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Digital Realty Singapore uses electrolysis to clean its cooling water

August 8, 2023 - Digital Realty is using electrolysis to clean the water used in a cooling tower in Singapore, saving more than a million liters of water per month.


The company is treating cooling water at SIN10 data using electrolysis instead of chemicals, which prevents scale and allows the water to go through the cooling system more often before being discharged as wastewater.


Digital is using DCI (DeCaIon) units from Singapore-based Innovative Polymers, supplied by Deston Pte, which use electrolysis instead of chemicals to remove minerals that have built up in "blow-down" water which has been condensed and drained from cooling equipment.


The DCI units use a small electric current, to generate OH- ions altering the pH of the cooling water near the electrode, which causes calcium and magnesium in the water to precipitate out as calcium carbonate and magnesium hydroxide.


Innovative's DCI units are widely used to clean the water in air conditioning systems for sites such as hospitals, according to BK Ng, owner of Innovative Polymers and one of the developers of the product. This is the first installation in a data center in Singapore, he told DCD: "Data centers have been slower to pick this up."


Digital has not given details of the size or cost of the deal, but said that the DCI systems would be more effective than chemicals at keeping the water clean. It can be operated continuously, and allows the water to circulate three times as often within the cooling towers before it is discarded as wastewater.


We have no information on this deal, but we understand from sources that each DCI unit can cost around SG$33,000 (US$25,000) and can treat - very roughly - enough water for about 1MW to 1.3MW of cooling infrastructure. To cover the whole output of SIN10 would therefore need 20 to 25 DCI units. That suggests a total cost of maybe US$500,000, although no figures have been quoted to us for the deal.


The installation was partially funded by a Singapore government program to save water, and Digital claims it saves 1.24 million liters of water per month.


Ng says that the DCI unit provides a bigger payback on energy than it does on water, since it removes a layer of insulating scale from the heat-exchanging parts of the cooling system, so the chillers do not have to work so hard.


"The irony is, if your system is doing well, we will give you a little saving," he told us. If the system is carrying a lot of scale before the unit is added, then the energy savings can be greater.


Ng told us that energy saving generally makes up 50 to 60 percent of the return on investment of the product, with water-saving around 35 percent, and lower maintenance and chemicals costs making up the balance.


Gavin Cherrie, at Allied Polymer's New Zealand partner 2Plus, told us that the unit uses some 700kWh per year (i.e. an average of less than 1kW of power),


Digital Realty says SIN10's electricity requirements have been reduced, as the cooling system operates more effectively, and the water eventually discharged is cleaner than before.


Since 2020, Digital says it has reduced its global water intensity by seven percent.


In Singapore, the company recently installed solar panels on its SIN11 facility, and began a project to install them on SIN12.


In its 2020 ESG report, Digital set itself a science-based emissions target of reducing Scope 1 and 2 emissions by 68 percent and Scope 3 emissions by 24 percent before 2030.

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