The use of sunflower biomass as a raw material for bioethanol production requires its pre-treatment to destroy the lignocellulosic structure, which makes the access of enzymes to the cellulose chains easier or directs the use of their lignocellulosic fractions[1]. The data on the theoretical yield of bioethanol from different types of biomass is provided in the table below.
The pre-treatment by steam and simultaneous saccharification and fermentation makes it possible to obtain 1 l of ethanol from 3.8 kg of pretreated sunflower stalks. In terms of the equivalent amount of raw material, it can be produced 101.4 liters of bioethanol from 1 ton of sunflower stalks[2]. Prehydrolysis at the temperature of 180-230°C with simultaneous saccharification and fermentation makes it possible to obtain 12 g of bioethanol/100 g of sunflower stalks (150 l/t), which is equivalent to 72.2% of the theoretical yield[3]. A typical scheme of bioethanol production from lignocellulosic raw material is shown in the figure below.
In a study of growing four varieties of sunflower in the semi-arid region of north-eastern Brazil with further processing into liquid biofuels46 (seeds for biodiesel, and stalks and heads for bioethanol), from one hectare was received 2537 kg d.m. of by-products and 1635 kg d.m. of seeds, respectively, 663 kg/ha of oil and 1115 kg/ha of sugars (871 kg/ha of cellulose and 244 kg/ha of hemicellulose). It was possible to obtain 293 l of bioethanol/ha from this amount of sunflower by-products.
[1] Osiris Ashton Vital Brazil et al. Integral use of lignocellulosic residues from different sunflower accessions: Analysis of the production potential for biofuels. Journal of Cleaner Production 221 (2019) 430-438.
[2] Ruiz, E., Cara, C., Ballesteros, M., Manzanares, P., Ballesteros, I., & Castro, E. (2006). Ethanol Production From Pretreated Olive Tree Wood and Sunflower Stalks by an SSF Process. Applied Biochemistry and Biotechnology, 130(1-3), 631–643.
[3] Evelin Raquel Ruiz et al. Strategies for bioethanol production from sunflower stalks Afinidad –Barcelona – 68 (556): 417-423. – November, 2011.