Safety requirements related to the end-user equipment

This LAP is concerned with the safety requirements (and design and operational aspects) for commercial and domestic end-user equipment operating with hydrogen gas blends resulting from hydrogen injected and transmitted in the gas grid at the TSO level

Glossary:

The requirements needed to guarantee the safety of the end user application.
Is it a barrier?
Yes
Type of Barrier
Structural barriers, Operational barriers, Economic barriers, Regulatory gap
Assessment Severity
2

Questions:

Question 1 Is there any legislation with regard to safety requirements related to end-user equipment (e.g.: limits in terms of H2 for use in gas appliances)? If yes, please answer the following question.
The threshold for the hydrogen amount in natural gas is 4% (Mol). This threshold is stated in the Austrian standard:/guideline ÖVGW 31
Question 2 Changes to gas supply composition may have implications for the design of gas appliances (safety) and the relevant legislation. What are the implications you expect with regard to the possible concentrations of hydrogen in the H2NG blend?
Basically the direct changes of the safety requirements are not that big – in particular when taking the threshold of the hydrogen amount in the mixture as given. The implications are to be expected more from the billing perspective (the customer pays for the gross calorific value and not for the consumed volume) and regarding the Wobbe Index. The Wobbe index is linked with the gross calorific value and is an indicator for the required nozzle. In case there is a wrong nozzle installed one could generate local hot spots and ruin the device. So it might happen that a lot of nozzles have to be adapted, hence costs could be high but the impact on safety will not be big.
Question 3 For which end user applications do you foresee the main consequences and at which level? Could you please provide references to underpin your opinion?
Regardless whether one deals with ICEs or heating boilers or gas turbines, the Wobbe Index is crucial in order to generate the required flame size, flame form and flame temperature in order to avoid local hot spots which can ruin the material which is in contact with the flame; besides the efficiency would suffer if the Wobbe index is not “transformed” to the proper nozzle
Question 4 Changes to gas supply composition may have implications for CNG compression, storage, and use in CNG vehicles. What are the additional safety precautions needed? Could you please provide references to underpin your opinion
The direct changes of the safety requirements are not that big – in particular when taking the threshold (4%) of the hydrogen amount in the mixture as given. The implications are to be expected more from the billing perspective (the customer pays for the gross calorific value and not for the consumed volume) and regarding the Wobbe Index. The Wobbe index is linked with the gross calorific value and is an indicator for the required nozzle. In case there is a wrong nozzle installed one could generate local hot spots and ruin the device. Regardless whether one deals with ICEs or heating boilers or gas turbines, the Wobbe Index is crucial in order to generate the required flame size, flame form and flame temperature in order to avoid local hot spots which can ruin the material which is in contact with the flame; besides the efficiency would suffer if the Wobbe index is not “transformed” to the proper nozzle

National legislation: