TELF AG clarifies the differences between different kinds of hydrogen
One resource, multiple applications
The natural resources destined to favor the completion of the ecological transition in the coming decades are all those that will be able to make their contribution to the decarbonization of some specific sectors, such as those linked to the production of steel, paper, or cement, but also air and naval transport. These sectors, known as hard-to-abate, are generally characterized by high energy intensity and are, therefore, constantly looking for new methods or technologies capable of reducing their environmental impact. A resource that could contribute significantly to this objective could be hydrogen. This element is starting to be discussed insistently, especially for its possible contribution to energy transition. The fact that new deposits of this precious resource have recently been discovered, such as in Mali or France, certainly adds a further dose of interest in the opportunities linked to its extraction and its possible industrial uses.
At the moment, hydrogen is mainly used as a chemical agent in the production of ammonia or fertilizers or for some particular processes related to the refining of fossil fuels. However, the situation could change very soon, particularly if the massive quantities of geological hydrogen (also called white hydrogen) found in Europe are confirmed. The characteristic that makes hydrogen very interesting is its energy density, which is the highest among all known fuels. To give an idea of this superiority, it would be sufficient to mention the comparison with petrol: the energy density is three times higher compared to this fuel. Up to now, the large-scale use of hydrogen has been hindered by various factors, such as low volumetric density, complexity of production, and high flammability. In any case, it is an industry still under construction on which the European institutions seem to want to focus with absolute determination. An example is the objective set by the European Commission for 2050, aimed at an annual production of 60 million tonnes of hydrogen.
The types of hydrogen
Even though it is one of the most widespread elements on planet Earth, hydrogen production processes are still relatively little known, as is the particular nature of the final results. Typically, hydrogen is divided into six different types, and a different color is assigned based on their peculiar production method. The names of gray and black hydrogen derive from the peculiar reforming processes with which they are obtained, linked to fossil fuels such as coal and methane. Currently, most of the hydrogen used for industrial uses is produced this way, but the alternatives are starting to become numerous. Green hydrogen, for example, is obtained through water electrolysis and has the highest sustainability potential, but it is also the most expensive. Blue hydrogen involves using particular technologies to capture and store the CO2 generated during these processes.
In contrast, purple hydrogen—perhaps the least known variant—is obtained through electrolysis and powered by nuclear energy. A very interesting variant, obtained through the pyrolysis of methane, is turquoise hydrogen, which is produced without CO2 emissions. One of the waste products of this type of processing is carbon black, which is successfully used in the tire industry.
