How do you use the heat generated by data servers in an economical and ecological manner? By heating the water of the swimming pool, says the mayor of Paris, who in July 2015 launched a tender for its pool at Butte-aux-Cailles on the supply of locally produced energy by recovery of the heat emitted by a data centre.

The young startup Stimergy responded by proposing the installation of a new device which would the saving of the equivalent of 45 tonnes of CO2 per year. The swimming pool in this historic part of the 13th district of the capital, historically heated by an artesian well (French article) of 580m depth, and now heated by district heating, will be equipped in the fall of 2016 with several “Digital Boilers” which will recover the heat generated by servers installed in the pool infrastructure and recycle it to provide the heated water needs of the indoor pool. Because they work 24/7, the production of this “digital heat” is constant.

With this world first, the city ...