**8. Conclusions**

Although microalgal biofuel systems theoretically have the potential to address both the food versus fuel challenges, to date no microbial biofuel system has achieved economic viability. Microbial lipid productivity must increase tremendously and the overall cost must significantly decrease before this approach can be commercially available.

#### **9. References**


More effective, cost-efficient, and environmentally sound fermentation means to produce lipids are urgently needed, as well as adaptation of the fermentation cells to utilize lignocellulosic biomass. It is also widely indicated that currently microalgal biofuel systems are dependent on the production of coproducts (e.g., biochar, pigments, and nutriceuticals) for profitability. Considering the large scale of biofuel production, the market of the

Labor cost \$4.03 26.69% \$2.96 11.90% \$0.29 10.88% Other production cost \$3.71 24.59% \$6.37 25.59% \$2.07 78.45% Capital cost \$7.35 48.71% \$15.56 62.50% \$0.28 10.66%

Table 4. Cost comparison among different microalagae cultivation methods (Alabi. 2009)

Although microalgal biofuel systems theoretically have the potential to address both the food versus fuel challenges, to date no microbial biofuel system has achieved economic viability. Microbial lipid productivity must increase tremendously and the overall cost must

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**8. Conclusions** 

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**6** 

*Egypt* 

Emad A. Shalaby

**Algal Biomass and Biodiesel Production** 

Biodiesel has become more attractive recently because of its environmental benefits and the fact that it is made from renewable resources. The cost of biodiesel, however, is the main hurdle to commercialization of the product. The used cooking oil and algae are used as raw material, adaption of continuous transesterification process and recovery of high quality glycerol from biodiesel by-product (glycerol) are primary options to be considered to lower the cost of biodiesel. There are four primary ways to make biodiesel, direct use and blending, microemulsions, thermal cracking (pyrolysis) and transesterification. The most commonly used method is transesterification of vegetable oils and animal fats. The transesterification reaction is affected by molar ratio of glycerides to alcohol, catalysts, reaction temperature, reaction time and free fatty acids and water content of oils or fats. In the present chapter we will focus on how algae have high potentials in biodiesel production

Microalgae are prokaryotic or eukaryotic photosynthetic microorganisms that can grow rapidly and live in harsh conditions due to their unicellular or simple multicellular structure. Examples of prokaryotic microorganisms are Cyanobacteria (Cyanophyceae) and eukaryotic microalgae are for example green algae (Chlorophyta) and diatoms (Bacillariophyta) [Richmond, 2004]. A more in depth description of microalgae is presented by Richmond [Richmond, 2004]. Microalgae are present in all existing earth ecosystems, not just aquatic but also terrestrial, representing a big variety of species living in a wide range of environmental conditions. It is estimated that more than 50,000 species exist, but only a limited number, of around 30,000, have been studied and analyzed [Richmond, 2004]. Algae are aquatic plants that lack the leaves, stem, roots, vascular systems, and sexual organs of the higher plants. They range in size from microscopic phytoplankton to gain kelp 200 feet long. They live in temperatures ranging from hot spring to arctic snows, and they come in various colors mostly green, brown and red. There are about 25,000 species of algae compared to 250,000 species of land plants. Algae make up in quantity what they lack in diversity for the biomass of algae is immensely greater than that of terrestrial plants (Lowenstein, 1986). Phytoplankton comprises organisms such as diatome, dinoflagellates and macrophytes include: green, red and brown algae. As photosynthetic organisms, these groups play a key role in productivity of ocean and constitute the basis of marine food chain. On the other hand, the use of macroalgae as a potential source of high value chemicals and in therapeutic purpose has a long history.

**1. Introduction** 

compared with other sources.

**2. Algae as biological material** 

*Biochemistry Dept., Facult. Of Agriculture, Cairo University* 

