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Techno-Economic Analysis of Whole Algae Hydrothermal Liquefaction (HTL) and
Upgrading System
YUNHUA ZHU Susanne B. Jones, Daniel B. Anderson, Richard T. Hallen, Andrew J. Schmidt,
Karl O. Albrecht, Douglas C. Elliott Pacific Northwest National Laboratory
2015 Algae Biomass Summit Washington, DC
September 29 - October 2, 2015
This presentation does not contain any proprietary, confidential, or otherwise restricted information
Growth, Harvest Dewater
20% Solids
Water & nutrient recycle
HTL Upgrading Naphtha
Diesel
CHG H2 Gen
Oil
Aqueous
Gas
NG
H2
Whole Algae HTL and Upgrading Overview
2
Hydrothermal liquefaction (HTL) ~3000 psia, 350°C, no catalyst Biocrude upgrading ~ hydrotreating and hydrocracking with hydrogen in
excess of chemical consumption Catalytic Hydrothermal Gasification (CHG) ~3000 psia, 350°C, fixed
bed
Process Simulation and Cost Analysis Assumptions
Feedstock: freshwater and saltwater algae Conversion only: 1340 tons per day algae, ash free dry weight (AFDW) basis Algae delivered at 20 wt% solids (AFDW basis) $1100/ton for feedstock (AFDW basis) 40% equity financing, 10% Internal rate of return, 60% debt financed at 8% for 10 years Costs in 2011 US $ for a mature nth plant
3
Feedstock Compositions: Freshwater and Saltwater Algae
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Carbon 54.7%
Hydrogen 7.4%
Oxygen 26.5%
Nitrogen 10.7%
Sulfur 0.7%
Freshwater algae
Carbon 49.4%
Hydrogen 6.9%
Oxygen 35.3%
Nitrogen 6.4%
Sulfur 2.0%
Saltwater algae
Dry ash free (DAF) basis for elemental compositions; Freshwater algae: ash content - 8.1 wt% (dry basis); Lipid content ~ 4% (DAF); Saltwater algae: ash content ~ 22 wt% (dry basis); Lipid content ~ 16% (DAF)
Oil Products Yields
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0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
Freshwater algae Saltwater algae
Oil
Yiel
ds, t
on/to
n A
FDW
A
lgae
HTL Bio-crude Hydrotreated oil Diesel Naphtha
Final product yields Freshwater algae Saltwater algae Diesel production, million gallon gasoline equivalent (GGE)/yr 26 37
Byproduct (naphtha) production, million GGE/yr 16 11
Carbon and Energy Efficiencies
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0%
10%
20%
30%
40%
50%
60%
70%
Freshwater algae Saltwater algae
Car
bon
Effic
ienc
y, %
Diesel and naphtha / Algae only Overall carbon efficiency
0%
10%
20%
30%
40%
50%
60%
70%
80%
Freshwater algae Saltwater algae
Ener
gy E
ffici
ency
, %
Diesel + Naphtha / algae only Overall energy efficiency
Cost Contributions for Algae HTL and Upgrading
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-5.0
0.0
5.0
10.0
15.0
20.0
25.0
$21.3/GGE $15.6/GGE
Die
sel S
ellin
g Pr
ice
($/G
GE)
Freshwater algae Saltwater algae
Feedstock HTL Oil Production CHG Water Treatment Bio-crude Upgrading Balance of Plant Naphtha Credit
Conversion cost only (not including naphtha credit): Freshwater algae: $4.4/GGE Saltwater algae: $3.3/GGE
Sensitivity Analysis – Saltwater Algae Case
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-$10.0 -$5.0 $0.0 $5.0 $10.0 $15.0
Hydrotreating Catalyst Life, years (5 : 2 : 1) Upgrading Capital (-40% : base : +40%)
CHG Catalyst Cost $/lb (30 : 60 : 120) CHG Catalyst Life, yrs (2 : 1 : 0.5)
Naphtha Value, $/gallon ($3.75 : $3.25 : $1.50) Project Contingency (0% : 10% : 20%)
CHG Capital Cost (-40% : base : +40%) HTL Capital (-40% : base : +40%)
Total Project Investment (-10% : base : +40%) Plant Scale Dry Feedstock, ton/d (2500: 1340 : 500)
No CHG - Recycle Untreated HTL Aqueous Internal Rate of Return, IRR (0% : 10% : 20%)
Fuel Yield (+10% : base : -20%) Feedstock Cost, $/AFDW ton (430: 1100 : 2000)
Cost Change from Baseline Case, $/GGE
Conclusions Algae composition and the salt in HTL aqueous phase affect the fuel yields Cultivation, harvest and dewatering (“algae feedstock cost”) cost is the largest fraction (85% to 89%) of the total production cost The HTL process cost represents the largest fraction of the conversion cost Feedstock cost and product yield are the key cost drivers
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Potential Improvements Increasing biocrude yield and reducing HTL process cost through improved HTL reaction conditions Increasing biocrude yield via improved phase separation of the HTL oil from the aqueous product Optimizing HTL aqueous phase treatment to reduce costs and enhance carbon recovery Reducing algae feedstock cost via research improvements in the cultivation, harvest and dewatering process
10
Future Work in Techno-Economic Analysis
Reduce the assumed HTL/CHG throughput to more typical algal cultivation scale
Decouple the upgrading process simulation to assess a larger scale, centralized upgrader fed by multiple HTL units
Disaggregate “feedstock cost” into cultivation, harvest and dewatering costs appropriate for a given scale
11
Acknowledgements
The authors would like to acknowledge funding of this work by the US Department of Energy’s Bioenergy Technologies Office (BETO)
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13
Additional Slides Methodology Major assumptions
Methodology
14
Process model
Cost Analysis
Minimum Fuel Selling Price
(MFSP) $
gge
Conversion Yields
Operating Conditions
Whole wet algae Conversion efficiency,
Product Yields (gasoline & diesel), etc. Mass and energy
balance information
Algae & chemical price
Cost parameters
Base cost of equipment
Major Assumptions for HTL Process
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HTL operating conditions Freshwater algae Saltwater algae
Temperature, °F (°C) 658 (348) 667 (350)
Pressure, psia 2930 3000
Feed solids, wt% DAF basis 20.0 20.0 Liquid hourly space velocity, h-1 2.2 2.2
Biocrude yields, wt% DAF algae basis 38 41
C wt% in biocrude 77 80
Major Assumptions for Upgrading Process
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Hydrotreating operating conditions
Freshwater algae Saltwater algae
Temperature, °F (°C) 752 (400) 752 (400)
Pressure, psia ~1515 ~1515
Liquid hourly space velocity, h-1 0.20 0.20
H2 consumption, wt H2/wt biocrude 0.047 0.041
Hydrotreated oil yield, g/g dry biocrude 0.81 0.87
Gas yield, g/g dry biocrude 0.10 0.07
C wt% in hydrotreated oil 86 86
Hydrocracking operating conditions
Freshwater algae Saltwater algae
Temperature, °F (°C) 752 (400) 752 (400)
Pressure, psia ~1000 ~1000
Liquid hourly space velocity, h-1 > 0.5 > 0.5
Hydrotreated Oil Distributions
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0%
10%
20%
30%
40%
50%
60%
70%
80%
Freshwater algae Saltwater algae
wt%
in h
ydro
trea
ted
oil
Hydrotreated oil distribution based on boiling point ranges
Naphtha Diesel Heavies
