Journal of Energy Bioscience 2025, Vol.16, No.3, 105-116 http://bioscipublisher.com/index.php/jeb 109 5.2 Bioethanol: using lignocellulosic residues After rapeseed is harvested, stems and straw are left. These are lignocellulosic agricultural wastes that can be used to make bioethanol. As long as they are processed by biochemical methods, they can be converted into ethanol and used to mix with gasoline as fuel. Many studies have found that these residues have great energy potential. If used well, they can not only increase the supply of renewable energy, but also meet the electricity needs of many households (Masarovičová et al., 2009; Şenocak and Gören, 2021). 5.3 Biogas and syngas: through anaerobic and thermochemical processes Rapeseed biomass can also be used to produce gas in two ways. One is anaerobic digestion, which can produce biogas; the other is thermal treatment technology, such as pyrolysis or gasification, which can produce syngas. Slow pyrolysis of rapeseed stems can not only produce liquid fuel (pyrolysis oil), but also have good yields, making it a potential biofuel (Karaosmanoğlu et al., 1999). Anaerobic digestion of these agricultural wastes can not only turn waste into resources, but also provide clean energy for rural areas (Karaosmanoğlu et al., 1999; Şenocak and Gören, 2021). 5.4 Solid biofuels: pellets and briquettes Rapeseed meal and straw can also be pressed into pellets or briquettes for use as solid fuel. The pellets can be burned directly and are suitable for use in domestic hot water equipment, etc. Because these pellets are renewable, they are also more environmentally friendly (Ciunel and Klugmann-Radziemska, 2014). Rapeseed straw that has been thermally treated will become biochar. This type of charcoal emits less CO and nitrogen oxides when burned and has a higher combustion efficiency (Malaťák et al., 2024). If some waste rapeseed oil is added, the calorific value of the pellets will be increased and the fuel effect will be better (Gheorghe and Neacsu, 2024). 6 Environmental and Economic Assessment 6.1 Carbon footprint reduction: LCA (life cycle assessment) perspectives From a life cycle assessment (LCA) perspective, rapeseed biomass performs well in terms of emissions reduction. Many studies have found that biodiesel made from rapeseed oil emits 56% to 74% less greenhouse gases than traditional fossil fuels. Among them, alternative fuels have the most significant emission reduction. Rapeseed still emits a lot of carbon when it is grown, especially when fertilizers are used and intensive cultivation is carried out, which can account for 65% to 100% of total emissions (González-García et al., 2013; Gupta et al., 2022; Yang et al., 2022) (Figure 2). To further reduce emissions, the planting method can be adjusted, such as reducing the amount of fertilizers used, while also using by-products such as glycerol. In some cases, this can reduce carbon emissions by another 14% to 33.6% (Gupta et al., 2022). Figure 2 (a) Spatial distribution of global warming potential (GWP) caused by direct emissions from producing one hectare of rapeseed and (b) magnitude of GWP resulting from indirect emissions from producing 1 t of rapeseed for catchments 1-10 (Adopted from Yang et al., 2022)
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