References

327

are used mainly for wastewater treatment or for feed production because they are

cheaper to set up and run. They also offer limited control over CO2 conditions, light,

and temperature. Closely packed bed reactors provide improved culture stability

and densities of biomass. There is a lower chance of contamination. They require

high capital and operating expenditure. The harvesting of microalgae is one of

the most challenging aspects of the biofuel production process when applied at

an industrial scale because of the high operational costs. Selection of harvesting

method depends on the strain, culturing conditions, as well as the intended use for

the biomass and the derived products [10, 12, 20].

20.4

Conclusion and Challenges in Commercializing

Microalgae

In the prevailing market circumstances, commercial biodiesel is not generated

from the microalgae. The major challenge in producing biodiesel from microal-

gae is the reproducibility of the results that have been obtained in the lab-scale

studies. It was inferred from the laboratory research that the oil production rate

is directly proportional to the microalgal growth rate and also oil content present

in the biomass. Hence, the microalgae with good oil production capacities may be

preferred for producing biodiesel. But producing biomass is highly expensive when

compared to growing crops. The temperature has to be maintained within the range

20–30 ^∘C. The most important economic challenge for microalgae producers is to

identify low-cost oil extraction and harvesting methods. It was also inferred that

the utilization of fatter algae with around 60% oil content in comparison to lower

oil content algae can reduce upto half of the size and footprint of algae biofuels pro-

duction systems. It will also reduce the capital and operating costs involved in the

entire process. A cost-effective and simple method can provide an enhanced scope

for commercialization. Usage of a nonlethal extraction process called milking can

indeed keep away from a sequence of processes such as harvesting and extraction.

References

1 Ravindran, B., Gupta, S.K., Cho, W.M. et al. (2016). Microalgae potential and

multiple roles-current progress and future prospects – an overview. Sustainability

8: 1215.

2 Caslesson, A.S., Van Beilen, J.B., Moller, R. et al. (2007). Micro and Macro Algae

Utility for Industrial Applications, Outputs from the EPOBIO Project, 86. Newbury,

UK: University of York, CPL press.

3 Nigam, P.S. and Singh, A. (2011). Production of liquid biofuels from renewable

resources. Progress in Energy and Combustion Science 37 (1): 52–68.

4 Moheimani, N.R., Parlevliet, D., McHenry, M.P. et al. (2015). Past, Present and

Future of Microalgae Cultivation Developments in Biomass and Biofuels from

Microalgae, 1–18. Switzerland: Springer.