Algae Biomass Summit

Transcription

1 Techno-Economic Analysis for the Production of Algal Biomass: Process, Design, and Cost Considerations for Future Commercial Algae Farms Algae Biomass Summit October 24, 2016 Ryan Davis, Jennifer Markham, Christopher Kinchin, Nicholas Grundl NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

2 Intro: 2016 Algal Biomass Design Report Projects goals to be achieved by 2022 and corresponding economics Focused on open pond cultivation, given challenges in publicly available cost/design details for PBRs (and widely varying PBR designs) PBR evaluation completed Sept Primary value is the use of four independent but credible sources for design and cost details for pond systems (key step of process) This approach shows significantly better agreement on what commercial pond systems should actually cost than typical statements made publicly Reduces uncertainty in underlying cost estimates, and highlights important economy of scale benefits Beyond base case, numerous sensitivity scenarios are considered CO 2 vs flue gas Lined vs unlined ponds Productivity vs cost Alternative strains Includes consideration of sustainability metrics including GHG, fossil energy, and water profiles 2

3 Background: Large public disparities on algae costs Algal Oil Cost ($/Gallon) Algal Oil Current Algal Oil Future Biomass Current Biomass Future Biomass Cost ($/U.S. Ton) Productivity (g/m 2 /day) Productivity (U.S. 330 days/yr) Focusing only on open pond cultivation estimates from literature: Today s performance claims for algae: $280-$2,450/ton biomass, $2-$112/gal biofuels 7-35 g/m 2 /day cultivation productivity (@ 330 day/yr uptime) Future goals: $ /ton biomass, $2-$25/gal biofuels g/m 2 /day cultivation productivity (@ 330 day/yr uptime) Much of this variability may be attributed to differences in several key underlying assumptions e.g. growth rates, pond system costs Given wide lack of agreement on these key metrics, analysis considers two approaches: 1) Top-down : What does performance + cost need to be to hit a given biomass cost goal 2) Bottom-up : Given a set of defendable assumptions, what is the resulting biomass cost 3

4 Approach: Top-Down Analysis Pond System Capital Costs ($/Wetted Acre) $300,000 $250,000 $200,000 $150,000 $100,000 $50,000 $ Productivity (g/m 2 /day) $1000/US Dry Ton $700/US Dry Ton $550/US Dry Ton $430/US Dry Ton $300/US Dry Ton Today s costs (small ponds with liner) Commercial cost goals (larger unlined ponds) Productivity (ton/acre/year) Y and X axes mutually independent variables Contours = resulting minimum biomass selling price (MBSP) MBSP reduces for higher productivity or lower pond cost Likely lower limit for system costs ~$30k/acre (commercial n th plant) At this limit $430/ton is possible (@ 30 g/m 2 /day), but challenging to reduce costs any further Even if ponds were free, CO 2 /nutrient/other costs still add up to $300-$400/ton lower boundary 4

5 Bottom-up Analysis Process Schematic AMMONIA DIAMMONIUM PHOSPHATE A200 INOCULUM SYSTEM ALGAE BIOMASS CONVERSION TO BIOFUELS (not modeled here) DIAMMONIUM PHOSPHATE AMMONIA INOCULUM ALGAE (0.05 wt% solids) WATER A100 BIOMASS PRODUCTION ALGAE (0.05 wt% solids) A500 DEWATERING ALGAE PRODUCT (20 wt% solids) CO2 CO2 RECYCLE WATER ALGAE PRODUCT (20 wt% solids) A300 CO 2 DELIVERY A400 MAKEUP WATER DELIVERY + ON- SITE CIRCULATION TO/FROM DEWATERING RECYCLE WATER A600 STORAGE CO2 (From outside of facility) MAKEUP WATER JULY 2015 OVERALL PROCESS: ALGAL PRODUCTION PROCESS PFD-001 5

6 Biomass Production: Process Considerations Metric Summer Fall Winter Spring Annual Average Biomass Productivity (g/m 2 /day AFDW) Productivity Variance versus Summer Peak NA (1:1) 1.4:1 3.0:1 1.2:1 NA Pond Evaporation (cm/day) Blowdown (MM L/day) goals: Productivity: targeting 25 g/m 2 /day (AFDW annual avg) External reviewer agreement that >25 is or must be achievable by 2022 to demonstrate sufficient progress over today s benchmarks Best performance published to date = 23 g/m 2 /day (+ 40% lipids) (Huntley/Cellana), 8-21 g/m 2 /day April-October (White/Sapphire) Composition: mid-harvest/high-carbohydrate Scenedesmus (HCSD), 27% FAME lipids Scenedesmus selected given detailed compositional data, commercial relevance Composition + productivity = ~3.9% PE to biomass (from full-spectrum irradiance), vs ~14% max Seasonal variability: 3:1 (max vs min seasonal growth) Key challenge unique to algae adds design constraints for downstream conversion facility Most recent basis from PNNL BAT model = ~5:1 average for Gulf Coast May be reduced either through strain engineering or seasonal strain rotation Current ATP3 data ~3-4:1 average of all sites, <2.5:1 for Florida ( representative Gulf Coast site) Evaporation: Based on prior harmonization modeling work (Gulf Coast average) 6

7 Pond Design Scenarios Typical Sump Location (varies by design) Circulation Pump 0.1% Slope 1% Elevation change Weir every 2 nd channel Circulation Pump Paddlewheel Station Paddlewheel raceway (typ) GAI gravity flow + pump Leidos serpentine pond NREL solicited 4 separate inputs on 8 pond designs/costs: Source 2 acre 10 acre 50 acre Leidos (engineeringfirm) R R S MicroBio (expert consultants) R R Harris Group (engineering firm) GAI (commercial developer) G G Key aspect of this work address common conceptions that commercial algae pond costs are too scattered, uncertain to really establish with any certainty Ponds grouped into 100-acre modules, in turn constituting a 5,000 acre facility based on cultivation area (~7-9k total farm footprint) Continuous cultivation at fixed 0.5 g/l AFDW harvest density Freshwater scenario, includes blowdown to control salt/inorganics à All pond designs are based on unlined ponds with native clay soils Plastic liners only used on berms or pond turns (2-25% of pond area) Full pond liners considered as sensitivity (strongly influence total costs) R R = paddlewheel raceway S = gravity-flow serpentine G = GAI design (gravity raceway with pump) 7

8 Pond Cost Estimates a Additional data points (not included in full TEA) added to this plot to further demonstrate cost alignment by pond size. b Beal costs based on extrapolating from published costs for fully lined pond to a minimally-lined design. If a fully lined pond were used for the Beal case, total installed cost would be $114,000/acre. c GAI cases include electrical costs under other pond costs. Pond costs show reasonable agreement based on small, medium, or large size groupings More strongly a function of scale highlights economy of scale advantages for building larger ponds >2-3 acres Largest cost drivers = paddlewheels + concrete ( other category), piping, civil Economies of scale are possible for piping (individual feed/harvest lines), paddlewheels, electrical No notable scale advantages for civil 8

9 TEA Results: Base Case Algal biomass selling price ($/ton AFDW) $700 $600 $500 $400 $300 $200 $100 $0 $576 $649 $452 $491 $545 $475 $491 $419 $392 OSBL Dewatering Ponds + Inoculum Fixed OPEX Costs Other Variable OPEX Nutrients CO2 MBSP results follow same trend as pond costs (largest driver on MBSP) Strong economy of scale advantages for pond design: $122/ton average premium for 2 vs 10 acre ponds $85/ton savings to move from 10 to 50 acre ponds, but becomes more speculative at such large scales For purposes of selecting a single MBSP value, average of the four 10- acre cases was used TEA Details (average of 10-acre cases): Facility size 5,000 acres (2,023 ha) wetted cultivation area CO 2 demand 417,700 ton/yr On-line time 7,920 h/yr (330 days/yr, i.e., 90% on-line factor) Biomass production rate 0.19 MM ton/yr (AFDW) Biomass yield 37.5 ton/acre/yr (84.1 tonne/ha/yr AFDW) Total installed equipment cost $238 MM Total capital investment (TCI) $390 MM TCI per annual ton biomass $2,080 Minimum Biomass Selling Price $491/ton AFDW Contribution from cultivation system $278/ton Contribution from CO 2 + nutrients $112/ton Contribution from remainder $101/ton 9

10 Sensitivity Analysis Algal biomass selling price ($/ton) $900 $800 $700 $600 $500 $400 $ Productivity (g/m 2 /day) Key drivers: Productivity: dictates economics, critical to achieve >25 g/m 2 /day Liners: adding full pond liners = >$120/ton MBSP penalty ($0.85/GGE MFSP impact on conversion costs) Farm size: 1,000 acres = $100/ton MBSP penalty ($70 labor cost + $30 capex) CO2 cost/sourcing Price for purchased CO 2 (flue gas CCS) $0-100/tonne = +$100/ton MBSP Additional scenarios considered for flue gas: 15 km flue gas transport infeasible Flue gas co-located with power plant: possible to reduce MBSP ~$45/ton, but logistical challenges for pond delivery 10

11 Summary and Concluding Remarks Algal biomass costs are tied strongly to productivity + cost of ponds, followed by CO 2 + nutrients To achieve economically viable MBSP, critical to: a) Increase productivity and strain robustness b) Maximize economy of scale benefits using >10-acre ponds c) Maximize farm size to >5,000 acres d) Demonstrate pond operability without pond liners Bottom-up modeling targets a 2022 base case MBSP of $491/ton AFDW Updated conversion models project 2022 targets near $5-6/GGE for this cost (CAP + HTL) Possible to reduce biomass costs to ~$430/ton, but achieving $3/GGE will require fundamental shift towards coproducts CAP pathway is well-suited for coproduct opportunities: nondestructive isolation of sugar/lipid/protein constituents Coproducts are a key focus of our TEA work moving forward 11

12 Questions? Funding for this work was provided by the Bioenergy Technologies Office in the Department of Energy's Office of Energy Efficiency and Renewable Energy. We thank Daniel Fishman, Christy Sterner, and Alison Goss Eng of that program for their support and input. Acknowledgements Jennifer Markham Chris Kinchin Nick Grundl Eric Tan Phil Pienkos Lieve Laurens Nick Nagle Bob McCormick Jake Kruger Mary Biddy NREL, Sept, 2010, Pic #18229 Dave Humbird, DWH Consulting Sue Jones, PNNL Ed Frank, ANL John McGowen/Valerie Harmon, ATP 3 Bill Crump, Leidos David Hazlebeck, GAI Ian Woertz, Tryg Lundquist, John Benemann, MicroBio Engineering John Lukas, Danielle Sexton, Harris Group Design report peer reviewers 12

13 Backup Slides 13

14 Facility layout 5,000 acre farm 5,000 acre facility based on cultivation area (7-9k acre total footprint = ~12 sq. mi.) Ponds divided into 100-acre plots; each plot includes circulation pipelines + primary dewatering Terraced facility design over gradual 1% slope with central dewatering, inoculum, conversion processing on-site 5,000 acre facility based on cultivation area (~7-9k acre total footprint) Ponds divided into 100-acre plots; each plot includes circulation pipelines and primary dewatering Graded over gradual 1% continuous land slope = terraced design allowing for downhill gravity circulation to central dewatering + downstream conversion (but requires uphill pumping of clarified water from central dewatering) Continuous cultivation/harvesting at a fixed 0.5 g/l AFDW harvest density from ponds Freshwater base case avoids introducing subjectivity for proximity/cost of saline water sourcing and brine disposal (consistent with prior harmonization models) Blowdown still included to mitigate salt/inorganics <4,000 mg/l taken off primary dewatering recycle line (lowest algae concentration point = minimize biomass losses) 14

15 Inoculum system H 2 O Evaporation Loss To Cultivation Ponds Covered Pond Lined Pond H 2 O + CO 2 + Nutrients Photobioreactor H 2 O + CO 2 + Nutrients H 2 O + CO 2 + Nutrients Seed Train (from lab) Inoculum system based on increasingly larger volume steps: PBR covered lined ponds open lined ponds Each step grows inoculum from 0.1 to 0.5 g/l based on the same seasonal productivities as main ponds Final stage inoculates production ponds at 0.1 g/l Inoculum system sized to require inoculation once every 20 days during peak summer season Equivalent to 5% of facility ponds requiring re-inoculation each day à Key n th plant assumption robust strains withstanding frequent culture crashes 15

16 Dewatering Recirculation to ponds 0.1 g/l 0.01 wt% Settlers are located in 100-acre pond modules Recycle to ponds 0.4 g/l 0.04 wt% Membranes and centrifuges are located in the central dewatering facility Blowdown 0.1 g/l 0.01 wt% 10 g/l 1.0 wt% Membranes From ponds 0.5 g/l 0.05 wt% Settlers 130 g/l 13.0 wt% Centrifuges Biomass to upgrading 200 g/l 20.0 wt% Primary dewatering occurs within the 100-acre modules to avoid circulating large volumes of water over entire facility Concentrates biomass from 0.5 g/l (0.05 wt% AFDW) to 10 g/l (1%) = 95% reduction in volume throughput Achieved using low-cost in-ground gravity settlers Lowest-cost dewatering option, critical for economically processing tremendous harvested culture volumes Demonstrated at large scale at Cellana [Huntley et al] and WWT facilities in CA [MicroBio] Highly strain-specific, but Scenedesmus is likely to settle well assumed 4 hr settling time, 90% recovery Secondary dewatering = hollow fiber membranes Demonstrated at large scale over sustained timeframe by GAI Cost, performance based on inputs from GAI Concentrates biomass to 130 g/l (13% AFDW) at >99% recovery Final dewatering = centrifugation Established technology, standard for algal biomass concentration Cost, performance based on inputs from engineering contractor (vendor quote) Concentrates biomass to 200 g/l (20% AFDW) at 97% recovery 16

17 Other design considerations CO 2 Sourcing via off-site flue gas carbon capture Priced at $45/tonne delivered to facility gate (supercritical) Consistent with average future CCS price projections in literature, DOE target of $40/tonne by Additional costs for on-site storage and delivery to ponds Bulk flue gas scenarios considered in sensitivity analysis Nutrients Set based on stoichiometric biomass composition at harvest, plus 20% excess allowance No recycle credits are taken on front-end model, to remain agnostic to back end conversion pathway; any recycle credits should be assigned to reduce $/gal MFSP instead Water circulation Maintains consistency with harmonization models to source freshwater via nearby ground water resource, ~0.8 mile pipeline distance to facility gate On-site circulation accomplished with aqueducts for downhill circulation to central dewatering, pipelines for uphill return of clarified effluent back to pond modules Storage Model also includes major storage tanks Dewatered biomass storage assumed to incur 1% loss to degradation should be processed as quickly as possible through downstream conversion 17

18 Scale impacts for farm size Algal Farm Size (Cultivation Acres) 5,000 1, Algal biomass to conversion (AFDW ton/day) Total volume flow to conversion (MGD) CAP oil yield to upgrading (bbl/day) 1, Biomass selling price (MBSP, $/ton AFDW) $491 $593 $691 CAP pathway MFSP ($/GGE) $5.89 $8.04 $10.47 HTL pathway MFSP ($/GGE) per Sue Jones, PNNL $4.77 $7.74 $10.85 Number of CAP facilities to support 5BGY 228 1,141 2,283 Number of HTL facilities to support 5BGY ,720 CAP MFSP ($/GGE) $12 $10 $8 $6 $4 $2 $0 $10.47 $8.04 $5.89 5,000 1, Farm Size (Acres) MFSP impact due to biomass cost MFSP impact due to scale Base MFSP at 5,000 acre farm size Significant economy of scale penalties <5,000 acre farm size MBSP = 1,000 acres, 500 acres $70/ton labor, $30/ton capex MFSP = 1,000 acres, 500 acres Driven by scale more than biomass cost Also equipment operability concerns i.e. upgrading (min boundary = 1,000 bbl/day which is still very small) Central upgrading possible, but may lose ability to recycle nutrients (critical for LCA) 18

19 TEA Details: Algal Biomass Design Case 19

20 Sensitivities Liners + Productivity Algal biomass selling price ($/ton AFDW) $900 $800 $700 $600 $500 $400 $300 $200 $100 $0 $667 $813 $537 $651 $644 $635 $617 $584 $552 OSBL Dewatering Full Pond Liners Ponds + Inoculum Fixed OPEX Costs Other Variable OPEX Nutrients CO2 Full liner costs contribute almost the same amount as pond + inoculum costs significant incentive to prioritize locations based on soil characteristics Biomass cost follows similar asymptotic curves as found in prior TEA very strong cost sensitivity <25 g/m 2 /day Above 35 g/m 2 /day, other costs start dominating (CO 2 + nutrients contribute >$100/ton in base case) Algal biomass selling price ($/ton AFDW) $900 $800 $700 $600 $500 $400 $ Productivity (g/m 2 /day) 20

21 Additional Sensitivity Scenarios CO 2 : carbon capture vs bulk flue gas 1) Bulk flue gas pipeline 15 km from source: requires more power to transport the needed CO 2 rate than the power generated to produce that amount of CO 2 Also translates to ~$49/tonne (vs $45/tonne target for purified CO 2 ) 2) Flue gas co-location with algae facility (no significant offsite transport): $447/ton (~$45/ton MBSP savings) But significant logistical/practicality questions regarding the use of multiple large ductwork pipelines routed around facility Alternative strains Considered 9 total strain scenarios for tradeoffs in biomass composition vs nutrient demands Early-growth/high-protein biomass added up to $80/ton to MBSP to sustain high N/P levels in biomass (*does not include N/P recycle considerations from downstream) Flue gas source 60" 60" 60" Centrif. Blower ID Fan 48" Alternative dewatering scenarios 1) Replace membranes with DAF Added substantial cost due to flocculant 2) Replace membranes with EC Appears competitive with membranes, but requires large-scale demonstration 3) Replace membranes/centrifuge with filter press Potential to reduce MBSP by ~$15/ton but requires large-scale demonstration and may require a flocculant (would add to cost) 21

22 Financial Assumptions: Algal Biomass Design Case Plant life 30 years Discount rate (IRR) 10% General plant depreciation General plant recovery period 200% declining balance (DB) 7 years Federal tax rate 35% Financing Loan terms Construction period First 12 months expenditures 8% 40% equity 10-year loan at 8% APR 3 years Next 12 months expenditures 60% Last 12 months expenditures 32% Working capital Start-up time Revenues during start-up 50% Variable costs incurred during start-up 75% 5% of fixed capital investment 6 months Fixed costs incurred during start-up 100% Model maintains the use of standard financial assumptions employed for other (biorefinery conversion) cases Exceptions: Indirect capital cost factors: treated separately for cultivation, dewatering, and OSBL operations based on best expectations for how such costs may factor into fixed capital investment (FCI) Labor: adjusted labor FTE categories and rates to more reasonably reflect algae farm (versus standard rates employed for a biorefinery) Labor costs scale inversely with pond size (fewer total ponds required when each pond is larger size = fewer ponds to service and maintain) 22

23 Algal biomass design case: indirect capital cost allocations 23

24 Algal biomass design case: capital cost details 24

25 Algal biomass design case: labor details 25