Servers designed to look like humans

David Atienza believes that when it comes to IT systems, everything that can be done locally, should be. That includes processing data where they are generated – thereby substantially reducing the amount of power required.

EPFL’s Embedded Systems Laboratory (ESL) is studying two major energy-related problems with servers. The first is that they aren’t being used anywhere near their maximum capacity. Actual use is closer to 60%, according to ESL head David Atienza. “Servers are designed for tasks that require a lot of processing power – such as running neural networks – but they’re being used mainly for watching movies or sending pictures via chat,” he says. As a result, they overheat. “It’s like driving a Ferrari at 40 km/h – it would burn up a lot more energy at that speed than a Twingo would,” he adds.

The problem is that even if the servers are the only equipment that overheats in a data center, operators still have to cool the whole center. To help find a solution, Atienza is working on the Compusapien research project, for which he received an ERC Consolidator Grant in 2016. His team found that cooling servers locally can cut a data center’s power requirement by 40%. They worked with engineers from IBM to develop a system where cooling water is used to lower the temperature of individual servers, as opposed to running fans to cool the entire room. With this system, heat is recovered in the cooling water and reused. The water runs through microfluidic channels that are just 50–100 µm high and sandwiched between two layers on a cooling plate. As the water absorbs heat from the servers, it transfers it to microfluidic fuel cells where it’s converted into electricity. The electricity can then be fed back to the servers as power, reducing the amount of power that the data center draws from the grid.

Processing data locally

“The human brain works the same way. Blood carries nutrients to the brain and cools it. It’s just that with servers, the process is a little more complicated!” says Atienza. While a lot of data centers already use cooling water, his is the first system to use microfluidic fuel cells to recover heat and turn it into electricity. The technology – nicknamed “electronic blood” – was tested in a 3D prototype developed in association with IBM, and proved to be feasible from a technical point of view. Now ESL engineers are building a 3D version of the integrated system and plan to develop a full server through a joint project with another company.

The second component of Atienza’s approach is to process data as locally as possible since transmitting them takes up a lot of energy. One example of this approach is a next-generation Nespresso machine that the ESL team developed. Their machine uses an embedded artificial intelligence system to manage maintenance and restocking completely on its own. “More and more applications – especially those for smartphones – operate locally and don’t go through data centers,” says Atienza. “That’s a lot like the human body. Our bodies have lots of tiny modules that can carry out two or three simple functions; the brain gets involved only when important decisions need to be made. That’s a lot more efficient than today’s data centers where everything runs all the time.”