长槽状，有如发光的运河。它们整夜朝向地面摆放，此刻开始醒了过来，并一路追随太阳，数量超过了18万2000面。
「看起来今天会有370度。」控制室里的一位操作人员说道。他的工作是监控成排的抛物镜，好让它们把阳光集中在注满循环油料的长条钢管上，使它加热到高达摄氏400度。高温的液体会从集热场流入巨大的散热器里，并把高热与滚水转变为蒸汽。蒸汽则会带动涡轮与发电机，进而把高达6400万瓦的电送进输电系统里──这足以供电给1万4000户，或是几座拉斯韦加斯的赌场。「系统在产生蒸汽时，它是非常传统的，也就是工业标准那套。」厂长罗勃．凯伯一面说，一面指着埃尔多拉多山谷大道另一侧的燃气发电厂。「我们所用的工具和零件就跟对街的那个地方没两样。」
内华达太阳能一号在2007年上线运转，是当时美国境内超过17年来所兴建的第一座大型太阳能电厂。在那段期间，太阳能科技则在世界的其它地方蓬勃发展。内华达太阳能一号属于阿希欧那公司所有，这家西班牙公司在此处发电，然后把电卖给当地的公用事业单位内华达能源公司。镜子是在德国制造。
戴上安全帽和墨镜，凯伯和我坐进他的小货车里，慢慢开过一排又一排的镜子。水罐车上的男子则拿着水管替其中一些浇水。「任何一种灰尘都会影响它们。」凯伯说。到了集热场的远边，我们停了下来，并下车看个仔细。为了证明玻璃有多坚固，凯伯像打鼓一样用力地敲下去。在他的头上方，也就是抛物镜的焦点，输油的管子外面包着黑色的陶瓷，以吸收光线，并套了一层真空玻璃管来隔离。在太阳高挂头顶的晴朗夏日，内华达太阳能一号大约可以把21%的日光转换成电力。燃气电厂的效率更高，但日光不花钱，而且这种燃料不会排放二氧化碳，导致地球暖化。
大约每隔30秒就会传出一阵细微的嘶嘶声，因为马达会把镜子调高一点点。等到正午时分，它们就会完全朝上。那里十分安静，你几乎察觉不到有多少事正在进行：760列镜子大约各能产出8万4000瓦，差不多等于113匹马力。在早上8点时，流过管子的油已接近运转温度，一阵阵的白烟从冷却塔里冒出来。半个小时后，发电站内的涡轮声音就变成了刺耳的尖叫声。内华达太阳能一号准备把电输入输电系统。


英文原文:

Early on a clear November morning in the Mojave Desert, the sun is barely touching the peaks of the McCullough Range with a cool pink glow. Behind them, a full moon is sinking over the gigawatt glare of Las Vegas. Nevada Solar One is sleeping. But the day's work is about to begin.

It is hard to imagine that a power plant could be so beautiful: 250 acres of gently curved mirrors lined up in long troughs like canals of light. Parked facing the ground overnight, they are starting to awaken—more than 182,000 of them—and follow the sun.

"Looks like this will be a 700-degree day," says one of the operators in the control room. His job is to monitor the rows of parabolically shaped mirrors as they concentrate sunlight on long steel pipes filled with circulating oil, heating it as high as 750 degrees Fahrenheit. From the mirror field, the blistering liquid pours into giant radiators that extract the heat and boil water into steam. The steam drives a turbine and dynamo, pushing as much as 64 megawatts onto the grid—enough to electrify 14,000 households or a few Las Vegas casinos. "Once the system makes steam, it's very traditional—industry-standard stuff," says plant manager Robert Cable, pointing toward a gas-fired power plant on the other side of Eldorado Valley Drive. "We get the same tools and the same parts as the place across the street."

When Nevada Solar One came on line in 2007, it was the first large solar plant to be built in the United States in more than 17 years. During that time, solar technology blossomed elsewhere. Nevada Solar One belongs to Acciona, a Spanish company that generates electricity here and sells it to NV Energy, the regional utility. The mirrors were made in Germany.

Putting on hard hats and dark glasses, Cable and I get into his pickup and drive slowly past row after row of mirrors. Men with a water truck are hosing down some. "Any kind of dust affects them," Cable says. At the far edge of the mirror field, we stop and step out of the truck for a closer look. To show how sturdy the glass is, Cable bangs it like a drum. Above his head, at the focal point of the parabola, the pipe carrying the oil is coated with black ceramic to soak up the light, and it's encased in an airless glass cylinder for insulation. On a clear summer day with the sun directly overhead, Nevada Solar One can convert about 21 percent of the sun's rays into electricity. Gas plants are more efficient, but this fuel is free. And it doesn't emit planet-warming carbon dioxide.

About every 30 seconds there is a soft buzz as a motor moves the mirrors a little higher; by midday they will be looking straight up. It's so quiet out here one can hardly fathom how much work is being done: Each of the 760 arrays of mirrors can produce about 84,000 watts—almost 113 horsepower. By 8 a.m. the oil coursing through the pipes has reached operating temperature. A white plume is spewing from a cooling stack. Half an hour later, the sound of the turbine inside the generating station has reached a high-pitched scream. Nevada Solar One is ready to go on line.

“Sunlight bathes us in far more energy than we could ever need—if we could just catch enough.”[qq]0[/qq]