Biomedical Engineering Reference
In-Depth Information
Contents
1
Introduction..........................................................................................................................
70
2
Progress and Challenges in Algal Feedstock Development ..............................................
72
3
Research Models .................................................................................................................
3
4
Advantages of Nannochloropsis .........................................................................................
74
5
Promises of Functional Genomics ......................................................................................
77
6
Coupling Feedstock Development with Downstream Processing .....................................
79
7
Conclusions and Perspectives .............................................................................................
80
References .................................................................................................................................
81
1 Introduction
Energy demand and environmental concerns have significantly constrained the
sustainable development of the Chinese economy, which has been experiencing
record levels of energy consumption. In 2009, China's energy consumption was
equivalent to over 3.1 billion tons of standard coal [
1
]. From 2007 to 2010, its
imported crude oil increased from 46% to a record level of 56% of total consumed
oil [
2
]. On the other hand, total CO
2
emission in China reached 67.2 billion tons in
2007, accounting for 24% of the total emission in the world (CO
2
Emissions from
Fuel Combustion, 2009 ed., IEA;
http://www.iea.org
)
. At the Copenhagen Climate
Summit (December 2009), China committed to a 40-45% reduction of CO
2
emission per GDP unit production by 2020 compared to the 2005 level. Renewable
and environmentally friendly energy sources have therefore become a crucial
factor defining the economical and social sustainability of the country.
Solar energy is the most abundant clean energy. Photosynthesis is the only
known biological approach in capturing solar energy and fixing CO
2
. The pho-
tosynthate derived, largely in the forms of plant biomass, has long been exploited
for energy via direct biomass burning or conversion to biogas, albeit at an
efficiency and scale unable to compete with fossil fuels. In a ''Consolidated
Bioprocessing of Solar Energy'' (CBP-SE) scheme (Fig.
1
), a number of tradi-
tionally discrete processing steps, including photosynthesis, accumulation of
energy storage compounds, and production of ethanol, biodiesel (triacylglycerol),
advanced biofuel (e.g. terpenoid and long-chain hydrocarbons), high-value
chemicals and food additives (pigments, proteins and polysaccharides), are con-
solidated into a single processing step, typically in a single cell or cellular system.
Such an ultimate reduction of processing steps from solar energy and inorganic
carbon to biofuels maximizes energy and cost efficiency, and thus represents one
of the most competitive strategies for producing biofuels on a large scale.
Microalgae are one promising feedstock for biofuel production in the CBP-SE
scheme. In addition, they can utilize marginal land and brackish and waste water, and
thus do not compete with agriculture for land and water resources [
3
,
4
]. Thus, large-
scale cultivation of oleaginous algae holds the potential to simultaneously alleviate
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