Dangers of Hydrogen: hazards and industrial risks

Green hydrogen, the new Eldorado

The hydrogen plan in France

Over the last few centuries, the intensification of human activity has led us to reach many planetary limits, such as the depletion of our ecosystem and natural resources. Another issue is the concentration of CO2 in the atmosphere and the quantity of greenhouse gases emitted, which are directly correlated to global warming and climate change.

In order to face this energy crisis, reinforced by the current political and economic context, the States have committed themselves via the Paris agreements to contain global warming (target limit of 2°C between 1850 and 2100). The objective is to reduce emissions but also to substitute the need for fossil fuels with the development of new sustainable and renewable energies.

At the heart of these alternatives, hydrogen is considered the future fuel. hydrogen can be produced, stored, transported and used. On the national level in France, the hydrogen industry is supported by 7 billion euros in funding, with a strong ambition for 2030: to develop green fuel, totally carbon-free hydrogen.

This implies the large-scale deployment of manufacturing techniques (steam reforming; partial oxidation; gasification; electrolysis) and the systematic consideration of the contribution vs. energy cost balance (Carbone 4 study - October 2022: Low-carbon hydrogen: what are the relevant medium-term uses in a decarbonized world?)

An industry in mutation

There are many players, as well as strategies to exploit the energy contained in hydrogen.

• Some players envisage that the hydrogen is reinjected in gaseous form into a network of dedicated pipelines, either in its pure form or mixed with another gas, depending on market needs.
• Others consider a preliminary storage step, via a fuel cell. In this case, the hydrogen fuel will be stored in gaseous or liquid form, and then used in a second step for electricity production.

If we reason globally, some factors will play a crucial role in this approach, notably the means of distribution, routing and storage of this energy on the territories in order to decarbonize the uses concerned (mobility, industry, heating / powering buildings, additional energy...).

The question then arises: what are the risks involved in handling hydrogen and how can these installations be made safe?

The safety issue of hydrogen

The safety issues surrounding hydrogen are real. One of the major difficulties is the youth of this industrial sector, which is still under construction and whose deployment model is still uncertain.

Hydrogen, a flammable gas

First of all, hydrogen is a low toxic gas. However, it is extremely flammable and reactive.

This gas has the capacity to form explosive mixtures with air within very large limits (4 to 77% by volume) and even explode spontaneously in case of a strong rise in temperature or pressure (massive leak in tens of bars) (source INRS).

As a reminder, a combustible gas or liquid can ignite in contact with an oxidizer (pure oxygen, enriched air or natural air) within the limits of the proportions of the mixture known as the lower explosive limit (LEL) and the upper explosive limit (UEL) and in the presence of an energy input. Below the LEL, the mixture does not contain enough fuel to ignite and above the UEL it does not contain enough oxidizer to ignite.

Source ADEME : Information guide on risks and safety measures related to decentralized hydrogen production

The risks of hydrogen leaks

Taking into account the flammability of hydrogen is an omnipresent problem in industry for the protection of people and equipment, both on production and energy transformation sites and during transport or storage.

In all cases, the risks of leakage are significant. According to scientific estimates, the production and use of one ton of hydrogen could release between 5 and 30 kg of this gas. This range would have the same impact on the climate as 1 to 6 tons of CO₂.

Hydrogen being a very flammable gas, the dangers of explosion and fire are real and can have great consequences.

A challenge of training and awareness

Whatever the emerging uses, the handling of a highly flammable gas requires awareness and training for many players.
Everyone, at their own level, must be aware of the need to make industrial sites safe, whether they are neophytes or already have experience with other types of energy (natural gas, for example).

This awareness-raising process should involve all players: manufacturers of storage units (tanks, batteries), mobility players (automotive, rail, air & space, etc.), infrastructure installers (distribution, recharging stations), not to mention contractors in charge of their maintenance.

Innovation in the service of safety

What means exist to detect hydrogen leak?

Today, there are different methods to detect hydrogen. The classic approach of using soapy water to create bubbles on each candidate component can be used.

There are also microelectronic hydrogen sensors (sniffers) that work with semiconductors, by catalytic oxidation. These devices are very efficient for some uses but have some limitations. In particular, they require an energy supply (electricity), which is not always possible, and which leads to a significant risk of explosiveness.

In addition, the detection is localized, punctual. For example, the use of electronic sensors to monitor the possibility of a hydrogen leak along a pipeline is impossible. It would require the installation of a complex network of sensors.

Where to detect hydrogen leaks?

The major difficulty in detecting hydrogen is the multitude of places to inspect. Traditionally, with a conventional gas, the main cause of leakage is located around the connections, junctions and welds.

With hydrogen, the situation is much more complex. Hydrogen molecules are small. The origins of hydrogen leaks are multiple:

• Permeation through certain types of materials due to the very small size of the hydrogen molecules,
• Wear of critical parts due to corrosion or simple mechanical fatigue,
• Leakage inherent to a bad crimping, tightening but also after exposure to repeated vibrations,
• Complete rupture following an external shock, an overpressure, or a sudden rise in temperature.

Color change paints: hydrogen leak detection

Using our unique know-how in color intelligence, our teams at OliKrom's research and development department have designed and produced color-changing materials with the aim of tracing hydrogen leakage.

We exploit the properties of certain chemochromic materials that are capable of changing color under the influence of a gas.

The production of hydrogen reactive inks and paints is a valuable tool for predictive maintenance and industrial safety. It allows to track hydrogen leakage on large surfaces, and in their entirety (tanks, metallic structures or technical textiles) whatever the environmental conditions: indoor or outdoor use, exposure to frost, strong heat, bad weather.

The use of color-changing inks and paints to signal a hydrogen leak has the advantage of being understandable by everyone, without the need for a computer.
Another advantage of this approach is that it is a chemical phenomenon programmed on the scale of the material, which does not require any energy or electricity. The change of color occurs autonomously, only when the detection threshold is exceeded.