INTERVIEW: the heat generated by our data center could warm thousands of homes

As the heating season has begun, many are concerned about how to get their homes warm and how much it all might cost. In Hüüru, in the vicinity of Tallinn, however, there is a high-tech building which has heat to spare. Kert Evert, chief development officer of Greenergy Data Centers, tells us what excess heat is and how data centers will become part of our heating solutions in the future.

The plots near the data center – residential as well as industrial buildings – would make ideal users for the excess heat. Photo: Pixabay

What is excess heat and how is it generated in data centers?

Everything that is on the internet must also have a physical location. As a rule, this location is the servers and other IT equipment located in data centers (clouds are actually also located in data centers). Such equipment consumes a lot of energy which is turned into heat in the course of this process. Jokingly, data centers may be compared to radiators which turn electricity into heat by doing useful work. In order to ensure a better working temperature for IT equipment, data centers must do something about this heat.

There are different methods for building a cooling system. Many data centers built years ago take fresh air from outside and blow out their hot air – the entire heat is released outdoors through the ventilation ports. We, for example, have chosen another path. Our heat carrier is water which circulates in closed pipes. This means that the entire heat released by equipment is transferred to the water, the hot water moves to heat exchangers where it is cooled and then moves on to take another lap. Heat exchangers are used to extract the heat from the water, so to speak, and there are currently three methods for doing so.

The first option is to extract the heat through heat exchangers and separate it for the consumption of our own building. Another option is to transfer it into glycol and lead to the heat exchangers on the roof of the data center where it is cooled by outdoor air. The third option is cooling the water in the building with a chiller. Those work the same way as modern refrigerators. This is the least efficient method from the perspective of energy use.

How can this heat be used outside of your data center?

For such use, the data center must have the technical preparedness, as well as a partner who wishes and is capable of taking advantage of the excess heat. We have the technical capability for dispatching the heat from our building. Negotiations with potential recipients are ongoing.

The plots near the data center – residential as well as industrial buildings – would make ideal users for the excess heat. For maximum benefit, the heating systems of those buildings should be designed to operate at low temperatures. In the case of a residential building, for example, this means underfloor heating with the input water temperature of just 30–40 degrees. We would already be capable of providing this with the help of our heat pumps today.

If you start sharing excess heat at some point, would you give it to a district heating plant or directly to a residential district?

Most likely to a plant. Just like we are currently sending warm water to our roof through heat exchangers and different pipes, the water will probably also be led out of our territory in the future. Outside of the territory, there is another pipe which will take the heat to the boiler room of a developer. If necessary, the water temperature in the boiler room can be increased.

Is it possible to calculate how many households with low-temperature heating systems could be heated with the excess heat from the GDC data center?

The first full house can ideally issue 6 MW of heat. This would be enough to heat one hundred apartment buildings or approximately 5,000 households.

The longer the route, the more heat is lost. Thus, those 5,000 households should be located quite close to us. This is why heating apartment buildings, larger offices, or industrial buildings is a good alternative. I know that this solution is used in shopping centers in Finland, for example. A shopping center would also be quite a good solution here.

Would it be a good idea to build a production building near the data center then?

In the case of so-called safe production with no risks to the data center, why not. For example, when the data center of Greenergy Data Centers was designed, the idea of building large greenhouses came up at some point. This way, the production residue of one business line would provide the production input for another. We would have been growing our digital society in one half of the garden and vegetables in another. This may sound strange, but there are several similar examples from the all over the world. In the end, it comes down to the most reasonable use of resources.

I am not planning to build greenhouses today, though, we are considering our options for generating green energy instead.

Is the excess heat from data centers already used for heating homes or production buildings somewhere in the world? Can you give a specific example?

According to the Energy Innovation think tank, very large data centers with the power of 100 MW can heat approximately 80,000 homes. For example, the Microsoft data centers in Helsinki have joined their forces with the district heating provider Fortum, as a result of which the excess heat from the servers is reaching thousands of households in the capital of Finland.

In Denmark, Fjernvarme Fyn which is in charge of district heating in Odense, the third largest city in the country, helped design and build a system for the data center of Facebook which provides up to 100,000 MWh of energy per year as excess heat. This is enough for heating up to 6,900 homes.

Thus, this is a functioning and proven model.

When would it be possible to start sharing the excess heat of GDC?

The larger the data center and the volumes thereof, the more excess heat is generated and the more reasonable it would be to take advantage of it. Our complex is only in the growth phase and the building itself and some of the technical equipment need heating, thus, the excess heat is only being generated.

It is important to highlight that distributing excess heat is not a beneficial business for us, but rather a green philosophy. As building and operating such system requires considerable resources, joint contributions by several different parties are needed for success. In addition to the company which provides heating, the state should also be interested in the project and thereby contribute to achieving the climate targets.

In conclusion, it can be said that a data center is basically a large machine for turning electricity into heat and it is inevitable for running the modern digital society. Clouds are also no exception, as they are located in data centers. Thus, it is reasonable to reuse the heat generated. Speaking of 5,000 private residences, for example, we can calculate the amount of other types of fuel or energy which will thereby be saved. This is replaced by the excess heat from the data center and there are some good examples from the nearby countries. Now we must only follow their good example, which is exactly what Greenergy Data Centers is planning to do.