Algal Turf to Fuel (ATF) System overview and preliminary assessment of the production of biofuels from chemical, biochemical, and thermochemical processing and conversion of benthic polyculture biomass produced by algal turf cultivation Ron Pate*, Sandia National Laboratories1, Albuquerque, NM (SNL/NM), Ben Wu, Sandia National Laboratories, Livermore, CA (SNL/CA), Ryan Davis (SNL/CA), Todd Lane (SNL/CA), Anthe George (SNL/CA), Stephen Horvath (SNL/NM), Walter Adey (Smithsonian Institution), Dean Calahan (Smithsonian Institution), Mark Zivojnovich (HydroMentia), Jason Quinn (Utah State University), and Justin Hoffman (Utah State University) Engineering & Analysis Track Session: Modeling a Sustainable Algae Industry 2014 Algal Biomass Summit San Diego, California September 29 – October 2, 2014 SAND2014-18367 PE 1Sandia is a multiprogramlaboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. Turf algal biomass for fuels offers significant benefits over raceway monoculture systems Algae Turf Scrubber Algae Raceway VS Hydromentia – Vero Beach, Florida NBT – Eilat, Israel • Monoculture – vulnerable • Polyculture – resilient to crashes • Growth – 2 to15 g/m2/day • Growth: 15-20+ g/m2/day annual • Fertilizer and external CO • No added nutrients or external CO 2 2 • Harvesting & dewater more • Harvesting & dewater – simple difficult & energy-intensive • Biomass focus - low neutral lipids • Lipid focus (historical) • Similarities with open field agriculture Key Points • Algal Turf to Fuels – Possible solution to key challenges: – Can avoid crashes … Cultivation resiliency with polyculture – Can avoid expensive, energy-intense harvesting & dewatering – Can avoid costly CO supply &/or co-location w/ industrial sources 2 – Can avoid commercial fertilizer costs • Turf algae pioneered in 1980s (Walter Adey) and commercialized for water treatment (HydroMentia) • Robust algae production 20-30 tons ac-1 yr -1 AFDW (15- 20+ g m-2 d-1) demonstrated 10+ years of operation • Focus on biochem &/or HTL conversion of total biomass – Optimize product yields – Recycle major nutrients (N & P) – Reduce nitrogen content in biomass residue & subsequent HTL biocrude product Algal Turf System… Open Field Algal Farming! Cleaning water while producing biomass A New Dimension in Algae Farming Consists of slightly tilted & Algal Turf Scrubbing – “Aquatic Field Crop for Fuel” lined planar open- 2D (conventional) vs. 3D (higher biomass productivity) liner surface texture field systems Innovative 3D substrate using pulsed, texture (3D Screen) can shallow, turbulent enable increased turf biomass water flow and productivity w/ possibly reduced exogenous mechanical ash content harvesting compatible with conventional agriculture. Conventional 2D substrate Commercial multi- used for water treatment acre scale systems -not optimized for systems have increasing biomass productivity been developed Farm implement-type mechanical harvesting & and used for water dewatering yielding 8-15 % solids wet biomass treatment. Illustration courtesy of Dean Calahan([email protected]) Algal Turf to Fuels (ATF) - Overview Agribusiness & CAFO WW -Cheese plants -Ag product processing -Dairies & Feedlots Harvested and Naturally Point Benthic Algae & Sources Consolidated Wet Algal Cyanobacteria Municipal & Nutrient- Biomass (7%-12% solids)* Polyculture Loaded Industrial WW * 20% with post-harvest pressing Assemblage Fresh & Water Saline Cultivation & Recycle Waters Water Bodies w/ Or, whole Harvesting Systems Non- Excess Nutrients Pre-Treatment biomass (Chemical &/or directly to Point -Bays Single-Pass Operation HTL Sources -Lakes Enzymatic) as a -Rivers baseline -Estuaries Multi-Pass Recycle Operation Non-soluble option Ash Separation Nutrient Proteins Carbohydrates Residue Recycle or, Carbs stay with Biomass Residue Ammonia Ferment Ferment Hydrothermal Liquefaction Biofuels & Intermediate Butanol / Pentanol Feedstocksfor Butanol / Ethanol Upgrading to Biocrude Oil Note: HTL biocrudewill have greatly reduced N-content based on using protein Fungible extracted biomass rather than whole biomass. Hydrocarbon (Nitrogen-free) Fuels Struvite Nutrient (N, P) Capture & Separation from Aqueous Phase Advantages of benthic algal polyculture turf for biofuels • Simple cultivation system configuration - more like open field ag – Utilizes pulsed, shallow, turbulent flow with excellent solar insolation exposure and gaseous exchange with atmosphere – Stable, diversified cultivation … extremely resilient and resistant to crashes – Years of commercial experience w/ multi-acre systems for water cleaning • One-pass operation (typically used for water cleaning) – Annual average AFDW biomass production of 15 -to- 20 g m-2 d-1 – No engineered addition of CO or nutrients required under single-pass operation 2 – System improvement potential for 25 to ≥35 g m-2 d-1 AFDW productivity – Recycle system operation can expand sustainable deployment opportunities • Ease of scale-up and low-energy harvesting/dewatering – Scale up to larger acreage simple matter of duplication of multi-acre “field” modules – Simple mechanical harvesting approaches consistent w/ ag operations – Immediately provides 8% to 15% solids content wet biomass Sample of Benthic Algal Polyculture Turf System Diversity over Multi-Year Period Normalized plots of dominant 15-20 species found provided courtesy of Walter Adey1 1 Data and analysis from: Haywood Dail Laughinghouse IV, “Studies of Periphytic Algae on Algal Turf Scrubbers Along the Chesapeake Bay - Community Structure, Systematics, and Influencing Factors”, PhD Thesis, U. of MD – College Park, 2012. Challenges with algal turf biomass processing & conversion to fuels • Low neutral lipid content ( 10%) – high in protein and carbohydrates • High ash content (~ 30-50+%) in raw harvested material seen with current systems (not optimized for reduced ash) – Ash is combination of biogenic and exogenous environmental material – Improvement possible with cultivation and harvesting systems & ops – Dilute acid pre-treatment & separation provides ash reduction • Heterogeneous polyculture biomass characteristics – Dynamically changes with season, water source chemistry – Provides robust and resilient culture immune to “crashes” • HTL biocrude can have high nitrogen content (5+%) – Biochem pretreatment of proteins can reduce and recycle nitrogen – Resulting HTL biocrude from residue has N-content 1% • Preliminary TEA looks promising for achieving cost- effective biofuels at large scale Algal turf biomass characterization* * Systems non-optimized for increased AFDW biomass w/ reduced ash • Variable composition: dependent on water source, climate, season • Composed of multiple phylogenetic groups: dominant clades include chlorophyta, diatoms, and cyanobacteria • Low lipid content • Biogenic and non-biogenic ash content • System not optimized for ash reduction Total harvest HydroMentia sample Ash 8.6% 27.4% 18.9% 51.9% 45% 4.9% 16.6% 1.7% 11.9% 6.8% 2.2% 4% Processing & Recycling Pathways Whole biomass to HTL option Nutrient-loaded Water & Sunlight Upgrading to Mixed Alcohols & Low-N hydrocarbon Neutral Lipids Organic fuels Residue Benthic Protein / Carb Dilute Polyculture Fermentation HTL Biocrude Acid P/T Biomass1 & Distillation w/ lower N- content following Non-soluble Ash upstream Separation Ash & Residual protein Nutrient removal Carbon (Char) N & P Recovery (Struvite) SNL process patent applications With multi-pass Water on fuel intermediate production from algae and nutrient recycling recycle operations Recovery 1 Benthic algal polyculture turf will also include entrained planktonic species