Global Life Cycle and Techno-Economic Assessment of Algal-Based Biofuels

Techno-economic analyses (TEAs) and life cycle assessments(LCAs)of algal biofuels often focus on locations in suboptimal latitudesfor algal cultivation, which can under-represent the sustainabilitypotential of the technology. This study identifies the optimal globalproductivity potential, environmental impacts, and economic viabilityof algal biofuels by using validated biophysical and sustainabilitymodeling. The biophysical model simulates growth rates of Scenedesmus obliquusbased on temperature, photoinhibition,and respiration effects at 6685 global locations. Region-specificlabor costs, construction factors, and tax rates allow for spatiallyresolved 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 productionin terms of environmental impacts and economic viability which areshown to follow biomass yields. Modeling results highlight the globalvariability of productivity with maximum yields ranging between 24.8and 27.5 g m(-2) d(-1) in equatorialregions. Environmental impact results show favorable locations trackedwith low-carbon electricity grids, with the well-to-wheels globalwarming potential (GWP) ranging from 31 to 45 g CO2eq MJ(-1) in South America and Central Africa. When includingdirect land use change impacts, the GWP ranged between 44 and 55 gCO(2eq) MJ(-1) in these high-productivityregions. Low-carbon electricity also favors air quality and eutrophicationimpacts. The TEA shows that minimum algal fuel prices of $1.89-$2.15per liter of gasoline-equivalent are possible in southeast Asia andVenezuela. This discussion focuses on the challenges and opportunitiesto reduce fuel prices and the environmental impacts of algal biofuelsin various global regions. Thisstudy uses biophysical process modeling with regionallife cycle and techno-economic assessments to investigate the sustainabilityof algal biofuel production across the globe.