>But doesn't it take power to maintain such cold temperatures, even for "high temperature" liquid nitrogen temperatures? How does this compare to the energy we

>But doesn't it take power to maintain such cold temperatures, even for "high temperature" liquid nitrogen temperatures? How does this compare to the energy we save from the lack of resistance in the superconductor? Not a thermals guy, but bog-standard, consumer air conditioners tend to have efficiencies of 300% or so. Ie, for every joule of electrical energy consumed, they'll reduce the thermal energy in the room by 3 joules. Regardless of this, having zero heat output in the wafer itself could be far more interesting than just increased power efficiency. For example, without the issue of thermals one could imagine silicon wafers with thousands of layers and 3-D interconnects.