Discussion of a recent publication on Life Cycle Assessment
(LCA) of biodiesel from microalgae may be instructive (Lardon
et al., 2009). The authors state quite precisely that the potential
environmental impacts are investigated via LCA. The inventory is
compiled after defining the production system reaching from algae
culture to the use of diesel in an engine. Bench scale research and
other extrapolations are employed since industrial operation to allow
an inventory does not exist at this time. The difference of this
LCA to the mass balance approach proposed here is immediately
obvious in the production system schematic: no materials are
actually ‘‘cycled”. The schematic does not indicate quantitative or
even qualitative tracking and reconciliation of any mass flows to
allow a test for (reasonable) closure of mass balances.