Microsoft is to build data centers at the bottom of the ocean. Among other benefits, it should greatly reducing power use.

One of the biggest problems with any large collection of servers is the sheer amount of heat generated and in turn the power needed to cool the equipment and stop it overheating and failing. That’s led to several creative solutions over the years ranging from siting the servers in Arctic and near-Arctic locations; building servers in underground vaults; and diverting the excess heat to a neighbouring building (thus reducing heating bills.

Sea water-cooled servers were also one of the most plausible explanations given when it emerged Google was operating a series of mysterious barges.

The Microsoft operation is known as Project Natick and was revealed in the New York Times. So far the staff involved have successfully placed a single server in an eight-foot diameter steel capsule and operated it while it spent 105 days located 30 feet below the surface of the Pacific Ocean.

The company is now exploring two ways to scale up the project. One is to build a farm of capsules, around three times larger than those in the test. Another is to instead use a single giant metal tube.

In the test, Microsoft used external power to make the server run, which led to a measurable but likely insignificant increase in the surrounding water temperature. However, the theory is that with a system in place to harness it, tidal power could be enough to operate the servers and thus make the server farm not only entirely self-powered, but with no temperature effects. The tests also showed the steel casing was enough to block the sound of the server to the point that it shouldn’t disturb any marine life.

Work on the project has had some fringe benefits. The nature of the set-up means the servers have to run for five years without any human intervention, which has prompted a rethink of their design. That in turn has cut the space taken up by each server. The streamlined design also means that it could take as little as 90 days to create a new server farm, which Microsoft says compares to two years on land.

Microsoft also notes that around half the world’s population lives within 200 kilometers of a coastline, meaning that underwater servers near shores could be an easier way to cut latency than trying to find suitable spare land.