Compared with other energy crops, algae benefit from their rapid
growth rate and productivity [5], high carbon dioxide fixation rate
[6, 7], and large lipid quantity [8, 9]. In addition, algae production
does not require high quality fresh water and arable lands like food and
feed crops [10]. Nevertheless, the environmental burdens associated
with any biofuel production routes should be appraised before upscaling and commercial implementation and relevant guidelines should
be observed to ensure the most sustainable technological developments [11]. Among various sustainability assessment tools introduced to date, life-cycle assessment (LCA) approach has attracted a
great deal of attention as it could not only allow researchers to comparatively assess the environmental impacts associated with algal fuels
with those of fossil fuels but also identify optimal production strategies resulting in lower environmental footprints [12]. An LCA would
show greenhouse gas (GHG) balances obtained from all inputs and
outputs using approved methodologies [13].
More specifically, LCA approach evaluates the environmental
impacts related to products and services by taking into consideration their energy/material inputs and wastes/pollutants discharged into environment [14]. Favorable LCA results could be
regarded as a significant and essential driver for promoting a particular type of biofuel or process pathway. Nevertheless, such assessments could be very complex upon the goal of study and might
contain more than 100 unit operations, innumerable inventory
items, and several midpoint/endpoint impact damage categories.
It is worth noting that different facets of LCA approach like system
boundary selection, inventory data source for the unit processes,
and strategies for dealing with co-product allocation can all markedly affect the results obtained [15].
For instance, LCA approach has been used to explore the
environmental implications of pilot- and large-scale algae-to-bioenergy projects [14, 16–19]. However, the results reported in these
studies are very diverse due to significant differences in assumptions
made and goals considered. These inconsistent outcomes have been
obtained unlike the fact that the majority of algae-to-energy LCA
researches report on basically the similar cultivation methods and
lipid extraction technologies. As shown in Fig. 1, algae are first
cultured in open ponds, then separated from the growth medium,
afterwards subjected to lipids extraction, and finally transesterified
with alcohol to form alkyl esters (biodiesel). Therefore, in order to
better compare the results of various studies, it is necessary to
adhere to a set of similar requirements and guidelines in assessing
the life cycle of alga fuel production. In line with that, this chapter is
devoted to scrutinize the diversity of the assumptions and approximation considered in the published literature while suggesting
comprehensive and systematic guidelines to boost and consolidate
future LCA of algae-to-bioenergy projects. Moreover, the steps to
conduct an accurate LCA of algae fuel are presented in detail
including the data required, etc.
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Homa Hosseinzadeh-Bandbafha et al.
growth rate and productivity [5], high carbon dioxide fixation rate
[6, 7], and large lipid quantity [8, 9]. In addition, algae production
does not require high quality fresh water and arable lands like food and
feed crops [10]. Nevertheless, the environmental burdens associated
with any biofuel production routes should be appraised before upscaling and commercial implementation and relevant guidelines should
be observed to ensure the most sustainable technological developments [11]. Among various sustainability assessment tools introduced to date, life-cycle assessment (LCA) approach has attracted a
great deal of attention as it could not only allow researchers to comparatively assess the environmental impacts associated with algal fuels
with those of fossil fuels but also identify optimal production strategies resulting in lower environmental footprints [12]. An LCA would
show greenhouse gas (GHG) balances obtained from all inputs and
outputs using approved methodologies [13].
More specifically, LCA approach evaluates the environmental
impacts related to products and services by taking into consideration their energy/material inputs and wastes/pollutants discharged into environment [14]. Favorable LCA results could be
regarded as a significant and essential driver for promoting a particular type of biofuel or process pathway. Nevertheless, such assessments could be very complex upon the goal of study and might
contain more than 100 unit operations, innumerable inventory
items, and several midpoint/endpoint impact damage categories.
It is worth noting that different facets of LCA approach like system
boundary selection, inventory data source for the unit processes,
and strategies for dealing with co-product allocation can all markedly affect the results obtained [15].
For instance, LCA approach has been used to explore the
environmental implications of pilot- and large-scale algae-to-bioenergy projects [14, 16–19]. However, the results reported in these
studies are very diverse due to significant differences in assumptions
made and goals considered. These inconsistent outcomes have been
obtained unlike the fact that the majority of algae-to-energy LCA
researches report on basically the similar cultivation methods and
lipid extraction technologies. As shown in Fig. 1, algae are first
cultured in open ponds, then separated from the growth medium,
afterwards subjected to lipids extraction, and finally transesterified
with alcohol to form alkyl esters (biodiesel). Therefore, in order to
better compare the results of various studies, it is necessary to
adhere to a set of similar requirements and guidelines in assessing
the life cycle of alga fuel production. In line with that, this chapter is
devoted to scrutinize the diversity of the assumptions and approximation considered in the published literature while suggesting
comprehensive and systematic guidelines to boost and consolidate
future LCA of algae-to-bioenergy projects. Moreover, the steps to
conduct an accurate LCA of algae fuel are presented in detail
including the data required, etc.
122
Homa Hosseinzadeh-Bandbafha et al.