@LunaDragofelis @dequbed @eniko @Njord

You can receive free electrons off of glucose through enzymatic breakdown similar than the body does - although the body stores it chemically in ATP or others.

It is however currently no longterm solution since the enzymes break down over time.

@eniko @Njord
Enocean is a conglomerate of smarthome appliances purely designed with energy harvesting. No changing batterys ever.

Unfortunately it is rather expensive and more difficult to integrate.