Security and Safety

Here both security and safety aspects are explained:

  • Security of the provision of energy.
  • Safety from accidents with hydrogen.

     As a result of the high import dependency of German energy supplies, the security of its energy provision is constantly threatened. That also limits German political independence. In a sustainable hydrogen economy all energy comes from the surrounding region. Even if sun, wind and water fail, the energy provision in all energy sectors is always ensured, as biomass is available as a dispatchable primary energy source, from which hydrogen can be produced just in time. That is as it used to be, when our coal-fired power stations could adapt to electricity demand second by second, because coal lay right at our front door.
     In contrast to coal-fired power stations, hydrogen plants do not have to be designed to meet peak demand, because gas reservoirs available in the gas network can buffer hydrogen for weeks or months. As hydrogen is the basis for electricity, heat and transport, the entire energy provision in all sectors is secured - not only electrical power.

Anxieties
    The public knows almost nothing about safe handling of hydrogen. Where there is a gap in understanding we are genetically programmed to react with fear and rejection. To fill these knowledge gaps, the safety-relevant properties of hydrogen are explained below.
     Firstly, it must be recognised, that our fears are still largely influenced by Nazi propaganda. That is why a brief clarification is needed.

The end of the Hindenburg in 1937 in Lakehurst

     These 1937 pictures show the catastrophe of the Hindenburg airship in Lakehurst USA. The cause was however not hydrogen. The catastrophe would not have proceeded much differently if an inert helium filling had be used. The cause was rather the coating of the outer shell.
     Today solid fuel rockets are made using components contained in this coating. It is no wonder that the outer shell burnt like tinder. There was no explosion.  Of the 97 passengers, 35 died, most of them from burning diesel oil, which was used by the engines.
     As a German high-tech product was not allowed to have a design flaw at this time, the Nazis blamed the Americans for not wanting to deliver any helium. A Nazi lie has dominated our feelings towards hydrogen since then.

Diffusion and embrittlement

     Even technically-oriented people often tell horror stories about the diffusion properties of hydrogen. Of course hydrogen diffuses more quickly through porous material. It also makes steel brittle under particular conditions, but none of these conditions are met in the current natural gas infrastructure. The conditions for embrittlement are as follows:

  • The pipe must be a type of steel which is susceptible to hydrogen embrittlement
  • Its surface must be a bright and shiny metal - i.e. naked metal with no oxide layer
  • The component must be subjected to continually alternating tensile stresses so that the naked metal surface can be exposed again and again.

     Pipes without an oxide layer cannot be produced, because they come into contact with air during production, immediately forming a stable oxide layer. Naked metal areas can only be occur during operation by changes in mechanical stress , for example by bending and changes in pressure. In addition, a slight crack must already be present in the pipe. With strong pressure changes the crack will become ever deeper. In this process naked metal areas are formed at grain boundaries into which dissociated hydrogen atoms can penetrate. If enough hydrogen is present, these atoms recombine into molecular hydrogen and expand the metal lattice. The steel crumbles at this point. This is called hydrogen embrittlement.
     Such conditions are only brought about by using an inappropriately brittle material in large high pressure pipes above 40 bar.  For smaller pipes the stress is too small due to the standardised minimal wall thickness. Large high pressure pipes are not operated under changing pressure, because cracks could also grow with natural gas. For a hydrogen economy, these transnational pipelines would be unnecessary, because bio-hydrogen is both produced and used in the same region. In these regions only small pipelines of under 25 bar are used. These pipes are not even made from this type of vulnerable steel.

Leaks in the pipe network

     In order for hydrogen to diffuse in significant quantities through metal pipes, they must be either porous or cracked. Pipes in the natural gas network are however neither porous nor cracked. Even the plastic pipes laid in cities can be operated with hydrogen without the slightly higher leaks posing a safety risk or an economic burden. The leakage rate in the European natural gas network is around 0.1% of the transported energy. The leaks are largely caused by cast iron pipes from the reign of the Kaisers which are inserted into each other with a simple coupler seal. The leakage rate by converting this network to hydrogen may be calculated from their physical properties. According to these, the leakage rate of 0.1% of the transported energy would reduce to 0.04% for hydrogen. There is however nothing which cannot be improved further. In the hydrogen network that would be principally the seals and fittings.

Danger in the home

     Hydrogen in closed spaces is almost as dangerous as natural gas. Although the energy released by a hydrogen explosion is actually less, it should not be left to chance. Explosions can be reliably avoided by attaching a postage stamp sized piece of platinum coated electrode from a fuel cell to the ceiling. Then hydrogen leaks simply smoulder away. But if hydrogen is suddenly released in large quantities, it can act as an ignition source.

Hydrogen can also be very simply detected, even in its lowest concentrations. Such devices cost no more than a smoke detector and also look like them. If really needed, a sulfur-free odorant may also be added. Then leaks smell of gas, as they do now. But in the 21st century this archaic and unreliable method should be dismissed.

Unlike town gas, or a natural gas appliance with inadequate ventilation,  hydrogen is not a silent poisonous killer as is carbon monoxide.

Danger on the road

     In open spaces, hydrogen cannot be detonated. The sudden release of large quantities of hydrogen in cars in current 700 bar pressurised tanks is extremely unlikely, as these containers are almost indestructible. Even if the pipe is sheared off, these containers do not become rockets. The pressure relief device inside the tank ensures hydrogen escapes only slowly and burns with an almost invisible flame, without significant thermal radiation. It is hard to imagine that anyone could be burned in a hydrogen car.

     In the illustration, the tanks of a hydrogen car (left) and a petrol car (right) were shot through. After 2 minutes and 20 seconds the passenger compartment of the petrol car exploded. The imaginary passengers of the hydrogen car would have got out without injury. The vehicle body hardly got any warmer than on a summers day. A film of this can be seen here. Hydrogen in road transport will result in fewer deaths from fuel than there are now.

Conclusion

The installation of a hydrogen economy leads to safety and security benefits in every respect.

COMMENT:

Few people knew that Town Gas contained 50% hydrogen by volume.  The fear of hydrogen might be much less if that were more widely known.

 

Founded in March 2009 H2 Patent GmbH, Bad Iburg, continues to promote the technology for the production and use of hydrogen and license worldwide.

WHP updated: 23.10.2015