What are dual-use data centers and how they drive energy efficiency
This article is part of a VB special issue. Read the full series here: Intelligent Sustainability.
In 1984, the global internet traffic was about 15GB per month. Today, the number is even higher, thanks to the rise of mobile devices and digital services that have brought close to 5 billion people online.
As more of the world’s population becomes connected, the internet protocol (IP) traffic will skyrocket, increasing the utilization of data centers – which see most of the world’s traffic and big data pass through – as well as the electricity needed to run them (produced primarily in coal-fired plants).
According to the International Energy Agency (IEA), global data centers already consume approximately 200-250 TWh of electricity, contributing to 0.3% of global CO2 emissions every year. This is more than the national energy consumption of some countries and around 1% of the global electricity demand. By 2025, with the increase in IP traffic and big data, these data factories are expected to consume one-fifth of the world’s power supply, making the problem much worse.
“The majority of the energy demand comes from powering the servers that process the data, but they, in turn, produce heat and need to be cooled,” Michael Strouboulis, business development director for digital infrastructure at Danfoss, told VentureBeat. “This cooling also requires a lot of energy and generates significant excess heat – most of which is currently being admitted into the surrounding environment,”
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This heat, currently being dissipated into the atmosphere, is the hidden golden opportunity to drive energy efficiency and decarbonize data centers.
Currently, most organizations are pushing efforts to offset the increasing data and electricity load by ditching legacy data centers in favor of hyperscale ones, streamlining computing processes, using lower-GWP (global warming potential) refrigerants and switching to energy-efficient measures like varying the speed of motors driving fans, water pumps or refrigerant compressors.
Google, for one, claims that its measures have reduced the average power usage effectiveness (PUE) – total data center power divided by the energy used just for computing – for all its data centers to 1.12, which is very close to the ideal score of 1.0.
“If a data center has a PUE of 1.0 it means that the information technology equipment (ITE) uses 100% of the power and none is wasted in the form of heat … But if the PUE is 1.8 then for every 1.8 watts going into the building, 1 watt is powering the ITE and 0.8 are consumed elsewhere for what is non-ITE power that most is rejected in the form of heat out of the building,” Strouboulis explained.
With heat that is otherwise considered ‘waste,’ organizations can meet electricity requirements elsewhere, possibly at a closely located location.
In addition to the above-mentioned measures, companies can capture the heat being discharged from their data centers and then turn it into steam or electrical energy for use at other sources. In case the heat temperature is too low, they can use a heat pump to elevate the levels to 60 degrees Celsius or higher to meet the requirements.
“Reusing heat generated by processing data in data centers requires technology such as heat recovery units and energy transfer stations to capture and distribute this energy to consumers that need this heat for their industrial or commercial process or simply for comfort heating,” Strouboulis said.
The heat from a data center can be used for a myriad of applications, starting from something as simple as servicing swimming pools and laundries to vertical farming or meeting the heat requirements of a hospital.
“The heat produced by data centers can serve as a new resource for an energy cluster, an integrated heating source, or as a source for a steam system which are all part of local district energy systems (which collects and generates heat for dispersion to a nearby campus or entire municipality),” said Baruch Labunski, president at RankSecure. “More than 940 district energy systems exist in the U.S. so any of them are suitable for garnering a new energy source like data center heat. This could help many local communities reduce energy costs and provide for additional energy needs as the city grows without leaving a major footprint on the environment.”
For some perspective, a NeRZ white paper notes that more than 13 billion kWh of electricity was converted into heat in Germany’s data centers and released unused into the environment.
This, if reused, could have met the energy needs of Berlin.
How enterprises are using data center heat?
While the possibilities are endless, leading enterprises are keeping their heat recovery efforts focused on specific areas, such as warming up households or their office buildings.
Facebook and H&M both have been reusing the heat from their data centers to heat thousands of nearby households and apartments in Denmark. Amazon, meanwhile, has built a setup to save energy at its Seattle headquarters.
“It has developed an internal energy and water system using its campus and a nearby building that houses a data center,” Labunski explained. “The headquarters gets waste heat produced by the data center. It moves underground and warms the water sent to the campus… providing hot water to the entire Amazon headquarters, which includes multiple high-rise buildings and a conference center. When the water cools, it is sent back to the data center to keep computer and data equipment cool before the cycle starts again.”
Similarly, Danfoss too plans to utilize excess heat from its data centers to provide 25% of the overall heat required by its headquarters.
Investment and gains
While heat recovery and utilization can defray energy use elsewhere, the project has certain hurdles.
Firstly, heat doesn’t tend to travel that well, which means the consumer of the captured heat must be closely located to the source data center. Secondly, the infrastructure for reusing heat comes with high upfront investment. Labunski estimates that data center improvements such as heat reuse come at $520 to $900 per gross square foot and can almost double the cost of developing the facility.
However, once the upfront investment is over, a data center reusing heat can also become a profit driver for the business.
“By capturing the waste heat and reusing this for neighboring buildings, you can get significant gains. Consider the cost of heating a building from scratch. Data centers, with their 24/7 operation and a constant stream of heat, are ready-made as a de-facto highly consistent and reliable ‘generator.’ Once that paradigm shift is made, the concept can pay for itself and quickly become a profit center based on recent demonstration projects,” Strouboulis added.
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