Waste heat has been a very tempting energy source, simply because there’s so much of it around. Lots of the heat from burning gas and coal can be harvested, but there’s always a substantial remainder that’s simply not different enough from the environmental temperature to make obtaining any more electricity feasible. Everything from car engines to computer chips need to be actively cooled to prevent the build up of waste heat from damaging the hardware. If we could effectively harvest this waste heat, it would open the door to a far more efficient energy economy.

Given the small temperature differences between these heat sources and their environment, the only realistic option for converting it to electricity is the thermoelectric effect, where some metals and semiconductors form a current along the direction of a heat gradient. Right now, the current generation of thermoelectric materials is almost, but not quite, efficient enough to make economic sense. Two papers released this week, however, describe materials that push us closer to having viable devices.

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Zeroing in on efficient thermoelectric power