Journal of Energy Bioscience 2025, Vol.16, No.5, 263-272 http://bioscipublisher.com/index.php/jeb 269 From a regulatory perspective, the biofuel industry involves multiple sectors such as agriculture, energy, and the environment, but coordinated regulation remains weak (Costa et al., 2018; Tedesco et al., 2023). In addition, the lack of stable financial support has hindered technological research and development, infrastructure construction and market growth. Uncertainty and a weak support system have made the sweet potato biofuel industry less competitive compared with traditional energy and other biomass energy sources. 7 Case Studies 7.1 Case 1: bioethanol production in Rural China Many rural cooperatives and small agricultural companies in China adopt advanced processes such as low-temperature enzymatic hydrolysis and synchronous fermentation. These methods help to convert sweet potatoes into ethanol more efficiently. They use conventional amylase to break down starch at a temperature of about 28 ℃~42 ℃ and carry out fermentation simultaneously. This saves energy, shortens production time, and increases ethanol output (Carvalho et al., 2023). In practice, some companies have improved the sequence of enzyme usage and fermentation conditions, increasing the ethanol output to 79.7% and reducing the reaction time by 8.6 hours. This has greatly enhanced efficiency and profits. Sweet potato ethanol performs better in energy use than ethanol made from corn or wheat. Its life-cycle energy efficiency is higher (Ren et al., 2014). Building and running bioethanol plants also create local jobs and help farmers earn more income. Using sweet potato ethanol helps reduce fossil fuel use and greenhouse gas emissions, supporting China’s carbon peak and neutrality goals (Costa et al., 2018). 7.2 Case 2: biogas projects in Sub-Saharan Africa In sub-Saharan Africa, sweet potato waste is often used in small household or community biogas systems. These projects help solve the problem of energy shortage in rural areas and reduce pollution. Many families build simple anaerobic digesters to convert sweet potato peels, vines and other organic waste into biogas for cooking, lighting and heating (Sheikha and Ray, 2017). The remaining liquid and solid substances in the biogas production process are used as organic fertilizers. Local cooperatives and community groups are responsible for managing and maintaining these biogas systems, creating new job opportunities. This has also enhanced the participation of women and vulnerable groups in the rural economy. These projects transform agricultural waste into useful resources, reduce pollution and decrease the spread of diseases. Although there are still technical, financial and management challenges, these sweet potato biogas projects offer a practical approach to improving rural energy utilization and protecting the environment. 7.3 Case 3: integrated bioenergy farms in Brazil Some farms and companies in Brazil have built integrated bioenergy plants. They process sweet potato roots, residues, and vines together to produce ethanol, biogas, animal feed, and organic fertilizer (Costa et al., 2018). These biorefineries use techniques like simultaneous hydrolysis and fermentation and combined anaerobic digestion. This not only improves energy conversion but also cuts waste and environmental pollution. Compared with traditional corn or sugarcane ethanol, sweet potato ethanol in Brazil performs better in reducing carbon emissions and making good use of land. Through a circular economy model, these farms earn money from energy products and also use by-products like organic fertilizer to improve soil and crop yields. Large-scale operation of these biorefineries creates jobs, promotes technology use, and supports rural infrastructure and local economic growth. 8. Future Outlook and Innovation 8.1 Advances in genetics and breeding Through traditional hybridization and molecular breeding methods, researchers have cultivated sweet potato varieties with high starch content, strong stress resistance and suitable for mechanical harvesting. These varieties not only increase the yield per unit area, but also optimize the bioconversion efficiency of raw materials (De Paula Batista et al., 2019). Some new varieties have both high carotene and anthocyanin contents, which can not only
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