Environmental Engineering Reference
In-Depth Information
an integrated biorefinery would be supported. Specialized materials produced
through recombinant DNA technologies are expected to be of high commercial
value but of relatively small volume.
H.
B
IOETHANOL
The consensus among researchers and supporters of bioethanol research, in addition to
those engaged in commercial projects, is that the improvement of cellulase enzyme activity
and cellulase production, both to increase the efficiency of release of fermentable sugars from
biomass and to reduce cellulase cost, are two of the greatest advances needed in the effort to
commercialize fuel ethanol production. In addition is the development of enzymatic
pretreatment processes to release lignin from carbohydrate components and further
improvement of fermentative organisms, with the particular goal of designing microbes
capable of consolidated bioprocessing.
I.
B
IODEISEL
The cost, quality, and performance of biodiesel, as well as its overall environmental
profile, could be improved by further efforts in several areas.
•
Altenative Feedstocks
. First, feedstocks other than virgin plant oils, most of which
are cultivated by non-sustainable, pesticide and energy intensive agricultural
practices, would ideally be explored and developed; alternatively, sustainable
cultivation of oil crops should be developed. Waste oil processing technology also
deserves developmental effort to allow recovery of its intrinsic energy, and microbial
and algal lipid production should be investigated to determine whether they might
provide feedstocks at lower cost.
•
Lipase Technology
. The further development of lipase technology will facilitate
efficient enzymatic transesterifications of feedstock oils and fats and production of
benign wastes with easily-recoverable coproducts, principally glycerol. Specifically,
genetic engineering of lipases for greater activity and durability, as well as metabolic
engineering of lipase-production pathways to understand lipase synthesis and
regulation and to facilitate extracellular production, are well-positioned to offer
valuable advances in enzymatic transesterification of oils and should be pursued.
Research in these areas could have potentially great impacts within relatively short
timescales and should be encouraged to the greatest extent possible.
J.
B
IOHYDROGEN
Approaches to biohydrogen production (direct and indirect photolysis,
photofermentation, the water-gas shift pathway, and dark fermentation), have been carefully
investigated for future practicability, and all face challenging problems that are nevertheless
