Heating apartments with waste heat from the data center
Data centers require a lot of energy for cooling the server rooms. It's just as well that waste heat is used now and then, as in the case of the Zurich 3 data center in Rümlang. It will go into operation next year and will supply the new Airport City energy network from 2024.
Interxion operates over 100 data centers in Europe. Can you say something about the energy concept?
Hans Jörg Denzler, Managing Director, Interxion (Schweiz) GmbH: There are relatively many initiatives underway in the European Union to optimize data centers. We operate our data centers in Europe entirely with renewable energy, and in Switzerland with hydroelectric power since 2011. High-performance data centers pack a lot of power into a very small space and are in constant operation. That's why they can be operated very efficiently.
What PUE (Power Usage Effectiveness) value are we talking about?
Small data centers of individual companies have a poor PUE value of mostly 2 and more. Our new data center in Rümlang, which will go into operation in 2022, will have a value of around 1.25; the lower the value, the better.
The Zurich 3 data center currently under construction is their largest, with 24 megawatts of capacity and over 11,000 m² of space. What does the energy concept look like?
In principle, our concepts always look similar, but we are constantly optimizing. Zurich 1 and Zurich 2 are completely different because there are 20 years between them: The concept of electricity feed-in is very different, as is that of cooling. Zurich 2 and Zurich 3 are practically the same - except that in the future we will be able to utilize the waste heat. This is the advantage of large data centers, because the waste heat can be bundled and fed into the district heating system, as in this case (see box below).
The energy service provider EBL is making the investments and will operate the Airport City energy network. They bear no entrepreneurial risk, but earn money from it.
No, we don't earn anything from this, because we give the heat away for free. The only compensation we receive is in the form of chilled water for the purpose of cooling our system. As I said, we want to be as environmentally friendly as possible, because that's what our customers want. Sustainability and climate management is becoming an increasingly important issue. I would like to add the following: Our new high-performance data center will have an output of 24 MW. We are annoyed that there is always talk of "power guzzlers". Many cloud providers are and will be renting from us. In other words, their customers are companies that are scaling back their sometimes inefficient IT infrastructure because they are outsourcing their data to the cloud.
International studies also prove this: computing power is increasing strongly, but the power demand for it remains stable overall. So we operators of high-performance data centers are only substituting computing power for many companies,
that operate with a poor PUE value.
Are solar cells coming to the new data center?
We would like to, but the roofs are each full of the recooling systems. So there is no space available - unfortunately. Solar cells would be ideal because they provide energy when we need a lot of power, so also in summer for cooling the server rooms. We also looked into solar facades, but the efficiency is too low. What about the cooling technology? Cooling the server rooms has a significant impact on the PUE value. That's why we try to run the data centers efficiently. Water cooling would be the ideal concept, but this could not be implemented at our site due to the lack of a river or lake.
We work with so-called free cooling: Server cooling with the outside air alone still works at around 18 degrees Celsius these days. We therefore cover around 70 percent in this way. For the remaining part, the energy-intensive but now environmentally friendly refrigeration system is used. But as soon as the district heating network of the Airport City energy network goes into operation in 2024, the energy service provider EBL will provide us with cooled water via the district heating process. This will make our cooling even more environmentally friendly.
EBL assures its heat customers of district heating through long-term contracts. What if Interxion closes the data center site in a few years for some reason? Will it then be cold in the houses connected to the district heating network?
We may be the only ones feeding the district heating network. But we are investing a three-digit million sum in Zurich 3. Anyone who invests that much money in a data center doesn't write it off in ten years. So we're staying at this site for a long time; that's contractually guaranteed to EBL. Will the data center be certified to ISO 14001? We are considering that. But as I said, regardless of that, we are committed to environmentally friendly business practices. In the medium to long term, the regulations will become stricter, and we are trying to anticipate this as far as possible. The fact that our waste heat fed into the district heating network can save around 15,000 tons of CO2 per year shows that we are on the right "climate path.
The planned energy network
The Airport City energy network will supply the Zurich airport communities of Opfikon and parts of Rümlang with district heating and cooling. The networks will one day be fed solely by the waste heat from the Zurich 3 data center of Interxion (Schweiz) GmbH, which will commence operations in the course of next year and gradually increase its output.
The waste heat is fed into the energy network's underground heating and cooling center and distributed from there to the connected properties via the heating and cooling networks. The plan is for the energy network to be ready for takeoff in 2024. As the operator of the energy network, EBL emphasizes that the waste heat from the data center is available as a stable energy source throughout the year. There is so much waste heat available that considerably more of it could be used elsewhere, according to the energy supply company.
The cold is generated by chillers, whose waste heat in turn benefits the energy network. EBL thus also provides property owners with regenerative energy in the form of cooling.
The key figures for the Airport City energy network
Heat:
Thermal power demand: 18.5 MW
Thermal energy demand: 50,600 MWh per year
Flow temperatures: 62-80°C
Length of district heating pipeline network: 7.7 kmCold:
Cooling power requirement: 14.8 MW
Cooling energy demand: 33,700 MWh per year
Flow temperatures: 10-14°C
Length district cooling pipeline network: 3 kmFor more information on the Airport City energy network
