The addition of hydrogen to an existing gas distribution network in Saxony-Anhalt, initiated as part of a joint project between Avacon and the German Technical and Scientific Association for Gas and Water (DVGW), has been successfully completed. Over a period of two heating seasons, up to 20 % hydrogen was gradually added to the natural gas. The appliance settings of the 350 or so household appliances connected were not changed.
At the end of the project, more than 90 % of participants were in favour of using hydrogen in the gas network or had overcome their reservations. Frank Schwermer, Managing Director of Avacon Netz GmbH, is delighted: "We are particularly proud of the fact that all the households affected in the study area took part in the project and that we received very good survey results in a final customer survey."
New findings from safety monitoring by DVGW
The joint project has also produced fundamental physical findings on the similarity of natural gas and hydrogen. They have been incorporated into the DVGW regulations and increase legal certainty for network operators.
One amendment to the regulations relates to gas quality, another to the scope of testing: with appropriate safety-related support from the DVGW, the testing of all individual gas appliances can be dispensed with in the case of a hydrogen feed-in. In future, random tests of gas appliances will be sufficient, the type and scope of which will be specified by the DVGW.
"We very much appreciate that the joint project is paving the way for such practical adjustments to the regulations. This enables us to gradually increase the proportion of hydrogen without compromising on the usual high safety standards", says Gerald Linke.
The DVGW plans to request information on hydrogen compatibility from all well-known appliance manufacturers and implement it in a revision of the DVGW adaptation database in the course of 2024.
Model region in Saxony-Anhalt: Representative grid infrastructure
A section of Avacon's gas distribution network in Jerichower Land in Saxony-Anhalt was selected for the project. This was particularly suitable because the network infrastructure installed there is representative of the entire Avacon gas distribution network and the results are therefore transferable. The network section is a medium-pressure distribution network from the 1990s with a pipeline length of around 35 km, from which around 350 network customers are supplied with natural gas. With the corresponding number of gas appliances, which are primarily used to supply heat, the selected network area covers a wide range of appliance technology: 352 appliances from 30 manufacturers were installed in the project area. Only five appliances were replaced at the request of the manufacturers before the start of blending. However, laboratory testing of the removed appliances did not reveal any safety-relevant defects, meaning that they could have remained in the grid.
Lower carbon dioxide emissions, carbon and nitrogen oxides
Samples were taken between all blending phases and were consistently positive. In addition, all appliances showed lower carbon dioxide emissions as well as lower carbon and nitrogen oxides during the mixing phases. For example, a gas mixture of 20 % hydrogen saves 7 % CO2. By modernising a heating appliance with condensing technology, a reduction of around 17 % CO2 is possible. If both factors are taken into account, CO2 savings of almost a quarter (23 %) are possible.
"Our joint project has impressively demonstrated that the door is open to the rapid absorption of significant quantities of hydrogen via the existing gas infrastructure as well as the operation of connected appliances", summarises DVGW Chairman of the Board Prof. Dr Gerald Linke. "The feed-in of hydrogen can thus be scaled up on a large scale and existing appliances can be converted to hydrogen en bloc." He goes on to describe the result as a "milestone towards a rapid, technically safe hydrogen transformation".
