The power consumption of data centers is a thorn in the side for many countries or regions, but there’s too little discussion about water usage in new installations that use water cooling. A potential solution could be the sea cooling a closed circuit.
The world’s largest heatsink, according to Schneider Electric. It makes sense in a way. Cool a closed loop with seawater, then send the water back to the sea. Sending saltwater directly into the data center is a bad idea anyway, hence the closed circuit.
Schneider Electric invited us to sunny Sines, about a hundred kilometers south of Lisbon. The city is charming, but you can tell it has grown due to the surrounding industry. A lot of industry. You might almost forget that Portuguese explorer Vasco da Gama was born here.
Which coal power plant?
You often can’t see a data center from a distance because the installation isn’t particularly tall. Five kilometers south of Sines we’re getting close according to the bus driver, but all we see is a large coal power plant. The undersigned immediately chuckled at the ‘green’ story this project was supposed to be. Of course, you’d put such a data center near the source so you never run out of power.
Fortunately, it’s quickly emphasized that the coal power plant was disconnected about four years ago. All coal power plants in Portugal, in fact. Of all the electricity the country consumes today, 71 percent is already renewable. By 2030, they’re aiming for 93 percent. An additional asset for future data center projects in Portugal.
There’s still plenty of room for growth in the data center market within the Iberian Peninsula. Today, all installations consume 2.8 TWh, barely one percent of total electricity production. Ireland leads in Europe with more than 10 percent. The Benelux is between five and ten percent.
1.2 gigawatt, the highest in Europe
There’s a reason why the Start Campus data center chose the site of the coal power plant. They previously used ocean cooling. The data center can use part of the existing pipe infrastructure and the intake and outflow channels.
Start Campus is set to become the largest and greenest data center in Europe. The total project is estimated at 8.5 billion euros and will consume 1.2 GW (gigawatt) of electricity. In Europe, it’s the first site to have a permit for more than 1 GW.
Today, only SIN01 is online, the first step and essentially a sort of proof-of-concept of 14 MW (megawatt) to test the seawater concept in practice. Later, an additional 12 MW of capacity will be activated. The groundbreaking for SIN02 (180 MW) will follow later this year. SIN03, SIN04, SIN05, and SIN06 (220 MW each) will follow after that. When SIN06 will be ready, the last of the total project, is not yet known. The budget is there, as is the power supply, which is the most important thing.
Cooling via water, air, or reserve water
The site looks very modest with plywood panels everywhere in the reception area. As far as we’re concerned, an excellent choice, it should be primarily functional. Throughout the presentations, you notice that Schneider Electric is particularly proud of this project. The people from Start Campus are too. They can tell a great story about a project that could become THE reference in the future for seeking more locations close to the sea.
The tour itself is, as you’d expect, very strict. All smartphones in a bag, we have to steal with our eyes. We start at the cooling installation where all the pipes come together. Here, seawater should run over titanium chillers that are corrosion-resistant. Should, because today that’s not yet the case. According to Start Campus, it should be operational within a few weeks. The data center has been active since Q4 2024.
A data center has a backup for everything, including cooling. There are various chiller installations outside that are currently cooling the data center in a traditional way until the seawater runs through the pipes.
Should even that fail, there are four water tanks of 150 m³ each that give the data center one hour of autonomy.
Batteries and generators
On the other side of the building, we find the lithium batteries that can deliver 2 MW of capacity, good for eight minutes of autonomy. Often, the batteries are used for only a few seconds to one minute. In case of a power outage, it takes a maximum of one minute for the diesel generators to start up. To bridge that time, the batteries spring into action to prevent downtime.
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These generators are tested monthly to ensure everything works properly. Start Campus emphasizes that they use locally produced biodiesel. Added benefit: it emits 90 percent less than traditional diesel. A full tank gives the data center 24 hours of autonomy. If longer is needed, it can be refueled.
We’re skipping the data halls. Too sensitive according to the Start Campus people to enter there. We have to make do with photos to get an idea of what it looks like.
Temperature control of the seawater
On to the coast where we’ll see how the seawater will soon be pumped in and discharged. Start Campus uses the existing infrastructure of the coal power plant for SIN01. In the photo, you can see that the pumps (in blue) are ready for installation. The piping infrastructure is in place, Start Campus speaks of ‘a few weeks’ until the water is connected. It’s a pity we can’t see that part actively working.
The temperature difference in the data center between seawater inlet and outlet is between 10 and 15 degrees. The coolant in the closed system operates between 18 and 20 degrees. At the sea outlet, the temperature would have already dropped further. At a measuring point in the sea, it is permanently monitored that the temperature difference is not higher than three degrees. That’s a hard limit, imposed by the Portuguese government.
At the sea inlet, 250 liters per second are pumped, 0.25 m³. When SIN02 and the rest open, much more flow is needed due to the higher capacity. Start Campus plans to lay five pipes of 3.5 meters in diameter per unit (3 needed, 2 redundant), good for 25 m³ per second of water volume.
Interesting detail: the temperature of the seawater is not constant throughout the year. During winter, less water needs to be pumped because the water temperature is lower. This is also incorporated into the system to automatically adjust when necessary.
Using seawater, not consuming it
What Schneider Electric and Start Campus are realizing in Sines is no small feat. When the project is completely finished, Start Campus may call itself the largest data center in Europe. That in itself is impressive, but it’s the approach and working with seawater that cools a closed loop that makes it even stronger.
The approach is not new: nuclear power plants or coal power plants have been using this approach for decades. For a data center, the technology is relatively new. Especially on this scale, Start Campus is unique. Many parties worldwide are closely watching how the data center project in Sines will function.
When the project is completely finished, Start Campus may call itself the largest data center in Europe.
We certainly hope for a successful conclusion, because something needs to happen. Many data centers worldwide consume enormous amounts of water, causing water scarcity in those areas. By using the ocean as a gigantic heatsink, you build a system that doesn’t consume water for cooling. No cooling towers needed, or even worse: consuming groundwater.
Let’s hope that Start Campus can become an important blueprint for data centers in the future.