school energy&environment

Using hydrogen

The annual production of hydrogen amounts to 500 billion cubic metres, corresponding to 44 million tons, that are obtained as follows: 90% is obtained from the reforming chemical process of light hydrocarbons (mainly methane) or from the cracking of heaviest hydrocarbons (oil) and 7% from coal gasification. Only 3% comes from electrolysis.
Hydrogen can be used to produce other compounds or as a fuel to produce energy.
In particular, the hydrogen produced is used in the chemical industry, to produce ammonia, methyl alcohol (methanol), fertilizers for agriculture and oil products, as well as being used in the metallurgic industry for metal treatment.
Hydrogen is also an excellent fuel. It can be used to produce energy in two ways. The first method is by burning hydrogen alone, or added to other fuels. The second method is based on a chemical reaction between hydrogen and oxygen (without burning it), obtaining electric energy directly through a device called fuel cell.
Directly as a fuel
The combustion of hydrogen does not provoke particular problems and produces emissions that are much less polluting than other fuels. Combustion in the air produces water, un-burnt hydrogen and traces of ammonia. Thus, using this gas to supply a household boiler or a car engine, energy would be produced avoiding the emission of toxic substances. For a few years now, hydrogen vehicles have been circulating experimentally. Moreover, any other fuel mixed with hydrogen improves its combustion and efficiency. Therefore, in the United States the use of methane to which hydrogen is added in the tune of 15% of the weight – commercially known as Hythane – is being assessed.
Fuel cells
Hydrogen can be used to supply cars operated with fuels cells.
Liquid hydrogen is also used as a fuel for the cells that supply electricity to activate the equipment on board of space ships. The water obtained as a by-product from fuel cells can be drunk by the crew.
As well as in transports, fuel cells could be usefully applied in buildings.
Finally, hydrogen could soon supply many popular electronic devices, such as mobile phones, laptop computers, toys, that today require heavy and expensive batteries. A miniature fuel cell is light, cheap and lasts longer than an ordinary battery. Mobile phones, for example, could work constantly for months, and it would be sufficient to periodically buy a small tube of fuel rich in hydrogen (such as methane or methanol) to be inserted into the device, in order to supply the small fuel cell.