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Dunlop E.H.,Pan Pacific Technologies | Coaldrake A.K.,Pan Pacific Technologies | Silva C.S.,University of Pennsylvania | Seider W.D.,University of Pennsylvania
AIChE Journal | Year: 2013

Algal biofuels are increasingly important as a source of renewable energy. The absence of reliable thermodynamic and other property data, and the large amount of kinetic data that would normally be required have created a major barrier to simulation. Additionally, the absence of a generally accepted flow sheet for biofuel production means that detailed simulation of the wrong approach is a real possibility. This model of algal biofuel production estimates the necessary data and places it into a heuristic model using a commercial simulator that back-calculates the process structure required. Furthermore, complex kinetics can be obviated for now by putting the simulator into energy limitation and forcing it to solve for the missing design variables, such as bioreactor surface area, productivity, and oil content. The model does not attempt to prescribe a particular approach but provides a guide toward a sound engineering approach to this challenging and important problem. © 2013 American Institute of Chemical Engineers.

Dunlop E.H.,Pan Pacific Technologies | Coaldrake A.K.,Pan Pacific Technologies | Silva C.S.,University of Pennsylvania | Seider W.D.,University of Pennsylvania
Computer Aided Chemical Engineering | Year: 2015

Modeling sustainable processes for biofuel production remains a challenge, especially in providing fully converged mass and energy balances to assess sustainability for commercial-scale projects. This chapter shows examples of how key parameters in process design (including thermophysical property data and chemical formulas of biologically relevant compounds) can be generated using computer-aided modeling tools like AspenOne®. Sustainability metrics (GREENSCOPE) and analysis tools (GREET) are also discussed. Finally, the importance of general process development principles is discussed, and it is shown how they contribute to more reliable technoeconomic models that incorporate sustainability measures and inform decision-making. This chapter thus demonstrates how an integrated modeling systems approach delivers converged mass and energy balances and how sustainability indicators can be incorporated in process design to deliver sustainable production in the context of commercial-scale biofuel processes. © 2015 Elsevier B.V.

Silva C.,University of Pennsylvania | Soliman E.,University of Pennsylvania | Cameron G.,University of Pennsylvania | Fabiano L.A.,University of Pennsylvania | And 3 more authors.
Industrial and Engineering Chemistry Research | Year: 2014

This article evaluates pathways to cost-effective production of biofuels at a commercial scale. A thermodynamic cultivation model was simulated using Aspen Plus V7.3.1 and used to predict the area required for algae growth. This model was combined with the most promising commercial-scale methods to harvest algae and extract the oil. Conversion experiments were conducted using oil extracted from Nannochloropsis salina algae, which was grown in salt water by Solix Biofuels. Glycerolysis was performed to reduce the free fatty-acid content of the oils. Transesterification was then carried out using a solid catalyst. Rate constants were regressed to adapt kinetic models to the rate data, which allowed the glycerolysis/transesterification process to be simulated using Aspen Plus V7.3.1. Cost estimates from the Aspen Process Economic Analyzer (APEA) were combined with industrial quotes and literature data. A cash flow analysis was performed for the entire carbon sequestration-to-biodiesel production train, yielding a biodiesel selling price of $4.34/gal. Finally, a sensitivity analysis was performed to examine the impact of various costing parameters on the viability of the process. These analyses show that the current bottlenecks for the large-scale production of biodiesel are cultivation techniques and extraction operations. © 2013 American Chemical Society.

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