The sealed chest was found off the coast of the Orkney Islands. Reeled up from the ocean deep – coated in algae, barnacles and sea anemone – the haul had been sunk, deliberately, years before. But what lay within wasn’t some long-lost plunder of precious pearls or rare stones. Instead, this payload contained enough power to store the knowledge, arts and secrets of millions of people.
This was Microsoft’s underwater data centre, the ‘Northern Isles’: 864 servers and 27.6 petabytes of disk (roughly equivalent to 27.6 million gigabytes), tightly packed into a steel cylinder, filled with dry nitrogen, and dunked into the North Sea’s icy, choppy waters. With enough storage for nearly five million movies, as powerful as several thousand high-end consumer PCs, it was retrieved in July following a two-year-plus stint on the seafloor with only passing fish and marine organisms for company.
It was the next phase of Project Natick, Microsoft’s ongoing research into determining the viability of subsea data centres. Analysis of the trial is still underway but, so far, the Northern Isles has been hailed a success. “The preliminary findings show that the underwater data centre had only an eighth the failure rate that we see on land,” says Ben Cutler, Project Natick’s director. “Overall, we’ve found that underwater data centres are feasible, as well as logistically, environmentally and economically practical.”
Dumping a shipping container’s worth of electrical equipment into the ocean initially sounds like a circuitry nightmare. But there’s a reason why submerged servers may be eight times more reliable than land data centres, which are pinged by billions of people every day for any action done online: be it emailing, browsing or binge-watching. Placed on the seabed, cocooned from corrosive oxygen, moisture and bumps, data centres can seemingly thrive. “Computers don’t actually operate well in the same environment that humans inhabit,” explains Cutler.
From photos to messages and documents, we use cloud services every day – even more so in the working from home era. The cloud might seem nebulous and invisible. But every click and keystroke generates a piece of data that is backed up by physical servers which require round-the-clock power and cooling. Cloud expert Paul Johnston estimates that nearly two per cent of all the world’s carbon footprint comes from data centres. It’s an industry which grows year-on-year: there are approximately 18 million servers deployed in data centres globally; worldwide spending on hardware and software topped more than £125 billion in 2019.
That’s why there’s more to Microsoft’s experiment than simply producing reliable hardware. Underwater data centres might actually be good for the planet. “Nearly 20 per cent of energy used by land data centres is keeping everything cool through air conditioning units and freshwater resources,” says Johnston, who is also a climate change and technology consultant. “What Microsoft has done is groundbreaking, with natural seawater acting as the coolant rather than air being artificially pumped. It could be an environmental win.”
Project Natick was born in 2014, exploring an idea of placing computers under water, powered by renewable ocean energy. The following year, a data center was dropped off the Californian coast for several months as a proof of concept. Scotland’s Orkney Islands was picked for the latest trial, due to its grid being wholly supplied by wind and solar energy. “Our findings show that perhaps we don’t need to have quite as much infrastructure to support power and reliability,” Cutler says. “Even in light winds there would likely be enough power.”
That’s in stark contrast to most land data centres, which are mainly powered by electricity generated by fossil fuels. And the Northern Isles experiment could be a sign of things to come. By placing underwater data centres close to turbines, energy providers would have a regular, local customer; those in charge of the data centres would receive efficient, reliable power. Johnston believes the demand could then further boost the UK’s thriving offshore wind industry. Smaller, underwater data centres could then lead to lightning-quick connections for remote coastal towns and villages, who currently rely on centralised data centres which can sometimes lie hundreds of miles away.
Cutler is confident that the underwater model can be scaled cost-effectively – it’s the potential next step for Project Natick. “The vessel is smaller than land-based data centres. To scale up, you could join several data centres on a single frame, like building blocks.” He adds that a submerged data centre can go from factory to operation in less than 90 days – a much faster rate than land versions.
But what happens when a data centre 50 metres deep into the Atlantic needs repairing? According to Cutler, the model is self-sustainable: servers that fail early would simply be taken offline, while a lights-out data centre would be retrieved once every five years. “It’s designed to have such high reliability that we can operate for several years without maintenance,” he adds.
Underwater data centres appear to be more reliable and energy efficient, but a coastline teeming with submerged data centres may not immediately seem like the best thing for sea life. However Andrew Want, a marine ecologist based in Orkney, doesn’t necessarily see a negative impact. “Any time you put anything into the sea you get a process called biofouling. A coating of microscopic bacteria appears in a few days, then organisms attach themselves to that coating. It can act as an artificial reef which fish then congregate around, which can promote biodiversity.”
There’s the potential for underwater data centres to become sanctuaries, similar to how offshore wind farms have led to some fishing bans. “Fish like to aggregate around solid structures around nooks and crannies,” Want says. “Being just off the seabed, a data centre could provide shelter for juveniles and act as a nursery habitat.” And although data centres would emit some heat, it’s unlikely that it’d be enough to warm surrounding waters. “It’s a similar phenomena that you see in subsea power cables, there’s negligible warming.”
But we shouldn’t start ripping out our land servers and dumping new ones in the ocean just yet. “We don’t see underwater data centres as replacing those on land, but view it as an additional offering to serve customers,” Cutler says. He adds that the Project Natick team is currently analysing what led to the limited failures that did occur with the Northern Isles. They’re also recycling its servers and components, while restoring the seabed to its previous state.
Although pinging a server at the bottom of the ocean as you scroll through Instagram isn’t imminent, it’s certainly on the horizon. “Our internet consumption and electricity use is an indirect emission which has an unseen cost,” Johnston says. “At least with data centres dropped on the seafloor, that’s a more direct, visible impact that can be discussed. It will open up conversations which could lead to a positive, long-term outlook.”
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