Journal of Energy Bioscience 2024, Vol.15, No.6, 358-367 http://bioscipublisher.com/index.php/jeb 365 9.3 Gaps in research and technological advancements Although sorghum has made a lot of progress in genetic and genomic research, there are still many research gaps to truly realize its bioenergy potential. Some molecular breeding and directed breeding methods have not fully utilized the existing genetic knowledge, especially in improving traits related to biomass, such as flowering time, plant height and carbohydrate metabolism, etc. (Yang et al., 2023). A more comprehensive life cycle analysis is still needed to identify which preprocessing and transformation methods are both effective and cost-effective. To improve the energy economy of sorghum, it is also necessary to establish a complete “biorefining” model to convert its biomass into various fuels and products more efficiently (Stamenković et al., 2020). At present, there is still a lack of detailed technical and economic analyses on the bioenergy path of sorghum, which also limits our understanding of whether it can be applied on a large scale (Appiah-Nkansah et al., 2019). 10 Future Directions and Recommendations 10.1 Development of multi-purpose sorghum cultivars To maximize the role of sorghum in bioenergy, it is necessary to cultivate multi-purpose sorghum varieties. This type of variety not only needs to have a high biomass yield, but also better quality of energy and raw materials in order to achieve higher comprehensive benefits. In recent years, many important traits that can be improved have been identified in sorghum genetics and genomics studies, such as flowering time, plant height and carbohydrate metabolism (Calvino and Messing, 2012; Mullet et al., 2014; Yang et al., 2023). By taking advantage of the rich genetic diversity of sorghum and modern breeding techniques, it is expected to breed excellent varieties that are both high-yielding and drought-resistant and tolerant to poor soil (Heitman et al., 2018; Batog et al., 2020; Lamb et al., 2021). If the characteristics that are conducive to the efficient conversion into energy sources such as bioethanol, biogas and biochar can also be integrated, the feasibility of sorghum as a multi-purpose crop will be further enhanced (Appiah-Nkansah et al., 2019; Stamenković et al., 2020). 10.2 Integration of sorghum in circular bioeconomy systems Incorporating sorghum into the circular bioeconomy system is conducive to enhancing the sustainability and economic benefits of bioenergy. Sorghum can be grown on marginal land with less input, so it is very suitable for this system (Lamb et al., 2021; Yang et al., 2023). The core concept of the circular bioeconomy is to maximize the utilization of resources. For instance, the waste from one stage can be used as raw material for another stage. For instance, the residue left after juicing sweet sorghum can be used for power generation or made into biochar to improve the soil (Heitman et al., 2018; Appiah-Nkansah et al., 2019). Moreover, the deep roots of sorghum can store soil organic carbon, enhance soil fertility, and reduce greenhouse gas emissions at the same time (Lamb et al., 2021). Through these practices, a closed-loop system can be established to make resource utilization more efficient and reduce the impact on the environment at the same time. 10.3 Collaboration between researchers, policymakers, and industry stakeholders To promote sorghum better as a bioenergy crop, the joint efforts of researchers, policymakers and all parties in the industry are needed. Scientific researchers can provide technical support, such as improving sorghum varieties and optimizing energy production processes (Mullet et al., 2014; Brenton et al., 2016; Yang et al., 2023). The government departments can encourage sorghum cultivation and infrastructure construction by formulating supportive policies, such as subsidies, tax incentives and relevant regulations (Stamenković et al., 2020). Industry participants such as farmers, bioenergy enterprises and equipment technology providers are the key forces promoting the large-scale application and economic feasibility of sorghum (Tang et al., 2018b; Batog et al., 2020). This multi-party cooperation also helps to establish a complete biorefining system, from sorghum cultivation to fuel processing and subsequent product development, achieving multiple uses of sorghum (Stamenković et al., 2020). Acknowledgments The author would like to thank two anonymous peer reviewers for their modification suggestions on the manuscript of the study and the team members for their help in collating the literature.
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