As if the opposition between supporters of electric mobility and the diehards of thermal mobility were not enough, a new duel is now emerging also on the front of the most radical environmentalists. There is always talk of electric traction, but on one side there are supporters of electricity stored in batteries, on the other those of electricity stored in cylinders, in the form of hydrogen. Also in this second case the motor will be electric, but the energy will come from a device called a “fuel cell” which transforms hydrogen into electricity, directly in the car.
A nice assist to supporters of fuel cells was given by the minister for ecological transition Roberto Cingolani stating that battery technology could be "passing"; and maybe in 10 years we will all travel on hydrogen. Even the European Commission, outlining the medium-long term climate plans, has included hydrogen among the solutions necessary to achieve the full decarbonisation of some sectors, referring in particular to industrial applications. This choice is no coincidence: in the fight against climate change it is in fact important to use resources and technologies efficiently; in mobility it is not worth using hydrogen (except in specific contexts, as we will see later). Moreover, the technologies with which this element is produced are still expensive to develop. However, the European Commission will make contributions available in order to accelerate the reduction of their costs, allowing the commercialization of hydrogen on a large scale with the aim of decarbonising the aforementioned applications.
But before understanding where it is best to use hydrogen, we need to evaluate how "clean" it is, and therefore sustainable. It is the most present element in the Universe and therefore it is inexhaustible. However, it is always associated with others: for example, with the oxygen in water (H2O), or to carbon in methane (CH4). Therefore it must be "extracted", providing energy to effect this separation. The vast majority of that in use today, and the only one that can be produced at acceptable costs, is obtained from methane, which is a fossil fuel, through a reaction called stream reforming. It is not sustainable at all, because in the process it releases large amounts of greenhouse gases (CO2) and is in fact defined as "gray" and rejected at the outset.
Many oil and gas companies, ENI for example, work on a so-called "blue" hydrogen which also derives from the stream reforming of methane, but with the simultaneous sequestration and storage of carbon. This process is still not competitive in terms of costs, not free from dispersions of both methane in its production and transport (also a greenhouse gas, with more pronounced climate-altering effects than CO2,) and carbon dioxide, given that the capture and storage process is far from 100% efficient and is complicated by the problem of finding a safe site for underground storage. Furthermore, the whole process requires large amounts of energy to be carried out.
The only truly clean hydrogen is the "green" one. Obtained from the electrolysis of water, it releases only pure oxygen into the atmosphere and does not generate CO2. Bingo? Almost. The electrolysis process requires a lot of energy: three times more than what it can store and subsequently return. Therefore, since it is a scarce resource, green hydrogen is best used only where there are no more efficient alternatives: these sectors are mainly industrial. On the other hand, if one day we really did have 100% "green" electricity, why not use that directly, rather than throwing away two-thirds of it to make hydrogen?
Regardless of all this, the "green" hydrogen electrolysis technology has costs that today are more than double those of the "grey", but numerous studies (including a report of the Energy Transitions Commission) predict that it will become competitive (compared to "grey" hydrogen) by the end of this decade. Finally, hydrogen must be handled with care. It's flammable. It is the smallest molecule in the universe so it can disperse easily if the containers have minimal porosity. Especially since it must be compressed to 700 atmospheres to reduce its volume and transporting it, distributing it and dispensing it is not child's play.
More concretely, the sectors where green hydrogen will see its first industrial applications in the short term are those that already use hydrogen derived from fossil fuels as a raw material: for example, it will be used in the sustainable production of ammonia, a basic product in fertilizers and in many other chemical processes.
Subsequently, acting as fuel will be essential to replace coal and methane in heat-based industrial processes, such as iron and steel, ceramics and cement factories. Even in air transport it seems to be the only alternative to kerosene to fuel jet engines. But transoceanic container ships? The trains that still today travel with diesel engines on lines that are 57% non-electrified? Maritime and rail transport are further areas in which green hydrogen will be able to develop since there is no alternative with accumulators (to date).
To conclude the analysis, the Potsdam Institute for Climate Impact Research sentences that the hydrogen car is a "false promise". And the president of Volkswagen Herbert Diess, says in a tweet: "It has been proven that the hydrogen car is NOT the solution for the climate. False debates are a waste of time. Please listen to the science!" Therefore, unlike the battery-powered electric car that we already see in our cities, we will (almost certainly) never see the hydrogen car in everyday life.
