Page 174 - Materials Chemistry, Second Edition

162 A. Singh and S. I. Olsen

Fig. 11 Percentage difference of single score of various impact categories for EURO 5
passenger car running with algal biodiesel produced in different scenarios in relation to fossil
diesel

of chemicals, electricity and heat for oil extraction and trans-esterification. In the
sensitivity analysis, algal biodiesel production with press and co-solvent oil
extraction showed savings on total impacts in comparison with fossil diesel
(Table 6).
The results of present investigation showed that harvesting with lime floccu-
lation and press and co-solvent oil extraction scenarios of algal biodiesel pro-
duction provides maximum savings on total impacts. Frank et al. (2012) also
reported a saving on GHG emissions from the use of algal biodiesel in comparison
with low-sulfur petroleum diesel. Brentner et al. (2011) concluded that cultivation
of algal biomass in FPPBR, harvesting with chitosan flocculation, and supercritical
methanol process for oil extraction and trans-esterification along with anaerobic
digestion and nutrient recycling reduce energy demand and eutrophication along
with reductions in water and land use. Batan et al. (2010) also reported a saving of
75 g CO 2 eq emissions per MJ of energy produced in a well-to-tank study of
microalgal biodiesel production. The scenarios in this study also provide GHG
savings over fossil diesel, but they are not better in terms of impacts on human
health, ecosystem quality, and resources. To make the model more feasible there is
need of more realistic commercial scale data and need to compare more scenarios
of different cultivation, harvesting, oil extraction and trans-esterification tech-
niques also need to expand the system boundaries to include utilization of co-
products and by-products.