A biorefinery is a plant that combines biomass conversion processes to produce fuels, electricity, and chemicals. It is defined as the most efficient use of biomass for materials, chemicals, fuels, and energy applications, taking into account costs, economics, markets, yield, the environment, impact, carbon balance, and social factors. Biorefineries have the potential to partially replace petroleum refineries. Apart from this goal, another goal is to be able to sustainably valorize the entire biomass. The scope of biorefineries must include feedstock as an intrinsic element of their goals. That involves conceiving of biorefineries not just as conversion plants, but as systems that span the creation of the feedstock to the replacement of a reference product.