deduced that biofuel production utilizing microalgae has multidimensional advantage against usage of conventional energy crops.
Some of these advantageous features are presented herein as follows
[9, 10]:
1. Limited land requirements as a result of microalgae high
growth rate
2. Less water requirements
3. No herbicide or pesticide requirements
4. Higher efficiency of CO 2 sequestration (higher tolerance to
high CO 2 content in gas streams)
5. Higher feedstock sustainability as microalgae could be harvested batchwise nearly all-year-round
In spite of the abovementioned advantages, commercialization
of algal fuels has been hindered by their comparatively higher
production cost than their counterparts produced by conventional
energy crops, i.e., first-generation biofuels. Such high production
cost could be ascribed to a number of technical barriers as mentioned below which are yet to be addressed by the research community [4, 11]:
1. Cost of downstream processing
2. Highly variable large-scale outdoor cultivation conditions and
the resultant inconsistency in algal biomass produced
3. Contamination by other microorganisms (wild algae and bacteria) for large-scale production conditions
4. Limitation on light penetration in dense microalgal cultivation
systems
5. Costly oil/carbohydrate extraction techniques
6. Low biomass recovery rate
7. Potentials of growth inhibition by a combination of high dissolved oxygen and intense sunlight
A number of strategies are given below that could be considered to partially address some of the abovementioned technical
barriers [12, 13]:
1. Designing advanced photobioreactors with unique features
such as high light penetration efficiency
2. Implementation of biorefinery approach aiming at generating
multiple products to enhance the economic attributes of the
whole system
3. Selection and development of high-yield, oxygen-tolerant,
oil-rich microalgae species by genetic and metabolic engineering methods.
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Mohammad Pooya Naghshbandi et al.
Some of these advantageous features are presented herein as follows
[9, 10]:
1. Limited land requirements as a result of microalgae high
growth rate
2. Less water requirements
3. No herbicide or pesticide requirements
4. Higher efficiency of CO 2 sequestration (higher tolerance to
high CO 2 content in gas streams)
5. Higher feedstock sustainability as microalgae could be harvested batchwise nearly all-year-round
In spite of the abovementioned advantages, commercialization
of algal fuels has been hindered by their comparatively higher
production cost than their counterparts produced by conventional
energy crops, i.e., first-generation biofuels. Such high production
cost could be ascribed to a number of technical barriers as mentioned below which are yet to be addressed by the research community [4, 11]:
1. Cost of downstream processing
2. Highly variable large-scale outdoor cultivation conditions and
the resultant inconsistency in algal biomass produced
3. Contamination by other microorganisms (wild algae and bacteria) for large-scale production conditions
4. Limitation on light penetration in dense microalgal cultivation
systems
5. Costly oil/carbohydrate extraction techniques
6. Low biomass recovery rate
7. Potentials of growth inhibition by a combination of high dissolved oxygen and intense sunlight
A number of strategies are given below that could be considered to partially address some of the abovementioned technical
barriers [12, 13]:
1. Designing advanced photobioreactors with unique features
such as high light penetration efficiency
2. Implementation of biorefinery approach aiming at generating
multiple products to enhance the economic attributes of the
whole system
3. Selection and development of high-yield, oxygen-tolerant,
oil-rich microalgae species by genetic and metabolic engineering methods.
154
Mohammad Pooya Naghshbandi et al.