MAKING HYDROGEN GAS

Hydrogen is a gas that is colorless, odorless and tasteless. Hydrogen or H2 has an energy content per unit weight of the highest, compared with any fuel. Hydrogen is an element that is chemically very active, so rarely found in free form. In nature, hydrogen is present in compound form with other elements, such as with oxygen in water or with carbon in the methane. So to be able to use them, the hydrogen must first be separated from their compounds to be used as fuel. There are several methods of making hydrogen gas that we already know. However, all methods of making the same principle, namely to separate hydrogen from other elements in compounds.

Each method has advantages and disadvantages of each. But in general the parameters that can be considered in choosing a method of making H2 is the cost, the resulting emissions, economic feasibility, scale of production and raw materials. Now let us discuss one by one his methods.

1. Steam Reforming
In this process, natural gas such as methane, propane or ethane is reacted with steam (water vapor) at high temperature (700 ~ 1000oC) with the aid of a catalyst, to produce hydrogen, carbon dioxide (CO2) and carbon monoxide (CO). A side reaction also occurs between the carbon monoxide with steam, producing hydrogen and carbon dioxide. Equation that occurs in this process are:

CH4 + H2O -> CO   + 3H2
CO   + H2O -> CO2 + H2

Hydrogen gas is then purified, by separating carbon dioxide by absorption.
Currently, steam reforming is widely used to commercially produce hydrogen gas in various industrial sectors, including the fertilizer industry and hydrogen peroxide (H2O2). However, this kind of production method depends on the availability of natural gas are finite, and produces CO2, a greenhouse gas effect.

2. Biomass Gasification
The second method is the gasification of biomass or natural materials such as straw, household solid waste or dirt. In the process, the materials were heated at high temperatures in a reactor. This heating process resulted in the molecular bonds in compounds that have become fragmented and produce a gas mixture consisting of hydrogen, carbon monoxide and methane.
Furthermore, in the same manner as in steam reforming, methane is converted into hydrogen gas.
Gasification of biomass or organic material has several advantages, among others, produces less carbon dioxide, a source of raw materials are abundant and renewable, can be produced in almost all places in the world as well as cheaper production costs.

3. Coal Gasification
Coal gasification is the oldest method of making hydrogen gas. Cost of production almost doubled compared with the method of steam reforming of natural gas. In addition, this method also produces exhaust emissions are more significant. Because CO2 is also produced in addition to sulfur compounds and carbon monoxide.
Through this way, the coal is first heated at high temperatures in a reactor to convert the gas phase. Furthermore, coal is reacted with steam and oxygen, which then produces hydrogen gas, carbon monoxide and carbon dioxide.

4. Electrolysis of Water (H2O)

 

 

Electrolysis of water use electric current to decompose water into its constituent elements, namely H2 and O2. Hydrogen gas appears at the negative pole or cathode and oxygen together in a positive pole or anode.
Hydrogen produced from water electrolisa process could potentially produce zero emission, if the electricity used is generated from pollution-free electricity generators such as wind or solar thermal energy.
However, in terms of energy consumption, this method requires considerable electrical energy.
Well, besides the four methods above, there are still other methods for producing hydrogen gas, which among other photoelectrolysis, decomposition of water at high temperatures (themal decomposition of water), photobiological production, plasmatron, fermentation of organic materials and others.