Ultimately, the entire biosphere serves only to more efficiently reradiate energy absorbed from the sun (plus a bit from older stars in the form of fissiles) in

Ultimately, the entire biosphere serves only to more efficiently reradiate energy absorbed from the sun (plus a bit from older stars in the form of fissiles) into space. All of the energy that originally went into carbon chains to form that wood came from those sources originally, and while the energy released by burning it has been lost forever, there's no shortage of replacement energy.