Google finds customers for waste heat from a data center

For the first time, waste heat from a Google data center is being diverted to third parties to cover their heat requirements. This so-called offsite heat recovery reduces costs and consumption of primary energy sources in the long term. Until now, Google has only used waste heat from its data centers for its own purposes, in particular to heat offices. From next year, the small Finnish town of Hamina with a population of around 20,000 is to benefit from free heat.

To this end, a 1.3-kilometer-long pipeline is being built to supply waste heat from a local Google data center to the district heating network of the town's own company, Hamina Energia. A 5 MW heat pump system will supply the heat, as the "natural" temperature of the data center waste heat is well below the operating temperature of a district heating network.

The pump can generate 40 gigawatt hours of district heating per year. This is enough to cover 80 percent of Hamina's current district heating volume. However, Hamina Energia is already planning to expand the local district heating network.

Free heat to combat global warming

For its part, Google is saving energy that it would otherwise have to spend on cooling the data center. Accordingly, it can "sell" the waste heat for a symbolic euro per year. The data company states that 97% of its data center in Hamina is currently operated with CO₂-free energy. Accordingly, the waste heat donated is also almost CO₂-neutral.

Increasing use of artificial intelligence is currently leading to a sharp rise in the energy consumption of many data centers. Microsoft is aware that AI has increased emissions by up to 40 percent. This makes it more difficult to achieve the goal it has set itself of becoming CO₂-neutral by 2030. Google has set itself the same goal.

Using waste heat instead of cooling it away helps to improve the carbon footprint. It is astonishing that Google has so far only used it to heat its own offices, but has not transferred any waste heat to third parties. Because the idea is not new.

Old idea facing old hurdles

In the Swiss municipality of Uitikon (near Zurich), IBM implemented a project back in 2008 in which the waste heat from a data center heats the water in a nearby indoor swimming pool. In Hanover, Hostway has been operating a data center since 2007, the waste heat from which is fed into commercial areas in the neighborhood. And in London's Docklands, residential and commercial buildings have been benefiting from waste heat from Telehouse West since 2009. The German platform Bytes2Heat has collected numerous examples.

One challenge for such projects is that the waste heat must be purchased reliably, otherwise the data center will run into trouble. Conversely, the consumer of the waste heat must be able to dissipate it throughout the year, even if they may not have any homes to heat at the time. This is because, unlike thermal waste recycling (a popular euphemism for waste incineration in the industry), waste heat from data centers is relatively constant and cannot be regulated.

Thirdly, the local conditions must be suitable. The waste heat from the data center must be fed into the existing district heating network at a suitable point, which in turn must not be too far away from the data center. In theory, the third-party use of server waste heat is therefore a wonderful thing, but in practice it is easier said than done. Even at the Google data center in Hesse, which will open in 2023, Google is "checking" whether the waste heat can be used to supply adjacent buildings.

• Read how data center waste heat can be used in practice at iX.

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