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
Whole Algae HTL and Upgrading Overview
Growth,Harvest
Dewater
20%
Solids
HTL
Oil
Upgrading
Aqueous
Water &
nutrient
recycle
CHG
Gas
Naphtha
Diesel
H2
H2 Gen
NG
  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
2
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
Saltwater algae
Freshwater algae
Nitrogen
10.7%
Oxygen
26.5%
Hydrogen
7.4%
 
 
 
Nitrogen
6.4%
Sulfur
0.7%
Carbon
54.7%
Oxygen
35.3%
Sulfur
2.0%
Carbon
49.4%
Hydrogen
6.9%
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)
4
Oil Yields, ton/ton AFDW
Algae
Oil Products Yields
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
HTL Bio-crude
Hydrotreated oil
Diesel
Naphtha
Freshwater algae
Saltwater algae
Freshwater algae
Saltwater algae
Diesel production, million gallon gasoline
equivalent (GGE)/yr
26
37
Byproduct (naphtha) production, million GGE/yr
16
11
Final product yields
5
Carbon and Energy Efficiencies
70%
Diesel and naphtha /
Algae only
Overall carbon
efficiency
70%
Energy Efficiency, %
Carbon Efficiency, %
60%
80%
50%
40%
30%
20%
60%
Diesel + Naphtha /
algae only
Overall energy
efficiency
50%
40%
30%
20%
10%
10%
0%
0%
Freshwater algae
Saltwater algae
Freshwater algae
Saltwater algae
6
Cost Contributions for Algae HTL and Upgrading
25.0
Diesel Selling Price ($/GGE)
Feedstock
HTL Oil Production
20.0
CHG Water Treatment
Bio-crude Upgrading
15.0
Balance of Plant
Naphtha Credit
10.0
5.0
Conversion cost only
0.0
Freshwater algae: $4.4/GGE
(not including naphtha credit):
Saltwater algae: $3.3/GGE
-5.0
$21.3/GGE
Freshwater algae
$15.6/GGE
Saltwater algae
7
Sensitivity Analysis – Saltwater Algae Case
Feedstock Cost, $/AFDW ton (430: 1100 : 2000)
Fuel Yield (+10% : base : -20%)
Internal Rate of Return, IRR (0% : 10% : 20%)
No CHG - Recycle Untreated HTL Aqueous
Plant Scale Dry Feedstock, ton/d (2500: 1340 : 500)
Total Project Investment (-10% : base : +40%)
HTL Capital (-40% : base : +40%)
CHG Capital Cost (-40% : base : +40%)
Project Contingency (0% : 10% : 20%)
Naphtha Value, $/gallon ($3.75 : $3.25 : $1.50)
CHG Catalyst Life, yrs (2 : 1 : 0.5)
CHG Catalyst Cost $/lb (30 : 60 : 120)
Upgrading Capital (-40% : base : +40%)
Hydrotreating Catalyst Life, years (5 : 2 : 1)
-$10.0
-$5.0
$0.0
$5.0
$10.0
$15.0
Cost Change from Baseline Case, $/GGE
8
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
9
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)
12
Additional Slides
  Methodology
  Major assumptions
13
Methodology
Whole wet algae
Operating
Conditions
Conversion Yields
Base cost of
equipment
Cost parameters
Algae & chemical
price
Conversion
efficiency,
Process
Product Yields
model
(gasoline &
Mass and energy
balance information diesel), etc.
Cost
Analysis
Minimum Fuel
Selling Price
(MFSP)
$
gge
14
Major Assumptions for HTL Process
HTL operating conditions
Freshwater algae
Saltwater algae
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
Temperature, °F (°C)
15
Major Assumptions for Upgrading Process
Hydrotreating operating
conditions
Freshwater algae
Saltwater algae
752 (400)
752 (400)
~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
86
86
Freshwater algae
Saltwater algae
752 (400)
752 (400)
Pressure, psia
~1000
~1000
Liquid hourly space velocity, h-1
> 0.5
> 0.5
Temperature, °F (°C)
Pressure, psia
C wt% in hydrotreated oil
Hydrocracking operating
conditions
Temperature, °F (°C)
16
Hydrotreated Oil Distributions
80%
wt% in hydrotreated oil
70%
60%
50%
40%
Naphtha
Diesel
30%
Heavies
20%
10%
0%
Freshwater algae
Saltwater algae
Hydrotreated oil distribution based on boiling point ranges
17