EFRI-PSBR: Closing the loop- towards a PSBR design framework for self-sustained marine microalgal-based fuel production

ABSTRACT

Intellectual Merit

Algal oils have many characteristics of an ideal feedstock for biofuels production, offering the ability to use poor quality water (municipal wastewater, brackish water, etc.), atmospheric carbon dioxide (CO2), and to reuse CO2 in flue gases in their preparation. However, there are several technical challenges associated with culturing and harvesting algae in current generation photosynthetic biorefineries (PSBRs). The overall goal of this project awarded jointly by NSF Emerging Frontiers in Research and Innovation Division and the Division of Molecular & Cellular Biosciences to Professors Amy Grunden, Francis de los Reyes III, Joel Ducoste, S. Ranji Ranjithan, and Heike Sederoff, all of North Carolina State University, Raleigh, NC, is to model, develop, implement, and evaluate a scalable PSBR that uses transformational nutrient recycle processes and supports efficient conversion of CO2 to oils in a marine microalgae-based system. Using synergistic engineering and biotechnological approaches, the team will: 1) genetically engineer a marine microalgae species (Dunaliella spp.) with enhanced CO2 uptake/fixation and the capability to recycle nitrogen and phosphorous from microalgal biomass; 2) design a small-scale PSBR using a kinetic model, which will be used to develop a scalable dynamic reactor model based on computational fluids dynamics simulation of the PSBR; 3) develop innovative, scalable approaches for algal harvesting and lipid extraction; and 4) develop a life-cycle analysis (LCA) framework that includes flexible and scalable cost and life-cycle inventory process models of the microalgal PSBR system. In a novel feature of the effort, the North Carolina State team plan the demonstration of novel Lagrangian microsensors that can assess accumulation of light radiation in proportion to its exposure during transport through the reactor, which will significantly aid in the modeling and testing of PSBR operation in response to light. Thus, genetic enhancement, reactor modeling, and LCA will be used to optimize the production of algal biomass and lipids in the PSBR.

Broader Impacts

Development of truly scalable and sustainable PSBRs offers tremendous economic and environmental impact by reducing the transportation sector reliance on fossil fuels. Innovative and transformative enabling-technologies that will permit robust production of marine microalgae biomass and lipids in scalable and sustainable PSBRs will bring significant environmental and economic benefits to the nation through the development of an efficient, high-yield alternative energy feedstock production platform.

In addition, through the proposed mentoring and outreach programs, this interdisciplinary project involving engineers, microbiologists, molecular biologists, and plant physiologists provides unique opportunities for broadening STEM participation among high school, undergraduate, graduate, and postdoctoral scholars who will be required to bridge traditional disciplines and become the new generation of scientists and engineers to develop renewable energy for future generations. Specifically, the NCSU team will develop widely distributable web-based teaching modules for secondary students based on PSBR technologies in collaboration with faculty from Research Triangle High School (RTHS, www.rthighschool.org), a STEM-focused public charter school serving a diverse population from seven North Carolina counties. The PIs will also host a 6-week high school student summer research program for students that have matriculated through a 1-week preparatory Research Methods Bootcamp developed by the RTHS team. In addition, the team will introduce a new undergraduate special topics honors course, Photosynthetic Biorefineries for Fuel Production, to train undergraduate engineering and biology students in an integrated Honors seminar/discussion course providing opportunities for independent study as well as teamwork on topics relevant to photosynthetic biorefinery design, modeling, and operation.