Next-Gen System Could Cool Data Centers Using Nothing But Their Own Heat

Server farms consume an absurd amount of electricity, often as much as entire neighborhoods. This is a big part of what fuels the pushback communities across America have mounted against AI data centers – even more so when some of the costs tied to all that consumption go downstream toward residents. A fair chunk of that electricity is also spent on cooling, which is ironic, considering power draw is what indirectly generates that heat in the first place. In fact, industry estimates put it as high as 40 percent of what a single facility hands its utility.

That figure is exactly what makes a machine — built by researchers at the Karlsruhe Institute of Technology in Germany alongside materials scientists at Japan's University of Tsukuba – so attractive. This thing's a small cooling device that runs on heat rather than electricity. This may almost sound like a violation of some law of thermodynamics, since heat is being consumed to produce cold, but that isn't what's happening here.

The thing is that the device never cools itself in a closed loop. Instead, it works by grabbing waste heat off one component, then spending that energy to drag warmth out of a different one. It pulls this off using two strips of nickel-titanium foil, which is a special metal here that changes shape on command. It can even be talked into pulling like a muscle, and that's exactly how it performs these cooling duties.

The whole process starts with heat arriving at the first of those two strips, both of which sit under moderate of tension before anything else happens. This actually makes the strip contract, and as that happens, it pulls with real force, roughly what you'd need to lift a bag of sugar off a kitchen counter. This first strip is connected to a second one with a small plastic link. When the first strip contracts, it tugs on the second strip, stretching it. That stretching makes the second strip warm, which sounds counterproductive at first. However, once the pull lets go, the strip ends up snapping back to its old length. This is what turns it cold.

Of course, that cold is lost quickly, so it needs to be collected. That task falls upon two small copper tabs, each one touching the strip at a different point in the cycle. While this prototype does what it's supposed to, which is cooling, it does a minuscule amount of it. Fed by an external heater that was held at 130 degrees Celsius (233 Fahrenheit) the device managed to open just a 2.2-kelvin gap between its warm and cold sides.

It's all early stages, so the prototype isn't quite ready for datacenter cooling just yet. The processors in those buildings run somewhere between 60 and 85 degrees Celsius internally, and the cooling systems looking after them today have to pull that figure down by 10 to 20 degrees. For instance, Nvidia's new data centers actually run way hotter than you'd expect. There's a solution for this, stacking a fair few of these strips in parallel. The KIT group is already on top of it.