第45回 レベル別・TOEFL iBT®テスト 4技能対策⑩ 上級Reading・高難易度の問題対策―その2―

1. 解答には最低3~4分程かかると考えてください。つまりそれまでの問題を16分程度で終える必要があります
2. Summary Questionsにたどり着くまでに12問解いているわけですから、本文の全体をほぼ読み終えているわけです。しかしあやふやな印象のままでsummaryを作るのは危険です
3. 1と2を踏まえて、パッセージのタイトルと、主旨をもう一度掴むべく全体を見直しましょう。画面右上にあるView Passageボタンを押すと、設問画面から切り替わりパッセージ全体を読み返すことができます
4. 上記概要で紹介したintroductory sentenceを読み、参考としてヒントを得ましょう
5. 本文とintroductory sentenceを参照しつつ、選択肢を分析する作業にかかります

Electricity from Wind

¶1　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.

¶2　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.

¶3　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.

¶4　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.

¶5　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.

¶6　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.

1. …wind power…important source of electric power.
   ― ○　本文の内容・トーンと合っています。
2. Smaller countries…especially suited
   ― ×　国の大小による比較はしていません。
3. …not economical in areas with steady winds
   ― ×　第4段落の内容と逆になっています。
4. human developments…more dangerous
   ― ○　第5段落で詳細に説明されている内容です。
5. …a small number of states…all the power needs of the US
   ― ×　第1段落の1センテンスに記述があるのみなので、間違ってはいませんが要約としては不適切です。
6. Wind power…advantages
   ― ○　これも本文の内容・トーンと合っています。