Recycling Waste Heat: How data centres are using waste heat to heat domestic homes – an interview with Lex Coors from Interxion

Recycling Waste Heat: How data centres are using waste heat to heat domestic homes – an interview with Lex Coors from Interxion
Courtesy Interxion

Data centres have developed a notorious reputation as a wasteful industry. However, Interxion has been  developing green technology that not only conserves energy but provides heat for the surrounding communities. For data centre providers, much of the daily operations involve ensuring the equipment is kept cool to ensure customers’ mission critical applications are kept running 24/7/365.

Interxion is one of the companies operating data centres in Stockholm, Sweden, where waste heat is being used to heat domestic homes instead of being blown out into the atmosphere, thereby adding to climate change.

REM talked to Interxion’s Chief Data Centre Technology & Engineering Officer, Lex Coors, to find out more.

Tell me about the company

Interxion is a European company. Although we are on the New York Stock Exchange, we are in 11 countries and 13 cities. We operate over 50 data centres. We’ve doubled our footprint over the last 4-5 years and we are in the process of doubling our footprint again. We design, build and operate these data centres and then we rent the space to the large platforms, the hyperscales and also the EO2 platforms like IBM and also to the customers who like to connect to these hyperscales through cloud access. Interaction is a very important topic. We always have 40 carriers per data centre and so we have these highly dense carrier networks.

What is the major problem with regard to data centres and the climate?

It is everyone on the globe who like to make use of data transmission. As this is growing exponentially, our industry is also growing, easily 15 to 20 percent on an annual basis. That comes with pressure, not, per se, on the climate if you design the data centre the right way. If you want to run the data centre solely on fossil fuels and not take into consideration energy efficiency or any sustainability, then obviously you will have a problem with the climate.

We are heavily involved in the EU 2020-2030 programme for energy efficiency and decrease of greenhouse gases, but the major issue we have is resources. It is more the energy resource, in that it is not easy to get any more, for instance we have direct connections for 20 or 40 or 100 MW and that is not as easy as it was a few years ago. What we do to protect the climate as much as we can, and especially with data centres, as we are a newer industry, we are not from the heavy industries like steel or aircraft, from the start, if we are not energy efficient, if we don’t look at sustainability, it is very difficult to exist. All of these factors come together, free use of energy is an important topic because the margins are not that, let’s say, fat on the bone that we can afford to misuse energy.

First of all, we like to use the free air instead of compressors. We like to use outside air to cool the IT surfaces. The other thing we do is that we are conscious of water usage, because we all know water is becoming a scarce commodity. We use a lot of water for cooling, but you have to balance that, so you have to make the trade between ‘Will I use a lot of water to cool down the IT or will I mix it with air, and on top, maybe in peak temperatures, when you are reaching above 35 celsius, maybe also some compressor motors’. You can’t always get it for free. It would be easy to use the water for free but your corporate social responsibility won’t allow you to do that.

As I understand it, there are two particular problems, the first being where the electricity comes from and the second being the whole issue of cooling. Data centres operate large fans for cooling and these utilise cold water pumped into the data centre.

Correct. That’s the first use. But what we also use, at Interxion, is aquifers, which are salt water aquifers, for instance in The Netherlands and the Nordic region. We drill into 180 metre deep layers and take out that cold water, use it and then put it back into the ground as hot water. When winter comes, we use those big fans you mentioned to recool that hot water back into cold water. We take some of the heat for our offices. We also use sea water, that’s in Stockholm. We also decrease the temperature there before we put it back into the sea.

Every time, Interxion is looking at this aspect, because I can put the water back into the rivers at 30 celsius, but we realised over time, especially when it becomes to 40 MW or 100 MW data centres, we would create an issue on the microclimate. Therefore we are always conscious of what we do. We cool back our resources to the original temperature and reuse it again. In the Nordic region, we also use the heated water to support the local community, where we heat up the tap water, and in Copenhagen we do the same. On top of that we buy green energy, because we are connected in Europe to the supergrid. We don’t always know where the energy is coming from, but by the use of PPAs, the money from that is used for new solar or tidal or hydro for power production, and this is why at Interxion we look at these things. We don’t look at simply what is the cheapest energy we can get.

When we were asked to provide heat for the local community to heat the houses, my first question to them was that it cannot be the case that if we cannot provide the heat for the houses, if we don’t provide the heat the people will freeze to death in the wintertime, so we are willing to provide the heat, but not all the heat, and then we found out that with our 4MW to 5MW installation that it was just a small part because the total heat that is used for this is 4000MW. It is easy to say ‘I am sustainable, I support that’, but you have to think the whole thing through, especially when that is not your core business.

These heat reuse schemes, are they happening just in the Nordic region or elsewhere as well?

Every one wants this, but it is happening mainly in the Nordic region. Ever since 2008-10, we offered all the local authorities to take our heat, and what we tell them is that it is free of charge, with the only thing they have to do being connection of the pipes. It is a chicken and egg, because they like to have the heat, but they don’t like having to invest to lay the pipes. So they often say it is too expensive because the temperature of the water is not yet high enough. When our industry moves to liquid cool chips, the water temperature will go from 30 celsius to 50 celsius, and then it becomes a really interesting business case for the local authorities to connect to our data centres because there is much more value in the hot water.

Is that starting to happen now?

We are at the tipping point. Recently, I have seen designs for open compute connected to liquid cooling so I believe it is starting to happen. Slowly.  

You said your data centres are using energy from renewables. Is that mainly from wind and solar or are you using other technologies as well?

Because in Europe we are connected to the supergrid, it can come from a hydro plant, wind, solar. It is not always completely clear. There has been so much demand for clean energy and that until recently the power plants could not produce any more, so now we see that the cost for the green energy is going up. This is a bad thing. We have been doing this for quite some years. We started with 30 percent 5-6 years ago and we reached 70 percent two years ago and we have now been at 100 percent for the past two years.

What is likely to happen over the near future? How will it progress do you think?

I think over the next 5-10 years we will see more off-grid solutions with large data centre deployments that will have their own wind farms or solar farms. If you are a company like Microsoft and you are deploying 300MW or 400MW of data centres in a region, you can imagine that it makes sense to participate in developing your own wind farm. I think wind, for Europe, and certainly for Spain, will be one of the best solutions, because solar does not give a large capacity per square metre. Wind is a relatively high capacity for a small footprint.

Also, I haven’t seen, in Arab countries, the use of mirrors where they can create molten sand to run a steam turbine, but I think they have the opportunity over there.

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