Marseille, France

In Marseille, France, a European data center company called Interxion uses a form of liquid-based free cooling to decrease the energy required to cool its data centers. The facilities pipe water from 'La Galierie de la Mer,' a tunnel that runs from inland mining towns into the Mediterranean Sea near Marseille. The tunnel, which was built from 1885 to 1907 to pump wastewater from mining, carries water that naturally maintains a temperature of around 15C year-round. Although the water still needs to be filtered before it can be used for cooling the data centers, its naturally cool temperature eliminates the need for the energy-intensive process of chilling the water.

Interxion estimates that this method will save up to 18,400,000 kWh per year, or the equivalent of 795 tons of CO₂, improving the Marseille data center's power usage effectiveness to 1.11, compared to the average PUE of 1.38 for traditional liquid cooling data centers. The company is also exploring the possibility of feeding the hot water output into the local urban heating network so it can be used to heat homes and offices. By repurposing what is essentially considered wastewater instead of competing for potable water, minimizing energy consumption through free cooling, and exploring ways to benefit the local community through heat export, Interxion's Marseille data centers represent an attempt to create more responsible, harmonious data infrastructure.