A biogenic substance is a substance produced by life processes. It may be either constituents, or secretions, of plants or animals. A more specific name for these substances is biomolecules.
Coal and oil are possible examples of constituents which may have undergone changes over geologic time periods.
Chalk and limestone are examples of secretions (marine animal shells) which are of geologic age.
grass and wood are biogenic constituents of contemporary origin.
Pearls, silk and ambergris are examples of secretions of contemporary origin.
Biogenic substance Wikipedia
Carbon, from using biogenic and non-biogenic fuels, has implications for estimating the efficiency and environmental benefits of waste-to-energy incineration processes.