Journal of Energy Bioscience 2024, Vol.15, No.2, 96-107 http://bioscipublisher.com/index.php/jeb 97 2 Microalgae as a Bioethanol Feedstock 2.1 Characteristics and advantages of microalgae Microalgae have garnered significant attention as a promising feedstock for bioethanol production due to their unique characteristics and numerous advantages. These microorganisms exhibit rapid growth rates and high photosynthetic efficiency, allowing them to convert atmospheric CO2 into valuable biomass efficiently (Figure 1) (Lee et al., 2015; Khan et al., 2018; Arcigni et al., 2019). Microalgae can accumulate substantial amounts of carbohydrates and lipids, which are essential for bioethanol and biodiesel production, respectively (Lam and Lee, 2012; Kim et al., 2014; Li et al., 2015). Additionally, microalgae can be cultivated in diverse environments, including freshwater, seawater, and wastewater, reducing the competition for arable land and fresh water resources (Tan et al., 2015; Wang and Yin, 2018; Arcigni et al., 2019). This adaptability, coupled with their ability to sequester CO2, positions microalgae as an environmentally sustainable and economically viable option for biofuel production (Lee et al., 2015; Simas-Rodrigues et al., 2015; Khan et al., 2018). Figure 1 Microalgae convert atmospheric CO2 to carbohydrates, lipids, and other valuable bioproducts by using light (Adopted from Khan et al., 2018) Image caption: Microalgae can be a rich source of carbon compounds, which can be utilized in biofuels, health supplements, pharmaceuticals, and cosmetics. They also have applications in wastewater treatment and atmospheric CO2 mitigation. Microalgae produce a wide range of bioproducts, including polysaccharides, lipids, pigments, proteins, vitamins, bioactive compounds, and antioxidants (Adopted from Khan et al., 2018) 2.2 Comparison with traditional bioethanol feedstocks When compared to traditional bioethanol feedstocks such as corn and sugarcane, microalgae offer several distinct advantages. Traditional feedstocks often require significant amounts of arable land, fresh water, and fertilizers, which can lead to food versus fuel conflicts and environmental degradation (Lam and Lee, 2012; Arcigni et al., 2019). In contrast, microalgae can be cultivated on non-arable land and utilize brackish or wastewater, thereby mitigating these issues (Wang and Yin, 2018; Arcigni et al., 2019). Furthermore, microalgae have higher biomass productivity and can be harvested multiple times throughout the year, unlike seasonal crops like corn and sugarcane (Lee et al., 2015; Tan et al., 2015; Khan et al., 2018). This continuous production capability enhances the overall yield and efficiency of bioethanol production from microalgae. Additionally, the lipid and carbohydrate content in microalgae can be optimized through various cultivation and pretreatment methods, further improving their suitability as a bioethanol feedstock (Kim et al., 2014; Simas-Rodrigues et al., 2015).
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