Thermal batteries, the kind used on spaceships, weight 15 kg and can generate 100W for decades. The human baseline metabolism is around 100W, so with two therma

Thermal batteries, the kind used on spaceships, weight 15 kg and can generate 100W for decades. The human baseline metabolism is around 100W, so with two thermal batteries and another classic battery for energy usage spikes (physical activity) you would have enough if we could feed electricity directly to cells (instead of in a round-about way through food)