Giant data centers, established to feed artificial intelligence, have become a growing problem. The excessive load they place on energy grids and their environmental damage are causing people to adopt an increasingly hostile attitude towards these data centers. Especially in the US, citizens have virtually declared war on data centers. It is precisely at this time that news from Denmark shows that different approaches are possible to make these data centers more acceptable to the surrounding communities.
These facilities, where hundreds of thousands of servers operate 24 hours a day, draw attention not only for their high electricity consumption but also for the large amount of waste heat they generate. In fact, a very large portion of the electricity a data center draws from the grid eventually converts into heat. According to some assessments, this rate is approximately 90 percent. However, since the temperature of the generated heat is not high enough for direct use, most of it is released into the atmosphere via cooling systems. In Odense, Denmark, Meta's data center uses this normally wasted heat to warm 11,000 homes.
Odense's System Utilizes Heat Pumps
As mentioned earlier, although the air coming from the servers is warm, it is not hot enough to directly heat homes. Therefore, for this heat to be usable, its temperature needs to be increased. The system in Odense uses an interesting method for this. Water from the city's district heating network is passed through the data center's cooling units. During this process, the low-temperature waste heat from the servers is transferred to the water. The heated water is then sent to heat pumps in a facility near the data center. The heat pumps then raise the water's temperature to a level suitable for use in homes.
Ramboll designed the system for the district heating company Fjernvarme Fyn. According to the company, the ammonia-based heat pumps used raise the water temperature to approximately 70-75 degrees Celsius. This allows the water to be sent to the city's district heating network and used in home radiators.
45 MW of Heat Transferred to the City Grid
According to Ramboll's data, the system can provide approximately 45 MW of heat to Odense's district heating network. On an annual basis, approximately 215,000 MWh of energy can be recovered, making it possible to heat over 12,000 homes.
Meta's initial data showed that the system provided enough heat for about 6,900 homes and recovered 100,000 MWh of energy annually. With the expansion of the project, these figures rose to 165,000 MWh and approximately 11,000 homes. As the data center's capacity and the scope of the heat recovery system grow, the amount of energy provided also increases.
Furthermore, Ramboll states, based on data from the Danish Data Center Industry, that 63 percent of data centers plan to utilize their excess heat in the near future.
The System Uses Existing Heat Pump Technologies
One of the striking aspects of this system is that the technologies used are not new. Heat pumps have been used in various fields for many years. Similarly, heat exchangers and cooling systems used to capture heat from servers are not new technologies. Lauren Edelman, Meta's energy expert, also states that the innovation in the system comes from combining these technologies on a massive scale rather than from individual components.
In the Odense example, the main advantage is that the data center was already built within an extensive district heating network. Thousands of homes that can use the heat generated by the data center, and the pipe infrastructure to reach these homes, already exist. Therefore, waste heat does not need to be transported over long distances. Denmark's widespread district heating system provides a significant advantage in this regard. This point is crucial because applying the same system everywhere in the world might not be feasible. However, like the Odense example, building data centers close to, or even directly within, a district heating network can pave the way for much more efficient data centers.
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