Overall, LCA results indicate that algal biofuels, particularly those utilizing
wastewater, have a large potential to introduce environmental benefits, especially
given that biofuel sustainability is a critical issue given impacts from direct and
indirect land use change associated with first-generation biofuels. A common theme
behind almost all LCA studies is the dominance of energy across all impact
categories. This may not be an issue at small scales, but with the goal of achieving
large-scale production, energy-related impacts can determine the success or failure
of algal biofuels of becoming sustainable. However, there is still work needed in
harmonizing LCA results of algal biofuels. Due to differences in production
pathways, assumptions, parameters, and data quality, the result is a large variability
of results, which makes it difficult to compare results, given changing geographical
or technological conditions (Chiaramonti et al. 2015). Despite these challenges,
LCA is an effective decision-making tool for developing solutions toward sustainable algal fuels.
3.5.2 Economic Sustainability
The economic feasibility of commercial algal biofuel production is dependent on the
large-scale productivity potential of microalgae. The biggest barrier to commercializing algal biofuels is the difficulty in replicating the productivity potential for largescale production. A significant advantage of microalgae is the potential for high
production rates relative to terrestrial feedstocks. However, achieving this at a large
scale has proven to be challenging (Quinn et al. 2012). Despite this difficulty, several
studies have performed techno-economic feasibility studies to understand the economic feasibility of various production pathways. These studies have typically
coupled engineering-based process modeling with economic analysis to determine
selling prices by the on a per-gallon basis. A review of literature performed by Quinn
and Davis (2015) shows a low cost for production at $1.65/gallon and a high cost of
$33.16/gallon. This variability is caused by differences in system boundaries,
production pathways, and temporal coverages. Sun et al. (2011) performed a harmonization of results, resulting in a narrower range of $11.68–$14.31/gallon. Differences between growth architectures contribute to the economic feasibility as well.
Open raceway ponds (ORP) and PBR are two major pathways. Studies that have
compared the costs between the two have concluded that ORP is more economic
feasible than PBR by more than a factor of 2 (Davis et al. 2011; Richardson et al.
2012). In addition to GHG emissions, Campbell et al. (2011) also compared costs of
algal biodiesel production to canola and ULS diesel. The costs of feedstock production, transformation and distribution, capital, and excise were all considered, for both
a low production rate of 15 g/m
2 /d and high rate of 30 g/m
2
/d. The results showed
that algal biodiesel costs range from 2.2 to 4.8 cents/tkm. The lower cost is via
delivery of flue gas, while the higher cost is from CO 2 delivery by truck. Canola and
ULS diesel have costs of 4.2 and 3.8 cents/tkm, respectively.
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297
wastewater, have a large potential to introduce environmental benefits, especially
given that biofuel sustainability is a critical issue given impacts from direct and
indirect land use change associated with first-generation biofuels. A common theme
behind almost all LCA studies is the dominance of energy across all impact
categories. This may not be an issue at small scales, but with the goal of achieving
large-scale production, energy-related impacts can determine the success or failure
of algal biofuels of becoming sustainable. However, there is still work needed in
harmonizing LCA results of algal biofuels. Due to differences in production
pathways, assumptions, parameters, and data quality, the result is a large variability
of results, which makes it difficult to compare results, given changing geographical
or technological conditions (Chiaramonti et al. 2015). Despite these challenges,
LCA is an effective decision-making tool for developing solutions toward sustainable algal fuels.
3.5.2 Economic Sustainability
The economic feasibility of commercial algal biofuel production is dependent on the
large-scale productivity potential of microalgae. The biggest barrier to commercializing algal biofuels is the difficulty in replicating the productivity potential for largescale production. A significant advantage of microalgae is the potential for high
production rates relative to terrestrial feedstocks. However, achieving this at a large
scale has proven to be challenging (Quinn et al. 2012). Despite this difficulty, several
studies have performed techno-economic feasibility studies to understand the economic feasibility of various production pathways. These studies have typically
coupled engineering-based process modeling with economic analysis to determine
selling prices by the on a per-gallon basis. A review of literature performed by Quinn
and Davis (2015) shows a low cost for production at $1.65/gallon and a high cost of
$33.16/gallon. This variability is caused by differences in system boundaries,
production pathways, and temporal coverages. Sun et al. (2011) performed a harmonization of results, resulting in a narrower range of $11.68–$14.31/gallon. Differences between growth architectures contribute to the economic feasibility as well.
Open raceway ponds (ORP) and PBR are two major pathways. Studies that have
compared the costs between the two have concluded that ORP is more economic
feasible than PBR by more than a factor of 2 (Davis et al. 2011; Richardson et al.
2012). In addition to GHG emissions, Campbell et al. (2011) also compared costs of
algal biodiesel production to canola and ULS diesel. The costs of feedstock production, transformation and distribution, capital, and excise were all considered, for both
a low production rate of 15 g/m
2 /d and high rate of 30 g/m
2
/d. The results showed
that algal biodiesel costs range from 2.2 to 4.8 cents/tkm. The lower cost is via
delivery of flue gas, while the higher cost is from CO 2 delivery by truck. Canola and
ULS diesel have costs of 4.2 and 3.8 cents/tkm, respectively.
12 Microalgae: An Eco-friendly Tool for the Treatment of Wastewaters for. . .
297