Page 161 - Materials Chemistry, Second Edition

Comparison of Algal Biodiesel Production Pathways 149

2.2 Life Cycle Assessment

The LCA was conducted by using SimaPro 7.2.3 software and ecoinvent 2.0
database. The cradle-to-grave system was adopted to analyze different scenarios of
algal biodiesel production system.

2.2.1 Goal and Scope

The goal of the study was to evaluate options for harvesting and oil extraction of
algal biomass in the biodiesel production and to identify the most sustainable algal
biodiesel production pathway. The system was modeled using literature data and
communications with scientists working in the area of algal biomass cultivation
and biodiesel production. Robust operational data were not included as there are
relatively very few facilities (even at pilot scale) available round the world. Thus,
documentation of most of the modeled process reflects laboratory-scale opera-
tional data. The key assumptions used in this study are presented in the Table 2.

2.2.2 Functional Unit

The functional unit used in the study is 1 person km (pkm). During the different
steps, reference flows change between 1 t algal biomass during cultivation step, 1 t
biodiesel during biodiesel step, and 1 pkm for comparing algal biodiesel with
fossil diesel.

2.2.3 Reference System

The EURO 5 passenger car running on diesel is used as reference system to
compare the impacts of algal biodiesel use for transport with EURO 5 passenger
car.

2.2.4 System Boundary

The algal biodiesel production system considered in this study included biomass
cultivation, harvesting, oil extraction, trans-esterification, and biodiesel use in
EURO 5 passenger car. This system does not include the potential use of
co-product and/or by-product. The material used in the construction of FPPBR was
considered inside the system boundaries, while the productions of other machin-
ery/buildings were out of the system boundaries. Allocation of impacts on
co-product/by-products was also not considered; hence, all impacts were allocated
to the biodiesel.