2023-07-25 06:30:13
Coordinated by the LNE, a European project aimed to revise the standards for gas meters in the face of the boom in renewable gases. On the French gas network, it appears that gas meters can be used to quantify biomethane, but that some of them have weak points with hydrogen.
Historically, the French gas network is supplied by foreign gas (Norway, Algeria, Russia, etc.) and regardless of its origin, it has more or less the same characteristics. For several years, France has been developing its own production system, through biomethane made from biomass, and hydrogen, from solar and wind energy, and produced by water electrolysis to deal with the intermittency of these energies. However, the physico-chemical properties of these new so-called renewable gases or their content of impurities differ from natural gas, which can impact the operation and metrological performance of gas meters. A European project, called Newgasmet [1] and coordinated by the LNE (National Metrology and Testing Laboratory), has just been completed and aimed to revise the standards for these meters.
The partners in this project concluded that current meters can be used to quantify biomethane. It certainly does not have exactly the same characteristics as natural gas, but nevertheless behaves similarly. “Biomethane comes from biogas that has been cleaned, purified and dried before being injected into the network,” says Christophe Brun, certification engineer at LNE. As far as flow measurement and the impact on metering are concerned, it can be considered to be equivalent to natural gas, and that it does not call into question the instruments used until now in the network. As a reminder, biomethane comes from biogas, which is produced directly at the outlet of a composter or a digester, and which contains sometimes dangerous compounds, in particular sulphur. Current meters cannot therefore be used as they are with this gas. »
As for hydrogen, the experts of this research program have analyzed that the meters currently in service are more or less suitable for quantifying this gas. This has in fact a mass and a lower molecular size than methane, which can pose problems of sealing of the network. To this, we must add that this gas can quite easily interact with other materials and damage them. The pipes may be affected by these deteriorations, but also certain mechanical parts, in metal and plastic in particular, present in the meters, and thus affecting their durability.
Gas meters more or less suitable for quantifying hydrogen
Faced with this, one of the objectives of the Newgasmet project consisted in adapting the test benches of the various players in metrology and flow measurement at European level, so that they can be used in the calibration of hydrogen meters. “A transfer standard has been developed, it is a reference standard used in the context of inter-laboratory comparisons, and which allows the same instrument sent to different European laboratories to be evaluated everywhere in the same way, adds the LNE expert. Yesterday, calibration benches could only be used for natural gas meters, and today they can also be used for hydrogen. »
The next step was to use these new hydrogen calibration benches to test the city meters currently in service. It appears that some of them are able to quantify the volumes of this gas, while others, operating in particular with moving parts, have weak points. “These meters do not necessarily present any measurement inaccuracy at time T0, on the other hand after several months, it is possible that we will see a deterioration in their performance. These meters would require specific redesign, as moving parts become critical parts. This situation is not alarming for the moment, because the French gas network contains on average only 6% hydrogen.
[1] The Newgasmet project brought together European national metrology laboratories as well as major industrial players, including two gas operators, including GRTgaz, as well as four meter manufacturers
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