Journal of Energy Bioscience 2025, Vol.16, No.2, 75-84 http://bioscipublisher.com/index.php/jeb 79 4.4 Economic and environmental impacts Economic analysis shows that these advanced planting technologies not only increase yields, but also make rapeseed more cost-effective for biodiesel. In some places, such as the European Union, agricultural subsidy policies have also played a big role, encouraging farmers to adopt more environmentally friendly practices. In terms of the environment, studies have also seen obvious benefits. Pollution and greenhouse gas emissions are reduced. Biodiesel made from rapeseed oil has lower emissions than traditional diesel, and pollutants such as carbon monoxide (CO) and particulate matter are significantly lower. These results suggest that practices like conservation agriculture are not only good for the environment, but are also more economically stable and are an important means of achieving long-term sustainable agriculture (Saqib et al., 2012; Viccaro et al., 2019; Ganev et al., 2021). 5 Post-Harvest Processing for Maximum Oil Recovery 5.1 Advances in mechanical extraction In recent years, mechanical extraction technology has made great progress in improving efficiency and environmental protection. Early mechanical extraction technology required several steps and was very energy-intensive. Now the new method has made the whole process simpler. The new technology can directly process the whole rapeseed into biodiesel without adding catalysts, and the whole process only requires one step (Tanner et al., 2023). The whole process reduces the use of water and solvents, which is more environmentally friendly. The new technology not only simplifies the extraction process, but also improves the yield and quality of the output oil, and has the hope of being put into large-scale production of biodiesel. 5.2 Role of solvent extraction and enzymatic processes In order to extract as much oil as possible, solvent extraction and enzymatic processing play a key role. Especially when these two methods are combined, the effect is better and the oil yield can be significantly increased. There is a method of "in situ transesterification" that uses mineral diesel as an extraction solvent, which works very well (Santaraite et al., 2020; Sendžikienė et al., 2022). This method saves energy and money by eliminating the need to extract oil separately. Azócar et al. (2010) mixed used frying oil with rapeseed oil and used enzymes to react to increase the yield of fatty acid methyl esters (FAME). This shows that biodiesel can be made from cheap raw materials at low cost and high efficiency, which has great potential. 5.3 Quality control for biodiesel feedstock Strict control of raw material quality is required to produce biodiesel that meets the standards. The physical and chemical properties of crude oil and processed biodiesel are usually tested to determine whether their quality meets the standards. Biodiesel produced from rapeseed oil generally meets the strict standards of Europe and the United States (Rashid and Anwar, 2008; Lovasz et al., 2023). Density, viscosity and sulfur content are key indicators for determining whether biodiesel can be used in engines. Optimizing reaction conditions and adjusting catalyst concentration and reaction temperature can also further improve oil quality and yield (Yuan et al., 2008; Saqib et al., 2012). 6 Sustainability Considerations in Rapeseed Oil Production 6.1 Environmental impacts of rapeseed cultivation Although rapeseed has many advantages, it also has some disadvantages. Rapeseed cultivation may exacerbate global warming, acidification and eutrophication, mainly because fertilizers are used during the cultivation process, which will cause pollutants to be released from the soil. Different planting methods will change the carbon content in the soil, which will cause local climate change (Ganev et al., 2021). Pollutants emitted during rapeseed cultivation are one of the main sources of global and regional environmental problems. Although biodiesel made from rapeseed can reduce greenhouse gas emissions compared to traditional fuels (56% to 71% lower) (Herrmann et al., 2013), the pressure on the environment caused by the rapeseed cultivation process cannot be ignored, so we need to use more sophisticated planting methods to reduce the adverse impact on the environment.
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