Energy

The hydrogen energy industry

The use of hydrogen as an energy source is becoming increasingly prolific. This is because the benefits of using hydrogen to heat our homes and fuel our cars are undeniable, and the reality is that the world is starting to adapt to be able to accommodate the use of hydrogen.

There is a growing understanding that pure hydrogen is the ‘ultimate’ clean fuel which certainly makes it seem futuristic. Indeed, it has its roots in the stars in more ways than one as not only is it one of the most common elements in the world and stars around us, but hydrogen fuel cells were also used to
provide onboard electricity for the Apollo 11 moon landing in 1969.

When hydrogen is burnt it reacts with oxygen in the air to produce only energy and water, as opposed to releasing carbon dioxide like natural gases.

However, the production, processing, storage and use of hydrogen presents significant challenges. This is because the materials required to transport it and store it safely have to have an extremely high strength to withstand high pressures and resist extremely low and high temperatures.

The good news is that stainless steels, especially austenitic grades, are ideally suited to meet the challenges of hydrogen.

Stainless steel as hydrogen storage

Usually, when hydrogen is stored and transported, it is liquified which means that its temperature has to be reduced to as low as -253°C. Austenitic stainless are safe to use in this situation and they can cope with this environment as they have a very high ductility.

Another way in which hydrogen is stored and transported is to compress gaseous hydrogen at high pressures, which can sometimes as high as 800 bar. In a worst-case scenario, this could lead to hydrogen embrittlement in some materials because the diffusion of the hydrogen gas into the surface of the material storing or transporting it could eventually result in cracking. Again, austenitic stainless steel is the steel of choice in this scenario because hydrogen diffusion is much lower in austenite, compared to ferrite and martensite metals.

Since many storage facilities will be in coastal areas with a salt-laden environment, the corrosion resistance of stainless steel becomes an important factor. The natural extension from storage is to filling stations, such as for refuelling a fuel cell vehicle. The properties of stainless steel make it ideal for the manufacture of fuel dispensers, tubes and compressors.

Stainless steel and hydrogen fuel cells and electrolysers

Specialised fuel cells are used to convert hydrogen and oxygen into energy and water, while electrolysers use energy and water to create hydrogen and oxygen. Stainless steel is yet again the metal of choice and can be found in many of the components that make these processes possible. These include interconnectors, the substrate for bipolar plates, anode- and cathode- plates, endplates, frames and connecting parts.

The actual grade of stainless steel that is chosen will depend on the operating temperature and environmental conditions. Stainless steel’s ability to resist corrosion, as well as its high strength means that the dimensions and size of the components can be optimised for each situation.

Electrolysis and stainless steel

The process of electrolysis is used to produce hydrogen energy. It occurs when an electric current is used to split water into hydrogen and oxygen. One of the most exciting things about this process is that the electric current can be produced through renewable sources, such as solar or wind. This means that the resulting hydrogen can be considered renewable as well.

To make this process possible, stainless steel is required to make many of the processes possible that are needed for water desalination and purification. Its ability to resist corrosion makes it a perfect metal in this situation. The actual grade of stainless steel used will be dependent on the water composition and temperature.

The future of hydrogen and stainless steel

Some of the applications used to create and harness hydrogen energy are already established, while others need much more research and development. One of the biggest areas of development will be the infrastructure required to ensure that the production of hydrogen energy is as efficient as possible and so that it can reach the people that need it and use it the most.

Many innovative and dynamic industrial companies are working hard on these solutions and new processes, techniques and developments are coming to light every day.

What cannot be denied is that hydrogen and stainless steel will always be interconnected as the properties of stainless steel make it the ideal metal to be used in this industry. Stainless steel’s ideal combination of electrical conductivity, high corrosion resistance, excellent formability, high strength and performance means that it will remain an important part of the worldwide efforts to reach net zero carbon through the use of hydrogen energy.