A study led by scientific researchers at Universidad Carlos III de Madrid has detected unexpected physical behaviour of hydrogen gas when it burns. The flames are able to survive in more extreme conditions than previously thought.

Hydrogen can propagate in incredibly narrow gaps. It can burn with very little fuel. It extends itself by breaking up into fractal patterns.

Lead Researcher Fernando Veiga says, “Our article shows that hydrogen flames are capable of propagating in very narrow spaces of a millimetre or so, creating an undesirable and dangerous situation”.

Using hydrogen as a fuel can help reduce carbon emissions. But there are certain risks in the storage and transportation of it. This study has shown that hydrogen can burn in unexpected situations. Even when its concentration is as low as 5% in volume.

Hydrogen flames are practically invisible to the naked eye. They also emit very little heat. So researchers had to use a high-speed camera to trace their movement during propagation.

Another Lead Researcher, Mario Sanchez Sanz, points out, “The video recording reveals this fractal path, which precisely permits the flame efficient access to new fuel as it burns”. 

Hydrogen is a clean and efficient energy. Technologies based on its use will increase rapidly in the near future. The design and safety of these technologies will need to take this study into consideration.

The results are also useful to engineers involved in hydrogen storage solutions, such as hydrogen fuel cells in cars. A leak and its accumulation in a confined space could lead to flames.

More studies are required to assess safety in relation to leaks. But in the context of reducing greenhouse gases and climate change, it seems imperative now to accelerate the development and use of hydrogen-based energy technologies.

The study containing details of the results has been published in the journal Physical Review Letters.