The production pathway and experimental methods used in this analysis has been described in detail in previous publications [6,14,19,20]. Further­more, the materials and energy consumption data used in the Experimen­tal Case and the Highly Productive Case are taken from Beal et al. that calculated the second-order energy return on (energy) investment (2nd O EROI) [14]. The term “second-order” refers to the inclusion of direct energy inputs (e. g., electricity consumed for pumping) and indirect en­ergy inputs for consumed materials (e. g., the energy embedded in nitrogen fertilizer that is consumed). Details regarding data collection and uncer­tainty analysis in the Experimental Case and modeling calculations in the

FIGURE 1: The production pathway is represented as three phases: growth, processing, and refining [6]. The data used for each input and output are shown for the Experimental Case (top) and Highly Productive Case (bottom). For the Experimental Case, the material and energy inputs crossing the system boundary were measured for five relatively large scale batches (970-2000 L, each), grown and processed at The University of Texas at Austin, except for the refining inputs (which were modeled from literature data, and are noted in the figure with an asterisk (*) [14]. The Highly Productive Case is an analytical model of a similar production pathway operated more efficiently.

Highly Productive Case can be found in the previous publication [14] and at greater length in a publically available doctoral dissertation (cf. Chapter 4, Appendix 4A, and Appendix 4B of [19]). The work presented herein expands those datasets to incorporate the new analyses mentioned above (water use, nutrients use, FROI, etc.).

Figure 1 shows that the biocrude production process for both of our an­alyzed cases consists of algal cultivation, harvesting (i. e., concentration) with centrifugation or chemical flocculation, cell lysing via electrome­chanical pulsing, and neutral lipid recovery using a microporous hollow — fiber membrane contactor. The Experimental Case is comprised of growth and processing data from five relatively large batches (970-2000 L each), with a total processed volume of about 7600 L. The energy and material inputs that were measured are shown in Figure 1 and the energy outputs are modeled to include bio-oil and biomass fuel (methane) (refining was not conducted during the experiments). The Highly Productive Case mod­els energy-efficient growth and processing methods with higher biomass and lipid productivities.