our new hope------ green energy: Post 7 : Hydrogen Economy

Hydrogen Economy

1. Definition

"The hydrogen economy is a proposed system of delivering energy using hydrogen. The term hydrogen economy was coined by John Bockris during a talk he gave in 1970 at General Motors (GM) Technical Center."(1#)

2. Using hydrogen as a kind of fuel

A process of using hydrogen as a fuel can be divided into three parts. They are production, storage of hydrogen and generation of electricity.

(1) production of hydrogen

Actually, there are tons of ways to produce hydrogen. I will only introduce two of them. One is "steam reforming" and the other one is "electrolysis".

steam reforming : Use hot steam to separate hydrongen from hydrocarbon(碳氫化合物). This method is the cheapest one among all hydrogen-production so far. It is obviously that this process need a lot of energy(heat). However, if the energy used in this production come from fossil fuel, the goal of "zero-emission" won't be achieved. Thus, it is quite a challenge of this method.

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electrolysis : Eletrolyze(電解) water to obtain hydrogen and oxygen. Since water is a weak electrolye, so we often add some strong electrolye, such as acid, base and salt to provide enough ions. Notice that this process need electricity. Green energy like solar power and wind power are ideal sources of the electicity needed. However, as I mention in my previous post, we haven't found economic way to take advantage of these green energy yet. Fossil fuel is still the cheapest fuel so far.

(2) storage of hydrogen

Since hydrogen is a dangerous gas, the storage of hydrogen is very difficult. The most common way to store hydrogen is to fill hydrogen into a iron jar with high pressure (about 100 atm). I think you guys are familiar with the gas storage tank in our campus. And there is also a method of storing hydrogen with a kind of alloy(合金) called "hydrogen storage metal". It is said that we can use lower pressure to store hydrogen through this alloy.

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(3) generation of electricity

It will too much content, if I introduce the way of generating electricity by hydrogen in this post.(I promiss I will talk anout it in next post) So, I will talk about one of the example of using hydrogen as a fuel, hydrogen car. A car hydrogen car(pic.3) is powered totally or partly by hydrogen fuel cell(I will talk more about it next time). Just like cars using fossil fuel, hydrogen car also need "gas" stations(pic.4) to fuel up.

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