In the suburbs of northeastern Paris stands a gigantic terracotta-colored warehouse, its interior a maze of windowless corridors. A deafening hum emanates from behind rows and rows of anonymous gray doors, and under white fluorescent lights, disposable earplugs are available to shield passersby from the noise.
These are the grisly innards of one of France’s newest data centers, completed earlier this year, now being used to heat the new Olympic Aquatics Center, visible from the data center’s roof. When American swimmer Katie Ledecky won her ninth Olympic gold medal last week, she did so by racing through water heated, at least partially, by the data center’s machinery.
This noisy site, known as PA10, belongs to American data center company Equinix. The humming sound comes from the company’s cooling systems trying to lower the temperature of its customers’ computer servers. “PA10 is specifically made for high-density racks,” says Imane Erraji, the site’s data center engineer, pointing to a tower of servers that can train AI.
Over the past month, the data center has been converting its hot air waste into water and piping it into a local energy system run by French utility Engie. Once it’s at full capacity, Equinix expects to export 6.6 thermal megawatts of heat from the building, the equivalent of more than 1,000 homes.
With projections suggesting that AI will vastly increase the amount of electricity data centers require (Equinix predicts power consumption per rack could increase by as much as 400 percent), PA10 reflects a European phenomenon where officials are trying to limit the environmental impact of the looming AI energy crisis and transform data centers into part of the infrastructure that keeps cities warm.
Erraji describes the project as a “win-win” for both Equinix and the local suburb of Seine-Saint-Denis. Equinix can direct the heat out of the building, so its cooling equipment doesn’t have to work as hard, she explained, while the city gets a cheap, locally produced source of heat. After the project received a €2 million ($2.1 million) investment from the city of Paris, Equinix committed to providing the energy for free for 15 years. In June, Seine-Saint-Denis Mayor Mathieu Hanotin also highlighted the environmental benefits, claiming that using the data center as an energy source would save the region 1,800 tons of carbon emissions per year.
Yet France has a “very low-carbon electricity mix,” according to the International Energy Agency (IEA), with 62 percent of its electricity generated by nuclear power. And critics say the proliferation of heat-reuse projects distracts from the real problem: the amount of land, water and electricity that data centers consume. “If the data centers are already there, of course it is better to reuse the heat than to do nothing,” says Anne-Laure Ligozat, a professor of computer science at France’s National School of Computer Science for Industry and Business (ENSIIE). “But the problem is the number of data centers and their energy consumption.” There would be less environmental impact to have a basic heating system that runs on electricity without the data center, she adds.
