Journal of Energy Bioscience 2024, Vol.15, No.1, 32-47 http://bioscipublisher.com/index.php/jeb 36 known as transesterification. It can be used in diesel engines, either pure or blended with petroleum diesel (Khairati, 2023). Biodiesel has excellent performance and environmental benefits, but during production, it is necessary to address issues related to free fatty acids and impurities to improve yield and quality (Ali and Khairuddin, 2023). Biogas is produced through the anaerobic digestion of organic materials, including agricultural waste, manure, and food scraps. It primarily consists of 50%-75% methane and 25%-50% carbon dioxide, along with small amounts of hydrogen sulfide, hydrogen, ammonia, and trace gases. Methane can replace fossil fuels for heating, electricity generation, and transportation (Atelge et al., 2020). Cellulosic biofuels are derived from non-food biomass such as agricultural residues, grasses, and woody plants, utilizing advanced technologies to break down cellulose and hemicellulose into fermentable sugars (Benedetti et al., 2019). These biofuels represent a range of sources and technologies, each contributing to the diversification and sustainability of the energy supply. 3.2 Energy content and efficiency The energy content and efficiency of biofuels vary depending on the type of biofuel and the feedstock used. Ethanol, for instance, has a lower energy content per gallon compared to gasoline, requiring adjustments in engine performance and fuel consumption (Iodice et al., 2021). However, ethanol blends can improve overall engine efficiency and reduce emissions. Biodiesel has a higher energy content than ethanol and is closer to that of petroleum diesel. Its use can lead to better engine lubrication and reduced particulate emissions (Vergel-Ortega et al., 2021). The energy yield from biodiesel production is also favorable, with a high energy return on investment (EROI). Research has found that palm-sesame oil biodiesel produced through ultrasound-assisted transesterification performs well in engines, demonstrating advantages in reducing carbon dioxide and carbon monoxide emissions (Freitas et al., 2022). Biogas, with its high methane content, is an efficient fuel for electricity generation and heating. Its production from waste materials also provides additional environmental benefits by reducing methane emissions from landfills and manure storage. Cellulosic biofuels offer high energy efficiency due to the abundant availability of feedstocks and their minimal competition with food crops. Advances in enzymatic hydrolysis and fermentation technologies continue to improve the energy efficiency of cellulosic biofuel production. Overall, the energy content and efficiency of biofuels depend on technological advancements, feedstock characteristics, and production processes, all of which are crucial for optimizing their use as sustainable energy sources. 3.3 Environmental impacts of biofuels The environmental impacts of biofuels are multifaceted, encompassing both benefits and challenges. On the positive side, biofuels can significantly reduce greenhouse gas emissions compared to fossil fuels (Hanaki and Portugal-Pereira, 2018; Jeswani et al., 2020). The carbon dioxide released during biofuel combustion is offset by the carbon dioxide absorbed by the feedstock plants during their growth, creating a closed carbon cycle. Additionally, biofuels can reduce dependence on fossil fuels, enhance energy security, and provide a sustainable use for agricultural residues and waste materials. The use of non-food feedstocks, such as cellulosic materials, can also mitigate concerns related to food security and land use competition. However, biofuel production can also pose environmental challenges. The cultivation of biofuel crops may lead to deforestation, loss of biodiversity, and soil degradation if not managed sustainably (Jeswani et al., 2020). Water usage for irrigation and processing can strain local water resources, particularly in regions with limited water availability. The use of fertilizers and pesticides in biofuel crop production can result in water pollution and negative impacts on ecosystems. To address these challenges, it is essential to adopt sustainable agricultural practices, improve biofuel production technologies, and develop policies that promote environmental stewardship. By balancing the benefits and impacts, biofuels can play a significant role in achieving sustainable energy goals and reducing the environmental footprint of the energy sector.
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