2014职称英语理工阅读理解课件.doc

 HYPERLINK / \t _self  PAGE  PAGE 5页 第七篇 Renewable Energy Sources Today petroleum provides around 40% of the world’s energy needs, mostly fuelling automobiles1. Coal is still used, mostly in power stations, to cover one-quarter of our energy needs, but it is the least efficient, unhealthiest and most environmentally damaging fossil fuel2. Natural gas reserves could plug some of the gap from oil3, but reserves of that will not last into the 22nd century either. Most experts predict we will exhaust easily accessible reserves within 50 years4. We could fast reach an energy crisis. We need to rapidly develop sustainable solutions to fuel our future5. Less-polluting renewable energy sources offer a more practical long-term energy solution. They may benefit the world’s poor too. “Renewable” refers to the fact that these resources are not used faster than they can be replaced. The Chinese and Romans used watermills over 2,000 years ago. But the first hydroelectric dam was built in England in 1870. Hydroelectric power is now the most common form of renewable energy, supplying around 20% of world electricity. China’s Three Gorges Dam6, which has just been completed, is the largest ever. At five times the size of the US’s Hoover Dam7, its 26 turbines will generate the equivalent energy of 18 coal-fired power stations8. It will satisfy 3% of China’s entire electricity demand. Surprisingly, some argue that hydroelectric dams significantly contribute greenhouse gases. In 2003, the first commercial power station to harness tidal currents9 in the open sea opened in Norway. It is designed like windmill, but others take the form of turbines. As prices fall, wind power has become the fastest growing type of electricity generation — quadrupling10 worldwide between 1999 and 2005. Modern wind farms consist of turbines that generate electricity. Though it will be more expensive, there is more than enough wind to provide the world’s entire energy needs. Wind farms come in onsh