> their "usable energy" is on the pico-watt to micro-watt scale devices which have long-term average power consumptions of micro-watts are perfectly reasonable

> their "usable energy" is on the pico-watt to micro-watt scale devices which have long-term average power consumptions of micro-watts are perfectly reasonable. it's how some BLE sensors can run for years off a single coin cell battery. you'd need some energy harvesting circuitry and something low-leakage to build it up in, but that's doable. more expensive than just stuffing a coin cell into the circuit, though. > It looks more and more like one of those "free energy" type devices. it's perfectly well understood that there's energy in RF. just very very little of it, as you note. that's qualitatively different from the claims of most free energy devices.