Submerged data centers promise to emit 40% less CO2

Text Silvia Lisboa and Bruno Garattoni

Data centers that make the Internet work consume 1% to 2% of the total electricity produced in the world. And that energy often comes from polluting sources, such as thermal power plants. Therefore, data centers are responsible for 0.3% of all global CO2 emissions, according to the International Energy Agency (IEA).

It may seem small, but it is not: it gives 150 million tons of CO2 per year, which is the equivalent of produced emissions for 35 million cars. And with online information traffic doubling every four years, the problem is only growing.

Data centers consume all that energy for two reasons: they have a lot of CPUs (a large data center can have more than 100,000 servers, with several processors each), and you also have to cool all those machines. The first problem is addressed by the chip industry, which releases more and more efficient CPUs every year. But the other requires more radical solutions – like building data centers underwater.

By the end of this year, the British company Subsea Cloud intends to open the first: a 6-meter-long closed container that will be sunk off the coast of Port Angeles, Washington. It will have 800 servers. No wonder the data center was named after Jules Verne, author of the science fiction classic “20,000 Leagues Under the Sea”. If successful, Subsea intends to set up subsea data centers in the Gulf of Mexico and the North Sea, between the coasts of Norway and Denmark.

The strategy may seem risky and counterintuitive (after all, water and electronics don’t mix), but it is considered one of the most promising for reducing CO2 emissions in the technology sector. According to Subsea, undersea data centers use 40% less electricity – because the seawater cools the tank, dissipating the heat generated by the servers.

Subsea containers are the same dimensions as those used to transport goods and are sealed to prevent water from entering. But they are made of a different type of steel, with a lower carbon content – ​​and are therefore more resistant to corrosion.

are also fulfilled with a special fluid based on fluorine, which conducts heat, but not electricity (prevents a short circuit in the computer, which would occur in contact with water). This liquid absorbs the heat generated by the servers and transfers it to the tank walls – which are cooled by contact with seawater.

The submerged data center is connected to the surface by a network of copper cables and optical fibers, which receive and send data to it – as well as the electricity needed by the servers. The container is at the bottom of the sea. But in coastal areas, where the depth is not so great.

So Subsea says it’s relatively easy to bring it back to the surface to service the servers: it says the process takes 4 to 16 hours. But the company claims that the need for maintenance will be reduced due to the fact that there is no dust in the sea and the low risk of the metal structure breaking.

Data center in the Arctic

In 2018, Microsoft tested an idea similar to that of Subsea: it was Project Natick, in which a large cylinder with servers inside was sunk off the coast of Scotland and operated remotely for two years. In 2020, it was raised – and the company’s engineers found that the failure rate for submerged servers was almost 90% smaller than the average for field servers.

So the idea worked. Microsoft is now considering taking the next step and placing submerged data centers near offshore wind farms, whose turbines would supply all the energy it needs.

Another idea to reduce CO2 emissions is to transfer data centers to icy lands. That was the option of Facebook, which built one of them in northern Sweden, just 100 km from the Arctic Circle. The center occupies an area the size of six football fields, and is located in the frozen forests of the North Pole.

Arctic temperatures hover around -50ºC most of the time. In order to use the naturally cooled air, the platform draws it into the building using turbines like an airplane. The energy used to drive the propellers comes from hydroelectric plants that work on nearby rivers. “The system uses almost 40% less energy than traditional data centers,” said Mark Zuckerberg. The numbers are similar to underwater modules being tested by Subsea and Microsoft.

Google, on the other hand, uses a number of strategies, including cooling its data centers with purified waste water, in order to reduce energy consumption and CO2 emissions. The company aims to use 100% clean energy in all of its data centers by 2030.

Despite all these initiatives, keeping the world connected is still far from a sustainable activity. Research from the consulting company Capgemini, who analyzed 1,000 IT companies, found that reducing their impact on climate change is still not a priority: only 43% of industry executives know how much CO2 their companies emit. Although half of the companies have sustainability plans, only 18% of them are actually structured, with well-defined goals.