It's a bit suspicious that the article doesn't actually mention how much power the system uses. The processor it powers doesn't need very much at all, so it makes one wonder
From what I can find [0] it uses 11 uW per MHz. If I’m not mistaken, that means it could run 100 cores at 1GHz and still only use about 1 watt, which sounds almost as impressive as powering it with algae!
https://www.silabs.com/mcu/32-bit-microcontrollers/arm-corte...