Chapter 8
Biofuels from Microalgae: Biodiesel
Lucas Reijnders
Abstract It has been argued that the energy output from microalgal biofuel production should at least be 5–8 times the energy input, apart from solar irradiation
driving algal photosynthesis. There is as yet no commercial production of
microalgal biodiesel or large-scale demonstration project to check whether this
criterion regarding the energy balance can be met in actual practice. There is,
however, a set of relatively well-documented peer-reviewed scientific papers estimating energy inputs and outputs of future autotrophic microalgal biodiesel production. Energy balances for biodiesel from autotrophic microalgae grown in ponds
tend to be better than for biodiesel from such microalgae grown in bioreactors. The
studies regarding energy balances for biodiesel derived from microalgae grown in
open ponds are considered here. None of these energy balances meets the criterion
that the energy output should exceed the energy input by a factor 5–8. Estimated
energy balances are variable due to divergent assumptions about microalgal varieties, applied algal and biodiesel production technologies, assumed parameters and
yields and due to differences in system boundaries, allocation, and the use of
credits. The studies considered here could have done better in handling uncertainties in estimated energy balances.
Keywords Biodiesel Á Energy balance Á Variability Á Uncertainties
1 Introduction
‘Microalgal biodiesel’ is used here in the narrow sense: methanol- (or ethanol-)
esters of microalgal fatty acids, obtained by the transesterification of triglycerides
(oil) from autotrophic microalgae. To qualify as a fuel of good quality, the biodiesel
L. Reijnders (&)
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam,
Science Park 904, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands
e-mail: l.reijnders@uva.nl
© Springer International Publishing AG 2018
E. Jacob-Lopes et al. (eds.), Energy from Microalgae, Green Energy
and Technology, https://doi.org/10.1007/978-3-319-69093-3_8
171
Biofuels from Microalgae: Biodiesel
Lucas Reijnders
Abstract It has been argued that the energy output from microalgal biofuel production should at least be 5–8 times the energy input, apart from solar irradiation
driving algal photosynthesis. There is as yet no commercial production of
microalgal biodiesel or large-scale demonstration project to check whether this
criterion regarding the energy balance can be met in actual practice. There is,
however, a set of relatively well-documented peer-reviewed scientific papers estimating energy inputs and outputs of future autotrophic microalgal biodiesel production. Energy balances for biodiesel from autotrophic microalgae grown in ponds
tend to be better than for biodiesel from such microalgae grown in bioreactors. The
studies regarding energy balances for biodiesel derived from microalgae grown in
open ponds are considered here. None of these energy balances meets the criterion
that the energy output should exceed the energy input by a factor 5–8. Estimated
energy balances are variable due to divergent assumptions about microalgal varieties, applied algal and biodiesel production technologies, assumed parameters and
yields and due to differences in system boundaries, allocation, and the use of
credits. The studies considered here could have done better in handling uncertainties in estimated energy balances.
Keywords Biodiesel Á Energy balance Á Variability Á Uncertainties
1 Introduction
‘Microalgal biodiesel’ is used here in the narrow sense: methanol- (or ethanol-)
esters of microalgal fatty acids, obtained by the transesterification of triglycerides
(oil) from autotrophic microalgae. To qualify as a fuel of good quality, the biodiesel
L. Reijnders (&)
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam,
Science Park 904, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands
e-mail: l.reijnders@uva.nl
© Springer International Publishing AG 2018
E. Jacob-Lopes et al. (eds.), Energy from Microalgae, Green Energy
and Technology, https://doi.org/10.1007/978-3-319-69093-3_8
171