how to get 115% efficiency from burning wood

If you employ a condensate trap, you can significantly increase combustion efficiency even beyond 100% to near 115% by retrieving the latent heat energy of vaporization from the woods moisture content AND HYDROGEN content (wood is a HYDROcarbon!).

If you condense it to the maximum by preheating cold outdoor intake air.

But you have to collect the acidic condensation in a drip bucket.

The condensate can be sold as real liquid smoke! Or dried to tar and used for a fire starter!

However you may need to force induce the flue gasses up the chimney stack!

A small air cooled TEG thermal electric generator fan can take care of this.