should be supplied by waste gaseous emissions such as flue gas from fossil fuel
burning power plants. Providing CO 2 in form of micronized bubbles could improve
mass transfer and consequently the CO 2 diffusion in the system (see
CN101555455A). Moreover, the US patent 5659977A elaborated on a closed
system for carbon sequestration in which CO 2 from the exhaust gas would be
introduced as nutrient to the microalgae production plant. It should be mentioned
that the electrical energy obtained from the algal biomass could be used to produce
artificial illumination and/or drive pumps, motors, and control unit in the
microalgae production plant. Having achieved this, such a system could be operated
like a sustainable biorefinery platform. Another cyclic system consisting of several
integrated processes is discussed in the patent US8510985B2 advocating a method
for simultaneous production of energy and some byproducts coupled with pollutant
sequestration.
The issue of CO 2 supplementation into algal growth chamber involves different
aspects which should be taken into serious consideration, from susceptibility of
microalgae strains to certain CO 2 concentrations to the impacts of different sources
of CO 2 and nutrients pollution which could be potentially caused by emissions of
power stations. These have been the subject of patents like US20130217082A1,
WO2010010554A1, US8262776B2, and US20080220486A1.
In brief, sustainable production of biofuels from microalgae still requires technological innovations and highly optimized cultivation systems, and without a
positive energy and carbon balance, microalgae cultivation presents a mixed
picture.
3.3 Downstream Strategies
The issue of transformation of biomass into biofuels is a very wide topic and more
than 28,000 scientific papers and 3000 international patents have been published to
describe this issue during the last decade only (Faba et al. 2015). Therefore, given
the diversity of the subjects, this section is only focused on different methods used
to obtain liquid biofuels (more specifically biodiesel) from algal biomass. While
solid fuels or other types of energy are generally obtained from the entire algal
biomass as feedstock, biodiesel production requires specific processes to transform
a certain fraction of algal biomass, i.e., FAs.
Extensive downstream processing, like biomass harvesting and drying, lipid
extraction and fuel processing are regarded as major hurdles in algal biofuel
commercialization. These steps (especially harvesting and extraction) usually take
up more than half of the input energy required for algal biodiesel production. Since
the final cost of the marketable produced lipid (regardless of their use in the health
or energy market) is determined during these steps, downstream category has a
strong impact on the other categories as well as final productivity. In addition to
that, downstream processes (especially extraction and transesterification) determine
the quality of the obtained biodiesel. In better words, the higher the biochemical
302
A. F. Talebi et al.
burning power plants. Providing CO 2 in form of micronized bubbles could improve
mass transfer and consequently the CO 2 diffusion in the system (see
CN101555455A). Moreover, the US patent 5659977A elaborated on a closed
system for carbon sequestration in which CO 2 from the exhaust gas would be
introduced as nutrient to the microalgae production plant. It should be mentioned
that the electrical energy obtained from the algal biomass could be used to produce
artificial illumination and/or drive pumps, motors, and control unit in the
microalgae production plant. Having achieved this, such a system could be operated
like a sustainable biorefinery platform. Another cyclic system consisting of several
integrated processes is discussed in the patent US8510985B2 advocating a method
for simultaneous production of energy and some byproducts coupled with pollutant
sequestration.
The issue of CO 2 supplementation into algal growth chamber involves different
aspects which should be taken into serious consideration, from susceptibility of
microalgae strains to certain CO 2 concentrations to the impacts of different sources
of CO 2 and nutrients pollution which could be potentially caused by emissions of
power stations. These have been the subject of patents like US20130217082A1,
WO2010010554A1, US8262776B2, and US20080220486A1.
In brief, sustainable production of biofuels from microalgae still requires technological innovations and highly optimized cultivation systems, and without a
positive energy and carbon balance, microalgae cultivation presents a mixed
picture.
3.3 Downstream Strategies
The issue of transformation of biomass into biofuels is a very wide topic and more
than 28,000 scientific papers and 3000 international patents have been published to
describe this issue during the last decade only (Faba et al. 2015). Therefore, given
the diversity of the subjects, this section is only focused on different methods used
to obtain liquid biofuels (more specifically biodiesel) from algal biomass. While
solid fuels or other types of energy are generally obtained from the entire algal
biomass as feedstock, biodiesel production requires specific processes to transform
a certain fraction of algal biomass, i.e., FAs.
Extensive downstream processing, like biomass harvesting and drying, lipid
extraction and fuel processing are regarded as major hurdles in algal biofuel
commercialization. These steps (especially harvesting and extraction) usually take
up more than half of the input energy required for algal biodiesel production. Since
the final cost of the marketable produced lipid (regardless of their use in the health
or energy market) is determined during these steps, downstream category has a
strong impact on the other categories as well as final productivity. In addition to
that, downstream processes (especially extraction and transesterification) determine
the quality of the obtained biodiesel. In better words, the higher the biochemical
302
A. F. Talebi et al.