is uncommon in the studies considered here. An exception in this respect is the
study of Razon and Tan (2011). An important source of uncertainty regards future
technologies, process parameters, physical inputs and outputs. The studies discussed here often considered examples of such uncertainties (e.g., Stephenson et al.
2010; Brentner et al. 2011; Clarens et al. 2011; Shirvani et al. 2011; Sills et al.
2012; Frank et al. 2012; Quinn et al. 2014; Yuan et al. 2015; Naraharisetti et al.
2017). Relatively good studies of uncertainty linked to process parameters would
seem to be the studies of Clarens et al. (2011) and Sills et al. (2012) that included
Monte Carlo analysis to quantify the role of uncertainty of parameters in determining the estimates of energy balances.
If compared with published methodologies for handling uncertainty in life cycle
assessment (cf. Huijbregts et al. 2003; Gregory et al. 2016), the studies considered
here could have done better in dealing with uncertainties.
7 Concluding Remarks
The peer-reviewed energy balances for microalgal biodiesel discussed here do not
meet the criterion that the energy output should exceed the energy input by a factor
5–8. It would seem extremely likely that this would still be the case when defensible choices regarding yields, allocation, valuing the use of wastewater, and
co-location with power plants would have been different as noted in this chapter.
This is not favorable to a near-term widespread use of microalgal biodiesel.
Moreover, microalgal biodiesel has a high near-term cost if compared with biofuels
from terrestrial plants (Wijffels and Barbosa 2010; Jez et al. 2017; Zhu et al. 2017).
The conclusion must be that the near-term outlook for widespread use of microalgal
biodiesel is bleak (also: Chisti 2013a).
References
Adesanya, V., Cadena, E., Scott, S. A., & Smith, A. G. (2014). Life cycle assessment on
microalgal biodiesel production using a hybrid cultivation system. Bioresource Technology,
163, 343–355.
Adhikari, B., & Pellegrino, J. (2015). Life cycle assessment of five microalgae-to-biofuels
processes of varying complexity. Journal of Renewable and Sustainable Energy, 7, 043136
(12 pp).
Batan, L., Quinn, J., Wilson, B., & Bradley, T. (2010). Net energy and greenhouse gas emission
evaluation of biodiesel derived from microalgae. Environmental Science and Technology, 44,
7975–7980.
Benemann, J. R. (2013). Microalgae for biofuels and animal feeds. Biotechnology Bioengineering,
110, 2319–2320.
Brentner, L. B., Eckelman, M. J., & Zimmerman, J. B. (2011). Combinatorial life cycle assessment
to inform process design of industrial production of algal biodiesel. Environmental Science and
Technology, 45, 7060–7067.
8 Biofuels from Microalgae: Biodiesel
177
study of Razon and Tan (2011). An important source of uncertainty regards future
technologies, process parameters, physical inputs and outputs. The studies discussed here often considered examples of such uncertainties (e.g., Stephenson et al.
2010; Brentner et al. 2011; Clarens et al. 2011; Shirvani et al. 2011; Sills et al.
2012; Frank et al. 2012; Quinn et al. 2014; Yuan et al. 2015; Naraharisetti et al.
2017). Relatively good studies of uncertainty linked to process parameters would
seem to be the studies of Clarens et al. (2011) and Sills et al. (2012) that included
Monte Carlo analysis to quantify the role of uncertainty of parameters in determining the estimates of energy balances.
If compared with published methodologies for handling uncertainty in life cycle
assessment (cf. Huijbregts et al. 2003; Gregory et al. 2016), the studies considered
here could have done better in dealing with uncertainties.
7 Concluding Remarks
The peer-reviewed energy balances for microalgal biodiesel discussed here do not
meet the criterion that the energy output should exceed the energy input by a factor
5–8. It would seem extremely likely that this would still be the case when defensible choices regarding yields, allocation, valuing the use of wastewater, and
co-location with power plants would have been different as noted in this chapter.
This is not favorable to a near-term widespread use of microalgal biodiesel.
Moreover, microalgal biodiesel has a high near-term cost if compared with biofuels
from terrestrial plants (Wijffels and Barbosa 2010; Jez et al. 2017; Zhu et al. 2017).
The conclusion must be that the near-term outlook for widespread use of microalgal
biodiesel is bleak (also: Chisti 2013a).
References
Adesanya, V., Cadena, E., Scott, S. A., & Smith, A. G. (2014). Life cycle assessment on
microalgal biodiesel production using a hybrid cultivation system. Bioresource Technology,
163, 343–355.
Adhikari, B., & Pellegrino, J. (2015). Life cycle assessment of five microalgae-to-biofuels
processes of varying complexity. Journal of Renewable and Sustainable Energy, 7, 043136
(12 pp).
Batan, L., Quinn, J., Wilson, B., & Bradley, T. (2010). Net energy and greenhouse gas emission
evaluation of biodiesel derived from microalgae. Environmental Science and Technology, 44,
7975–7980.
Benemann, J. R. (2013). Microalgae for biofuels and animal feeds. Biotechnology Bioengineering,
110, 2319–2320.
Brentner, L. B., Eckelman, M. J., & Zimmerman, J. B. (2011). Combinatorial life cycle assessment
to inform process design of industrial production of algal biodiesel. Environmental Science and
Technology, 45, 7060–7067.
8 Biofuels from Microalgae: Biodiesel
177