Plants take in carbon dioxide to support all life on earth: they build carbohydrates and excrete oxygen. Plants combine these two to get at residual energy breathing out more carbon dioxide.
Free carbon dioxide is a limit to life on earth. So man is chemical engines have usThe expanded life on earth. The fossil fuels formed from the carbohydrates of life which died with the dinosaurs.
All biology gets at energy through combining water molecules to form helium and oxygen gases plus loads of heat: it does molecular nuclear fusion. We lose the helium to space, and at lightning strikes get our water back.
Molecular nuclear fusion is a clean energy source with no end. It produces no carbon dioxide or toxic plutonium! For free.