0.11 ml H
2
SO
per 1 g Chlorella. On the other hand, only 86% yield
of FAME was reported from Chlorella at 60 C for in situ transesterification
with sulfuric acid within 19 h, when the molar ratios of
methanol to lipids and sulfuric acid to lipids were 600:1 and
0.35:1, respectively [15]. The latter ratio corresponds to 0.02 ml
sulfuric acid per g algae, which is 5.5 times less than that used in
the current case, explaining a lower conversion. From the economic
point of view it should be stated that in the current case a
large excess of methanol was used together with 20 wt% sulfuric
acid, which is not feasible in the large scale. As a comparison
wet algae paste (containing 10% solid material) was in situ transesterified
in supercritical methanol at 260 C during 30 min with
12 wt%/vol methanol giving 85.75 % FAME [19], which might be
one potential route in the future.
4