Techno-economic analyses (TEAs) and life cycle assessments
(LCAs)
of algal biofuels often focus on locations in suboptimal latitudes
for algal cultivation, which can under-represent the sustainability
potential of the technology. This study identifies the optimal global
productivity potential, environmental impacts, and economic viability
of algal biofuels by using validated biophysical and sustainability
modeling. The biophysical model simulates growth rates of Scenedesmus obliquusbased on temperature, photoinhibition,
and respiration effects at 6685 global locations. Region-specific
labor costs, construction factors, and tax rates allow for spatially
resolved TEA, while the LCA includes regional impacts of electricity,
hydrogen, and nutrient markets across ten environmental categories.
The analysis identifies optimal locations for algal biofuel production
in terms of environmental impacts and economic viability which are
shown to follow biomass yields. Modeling results highlight the global
variability of productivity with maximum yields ranging between 24.8
and 27.5 g m–2 d–1 in equatorial
regions. Environmental impact results show favorable locations tracked
with low-carbon electricity grids, with the well-to-wheels global
warming potential (GWP) ranging from 31 to 45 g CO2eq MJ–1 in South America and Central Africa. When including
direct land use change impacts, the GWP ranged between 44 and 55 g
CO2eq MJ–1 in these high-productivity
regions. Low-carbon electricity also favors air quality and eutrophication
impacts. The TEA shows that minimum algal fuel prices of $1.89–$2.15
per liter of gasoline-equivalent are possible in southeast Asia and
Venezuela. This discussion focuses on the challenges and opportunities
to reduce fuel prices and the environmental impacts of algal biofuels
in various global regions.