Hydrogen: everything you need to know in 7 questions

Hydrogen is the smallest and most abundant of the natural elements that make up the universe!

Just like iron and copper, hydrogen is one of the 118 natural elements that are known to make up the universe. Like all elements, it exists in the form of atoms: each atom contains a nucleus, with electrons gravitating around it. Hydrogen’s structure is pretty simple: there’s just one electron which gravitates around a nucleus composed of a single proton.

Hydrogen is the most abundant molecule in the universe with a distinctive characteristic: it definitely can’t be described as a loner! In nature, it almost always combines with other elements, starting with water or H₂O (two hydrogen atoms, combined with an oxygen atom) and fossil fuels/hydrocarbons, in which hydrogen is combined with carbon atoms (petrol = C₇H₁₆).

Hydrogen has dozens of applications in a wide range of fields!

Hydrogen has been used for years in many industries. 

Most of the hydrogen produced today is used to make ammonia (a vital product for the fertilizer industry); it’s also used to refine petroleum products, including desulfurizing fuels. Hydrogen is also used to manufacture electronic components and for rocket propulsion. To support energy transition, new applications for hydrogen are being developed, including in carbon-intensive industries (such as steel and glass) and in mobility (car, bus, truck, train, boat, plane powered by hydrogen).

Hydrogen is also often described as an ally of renewable energy because it can be used to store energy for long periods of time, thereby compensating for the intermittency of renewable energy.

Traditionally, hydrogen has been produced from fossil fuels but it has a low-carbon and renewable future ahead!

Today, around 95% of the world’s hydrogen is still produced from fossil fuels (including methane: CH₄)¹. Specifically, we produce hydrogen through a process called “steam methane reforming” (SMR), which consists of producing a reaction between methane and water giving CO₂ on one side and H₂ on the other. This process thus generates CO₂ emissions.

We aim to convert all our carbon-based hydrogen production methods to decarbonized methods as quickly as possible.

There are already several options to do so:

Still from methane but:

• adding CO2 capture to the steam methane reforming process. Hydrogen produced in this way is considered to be low-carbon.
• using “biomethane”, produced by the fermentation of organic matter such as food waste instead of fossil sources. In that case, hydrogen is considered to be renewable.

And also from… water! 
Electrolysis of water (H₂O) also produces hydrogen by breaking the water molecules with electricity. If the electricity has a renewable source, hydrogen produced in this way is considered to be renewable (ex: from solar energy) or low-carbon (ex: from nuclear energy) giving respectively renewable and low-carbon hydrogen.

Although it isn’t the solution to every problem, the energy transition won’t happen without hydrogen!

There’s no single solution to climate change. Although it isn’t the only solution to the energy transition, it is essential to its success. 

Hydrogen - and its derivatives - is widely acknowledged as the key to achieve a successful energy transition and could account for between 10 and 20% of the energy mix by 2050 (sources: IRENA, the Hydrogen Council), particularly because it can be used to decarbonize industry and heavy transport when there are very few or no alternatives (see question “What is hydrogen used for?”).

Let’s be clear: to decarbonize our society, it’s vital that the hydrogen that’s produced is as low-carbon as possible; otherwise, there’s no point! Luckily there is already decarbonized hydrogen available! Our biggest challenge is now to have enough of it to decarbonize at a large scale. And guess what? Production capacities are being developed and the hydrogen industry as a whole is accelerating!

Hydrogen is a gas. As with any gas, its properties must be understood if it is to be used safely!

Hydrogen is a non-toxic, non-corrosive, non-polluting gas with no known toxicological effects (non-carcinogenic, non-teratogenic*). It can be flammable and/or explosive but is not more dangerous than natural gas or gasoline and some of its properties make it in a way even safer: because it is much lighter than air, it dissipates rapidly when released, whether it be in the open air or in a confined and ventilated space.

In industry, hydrogen has been used routinely for decades in a wide range of applications and has a lower accident rate than the industrial accident rate**.

When it comes to the mobility sector, for which hydrogen applications are being developed, the hydrogen storage tank installed inside the vehicles is designed for this specific purpose. The most stringent tests have shown that a hydrogen car is no more dangerous than a petrol car.

In case of a car accident, in an underground parking or in a tunnel, hydrogen fuel tank safety is guaranteed by ventilation and, in the event of a fire, through the controlled release of hydrogen in the air, resulting in a flame without causing any explosion.

In short, with hydrogen, as with any energy source, protective safety measures must be respected!

Electric battery isn’t always the answer: in some cases, hydrogen is the best choice! It’s all about complementarity and use.

If you’ve been reading carefully, you’ll have understood that producing renewable hydrogen requires the use of electrical energy. Hydrogen can then be used to produce electricity on demand as with a hydrogen car fuel cell, for instance. So, shouldn’t we focus on electric batteries that seem to work well, without bothering with hydrogen production? 

Today, certain applications are perfectly suited to electric batteries, such as passenger cars. 

But in some cases, such as when large quantities of energy need to be stored (which is necessary when traveling long distances or transporting heavy goods), when it is not technically possible to carry all the necessary batteries because of their weight and when refueling times need to be minimized (it takes 30mn to recharge a battery electric vehicle at a fast charging station while it actually takes the same time to refuel a hydrogen car as a car with a regular fuel), hydrogen is an interesting option. We’re convinced that it’s the right choice for applications including heavy transport, captive fleets (like cabs), aviation and maritime industries. Hydrogen is not intended to be used everywhere and at all times. Energy sources will have to be tailored to different uses.

Hydrogen provokes debate and that’s good news!

When it comes to hydrogen, it’s not hard to find critics and supporters. For example, many critics argue that hydrogen is still mainly produced from fossil fuels (that’s right!) and that it’s not advisable to develop its applications.

Air Liquide has been an expert in hydrogen for 60 years. The Group has acquired unique expertise in this gas, from production to storage and distribution. The Group is a firm believer in hydrogen without making it a silver bullet for all applications.  

Indeed, we think that using hydrogen isn’t always the most efficient option especially when electrification is possible. The Group promotes the use of hydrogen as a substitute for fossil fuels in certain industrial processes and in mobility, primarily heavy mobility, captive fleets and the aeronautical and maritime industries. 

As we know that both mobility and industry sectors account for 46% of the global CO₂ emissions, we think that it would be a pity not to take full advantage of such a solution to make the energy transition a success…