New Scientist – To power chips using liquids, Bruno Michel of IBM has chosen a redox flow battery, which exploits the energy released when the oxidation state of a chemical changes. In this set-up, two electrolytes supplied by tanks outside the chip are pumped into the device in parallel channels. These fluids contain different types of vanadium ions, and electrons will flow from one to the other in an external circuit to create a current. Recharging the battery involves applying a voltage to reverse the process.
Flow batteries are ideal for chips because of their high power density, says Michel. The design is usually bulky, but Michel miniaturised it by lining the microfluidic channels with an electrode catalyst.
It takes about 85 kilowatts to run Watson, for example – enough to heat a dozen homes. And the machine’s servers take up the same amount of space as 10 large refrigerators.
Using this biologically inspired approach to combine the electrical and cooling systems into one should make it possible to reduce that power consumption considerably. Michel says he and his colleagues have demonstrated that it is possible to use a liquid to transfer power via a network of fluidic channels, and they plan build a working prototype chip by 2014. If successful, we could end up with Watsons in our pockets, powered by a battery akin to that found in a cellphone.
This paper presents the exploration in CMOSAIC of novel cooling technologies, as well as suitable thermal modeling and system-level design methods, which are all necessary to develop 3D MPSoCs with inter-tier liquid cooling systems. As a result, we develop energy-efficient run-time thermal control strategies to achieve energy-efficient cooling mechanisms to compress almost 1 Tera nano-sized functional units into one cubic centimeter with a 10 to 100 fold higher connectivity than otherwise possible. The proposed thermally-aware design paradigm includes exploring the synergies of hardware-, software- and mechanical-based thermal control techniques as a fundamental step to design 3D MPSoCs for HPC systems. More precisely, we target the use of inter-tier coolants ranging from liquid water and twophase refrigerants to novel engineered environmentally friendly nano-fluids, as well as using specifically designed micro-channel arrangements, in combination with the use of dynamic thermal management at system-level to tune the flow rate of the coolan in each micro-channel to achieve thermally-balanced 3D-ICs. Our management strategy prevents the system from surpassing the given threshold temperature while achieving up to 67% reduction in cooling energy and up to 30% reduction in system-level energy in comparison to setting the flow rate at the maximum value to handle the worst-case temperature.
Cooling of Next Generation Computer Chips: Parametric study for single and two phase cooling is another paper on this new approach to cooling and compacting 3d chips.