Sustainable and efficient cooling for data centres

Manufacturing & Process
13 May 2019

Data centres house large numbers of servers, usually contained within relatively compact spaces. While data centres often have huge floor surface areas - 50,000 m² or more is not exceptional - much of the space is taken up by long rows of 19-inch racks filled from top to bottom with servers. Substantial heat is therefore generated, which means that data centres must be equipped with powerful and reliable cooling.

Most European data centres use water for this. The water cools the servers via a dedicated circuit, after which the heated water is cooled by means of one or more cooling towers. This type of system works well, but the water has to be mixed with a strong acid - often sulphuric acid - to prevent limescale deposits, and the water can only be used for a limited time.

Billion-euro data centre

“That’s why this technique is not very sustainable,” explains Sebastien Marion, Complex Designs & Equipment Architect. “So our customer asked if we could come up with a better solution. The new cooling system of course had to be at least as efficient and reliable as the traditional method, but had to be considerably more sustainable. The method we developed was put in place for the first time in a data centre in the Walloon part of Belgium.”

“The data centre - involving a total investment of more than a billion euros - belongs to a well-known internet giant, who asked our customer to optimize the existing cooling system based on the new method,” explains Marion.

From coffee machine to data centre

“Water is an excellent cold conductor, but every time it’s heated, some of it evaporates. This involves a change in the chemical composition, resulting in scaling - limescale deposits in the form of calcium carbonate. And just as with a dishwasher or coffee machine, this type of calcification in a billion-euro data centre also greatly shortens the lifespan of some components.”

“In a traditional cooling system, an aggressive acid, such as sulphuric, is added to the water to combat scaling. The disadvantage is that this is not a sustainable solution, and it releases airborne carcinogens. It’s also difficult to get precisely the desired acidity level in the cooling circuit using sulphuric acid.”

The natural approach

“So, we developed a solution for the pilot project based on carbon dioxide, which forms a much less aggressive acid that is safer and can be better controlled. Another advantage is that water quality is maintained for longer, resulting in a decrease in water consumption by some 50%.”

Because the CO2 pH installation adds a specific amount of CO2 each time - using a dosing skid specifically designed for data centres - the chemical balance of the water remains intact for longer. This process, known as the calcium-carbon balance, also occurs in nature. An important aspect here is that the CO2 used for this project complies with the “green origin” standard, and therefore causes no additional emissions.

Safer and no risk of overdose

The CO2 pH installation consists of storage tanks (each cooling circuit is connected to a tank with 36,000 litres of liquid CO2) and dosing skids with an associated control and monitoring section. The whole process runs more safely than before because it no longer involves corrosive acids, and there is no risk of overdose. On the contrary, because CO2 is used the system can be fine-tuned with great precision.

“The data centre in Wallonia is one of the first in the world to use this cooling technology, and, for the same customer, we have set up a similar CO2 pH installation at a second data centre, and we’re now working on the cooling design of a third,” says Marion. “In any case, this technology is effective for any water-cooled data centre.”

Please contact Rudy Lamond for more information.