Ceramics are already used a lot in electronics. Ceramic capacitors are the most well known. But you can find it in resistors, inductors and even PCBs. See for example:
The article acknowledges this, and says they chose clay over ceramics for electricity consumption. Although I am not sure why they then chose an open wood fire, which is likely far more polluting than even non-renewable grid power
The reason the power grid exists is because enough people want to do enough of this kind of activity that if we were still burning wood to do it there would be no trees left. Scale does matter, and this kind of 'sustainability' can't sustain a fraction of the people on the planet.