A few days ago, Toyota unveiled its definitive commercial commitment to the hydrogen fuel cell, materialized in . This element, the most abundant in nature, is also the cleanest in terms of emissions of those considered as substitutes for fossil fuels.
However, since it hardly exists freely in nature, to obtain it in large quantities requires an industrial process to which the Total company dedicates a recent informative report.
On Earth, hydrogen is often bound to other elements. The most abundant association is with carbon, with which it forms methane gas, and with oxygen to form the most abundant liquid on our planet, water. The cleanest way to obtain unpolluted methane during the industrial process is to use renewable energies such as wind or solar energy to produce electrolysis that releases hydrogen molecules.
Today, 95 percent of hydrogen is obtained from fossil energy sources: natural gas and oil, or biomass derived from wood. There are three industrial methods to obtain hydrogen: molecular transformation, carbon gasification and water electrolysis.
The first technique consists of the use of chemical reactions to obtain hydrogen from natural gas from oil fields. Water vapor at very high temperatures is used to dissociate the carbon from the hydrogen that makes up natural gas. In two successive reactions, it gives rise to dihydrogen on the one hand and carbon dioxide on the other.
In the case of coal gasification, a reactor is used to burn the coal at very high temperatures. Combustion releases gases that give rise to dihydrogen on the one hand and carbon monoxide on the other.
inexhaustible resource
Finally, the electrolysis of water is the most environmentally clean method of the three, as long as non-polluting solar or wind energy is used in its process, as we have already pointed out. For this method of obtaining hydrogen, a large amount of electrical energy is needed, which is not always available. This circumstance means that, for now, electrolysis is not generally profitable in obtaining hydrogen directly from water. The use of surplus electrical energy when the consumption cycle declines would be a good way to generate hydrogen at reduced costs.
The prospects of hydrogen as an inexhaustible source of storable energy to replace fossil fuels has led to new avenues of research. Still in the experimental period are photosynthetic techniques that obtain hydrogen from microorganisms, photoelectrolysis applications by immersing photoelectrochemical panels that decompose water using solar energy, and the direct decomposition of water using nuclear energy with the dependence on uranium that this implies.
Although it is difficult to quantify today the price of hydrogen in its application for transportation, it is estimated that in comparable quantities it would be on par with gasoline. But keep in mind that the demand for this type of fuel in the car is still practically non-existent. As the need for automotive hydrogen increased, industrial costs would decrease, making this fuel progressively cheaper.