Journal of Energy Bioscience 2025, Vol.16, No.3, 117-127 http://bioscipublisher.com/index.php/jeb 124 8.2 Key findings: yield performance, processing efficiency, community impact. 8.2.1 Yield Performance Of the three varieties, Theis had the highest theoretical ethanol yield, reaching 7 619 liters per hectare, while Dale had the lowest, at 5 077 liters. M81 E had the highest stem dry weight, reaching 27 tons per hectare, while Theis had the lightest stem, at 21 tons. In terms of juice extraction, M81 E produced the most juice, up to 10 915 liters (Ekefre et al., 2017). 8.2.2 Processing efficiency The sugar content (°Bx) and the amount of sugar that can be extracted from these sorghums vary greatly, which directly affects how much ethanol can be produced. Theis has the highest sugar content, reaching 14.9°Bx, while Dale has the lowest (Ekefre et al., 2017). 8.2.3 Community impact Sorghum is highly adaptable and requires little fertilizer and pesticide, making it very suitable for promotion as an energy crop. For the local area, such crops can enrich agricultural varieties and help the rural economy develop better (Ekefre et al., 2017; van Rijn et al., 2018). 8.3 Lessons learned: bottlenecks, technical successes, policy support. From the pilot, the yield and sugar content of different varieties vary greatly, which makes ethanol production unstable. In addition, there is still room for improvement in the current pretreatment and saccharification efficiency (Ekefre et al., 2017; Joy and Krishnan, 2022). By breeding new varieties and adjusting planting methods, sorghum yield and sugar content can be higher. In terms of processing technology, some new methods, such as phosphoric acid catalytic pretreatment and L+SScF process, can also increase sugar and ethanol production (van Rijn et al., 2018; Joy and Krishnan, 2022). This pilot also found that if there is policy support, such as subsidies for ethanol prices and rural development funds, sorghum ethanol can compete with gasoline in price. In this way, it can not only promote renewable energy, but also drive rural development (Prasad et al., 2007; van Rijn et al., 2018). 9 Future Prospects and Research Directions 9.1 Genetic improvements and breeding: high-biomass, low-lignin, high-sugar cultivars. The most critical step to increase sorghum ethanol production is to improve its genetic characteristics. Studies have found that by digging deeper into the genetic diversity of sorghum, especially using some mutants such as brown midrib (BMR), the lignin content can be greatly reduced (Rivera-Burgos et al., 2019). This makes it easier for cellulose to be broken down into sugars, ultimately increasing ethanol production. Varieties with high sugar content and high yield, such as Sucrosorgo 506, BRS 506 and Theis, have performed well in different regions and under different planting methods, with high ethanol production and biomass (Ekefre et al., 2017; Batog et al., 2020; Ferreira-Neto et al., 2021). In the future, in terms of breeding, the focus should be on selecting varieties that can achieve "high yield, high sugar, and low lignin" at the same time. This not only improves conversion efficiency, but also adapts to more environmental conditions (Ekefre et al., 2017; Rivera-Burgos et al., 2019). 9.2 Integration with biorefineries: co-generation, circular bioeconomy models. Sorghum can not only be used to make ethanol, but also cooperate with biorefineries to achieve an integrated utilization method. Joy and Krishnan (2022) used crude glycerol, a byproduct of biodiesel, to treat sorghum in their research. This approach can greatly increase the production of sugar and ethanol, and can also better link the ethanol and biodiesel industries. If sorghum is irrigated with treated domestic sewage, its biomass can also be increased, and it can generate electricity and produce ethanol at the same time, thus using wastewater resources and promoting recycling (Ferreira-Neto et al., 2021). In the future, it is necessary to further promote the deep integration of sorghum and biorefineries, develop a more energy-saving, low-carbon and efficient industrial model, and make the entire system more sustainable (van Rijn et al., 2018; Ferreira-Neto et al., 2021; Joy and Krishnan, 2022).
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