The hazards of Hydrogen – and how to handle them

Hazards are just problems to be solved.  When you know enough about the hazards posed by a substance, you can begin to develop ways and means of getting them under control. This is certainly as true for Hydrogen as for any other substance.

Hydrogen: An essential element in the energy revolution – despite the dangers

Whenever the Science teacher handed out safety goggles and told all of us to stay in our seats, that's when you knew something exciting was about to happen.  After all, is it real chemistry unless it's smelly or noisy or even better both?  Our teachers were always delighted to demonstrate this to us in a number of ways. The one that I really remember is the oxyhydrogen test.  Who would have thought that a seemingly empty test tube, sealed with a plug, and a small candle would cause such a reaction?  Almost as soon as the plug was removed and the test tube held over the candle flame, we hear chemistry at work. Sometimes a squeak, sometimes a pop or even a real bang.  Students watching closely would have noticed a few droplets in the test tube. The lesson? Hydrogen (the invisible gas filling the test tube) and oxygen (around and inside the tube) and a flame (or, more precisely, ignition energy) combine to produce an explosion however small, as well as a small amount of water.  This experiment sounds harmless, and relatively it is. However, many people think of much more dangerous situations when they think of Hydrogen. 

In fact, Hydrogen has been a factor in several accidents throughout history. Of course, the most famous happened in 1937, when the Hydrogen-filled Hindenburg airship caught fire, whilst this would also have happened with other gases, the explosion was very severe.

Less well known is the accident at the Polysar styrene manufacturing plant in Sarnia, Canada. In 1984, a hydrogen gas leak occurred there, resulting in an explosion. It claimed two fatalities and caused damage within a radius of up to one kilometre. So Hydrogen definitely has a considerable explosion energy.

Hydrogen is a key energy storage medium for renewable energy

We believe that using these negative examples may not be particularly the best way to discuss the hazards involved in working with hydrogen.  However, the bottom line is still that hydrogen can burn and even worse it can explode. Despite this, the industry is excited with talk about hydrogen being responsible for a major part of the decarbonization journey including combustion, home and industrial heating, vehicles and balancing the electricity grid (particularly with respect to renewable energy generation). So, can these two perspectives coexist? To put it concisely: Yes, hazards are there to be overcome. We are used to this concept when dealing with conventional energy sources, such as oil, petrol, and gas. When you know enough about the hazards posed by a substance, you can begin to develop ways and means of getting them under control. This is as true for hydrogen as for any other flammable substance.

It is a fact that hydrogen will play a key role in the future mix of energy sources. After all, solar and wind power will soon be some of the most important energy sources when it comes to satisfying global demand for power. Solar and wind power supply almost inexhaustible supplies of energy, in that they are renewable and not finite.  However, these two primary energy sources are not consistently available and are rarely predictable. They are highly weather-dependent, furthermore the sun doesn't shine at night and the wind doesn’t below all of the time. Therefore, there is an enormous problem regarding supply and demand. The transition to renewable energy sources can only succeed if we solve the problem of storing the power generated using solar and wind energy.

Hydrogen is a key energy storage medium for renewable energy

Existing technology such as batteries are insufficient to provide the necessary levels of storage. This is where hydrogen has the answer. With the power-to-gas process, it can be generated at any time through the electrolysis of water when there is over supply of electricity compared with the demand. The gas can then be stored and/or transported over long distances. When electricity demand outstrips supply, the hydrogen can be converted back into the electrical energy required via fuel cells or hydrogen fired turbines.  

The processes involved must be performed in a safe manner that pose no danger to people or the environment. As stated earlier, hazards can only be overcome if you know them well. In the case of hydrogen, it is particularly the risk of fire and explosion that it poses if certain conditions are met.  For example, a hydrogen-air mixture with a hydrogen concentration of between 4% and 77% by volume is flammable. It is also important to know that most ignition sources lead to the ignition of an explosive hydrogen-air mixture. The dangers posed by cryogenic liquid hydrogen are also special. So before considering the use of hydrogen as an energy carrier, be sure to read and understand in detail about the properties of hydrogen and its hazards.

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