Geographical assessment of open pond algal productivity and evaporation losses across the United States

Regionalized Life-Cycle Water Impacts of Microalgal-Based Biofuels in the United States

“…Given the open nature of these systems, ORPs are subjected to the changing conditions of the environment; therefore, models with hourly timescales are required to accurately simulate pond conditions. Thermal conditions in the ORP system were calculated using the model validated by Quiroz et al, 11 while growth rates were simulated using the dynamic growth model validated by Greene et al 21 Temporally and spatially resolved outputs for a 400-hectare facility cultivating the strain UTEX 393 were generated following the framework in previous modeling work with results presented in the Supporting Information. 11 The foundational model from Quiroz et al 11 was modified to include precipitation data for modeling realistic pond operations.…”

“…An accurate water balance requires models able to calculate evaporation rates at a high spatiotemporal scale and careful tracking of algal pond depth to avoid culture dilution caused by high precipitation rates . For example, the studies by Wigmosta et al and Béchet et al do include rainwater in their water balance calculations; however, the evaporation models used in these analyses were validated with small-scale pond data or were not designed to estimate the evaporation rates of commercial-scale systems accurately . Wigmosta et al validated their model with pan evaporation data, and Béchet et al , did not account for the effects of evaporation derived from natural convection, which is impactful in commercial-scale algae ponds. , This is critical as evaporation rates not only impact water balances but also propagate to temperature and growth rate calculations .…”

“…11,19 This is critical as evaporation rates not only impact water balances but also propagate to temperature and growth rate calculations. 11 The WF of algal systems has not been clearly defined in the literature due to a lack of appropriate models, incorrect modeling assumptions, or methodological inconsistencies.…”

“…This study focuses on estimating the WF and WSF of renewable diesel derived from algal biomass by integrating water LCA methodologies with a robust dynamic cultivation model. This work builds upon previous modeling work 11 with novel aspects including a thorough investigation of the impacts of water recycling, rainwater, and indirect water consumption on the WF of the system. Using the high-fidelity model validated by Quiroz et al, 11 the impacts of system scale on evaporation rates and consequently on water consumption, pond temperatures, and growth rates are accurately modeled.…”

“…This work builds upon previous modeling work 11 with novel aspects including a thorough investigation of the impacts of water recycling, rainwater, and indirect water consumption on the WF of the system. Using the high-fidelity model validated by Quiroz et al, 11 the impacts of system scale on evaporation rates and consequently on water consumption, pond temperatures, and growth rates are accurately modeled. In addition, the cultivation model was coupled with a state-ofthe-art conversion model 20 to analyze the direct and indirect water consumption of the biomass-to-fuel process.…”