Is hydrogen a dangerous gas? What about explosions and fires? Is it an expensive fuel that can never compete with gasoline? And what about its production? At DEVINN, we looked at the most common misconceptions and myths associated with hydrogen. And because we consider this light gas to be the fuel of the future, we want to set the record straight.
Probably the most common label for hydrogen is its potential danger. As we mentioned in an earlier post on hydrogen safety, the Hindenburg airship explosion or hydrogen bomb experiments have given the fuel the stigma of being extremely unstable and explosive.
But this reputation hydrogen carries largely unfairly. NASA scientist Addison Bain, for example , says that hydrogen played no role in the explosion of the Hindenburg. By comparison, Hindenburg's sister airship, the Graf, flew over a million miles without mishap.
Today, hydrogen is comparable in safety to fossil fuels such as petrol and CNG. The physical properties of the element even speak in its favour - thanks to its lightness and higher ignition temperature, hydrogen burns later and in less dangerous places compared to other fuels. While the underside of the car is more likely to catch fire when a tank of petrol ignites, the potential for a hydrogen fire is more likely to occur a few tens of centimetres above the vehicle.
However, the likelihood of ignition is very low due to the quality of the storage in pressure vessels. Even though the hydrogen is stored in the tank at pressures of hundreds of bar, the tanks are equipped with a number of safety systems that perfectly address issues such as overpressure venting. The tanks have to pass a number of destructive tests, one of which is the puncture test, without which the tank cannot be used.
Hydrogen also has an undeniable advantage over other fuels in that it is not toxic to humans or nature. "Hydrogen itself is neither dangerous nor toxic, and there are no proven negative effects in breathing or in contact with fauna. It is important to be aware of the risks associated with hydrogen as with any other fuel - to respect it, but not fear it," adds Karel Souček, DEVINN's development director.
Another oft-repeated myth is the claim that it is not entirely easy to produce and is therefore expensive and difficult to obtain as a fuel. However, this is not entirely accurate either.
Hydrogen can be produced in several ways, and the method of production obviously has an impact on the final price of hydrogen. The basic option, which offers great possibilities due to its simplicity, is electrolysis. And yes, this is indeed the experiment from primary school chemistry lessons, where two electrodes immersed in a container are used to break down water into hydrogen and oxygen molecules.
This method is very ecological, but at the same time the least economical in terms of efficiency - the efficiency of this process is around 55-60%, 60 kWh of energy is needed to produce one kilogram of hydrogen by electrolysis.
The price for the lower efficiency of this process is location independence - this way, hydrogen can be produced anywhere there is water and electricity. Electrolysis can thus serve as a process for storing electricity: using the electricity generated from a solar or hydroelectric plant, we can produce hydrogen that can later be used as fuel in, for example, our H2BASE hydrogen generator. This method is also ideal for using surplus electricity within the transmission grid.
For economic reasons in particular, however, around 95% of the world's hydrogen production today comes from steam reforming of natural gas, which produces so-called grey hydrogen. This method is, however, generally on the decline in favour of greener forms of fuel production, which are also beginning to gain support from international organisations, led by the European Union. Support is mainly being given to green hydrogen produced using electricity from renewable sources.
Hydrogen is also produced as a by-product of many processes in the petrochemical industry, and such hydrogen is often not efficiently recovered despite its relatively large quantity.
But what about hydrogen storage? There are many myths about its complexity and material requirements.
The standard and easiest method of storage is the carnival balloon method, where hydrogen is forced into a pressurised vessel under a pressure of hundreds of bar. Thanks to decades of development, these containers are technologically very advanced and the easiest to use in practice.
A frequent objection to storage in pressure tanks is the alleged leakage of hydrogen due to the small size of the molecule - but even this is no longer true: "Historically, this was a problematic discipline, but today the problem has been solved with modern materials and procedures - the leakage is below a measurable value," says Karel Souček about another myth.
Hydrogen can thus be produced using electricity and stored indefinitely in a pressurised vessel where the fuel does not degrade or leak. No conventional fuel has similar properties, and this is what makes hydrogen the fuel of the future.
For bulk storage and transport, hydrogen should be deeply subcooled and liquefied. The energy density stored in liquid hydrogen is enormous, but it is a technologically demanding cooling device and needs to be cooled constantly as the surroundings keep heating up the contents.
For low-energy applications, a very promising method of storage in metal compounds is so-called hydrides, where hydrogen is bonded to metal molecules and the hydrogen is transported in the form of metal powder, so there is excellent safety and refuelling, but the energy density is worse than for pressurised storage.
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