英语六级考试快读阅读练习及答案（9）.docx

本文格式为Word版，下载可编辑英语六级考试快读阅读练习及答案（9） The Hydrogen Economy While fossil fuels have played an important role in getting society to the point it is at today, there are four big problems that fossil fuels create. Air pollution-When cars burn gasoline, they would ideally burn it perfectly and create nothing but carbon dioxide and water in their exhaust. Unfortunately, the internal combustion(燃烧)engine is not perfect. In the process of burning the gasoline, it also produces carbon monoxide, a poisonous gas; nitrogen oxides, the main source of urban smog; and unburned hydrocarbons, the main source of urban ozone . Catalytic converters eliminate much of this pollution, but they arent perfect. Air pollution from cars and power plants is a real problem in big cities. It is bad enough now that, in the summer, many cities have dangerous levels of ozone in the air. Environmental pollution-The process of transporting and storing oil has a big impact on the environment whenever something goes wrong. An oil spill, pipeline explosion or well fire can create a huge mess. Global warming-When you burn a gallon of gas in your car, you emit about 5 pounds of carbon into the atmosphere. If it were solid carbon, it would be extremely noticeable-it would be like throwing a 5-pound bag of sugar out the window of your car for every gallon of gas burned. But because the 5 pounds of carbon comes out as an invisible gas, carbon dioxide, most of us are oblivious to it. The carbon dioxide coming out of every cars tailpipe is a greenhouse gas that is slowly raising the temperature of the planet. The ultimate effects are unknown, but it is a strong possibility that, eventually, there will be dramatic climate changes that affect everyone on the planet. For example, if the ice caps melt, sea level will rise significantly, flooding and destroying all coastal cities in existence today. Thats a big side effect. Dependence-The United States, and most other countries, cannot produce enough oil to meet demand, so they import it from oil-rich countries. That creates an economic dependence. When Middle East oil producers decide to raise the price of oil , the rest of the world has little choice but to pay the higher price. Advantages of the hydrogen economy In the previous section we saw the significant, worldwide problems created by fossil fuels. The hydrogen economy promises to eliminate all of the problems that the fossil fuel economy creates. Therefore, the advantages of the hydrogen economy include: The elimination of pollution caused by fossil fuels-When hydrogen is used in a fuel cell to create power, it is a completely clean technology. The only byproduct is water. There are also no environmental dangers like oil spills to worry about with hydrogen. The elimination of greenhouse gases-If the hydrogen comes from the electrolysis of water, then hydrogen adds no greenhouse gases to the environment. There is a perfect cycle-electrolysis produces hydrogen from water, and the hydrogen recombines with oxygen to create water and power in a fuel cell. The elimination of economic dependence-The elimination of oil means no dependence on the Middle East and its oil reserves. Distributed production-Hydrogen can be produced anywhere that you have electricity and water. People can even produce it in their homes with relatively simple technology. The Hydrogen Economy While fossil fuels have played an important role in getting society to the point it is at today, there are four big problems that fossil fuels create. Air pollution-When cars burn gasoline, they would ideally burn it perfectly and create nothing but carbon dioxide and water in their exhaust. Unfortunately, the internal combustion(燃烧)engine is not perfect. In the process of burning the gasoline, it also produces carbon monoxide, a poisonous gas; nitrogen oxides, the main source of urban smog; and unburned hydrocarbons, the main source of urban ozone . Catalytic converters eliminate much of this pollution, but they arent perfect. Air pollution from cars and power plants is a real problem in big cities. It is bad enough now that, in the summer, many cities have dangerous levels of ozone in the air. Environmental pollution-The process of transporting and storing oil has a big impact on the environment whenever something goes wrong. An oil spill, pipeline explosion or well fire can create a huge mess. Global warming-When you burn a gallon of gas in your car, you emit about 5 pounds of carbon into the atmosphere. If it were solid carbon, it would be extremely noticeable-it would be like throwing a 5-pound bag of sugar out the window of your car for every gallon of gas burned. But because the 5 pounds of carbon comes out as an invisible gas, carbon dioxide, most of us are oblivious to it. The carbon dioxide coming out of every cars tailpipe is a greenhouse gas that 。