Algal biofuels have the potential to be a sustainable alternative to conventional transportation fuel, but there is not yet consensus on whether their commercial-scale production is environmentally beneficial. This study employs a culture-to-pump life-cycle assessment (LCA) approach to investigate the overall sustainability and net energy balance of photosynthetic bio-refineries (PSBRs).<br/>The functional unit for the LCA is 1 Liter of biofuel produced. The model incorporates potential options for each process in the system, which allows us to compare all the available process choices (Table 1) based on their environmental performance. Operation of a PSBR is classified into five stages: cultivation, separation, dewatering/drying, extraction and conversion (Fig. 1). Stand-alone data-driven models were developed for each stage to estimate life-cycle impacts including offsets and management of co-products and wastes. In addition to greenhouse gas emissions, electricity, fossil fuel, and freshwater consumption are estimated in each stage of the production process. All of the process models are integrated to simulate the entire biofuel production system since the processes are interdependent and affect the overall system performance. The integrated model is coupled with an optimization framework to search for a process configuration that minimizes environmental impact factors such as global warming potential (GWP) under constraints on technology selection, mass-energy balance and environmental targets.

Life cycle-optimization framework for photosynthetic biorefineries

249th National Meeting (2015)

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