I always knew it was BS when they said these things don’t leak, and now we know just how much,
With a team from Georgia Institute of technology in Atlanta, Kawahara began studying the energy leakage from a range of ovens to see what useful power levels might be harvestable to replace button cell batteries in kitchen gadgets.
Kawahara’s leakage tests on a range of popular ovens, including those manufactured by Sharp, Panasonic, Whirlpool and National. The average leakage is generally lower than the legal limit at around 0.5 milliwatts per square centimetre, he told a conference on ubiquitous computing in Zurich, Switzerland on 11 September. That made around 1 milliwatt of power available in front of the oven.
To harness that energy, they then designed a power harvester the size of a US quarter, or UK 10 pence piece, that combined with a 1-cm-long microwave antenna to generate an electric current that could charge a circuit. “The energy accumulated over a two-minute run of the microwave oven was enough to operate some low-power kitchen tools for a few minutes,” says Kawahara. So by leaving gadgets close to the microwave, they would be gradually charged up enough to operate. He says the harvester is small enough to be embedded in most kitchen gadgets.