Data Center Heat Reuse Revisited 2021

Data center heat reuse
There are many companies and engineering designers that realize the dramatic energy savings of reusing the waste heat of data centers. This can be done easily when deploying liquid cooling, but also by using the energy removed from the data center for space heating in other areas of the same building. There are several projects in Europe (Frankfurt, for offices and conference rooms) as well as the U.S. (California for perimeter office and back-of-house spaces).
There is often a large amount of waste heat compared to the need, but that peak need might not be met immediately by the heat shed by the data center. To help with the timing of the demand heat storage tanks can be deployed to capture the waste heat and reuse as needed. A heat exchanger will be coupled between two systems to be the energy transfer point as well as provide separation between the heat source and distribution. The temperature of the heating system can be regulated on the flow required, which is supported by the combination of the data center waste heat and the building heating plant. Since the system flow can be governed separately, the heating system can provide exactly 120 degrees F (48.9 degrees C), or whatever temperature is needed.
At one time this type of system was considered leading edge for a data center; however similar systems have been in use for decades to capture and move heat and energy between systems. What is new is that the reliability and controls have improved significantly to allow this to be implemented without any risk to the systems supporting the data center. Although it is discussed as being implemented by big companies with large data centers that are willing to take such risks, these same designs are being introduced with smaller data center operators as well. They understand that reducing the energy use of the heating systems of a building can see significant, immediate savings. This links directly to a reduction of carbon footprint and cost.
There is also the push to co-locate (not the regular definition of colo) the data center with other facilities that regularly need heat for their processes. This works fantastically for smaller data center operators that can flexibly locate their data center in a brownfield site close to where the heat will be reused. Having 100 racks with a regulated output of 104-140 degrees F (40-60 degrees C) can be met to offset the heating costs of the rest of the facility. For large downtown office buildings that can stash a small data center next to their heating plant, this can mean big wins for both the heating and data center cooling systems.
As the data center may reach peak utilization at different times, the heat storage tank can capture those peaks and reuse them at the peak heating times. The heating cost reductions can mean about $200,000 in savings, while the data center cooling costs can also see the same cost reduction or more per year. Adding in the connections and heat storage tank might seem like an expense that isn’t justified, but with those savings the payback period is within two years or better, and that’s with conservative partial loading of the data center and a low heating need – for the year.

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