1. Algae are a large and diverse group of simple plantlike organisms, ranging from unicellar to multicellar forms. These cells have the ability to convert carbon dioxide to biomass that can further be processed downstream to produce biodiesel, fertilizer and other useful products.
2. Photosynthetic growth of algae requires
All of the above
3. In order to have good growing conditions Temperature should be in the
range of 5–15_C
range of 20–30_C
range of 50–60_C
4. Algae also need other inorganic nutrients like phosphorus and nitrogen in order to grow.
5. Which one of the following could be considered an advantage for using algae?
No competition for land with crops
No competition with the food market
Ability to grow in water with high levels of salt so there is no additional demand of fresh water. Also, areas with saline ground water that has no other useful applications can be targeted
Overall use less water than oilseeds
High oil yield: algae (of the aquatic species) require less land for growth than biodiesel feedstock from terrestrial plants because they are capable of producing more oil per hectare (Chisti 2008a). Table 1 shows the potential gallons of oil per acre per year from different crops. Furthermore, the oil content in algae (per dry weight) can reach as high as 80% (Chisti 2008a). It is worth noting that the oil from microalgae can be extracted with yields up to 80–90% (Grima et al. 1994; Fajardo et al. 2007; Belarbi et al. 2000).
Efficient sequestration of CO2: another reason why microalgae are attractive is that CO2 (of about half of the of dry algae weight) is needed for growth (Chisti 2008a). CO2 is a common industrial pollutant, thus microalgae can contribute to reducing atmospheric CO2
by consuming CO2 wastes from industrial sources such as power plants.
All of the above
6. The overall system is composed of two main sections: an upstream processing section which is aimed at sequestering the CO2, growing the algae, and producing the lipids and a downstream processing section which includes the pretreatment of the lipids followed by transesterification then separation and finishing to yield the biodiesel. Figure 1 illustrates these key steps.
7. The choice of algae species should address specific characteristics that allow the use of flue gas as the CO2 source. Much research has been done on the tolerance of different species to flue gases. Several species were found to be suitable for the growth of algae using flue gas. One of these many species is Chlorella species. Hanagata et al. (1992) found that Chlorella is tolerant to CO2 concentrations of up to 40% by volume. Sung et al. (1999) reported that chlorella grew in conditions of up to 40_C. These results indicate that Chlorella is a good choice for this study. In this work,
8. In general, the biodiesel process in this work consists of seven sections: Which one of the following is in the seven section
FAME and glycerol separation
Water washing (FAME purification)
All of the above
9. In this study, the use of microalgal oil from the Chlorella species to produce biodiesel via a two-step alkali-catalyzed reaction was investigated and simulated in ASPEN Plus. The oil content of the algae was assumed as 30 and 50%. Using a previously analyzed cultivation process, it deemed possible to obtain algal oil from high-performance and low-performance alternatives that could be analyzed for both the 30 and 50% oil content cases.
10. As an outcome of analyzing the results of the calculations for profit, payback period, return on investment and breakeven analyses, it was found that the most profitable scenarios for producing biodiesel from Chlorella species microalgal oil are those assuming 50% oil content and incorporating heat integration. These results reveal that the production of biodiesel from microalgal oil will indeed prove profitable and will be a competitive alternative to food derived plant oils under the appropriate conditions (selection of algae, algal growth and processing, selection of a high-yield biodiesel process, and achieving high levels of process integration).