[suoduandao2]

No, fungi evolved that can digest lignin now ;).

On a less facetious note, Solar needs time to renew the energy it made the day before as well. Time scale is very important to questions of renewables, and people have been sustainably burning wood for a long time. Unsustainably too, but I would bet that’s not the case here if it’s being included in a census of sustainable sources.