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We rely on data center services constantly to keep us working, connected, and entertained. However, these facilities use significant amounts of energy and water, which have been highlighted by the Lawrence Berkley National Laboratory and the EPA as an environmental issue.
Data center companies have been pledging to improve sustainable practices, but when it comes to water and energy conservation, they must work closely with their water treatment provider to achieve their ambitious goals.
It is important for the water treatment provider to have the necessary expertise to approach systems holistically and determine the best program to balance protecting equipment while realizing water and energy savings.
Part 1 of this three-part series on data center efficiency focuses on preventing excessive water usage.
Water-conscious data centers have adopted the water usage efficiency (WUE) metric to monitor and manage their water usage. One way data centers can improve WUE is to stay ahead of excessive water consumption, looking out for critical control parameters in their water treatment program.
Excessive water usage can come from several key areas:
Unchecked overflow or consistently running a cooling tower program at unnecessarily low cycles of concentration can cost a data center millions of gallons of water per year.
Consider a single 500-ton system running at an average annual load of 65%. Running the system at 2.0 cycles of concentration instead of a higher 3.0 cycles of concentration consumes an additional 1.94 million gallons of water per year*.
A key part of data center water treatment is to regularly analyze the incoming makeup water and set cooling tower program control ranges that minimize water consumption without putting the system at risk of scaling.
Data centers need water treatment programs designed with water conservation in mind, and it is important to communicate critical control parameters with water treatment partners regularly to mitigate excessive water usage.
Control ranges for water savings metrics such as conductivity and target cycles of concentration can be communicated to data center operators via regular service reports. Additionally, cooling tower controllers and building management systems can be programmed with alarms to notify operators if key control parameters like conductivity deviate from the narrow control range.
Of course, all systems are different, and due diligence is necessary to determine the feasibility for utilizing these methods. Always consult your equipment manuals and guides.
*Based on calculations made in ChemTreat’s CTVista®+ Cooling Configurator and Calculator
Part 1 of this series discussed key factors for mitigating excessive water usage at data centers. Energy management is another area of focus for these facilities, specifically when it comes to heat exchange.
Data centers use an estimated 2% of power in the US, but there has not been an ideal model for assessing energy efficiency because of rapidly evolving data center designs. Rack densities in modern data facilities can range from 40 to 500 W/ft2 and result in uneven heat load, making typical commercial building energy modeling a poor fit. Furthermore, IT equipment, cooling, and HVAC equipment are not always evolving at the same rate.
Operators measure power usage effectiveness (PUE) as one way to control energy consumption at their facilities.
Operators can sometimes overlook the impact that improper water treatment can have on energy consumption. Microbiological fouling in water-side heat exchange and chilled water systems can be the culprit that makes or breaks a site’s PUE and sustainability targets.
On water-side heat exchange surfaces, fouling will not only result in much higher energy consumption because of poor heat exchange efficiency, but often shorten the lifespan of the heat exchange equipment itself.
Microbiological fouling can also be a huge issue in chilled water systems, especially when large thermal storage tanks are used. Proper microbiological control is often overlooked in this area because the chilled water is thought of as a “closed” system. However, the low flow in the tank creates an area ripe for sediment to settle, promoting bacteria and biofilm growth.
When biofilm spreads and establishes itself on heat exchange surfaces, it will significantly inhibit heat exchange efficiency. Whereas the thermal conductivity of copper, aluminum, and stainless steel are 384.0, 138.5, and 16.3 W/mK respectively, the thermal conductivity of biofilm averages 0.65 W/mK1. A biofilm layer reducing tube diameter by 10% would reduce heat exchange by 55%.
In the language of operating costs, a 0.6mm-thick layer of biofilm on heat exchange surfaces of a 500-ton chiller would cost an additional $15,000 per year to operate.
Premature and unexpected equipment failure can be a threat to uptime and data center reliability. Chiller tube lifespan is drastically reduced by persistent microbiological issues. Taking the equipment off-line for retubing or replacement is neither cheap nor ideal for preserving redundancy. The same 500-ton chiller would cost nearly $125,000 to retube or $350,000 to fully replace.
Generation 5 data centers are steadily moving away from traditional chiller plant cooling systems, opting instead for more modular solutions designed to be more water- and energy-friendly.
These new generation cooling strategies still rely heavily on water for cooling and are not without their treatment challenges. Microbes still proliferate in these systems, and proper water pretreatment or preventative programs are necessary to preserve equipment life. Failing to implement an appropriate treatment strategy can lead to health hazards via waterborne pathogens and unnecessary early cooling media replacement. A little preventative maintenance can go a long way in new generation cooling systems.
Contact ChemTreat today for a consultation on preventative maintenance in your cooling systems. Our team has experience helping data center customers solve their water treatment challenges.
Always remember that all systems are different, and due diligent is necessary to determine the feasibility for utilizing these methods. Consult your equipment manuals and guides.
In parts 1 and 2, we discussed the importance of water treatment for maintaining data center efficiency.
However, simply adding chemistry to cooling water systems is not enough. Creating a water treatment program that protects heat exchange efficiency and minimizes water usage takes a holistic approach.
Data centers rely on a lean staff, so it is critical to have a water treatment partner to act as a part of your team and run programs to achieve your PUE, WUE, and sustainability targets.
Water treaters should communicate with data center operators regularly to ensure chemical feed programs align with preventative maintenance circulation schedules.
Regular water testing may include things like mineral balances and laboratory bacteria analysis to look for indicators of scaling and biofilm formation before they become insurmountable challenges.
A water treatment program that uses a reactionary strategy will end up costing more in labor, chemistry, equipment years, and downtime compared to a program that uses a consistent and proactive approach.
ChemTreat is here to help you manage your water treatment program efficiently. We have assembled a highly experienced team ready to help you implement a water treatment program customized to your unique system needs.
The ChemTreat team can help your facility develop a winning water treatment strategy.
Our programs may include:
Citations:
Cost estimate based on a 500-ton chiller with 3,000 annual operational hours and a $0.09/kWhr cost of electricity.
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