Hydrogen as fuel gas
Behaviour of controls and systems
Decarbonisation:
Fossil energy carriers are increasingly being replaced by renewable energy carriers in order to achieve environmental objectives.
Hydrogen alternative:
Produced by means of electrolysis using electricity from Power-to-Gas systems.
The hydrogen content in natural gas is currently limited to < 10 vol. % (DVGW Work Sheet G 260:2013/G 262:2011).
DVGW (May 2019):
Theoretical study of leakages for various media, among them CH4 and H2 (100 %).
Leakage rates:
The limit values for leakage rates for many gas installation systems and of gas appliances are specified in DIN EN 13611:2019.
Absolute tightness does not exist!
H2 twice the leakage rate than CH4
The theoretical calculated leakage rate of hydrogen is about 1.2 to 1.3 times compared to methane. Under actual conditions a leakage rate approximately twice as high as for CH4 is to be expected.
Safety:
A very rapid dilution of the escaping gas was detected in a simulation in a defined test space and at very low rates of air replacement.
The study also shows that at higher leakage rates of hydrogen vis-àvis air or methane the alarm thresholds are sizably undercut even at low rates of air replacement.
Risk reduction – the system operator’s responsibility
The operator must take the increased hydrogen leakage rates into account as part of a risk assessment particularly when selecting the installation space. The installation space for the gas system should always have enough natural ventilation. Additional safety measures need to be taken if necessary(gas leak detector).
Conclusion:
Taking all of the system-specific characteristics into account operation with hydrogen is possible without technically relevant reduction of the safety level. DUNGS type-tested gas safety and regulating controls and system solutions can be used for this purpose.
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