Journal of Energy Bioscience 2024, Vol.15, No.6, 368-377 http://bioscipublisher.com/index.php/jeb 373 frying oil and rapeseed oil has been shown to increase fatty acid methyl ester (FAME) yields, highlighting the potential for cost-effective and efficient biodiesel production (Azócar et al., 2010). 5.3 Quality control for biodiesel feedstock Ensuring the quality of biodiesel feedstock is essential to produce high-quality biodiesel that meets industry standards. Quality control measures include monitoring the physical and chemical properties of oils and their biodiesel products. Studies have shown that biodiesel produced using rapeseed oil can generally meet the stringent standards in Europe and the United States (Rashid and Anwar, 2008; Lovasz et al., 2023). Parameters such as density, kinematic viscosity, and sulfur content are key to assessing the suitability of biodiesel for engine use. In addition, by optimizing reaction conditions (such as catalyst concentration and reaction temperature), the quality and yield of biodiesel can be further improved, ensuring that it becomes a viable alternative to traditional diesel fuel (Yuan et al., 2008; Saqib et al., 2012). 6 Sustainability Considerations in Rapeseed Oil Production 6.1 Environmental impacts of rapeseed cultivation Rapeseed cultivation has significant impacts on multiple environmental categories, including global warming, acidification, and eutrophication. Fertilizer use and its associated soil emissions are the main causes of these impacts. For example, soil carbon changes caused by different agricultural practices are particularly important in the global warming impacts of rapeseed biodiesel (Ganev et al., 2021). In addition, emissions from rapeseed cultivation are the main contributors to global and regional environmental impact categories, among which rapeseed biodiesel has greenhouse gas (GHG) emissions reduced by about 56% to 71% compared with fossil fuels (Herrmann et al., 2013). However, the environmental burden of rapeseed cultivation is still quite significant, which requires careful management of agricultural practices to mitigate these impacts. 6.2 Carbon footprint analysis of rapeseed-based biodiesel The carbon footprint of rapeseed biodiesel is an important factor in assessing its sustainability. Life cycle assessment (LCA) studies have shown that the production and use of rapeseed biodiesel significantly reduces carbon emissions compared to traditional fossil fuels. For example, the climate change potential of biodiesel production and use is 57 kg CO2 equivalent per 1,000 km driven, compared to 214 kg CO2 equivalent for petroleum diesel (Malça et al., 2014). In addition, replacing traditional products with bio-based materials, such as using biofumigants instead of chemical fumigants, can achieve a net saving of 134 g CO2 equivalent per megajoule of biodiesel (Tanner et al., 2023). These research results highlight the potential of rapeseed biodiesel in reducing carbon emissions. 6.3 Strategies for minimizing waste and enhancing circularity To improve the sustainability of rapeseed oil production, strategies to reduce waste and promote recycling are essential. One approach is to optimize the utilization of by-products in the biodiesel supply chain. For example, the value-added utilization of oilseed meal as animal feed or biofumigant can significantly improve the sustainability of the bioenergy supply chain (Lovasz et al., 2023). In addition, innovative production methods, such as producing biodiesel directly from whole rapeseed without the addition of catalysts, can reduce the demand for water, organic solvents and catalysts, thereby reducing environmental pollutants (Tanner et al., 2023). Another strategy is to adopt conservation agriculture practices, such as crop diversification and minimum tillage, which can promote sustainable biofuel production and reduce environmental impacts (Figure 3) (Yang et al., 2021). Together, these strategies promote a more sustainable and circular rapeseed oil production system. 7 Global Trends and Market Opportunities 7.1 Rapeseed oil production in key biodiesel markets Rapeseed oil is an important feedstock in biodiesel production, especially in Europe, where it is the main source. Rapeseed cultivation has grown significantly in regions with favorable climatic conditions, such as Iran, where yields and efficiency have been improved by optimizing production processes (Almasi et al., 2019). In high-altitude regions such as the Qinghai Plateau in China, unique environmental conditions contribute to higher
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