Environmental Engineering Reference
In-Depth Information
Applications of Biotechnology for the Utilization
of Renewable Energy Resources
Om V. Singh and Steven P. Harvey
Introduction
Even given the seemingly unlikely near-term resolution of issues involving atmo-
spheric CO
2
levels and their effect on the climate, the adoption of global conser-
vation measures, and the stabilization of fossil fuel prices, it is still a certainty that
global oil and gas supplies will be largely depleted in a matter of decades. That
much is clear from even a cursory comparison of the independent estimates of the
world's oil and natural gas reserves and the respective data on their consumption,
as published regularly on the internet by the US Government Energy Information
Administration [1]. Nature of course, offers abundant
renewable
resources that can
be used to replace fossil fuels but issues of cost, technology readiness levels, and
compatibility with existing distribution networks remain. Cellulosic ethanol and
biodiesel are the most immediately obvious target fuels, with hydrogen, methane
and butanol as other potentially viable products. Other recent reports have cov-
ered various aspects of the current state of biofuels technology [2-4]. Here we
continue to bridge the technology gap and focus on critical aspects of lignocellu-
losic biomolecules and the respective mechanisms regulating their bioconversion to
liquid fuels and value-added products of industrial significance.
The lignocellulosic structure does not readily yield its component five- and six-
carbon sugars so the efficient biological conversion of biomass typically requires
a pretreatment step to render the polysaccharide molecules accessible to enzymes.
Several thermochemical or biochemical approaches are currently in various stages
of development, and have the potential for major impact on the economics of biofuel
