Journal of Energy Bioscience 2025, Vol.16, No.5, 216-226 http://bioscipublisher.com/index.php/jeb 222 7 Challenges and Future Prospects 7.1 Agronomic and environmental challenges (land use, fertilizer input, GHG emissions) The environmental problems of rapeseed oil biodiesel mainly occur in the planting stage. Land use change, the input of chemical fertilizers, especially nitrogen fertilizers, and irrigation demands are all important sources of greenhouse gas emissions. Emissions at this stage account for more than 65% of the entire life cycle (Gupta et al., 2022). Extreme weather, such as drought, can cause unstable production and increase economic and environmental risks (Yang et al., 2021). If bio-fertilizers (PGPR) and organic fertilizers are used, the amount of chemical fertilizers can be reduced, while increasing production and oil quality, and it is also more in line with the goal of sustainable production (Nasrollahzadeh et al., 2023). 7.2 Competing uses of rapeseed oil (food vs. fuel) Rapeseed oil can not only be used as edible oil but also serves as an important raw material for biodiesel. As the demand for biodiesel rises, the competition between food and fuel is becoming increasingly prominent. This will push up the prices of raw materials and may also affect food safety (Santaraite et al., 2020). In Europe, more than 70% of rapeseed oil is used to produce biodiesel, which has a significant impact on the food market (Nath et al., 2016). 7.3 Advances in process optimization and co-products (e.g., glycerol valorization) Researchers are experimenting with new catalysts, such as carbon-based, solid base and enzyme catalysts, and are also developing new process methods, such as enzymatic in-situ transesterification, green solvents and nanocatalysts. These improvements can increase yield, reduce energy consumption and production costs (Santaraite et al., 2020; Babadi et al., 2022; Khan et al., 2023; Hasannia et al., 2024). Glycerol, a by-product in production, can also be utilized, such as as animal feed, chemical raw materials, or as a substrate for fermentation to produce biogas. These methods can enhance economic and environmental value. However, the market for glycerol is not large and its economic value is limited. There is still controversy over how to allocate by-products in the assessment (Yang et al., 2021). 7.4 Integration with circular bioeconomy approaches The rapeseed oil biodiesel industry is developing towards a circular bioeconomy, with increasing emphasis on by-product reuse, waste recycling and energy diversification (Yang et al., 2021). For instance, rapeseed cake can be used as feed or for biomass energy, and glycerol can be utilized to produce biogas. All these can promote the coordinated development of agriculture, energy and the environment (Suchocki, 2024). 7.5 Outlook on next-generation rapeseed-based biodiesel One of the future development directions is new fuels such as green diesel (HVO). This type of fuel has a higher calorific value, better chemical stability, and is well compatible with petro-diesel. It is an important trend in the deep processing of rapeseed oil (Stiemicek et al., 2009; Ershov et al., 2022; Di Vito Nolfi et al., 2025). Gene editing technologies (such as CRISPR) and molecular breeding will also continue to increase the yield and quality of oils, cultivate new varieties with high oleic acid and high stress resistance, and promote the development of low-carbon agriculture and clean energy (Nath et al., 2016; Ali and Zhang, 2023). Meanwhile, process integration, raw material diversification and policy support will further promote the global promotion and sustainable expansion of rapeseed oil biodiesel (Yang et al., 2021; Babadi et al., 2022; Suchocki, 2024). 8 Conclusion Rapeseed oil holds an important position in the global biodiesel industry due to its high oil content, appropriate fatty acid composition and strong adaptability. Many comparative studies have shown that rapeseed oil biodiesel has obvious advantages in fuel performance, environmental benefits and process optimization, but it also encounters problems such as high raw material costs, tight land use and competition for food applications. In terms of fuel performance, the cetane number, viscosity, density and calorific value of rapeseed oil biodiesel all meet the ASTM and EN standards. Its combustion performance is close to that of mineral diesel, and sometimes
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