Invest in new gas pipelines on French territory… but to transport decarbonated hydrogen. This is the promise of Teréga, the second operator of the gas transmission network in France (with GRTgaz), which is deployed in the South-West. Indeed, its managing director, Dominique Mockly, announced this Wednesday morning to the press the launch of a project of 600 kilometers of pipes in the Occitanie and New Aquitaine regions, called HySow, as part of the deployment of the European backbone. hydrogen.
In order to connect the places of production and consumption, it will be connected to H2Med, this future hydrogen pipeline between Barcelona and Marseille, torn off at the end of 2022 by Madrid and Berlin despite the reluctance of France. The idea: to weave a vast network intended to transport the precious molecule between the Iberian Peninsula and France. Which will obviously be linked to Germany, eager to secure its supplies.
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While H2Med will, in theory, have the capacity to transport up to 2 million tonnes per year of renewable hydrogen from 2030 (i.e. 10% of consumption expected in Europe in 2030), HySow will be able to transport up to 0.5 million tonnes per year of this energy vector, says Teréga. Considered by the two gas transport managers as crucial for the energy transition, the two projects are thus candidates for the Project of Common Interest (PIC) label, in order to receive European subsidies.
The conversion challenge
However, the challenges are numerous. Unlike H2Med, which will be built from A to Z without relying on current infrastructure, 60% of the pipes concerned by HySow already exist, and will therefore have to be converted. However, modifying gas pipelines to allow them to receive hydrogen is not an easy task. ” All the experts tell me that it is wrong to say that a gas pipeline will be able to transport hydrogen tomorrow, that this requires very heavy work “, had also slipped Emmanuel Macron in September, before giving in politically.
In fact, many obstacles still need to be removed. Indeed, beyond safety issues (hydrogen being highly flammable), methane pipes were not designed to transport hydrogen, whose molecules are so small that they can diffuse into the metal structure and weaken it.
« Existing infrastructure cannot be reused to a large extent. We can certainly inject a little hydrogen into the current networks, but probably not much “, we explain at RTE, the French manager of the electricity transmission network..
Result : “ Either it will be necessary to change pipes, whereas 90% of them are buried. Either put coatings inside, when we are talking about thousands of kilometers on a European scale “, explains to La Tribune Ludovic Leroy, engineer at IPF Training.
Added to this is the question of changing equipment, such as valves, taps, meters, but also compressors, ” absolutely not compatible with hydrogen transport “, according to the engineer. Especially since the volume density of this energy carrier is four times lower than that of natural gas. In other words, to obtain the same number of megajoules transported, it will be necessary to multiply the flow rates in volumes by four.
Current experiments
For his part, Teréga is reassuring. ” It is true that hydrogen has a tendency to penetrate steel, because it is a very small molecule. But with a certain number of modifications, we can transit hydrogen “says to the Tribune Laëtitia Mahenc, head of strategic hydrogen projects. Nevertheless, today, the maximum injection of the famous molecule in a gas pipeline is capped at 20%, as part of an experiment conducted by GRTgaz.
To remedy this, Teréga claims to be working on the possibility of coating these pipes with a specific material, in order to see what “ this could overlook hydrogen porosity “. Another option under study: reduce the pressure in the pipes to avoid the transit of hydrogen through the steel. In any case, assures Laëtitia Mahenc, the retrofit would remain between 30% and 40% cheaper than building a new hydrogen pipeline, according to estimates by European gas transport managers.
Cost uncertainties
Nevertheless, the project will constitute a ” challenge “, admits Laëtitia Mahenc. With, as a corollary, great uncertainties in terms of costs. For now, the range varies from simple to double: the average cost of transporting hydrogen over 1000 km will be 0.11 to 0.21 euros per kg of hydrogen, estimate the gas transporters.
If it saw the light of day, this new network would in any case mark a paradigm shift in France, by constituting an important milestone in the European hydrogen backbone, so far rather rejected by France. “All the experts explain to me that it is absurd to transport hydrogen from Spain to France […] and that electrolysis should be done [pour produire de l’hydrogène, ndlr] directly on the production site “, said in September Emmanuel Macron. A speech that seems far away today, to the delight of gas transport managers.
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