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Electricity from Wind

Since 1980, the use of wind to produce electricity has been growing rapidly. In 1994 there were nearly 20,000 wind turbines worldwide, most grouped in clusters called wind farms that collectively produced 3,000 megawatts of electricity. Most were in Denmark (which got 3 percent of its electricity from wind turbines) and California (where 17,000 machines produced 1 percent of the state’s electricity, enough to meet the residential needs of a city as large as San Francisco). In principle, all the power needs of the United States could be provided by exploiting the wind potential of just three states—North Dakota, South Dakota, and Texas.

Large wind farms can be built in six months to a year and then easily expanded as needed. With a moderate to fairly high net energy yield, these systems emit no heat-trapping carbon dioxide or other air pollutants and need no water for cooling; manufacturing them produces little water pollution. The land under wind turbines can be used for grazing cattle and other purposes, and leasing land for wind turbines can provide extra income for farmers and ranchers.

Wind power has a significant cost advantage over nuclear power and has become competitive with coal-fired power plants in many places. With new technological advances and mass production, projected cost declines should make wind power one of the world’s cheapest ways to produce electricity. In the long run, electricity from large wind farms in remote areas might be used to make hydrogen gas from water during periods when there is less than peak demand for electricity. The hydrogen gas could then be fed into a storage system and used to generate electricity when additional or backup power is needed.

Wind power is most economical in areas with steady winds. In areas where the wind dies down, backup electricity from a utility company or from an energy storage system becomes necessary. Backup power could also be provided by linking wind farms with a solar cell, with conventional or pumped-storage hydropower, or with efficient natural-gas-burning turbines. Some drawbacks to wind farms include visual pollution and noise, although these can be overcome by improving their design and locating them in isolated areas.

Large wind farms might also interfere with the flight patterns of migratory birds in certain areas, and they have killed large birds of prey (especially hawks, falcons, and eagles) that prefer to hunt along the same ridge lines that are ideal for wind turbines. The killing of birds of prey by wind turbines has pitted environmentalists who champion wildlife protection against environmentalists who promote renewable wind energy. Researchers are evaluating how serious this problem is and hope to find ways to eliminate or sharply reduce this problem. Some analysts also contend that the number of birds killed by wind turbines is dwarfed by birds killed by other human-related sources and by the potential loss of entire bird species from possible global warming. Recorded deaths of birds of prey and other birds in wind farms in the United States currently amount to no more than 300 per year. By contrast, in the United States an estimated 97 million birds are killed each year when they collide with buildings made of plate glass, 57 million are killed on highways each year; at least 3.8 million die annually from pollution and poisoning; and millions of birds are electrocuted each year by transmission and distribution lines carrying power produced by nuclear and coal power plants.

The technology is in place for a major expansion of wind power worldwide. Wind power is a virtually unlimited source of energy at favorable sites, and even excluding environmentally sensitive areas, the global potential of wind power is much higher than the current world electricity use. In theory, Argentina, Canada, Chile, China, Russia, and the United Kingdom could use wind to meet all of their energy needs. Wind power experts project that by the middle of the twenty-first century wind power could supply more than 10 percent of the world’s electricity and 10-25 percent of the electricity used in the United States.

【正确答案】 D

【答案解析】

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风力发电

风力发电的运用从 1980 年起一直迅猛增长。1994 年，世界各地有近 2 万台风力涡轮机，大量风力涡轮机集中在一起组成风力发电厂，可共同发电 3000 兆瓦。风力发电厂主要集中在丹麦和美国的加利福尼亚州，丹麦全国电力的 3%来源于风力发电，美国加州风力发电厂 17000 台涡轮机的发电量占全州电量的 1%，足以满足旧金山这种大城市的居住用电需求。全美的电力需求基本上都可以通过挖掘北达科他州、南达科他州和得克萨斯州的风力发电潜力来满足。

大型风力发电厂可在 6 个月至一年内建成，后续可根据需要随时扩建。发电厂里的设备在实现大量电能高产的同时，不仅做到了温室气体二氧化碳和其他空气污染物的零排放，并且无需用水对设备进行降温；同时，风力发电基本不会造成水资源污染。风力涡轮机的所在地还可用于放牛等其他用途，农民们和农场主可以通过土地出租供风力发电来增加额外收入。

风力发电和核电站发电相比具有明显的成本优势，在很多地方与燃煤发电也不相上下。随着新技术的进步和大规模生产，预期的成本下降会使风力发电成为世界上成本最低的发电方式。未来，偏远地区的大型风力发电厂发电量高于用电高峰需求量时，多出的电量可能会为从水中制造氢气提供支持。氢气可以存储起来，在需要额外或后备电源时用来发电。

在风源稳定的地区，风力发电是最经济。在风源不足的地方，需要稳定的备用电力来源，如电力公司司、能量储存、太阳能电池、传统水力发电机和抽水蓄能，或者燃烧天然气的高效涡轮机。虽然风力发电会带来视觉污染和噪音，不过这些缺陷都可以通过设计的改善以及地点安排来弥补。

某些区域的大型风力发电厂很可能会影响候鸟的飞行方式，他们杀害了大型猛禽（尤其是老鹰、猎鹰和鹰），这些猛禽喜欢沿那些风力涡轮机所处的理想嵴线捕食。针对风力涡轮机对猛禽造成伤害的这一事实，主张保护野生动物的环保主义者和主张发展再生能源的环保主义者各持己见。研究人员还在对这个问题的严重程度进行评估，他们希望能想办法来消除或者大幅减少这个问题。有的分析家评论认为，由风力涡轮机导致的鸟类的死亡数目和由其他人为原因造成的死亡数目以及整个鸟类可能因全球变暖中而死亡数目相比是少之又少。据记载，美国风力发电厂伤害的猛禽和其他禽鸟的死亡数量每年不超过 300 只。相比之下，在美国估计每年有 9700 万禽鸟由于碰撞到建筑物的厚玻璃板而死亡，5700 万禽鸟死在高速公路上，至少有 380 万禽鸟死于污染和中毒，每年数以百万计的禽鸟在燃煤电厂和核电厂的输电和配电线缆上触电致死。

促使全球范围内风力发电应用扩张的技术已经到位。在合适的地点，风力发电几乎用之不尽取之不竭，即使排除这些环境敏感地区，全球潜在的风力发电量远高于目前的世界耗电总量。理论上来说，阿根廷、加拿大、智利、中国、俄罗斯和英国可以利用风力来满足他们所有的能源需求。风力发电专家估计，在二十一世纪中叶，全球超过 10%的电力，及美国 10-25％的电力需求都可通过风力发电来满足。