Climate Change & Natural Capital (360 ESG) | AI & water: the opportunity angle

Research evidence excerpt

Climate Change & Natural Capital (360 ESG) | AI & water: the opportunity angle

Climate Change & Natural Capital

Evaporative cooling is the leading driver of data centre water use

A data centre’s direct water footprint is largely determined by the choice of primary and secondary

cooling circuit technologies. Data centres typically use two coupled cooling loops that exchange

heat with each other without mixing the fluids they contain – the secondary cooling loop captures

heat generated from computational units and transfers it to the primary loop, which ultimately

rejects heat to the outside environment.

Chart 18: (a) Flow of heat from heat sources to heat sink through secondary and primary loop; (b) An example data

centre in which the secondary cooling loop is liquid cooling and the primary loop is a cooling tower

Source: COMPASS Research Affiliates Program at the University of Texas at Austin, Kepler Cheuvreux

Globally, around 56% of data centre capacity uses evaporative cooling of some type, according to

GWI, and even the most efficient cooling systems return only 15% of the water withdrawn back

into the environment.

Most water consumption in data centre operations takes place in the primary cooling circuit, which

rejects heat into the atmosphere. Cooling towers rely on continuous water evaporation to reject heat

and require regular water discharges and replenishments (known as “blowdown”) to control

contaminant build-up.

Conventional cooling towers still represent the dominant technologies employed for primary

cooling loops, owing to their technological maturity and energy efficiency. They are generally

used continuously throughout the year and typically require around 2.75L/kWh of water to

operate, 67% of which is typically lost in the form of consumptive use.