## 1 Introduction  
The two major problems facing humanity today are the global energy crisis and global warming, caused mainly by growing population expansion, rapid industrialization, and a greater consumption of fossil fuels. Therefore, current research has been focused on developing clean energy and sustainable fuels that may replace and reduce the usage of fossil fuels [1, 2, 3]. Several alternative energy sources have been studied and implemented, for example, solar energy, wind, hydroelectric, geothermal, and biofied sources. Among all these renewable energies, biofied is arguably a potential alternative source that can replace fossil-based fuel [4]. Biofuels are fuel produced from organic materials (plant, animal, and algae), which can be solid, liquid, or gas. Currently, microalgae are being promoted as the suitable feedstock for third-generation biofuels [5]. Microalgae are oleaginous microorganisms and microalgal lipids can be used as feedstock in biodiesel production [6]. Microalgae-based biodiesel has many benefits, such as having a high lipid content and fast growth rate and being easily modified by biotechnological techniques [7]. Microalgae cells are made up of many components. The main components are lipids; 2-70% of the lipid content by total dry weight can be extracted from the algal biomass, but it does vary according to the growth conditions and species type [8]. The potential of algae-based biodiesel production depends on the selection of suitable strains regarding profitable yields and lipid quality [9]. Although the maximum biomass productivity of algae will be found under optimal cultivation conditions, it does not serve as a guarantee of the maximum lipid content. Some species have high lipid content, but their growth rate is prolonged. It has been reported that the lipid content of _Botryococcus braunii_ could reach 75% of the dry weight, but it is associated with low biomass productivity. Most common microalgae (_Chlorella_, _Dunaliella_, _Isochrysis_, _Nannochloropsis_, _Scentesmus_, _Spirulina_) possess lipid contents in a range of 15-50%, but they have higher biomass productivity [10]. This indicates that the selection of suitable strains of microalgae is essential. Some factors, such as algae's ability under specific environmental conditions and the ability to uptake nutrients by algae, should be considered before selecting the most suitable strains or sufficient species for use as biodiesel feedstock [8]. Besides biodiesel production, it has been reported that microalgae have a high potential for CO\({}_{2}\) capture. Microalgal biomass contains approximately 0.5 g carbon of g dry weight. All of this carbon is typically derived from atmospheric CO\({}_{2}\). Theoretically, microalgae could fix about 183 tons of CO\({}_{2}\) in producing 100 tons of biomass [11]. Thus, biological CO\({}_{2}\) sequestration using photosynthetic microalgae for CO\({}_{2}\) mitigation has received widespread attention. [PERSON] et al. [12] revealed that the growth of mixed microalgae, including _Chloorella_ sp., _Senedesmus_ sp., _Spharocystis_ sp., and _Spirulina_ sp., cultured under 20-50% (\(v/v\)) CO\({}_{2}\) concentration was higher than that of ambient air (0.03% CO\({}_{2}\)) and showed high CO\({}_{2}\) sequestration, 150-291 mg/g. The microalgal consortium, which contained dominantly _Senedesmus_ spp., could grow well at 30% (\(v/v\)) CO\({}_{2}\) aeration with the maximum values of lipid content (27.60% of dry weight) and the CO\({}_{2}\) fixation rate (0.0271 gCO\({}_{2}\) /L/day) [13]. The CO\({}_{2}\) fixation rate of microalgae was associated with the photosynthesis efficiency and cell density of microalgae. Also, CO\({}_{2}\) fixation efficiency of microalgae depends on the microalgal species, nutrient supply, light intensity, temperature, pH, photo-bioreactor type, CO\({}_{2}\) concentration, and CO\({}_{2}\) flow rate [14; 15; 16]. The green algae _Chloorella_ spp.