On the edge of the Eole site, in Courbevoie, the terminus of a railway line seems to have emerged from the bowels of La Défense. In fact, this train line is being rehabilitated. In the 1960s, it supplied coal to the power station which supplies most of La Défense with heating and air conditioning. In October 2022, agropellets, granules from agricultural waste (rapeseed or corn straw, miscanthus, nut shells or olive pits) will thus arrive from Île-de-France. These will be ground into a fine powder to feed the burner of the boiler. In fact, two out of six boilers at the plant, each of 45 megawatts (MW) and reconditioned, will be dedicated to this new fuel, at the end of the work started in June 2021. Now empty,old fuel tanks are ready to store this new fuel over 1,500 m3, in order to be able to respond to heating peaks in winter. La Défense will thus become the first European business district to be certified "green", avoiding the release of 54,000 tonnes of CO2 each year, explains Benjamin Fremaux, president of Idex, the energy services operator supplying the district.
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A heating network can be based on biomass or geothermal energy, when possible (as in Strasbourg), but also on sea water: Marseille is experimenting with thalassothermal energy with an EDF subsidiary.
Reinventing hot water
Another promising avenue: thermal solar power plants, like the one that has just been created in Narbonne with the help of Newheat, a specialist in this technology.
In summer, the water tubes heated by 3,200 m2 of solar panels take over from the biomass that heats a district of the city in winter.
"A heating network is the easiest way to decarbonize a community"
, estimates Hugues Defréville, president and co-founder of Newheat, especially in ten years, the share of renewable energies supplying them has increased from 30% to 60% : "
A city can force social landlords to heat their buildings as well."
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In La Défense, near Paris, nothing will be the same
In the Netherlands, each district heating network is equipped with solar thermal; in France they are 4 out of 800. Above all, why are urban heating networks so little developed in our country? Their potential is largely
"under-exploited
", lambasted the Court of Auditors in a report in September. Their capacity represents barely more than a third of the 3.4 million tonnes of oil equivalent that they must have in 2030, according to the energy transition law of 2015. Despite their competitiveness,
“investments require communities to commit on the long term"
, analysis Dominique Kieffer, director of public affairs at Dalkia and member of the board of the National Union of District Heating.
The 350 million in aid to the heat fund and a reduced VAT rate are very far from the 5 to 6 billion euros per year of subsidies paid to electricity for twenty years.
However, heat represents half of French energy consumption.
In Bordeaux, plans were not made because the price of gas was lower.
But with the surge of the latter, the situation has changed, the heat being, it, protected from price fluctuations.
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