Modeling water‐energy tradeoffs for cultivating algae for biofuels in a semi‐arid region with fresh and brackish water supplies

Abstract

We analyze water-energy tradeoffs for hypothetical algae production for biofuel feedstock in the US-Mexico middle Rio Grande watershed with a coupled water, salinity, and algae biomass balance model. Suitable areas for algae cultivation in the region are selected and associated with fresh or brackish groundwater sources. We examine the potential of using two algae species with markedly different energy content and tolerance to salinities. Location-specific water quality and time-varying climate variables were important when analyzing water-energy tradeoffs for each species. In this regional study, water demand rates for the salinity-tolerant species were similar to rates for conventional local crops, whereas the salinity-sensitive species' values exceeded local demand rates. Optimizing the spatial selection of species resulted in water footprint reductions of as much as 18%. Water demand rates and footprints are highly sensitive to salinity and temperature tolerance and thus local variations in water quality and seasonal variations in climate.

Potential use of saline resources for biofuel production using halophytes and marine algae: prospects and pitfalls

“…The availability of fresh water is limited especially in areas where productivity of algae is potentially high -i.e. regions with high year-round solar radiation (Mayer et al, 2020). Algal growth and subsequent processing likely cause substantial water pollution (Rahman et al, 2020).…”

An appraisal of the variable response of microalgal lipids to culture salinity

“…Interesting options have also been proposed for semi-arid regions. 11 Among different applications, salinity plays an important role in controlling unwanted competitors or predators in microalgal production. [12][13][14] Proper salinity management is an important aspect within the ecological approach to microalgal production.…”