How Hydrogen is Produced: Techniques and Main Differences

THE’hydrogen is one of the fuels more interesting for the Energy future of humanity. If we start from 100% pure hydrogen its combustion is in fact among the least polluting in the world, with the only combustion product being water. Furthermore the possibility of obtaining it also from renewable sources makes it a good ally in the fight against climate change. However, producing hydrogen has a very high energy costwhich could potentially reduce its benefits in real-world application, at least for now.
There energy source used to produce it ultimately determines the real sustainability of this biofuel.
But what are the differences between hydrogen, green hydrogen and biohydrogen? It depends on the production method.

Methods for hydrogen production

Hydrogen can be produced through different techniques, some more impactful than others.
Among the first methods to be discovered are those that involve the use of fossil fuels and those that are based on thewater electrolysis. However, if we compare costs and revenues we immediately see that these methods are, unfortunately, not very convenient on the energy front.

THE’water electrolysis has been made more sustainable in recent times by allowing the formation of the so-called green hydrogenbut perhaps the most interesting methodology among those developed to date is the one that exploits microorganisms such as algaeTo simplify, we can divide the production methods into renewable And non-renewablebased on the energy source used (and therefore on the real environmental impact of hydrogen itself) and above all on the production method.

Non-renewable hydrogen production

By “non-renewable” we mean hydrogen produced from sources that are not renewed in human timeswhether they are sources of matter or energy. To simplify, we can say that even if hydrogen is sustainable, if it has been produced in a non-renewable way – whether material starting (such as oil or coal) or for energy (like that from fossil fuels) – it becomes non-renewable and takes the name of grey hydrogen.

Hydrogen from fossil fuels

Hydrogen can be obtained through some processes involving non-renewable raw materials such as the process of reforming from petroleum, methane cracking And coal gasification.

In the case of reforming, through treatments that require large amounts of energy, the hydrogen atoms present in the organic molecules of petroleum are released. This process, in addition to requiring a lot of energy (both for the extraction of the raw material, the treatment, and the subsequent purification phase), has the enormous disadvantage of releasing carbon dioxide.
In cracking, on the other hand, the methane molecule is broken, with the consequent release of thehydrogen and carbon atoms mainly in the form of carbon monoxide (CO).
The last process is gasification, which involves reacting coal with water to obtain hydrogen and carbon monoxide.

Electrolysis of water generates hydrogen and oxygen

A final methodology within this category is that of water electrolysis. Essentially what is done (as you can see in the image below) is break the water molecule by electric current obtaining oxygen (O2) and hydrogen (H2) molecules, breaking the bonds that hold them together.

Hydrogen from renewable sources

All the procedures just seen require large energy investments which make the entire process less sustainable, causing the loss – in part – of the advantage of cleaner combustion.

Green hydrogen

One of the possible solutions to obtain hydrogen with a lower environmental impact is to use only energy from renewable sources in the electrolysis process. In terms of efficiency, energy is lost but a gain is made. zero emission fuel without all the disadvantage of the environmental impact linked to its creation. The process is the same as the electrolysis seen previously but what changes is the energy source usedIf energy comes from non-renewable sources such as coal and oil, the process is unsustainable, but it is much better if electricity is obtained from wind, solar or wave power.

Biohydrogen from algae and other plants

Biohydrogen is hydrogen produced by organic meansobtained thanks to some H2-generating microorganisms (mainly algae) such as waste product of one’s metabolism.
The production process takes place in the bioreactorsspecial “ovens” used to facilitate the growth of microorganisms. These structures allow you to regulate parameters such as temperature and pH to favor the growth of the microorganism in question.

The main advantages of this technique are several. First of all, since algae are autotrophic organisms, the amount of nutrients necessary for their cultivation (and indirectly the costs) will be very lowFrom a waste point of view, combustion It does not produce waste but it releases water molecules, mind if we want to look at the CO2 emissions This technique has a very low environmental impact. To conclude, no food is used but food waste and there is no need for agricultural land since the whole process takes place in bioreactors.