لخّصلي

Global warming due to increased carbon dioxide concen￾tration in the atmosphere is receiving a great deal of at￾tention. Atmospheric increases of carbon dioxide are po￾sitively correlated with the amount of fossil fuels being
burned [1]. In an effort to retard this increase and, there￾fore, the greenhouse effect, most industrialized countries
have joined in a policy to hold carbon dioxide emissions
[2]. However, it is not clear if technology exists to achi￾eve this goal.
Generally, photosynthetic system provides critical
oxygen renewal along with the recycling of carbon into
potentially beneficial biomass [3,4]. The efficiency of such
system depends on the type of the organism used [5,6].
Microalgae are the most promising production facilities.
They are capable of fixing several-fold more CO2 per
unit area than trees or crops. Such CO2 fixation by photo￾autotrophic algal cultures has the potential to diminish
the release of CO2 into the atmosphere, helping alleviate
the trend toward global warming. To realize workable
biological CO2 fixation systems, selection of optimal mi￾croalgae species is vital. The selection of optimal micro￾algae species depends on specific strategies employed for
CO2 sequestration.
Viewing microalgae farms or bioreactors as means to
reduce the effects of a greenhouse gas (CO2) changes the
view of the economics of the process. Instead of requir￾ing that microalgae-derived fuel be cost competitive with
fossil fuels, the process economics must be compared
with those of other technologies proposed to deal with
the problem of CO2 pollution. However, development of
alternative, environmentally safer energy production te￾chnologies will benefit society whether or not global
climate change actually occurs [7]. Microalgal biomass
production has great potential to contribute to world en￾ergy supplies, and to control CO2 emissions as the de￾mand for energy increases. This technology makes pro￾ductive use of arid and semi-arid lands and highly saline
water, resources that are not suitable for agriculture and
other biomass technologies [8].
Although CO2 is still released when fuels derived from
algal biomass are burned, integration of microalgal farms
for flue gas capture approximately doubles the amount of
energy produced per unit of CO2 released. Materials de￾rived from microalgal biomass also can be used for other
long-term uses, serving to sequester CO2. Flue gas has
the potential to provide sufficient quantities of CO2 for
such large-scale microalgae farms [9].