In Alsace, a solar heat network offers ecology and yields

A frank sun is already hitting strong in early April on Saverne (Bas-Rhin). In front of her bay window, Catherine Kleitz savor the panorama on the Vosges and the ruins of the Château du Haut-Barr. But it is not only the return of spring that illuminates it. “The heat network they build for us, I find it great!” She enthuses. The retiree is not only curious, it is also impatient: within a year, its building will be connected to a titanic infrastructure which transforms the basement of the town of Saverne.

Because under the cobblestones, the heat: 20.4 km of pipes already wind in the bowels of this city of 11,000 inhabitants. They will send 100 % renewable heat to schools, gymnasiums, public buildings and collective housing. The network will combine three energy sources: wood (from forests located less than 100 km), residual heat from local industries, and above all, thermal solar. In variable proportions according to the seasons, the sunshine and the contracts signed with the companies.

Another originality, the Savernois were invited to finance a small part of the project: 250,000 euros – out of a total budget of 38 million – were raised in a few hours thanks to a call for citizen savings. With an investment at the attractive interest rate (6.5 %), capped at 10,000 euros per person. The operation quickly refueled. Thirty forty-one were able to subscribe to it. “I would like to know who managed to invest,” sighs Catherine, placed on the waiting list. Like many, she had spotted the “good plan”, but too late. “The day before, 80 people were present in the public meeting, recalls Stéphane Leyenberger, various right mayor of the town. I joined by saying that it should not be camping to be the first the next day, that there would be for everyone. I was wrong … “Since then, HAPPY Few (The few privileged) prefer to stay in the shadows. The rumor runs and arouses jealousy.

Major economies

In town, many regret that this part was not greater. They forget that Electricity of Strasbourg (ES) energy services, delegate of public service, will have to pay these dividends. Behind the successful coup, the company has financial imperatives, aimed at a turnover of 80 million euros by twenty-five years. “It was their idea to provoke the appropriation of the project by the citizens, they did not need it financially,” refrains the councilor from his office in the Gothic style.

It is here, under the medieval woodwork, that the political decision was taken in 2022. The war in Ukraine has just started. In a few weeks, the price of double gas, that of quadruple electricity. Initially confined to the municipal swimming pool and a priority district, the heat network project suddenly takes on another dimension. ES now targets 140 connected buildings. A change of scale based on a double promise: ecological, certainly, but also economic.

“At the start, we were looking for environmental exemplarity, but today, the main motivation has become a budgetary,” admits the mayor. An example? The Saverne hospital calculated that in 2024, if it had already been connected to the network, it would have saved one million euros on its energy bill.

A large -scale network

On the site, this ambition gives headache to Christophe Lehmann, the operator of the works. “It must be completed next September,” it seems to pray in front of the concrete skeleton of the future giant boiler room. Currently, two minireseaux, at the ends of the city, are already operational, supplied by the brand new biomass boiler of the swimming pool, and will be connected by the end of the year. From this vertebral column will gradually be deployed from ramifications until 2028, or even 2030.

“If we do not come across Vercingétorix’s ear”, he jokes with his Alsatian accent, evoking the archaeological vestiges which sleep under the city, called TERS TABERNæ in the Gallo-Roman era. In a freshly connected social building, it proudly shows the gleaming boiler. Exit the old gas boiler: “Do you see the magnitude?” It’s not just cable in a field! »»