Process Design and Economics for the Production of Algal Biomass: Algal Biomass Production in Open Pond Systems and Processing Through Dewatering for Downstream Conversion Ryan Davis, Jennifer Markham, Christopher Kinchin, Nicholas Grundl, and Eric C.D. Tan National Renewable Energy Laboratory David Humbird DWH Process Consulting NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy Operated by the Alliance for Sustainable Energy, LLC This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. Technical Report NREL/TP-5100-64772 February 2016 Contract No. DE-AC36-08GO28308 Process Design and Economics for the Production of Algal Biomass: Algal Biomass Production in Open Pond Systems and Processing Through Dewatering for Downstream Conversion Ryan Davis, Jennifer Markham, Christopher Kinchin, Nicholas Grundl, and Eric C.D. Tan National Renewable Energy Laboratory David Humbird DWH Process Consulting Prepared under Task No. BB14.1110 NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy Operated by the Alliance for Sustainable Energy, LLC This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. National Renewable Energy Laboratory Technical Report 15013 Denver West Parkway NREL/TP-5100-64772 Golden, CO 80401 February 2016 303-275-3000 • www.nrel.gov Contract No. DE-AC36-08GO28308 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. 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Acknowledgements We gratefully acknowledge inputs and assistance from the following individuals who furnished the National Renewable Energy Laboratory (NREL) with detailed design and cost estimates for the pond system configurations considered in the present analysis: Bill Crump – Leidos Engineering David Hazlebeck – Global Algae Innovations Ian Woertz, Tryg Lundquist, John Benemann – MicroBio Engineering John Lukas, Danielle Sexton – Harris Group iii Executive Summary The U.S. Department of Energy (DOE) promotes the production of a range of liquid fuels and fuel blendstocks from biomass feedstocks by funding fundamental and applied research that advances the state of technology in biomass production, conversion, and sustainability. As part of its involvement in this program, the National Renewable Energy Laboratory (NREL) investigates the conceptual production economics of these fuels. This includes fuel pathways from lignocellulosic (terrestrial) biomass, as well as from algal (aquatic) biomass systems. Over the past decade, NREL conducted a campaign to quantify the economic implications associated with observed and aspirational performance for the conversion of corn stover to ethanol through techno-economic modeling. This effort served two important purposes: (1) to establish a benchmark representing the initial “state of technology” at the time and (2) to set goals for near-term R&D and cost targets, as well as to track progress toward achieving these targets by periodically updating the models based on the latest research improvements. Beginning in 2013, DOE began transitioning from a singular focus on ethanol to a broad slate of products and conversion pathways targeting hydrocarbon fuels, including a number of pathways from terrestrial biomass (woody/herbaceous feedstocks) and from algal biomass. To date, two reports have been published under the DOE platforms considering the economic potential for conversion of algal biomass to fuels, both based on an assumed feedstock cost for upstream biomass production and processing which was outside the scope of the analyses, but which also contributed to fuel production costs substantially more than conversion costs [1,2]. This report describes in detail a set of aspirational design and process targets to better understand the realistic economic potential for the production of algal biomass for subsequent conversion to biofuels and/or coproducts, based on the use of open pond cultivation systems and a series of dewatering operations to concentrate the biomass up to 20 wt% solids (ash-free dry weight [AFDW] basis). The overarching process design utilizes purified CO2 sourced from power plant flue gas (the CO2 purification step is outside scope boundary limits) and commodity fertilizer nutrients to support the cultivation of algal biomass to a mid-level lipid content of 27 wt%. This is followed by harvesting the biomass from the ponds and processing it through three dewatering steps in series consisting of gravity settling, hollow fiber membranes, and centrifugation, to concentrate the biomass from 0.5 g/L (0.05 wt% AFDW) at harvest up to 200 g/L (20 wt%) in the product stream. The production ponds also are coupled with an inoculum propagation system consisting of closed photobioreactors, covered ponds, and open fully-lined ponds of increasingly larger culture volumes. Ancillary areas required to support the facility operations—CO2 storage and distribution, water circulation pipelines, and product storage tanks—also are included in the design. A key attribute of this analysis is the consideration of eight separate open pond systems furnished by four separate consultants and experts in the field across three discrete pond sizes, incorporated into the integrated process model to elucidate implications on biomass production costs associated with pond sizing and resultant economy of scale impacts. Detailed material and energy balances and capital and operating costs for the process models also are documented. This case study techno-economic model provides a production cost for the thickened algal biomass product that can be used to gauge the technology potential and to quantify critical cost drivers. The analysis presented here also includes consideration of life-cycle implications by tracking environmental sustainability metrics for the modeled production facility, including greenhouse gas emissions, fossil energy demand, and consumptive water use. iv This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. Following similar methods for design report modeling as conducted over recent years, NREL, supported by four expert contributors who furnished pond design and cost estimates (see Acknowledgements section), performed a feasibility-level analysis for a plausible commercial algal biomass production facility to understand “what it really takes” to reach a range of algal biomass costs. The modeled facility consists of 5,000 acres (approximately 2,020 hectares) of production pond cultivation area with a total facility footprint of 7,600 acres (3,075 hectares) and achieves an annual biomass product yield of 38 U.S. ton/cultivation acre/year attributed to a cultivation productivity target of 25 g/m2/day as an annual average across varying seasonal rates. Based on “nth-plant” design assumptions, project costs, and financing, coupled with targets projected to be demonstrated by the year 2022, the minimum biomass selling price (MBSP) is seen to distinctly follow a trend inversely proportional with individual pond size, varying from $576–$649/ton AFDW (average $612/ton in 2011 dollars) of dewatered biomass for “small” 2- acre pond designs, $452–$545/ton (average $491/ton) for “medium” 10-acre pond designs, and $392–$419/ton (average $406/ton) for “large” hypothetical 50-acre designs, although the latter scenario was primarily only considered to further quantify economy of scale trends over a larger range of pond sizes. This result suggests that although algal cultivation ponds larger than approximately 2–3 acres in size do not currently exist commercially today, moving toward larger pond sizes on the order of 10 acres is critical in enabling economically viable algal biomass