Helsinki has found an unexpected ally to decarbonize its heating in the midst of the rise of artificial intelligence: waste heat from data centers. The same heat that servers generate when processing millions of queries, training AI models, or moving Internet traffic is no longer wasted. In the Finnish capital, this thermal flow – which is growing at the same rate as the digital world – is beginning to become shelter for tens of thousands of homes.
A digital sector that is now heating up cities. For years, data centers were known for one uncomfortable characteristic: they generated a lot of heat and needed huge cooling systems to dissipate it. Now that residual heat is already being channeled to the Helsinki heating network, thanks to agreements signed with operators such as Equinix, Telia and Elisa. Data Center Dynamics remember that the company It has been testing this model for more than a decade – the first pilot tests date back to 2010 – but now the scale is completely different: the thermal demand of the city is enormous and the volume of heat generated by the digital economy is growing non-stop.
The result can already be seen, a single data center can heat up to 20,000 homes, according to official figures from Helen. The Telia plant, for example, already recovers up to 90% of the heat generated by its servers, enough to heat 14,000 apartments, and in a few years it could double that figure to 28,000.
A change in the way heat is produced. Digital heat recovery is more than just a technological curiosity. It represents a change in the way district heating is conceived. In the words of the Finnish company“the electricity consumed by data centers always ends up being converted into heat.” The difference is that now that heat is no longer released outside: it is reused.
The engineering behind urban heat. Finland can convert digital heat into district heating because it has a network of district heating especially advanced: a network of pipes that distributes hot water to homes, schools and public buildings.
The process is as follows. A data center generates heat: the servers run 24/7 and are continuously cooled. That heat, instead of being dissipated outside, is captured. It is then recovered and transferred; To do this, data centers can install their own recovery systems or use those offered by the energy company. The heat is sent to an “energy platform”, where heat pumps raise it to useful temperatures. Then, the temperature is adjusted to the 85–90 ºC necessary so that the water can circulate through the urban network. This is where high-temperature heat pumps come into play—some of which, like Patola’sthey work even with outside air at –20 ºC. Finally, the heat is injected into the grid and distributed throughout the city to heat thousands of buildings.
Closing the energy circle. To understand why Finland leads this model, we must look at an essential technological element: heat pumps. Not only domestic ones, but also large-scale industrial ones, capable of raising waste heat to temperatures useful for an urban network.
Europe—and especially the Nordic countries— has become a world leader of this technology. Finland has 524 heat pumps per 1,000 homes, a figure second only to Norway, and its cities have been electrifying heating for decades. This combination—cold climate, tradition of district heatingheat pump industry and the need to decarbonize quickly—turns Finland into an urban-scale energy laboratory.
A model with limits. Although the system works, it is not a panacea. As Middle Parenthesis remembersnot all data centers are close to cores with thermal demand, not all generate enough heat to justify the investment, heat recovery improves efficiency but does not reduce the electrical consumption of data centers, and in hot climates or widely dispersed cities, replicating it is much more difficult.
Still, the trend is clear. With the expansion of AI and the growth of cloudthe amount of heat available will only increase. The Nordic countries – Sweden, Norway, Denmark – already take advantage of it, and large operators such as Microsoft and Google They explore similar systems across Europe.
From silicon to the stove. The Finnish model shows that, even at the heart of digital infrastructure – those data centers that power our online lives – there can be hidden a useful and concrete source of energy for everyday life. The heat produced by our searches, our videos or our conversations with AI can be transformed, with the right infrastructure, into heating a home in Helsinki.
In a world desperately seeking clean heat, Finland has already found a tangible, scalable and surprisingly logical answer: turning the thermal problem of the digital age into a solution for the Nordic climate. A silent reminder that, sometimes, the energy transition advances with a simpler approach: taking advantage of the heat that servers already produce tirelessly.
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