Agro and forest wastes valorization: the challenges toward sustainability in biofuels production

Abstract Lignocellulosic biomass is the most abundant biobased raw material worldwide. This category involves agricultural residues, forestry waste, and municipal solid waste. The estimated annual availability of lignocellulosic biomass is between 181 500 and 200 000 million metric tons. From the total, 3.8–4.0% comes from dedicated forest, agricultural, and grass sources, while 2.5–2.6% corresponds to agricultural waste. The availability of this biomass makes biofuels production attractive, representing a promising alternative. Conversion technologies, including thermochemical and biochemical, have demonstrated promising results for biofuels, such as bioethanol, sustainable aviation fuel (SAF), renewable diesel (RD), renewable natural gas (RNG), and hydrogen (H 2 ). Conversion yields can reach 330 L of bioethanol, up to 250 L of RD, up to 150 kg of SAF and up to 130 kg of H 2 per dry metric ton of biomass, as well as approximately 60% of RNG for each ton of biogas. The projected annual growth rates for biofuels range from 4 to 6% for bioethanol, SAF, and RD and up to 30% for RNG, and are expected to increase exponentially for H 2 . Industrial‐scale implementation faces several challenges, including seasonal variability, biomass fractionation, and transportation, which in some cases account for up to 50% of the costs. Conversion, fractionation, and enzymes account for approximately 25–30% of operating costs. Current production costs for bioethanol, SAF, and RD range from $0.52 to $0.57 L −1 , and can decrease with integration strategies such as byproduct valorization. For hydrogen, it is expected to have a value of $2 kg −1 of H 2 by 2026. Additionally, strategies such as CO 2 capture in biofuel production and the addition of high‐value products led to significantly promising results, achieving a notable decrease in environmental impacts. Finally, challenges related to social acceptance and policy support are critical for the long‐term success of alternative biofuels.