A P.E.M. fuel cell has two sides separated by a thin substance or membrane. Hydrogen gas is forced through one side where it comes in contact with a reactive material containing the metal platinum.
The membrane separates the electrons(电子) from the protons(质子) in the hydrogen atoms(原子). The protons pass through it to the other side of the fuel cell. But the electrons are captured to do work: like powering a motor.
Oxygen from the air is forced into the other side of the fuel cell. There, the gas meets the protons that have passed through the membrane. They combine to form water and heat.
A single fuel cell does not produce a lot of electricity. But when many fuel cells are combined, they can produce enough electricity to power a vehicle. The product of the chemical reaction that powers fuel cells is water. This makes fuel cells a very clean technology.
But fuel cell cars have been slow to develop because of many technical problems that have to be solved. For example, it is unclear how long the membranes in P.E.M. fuel cells will last.
Also, fuel cells need water for their chemical reactions. They must be designed to start easily in low temperatures and in dry climates. And smaller, less costly fuel cells must be designed before they can truly take the place of gasoline engines.
There are more models of fuel cell vehicles being tested than ever before. The threat of climate change and the high cost of oil has increased interest in these vehicles that do not cause pollution. But car buyers should not expect to see fuel cell cars at their local dealer any time soon. Automakers say they will not build many fuel cell cars until hydrogen fueling and service stations are widely available. And that will cost billions of dollars and years of effort.
【考前30天之备战2017高考英语精品学案:专题四 任务型阅读 第一节 任务型阅读解题方法突破 要点导学】相关文章:
★ 湖南省长沙县实验中学2016届高三英语二轮复习书面表达复习重点话题指导专题02 报道评论话题指导(学生版)
★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (12)
★ 2017高考四川省广安市英语阅读理解一轮系列训练:18(含解析)
★ 【外研英语,七省专用】2014《走向高考》英语一轮总复习(2016春出版)第一部分 教师讲义手册:选修七专项语法突破13
★ 【三维设计】2017届高考英语(江苏专用)二轮复习阅读理解解题技法示范课件:9
★ 【优化方案】2017届高考英语二轮复习全国卷Ⅱ题型重组训练:第12组(含解析)
★ 【课堂新坐标】2017届高考英语(通用版)二轮复习短文改错专题训练:模式1 缺一词(含解析)
★ 浙江省湖州市2014高考英语阅读理解一轮(暑假)精炼(1)含答案
★ 2017年高考英语二轮复习精品资料:专题14 阅读理解(押题专练)(原卷版)
★ 【三维设计】2017届高考英语(江苏专用)二轮复习阅读理解解题技法示范课件:6
最新
2017-04-24
2017-04-24
2017-04-24
2017-04-24
2017-04-21
2017-04-21