NREL Wind to Hydrogen Project: Renewable Hydrogen Production
for Energy Storage & Transportation
NRELHydrogen Technologies and Systems Center
Todd Ramsden,Kevin Harrison, Darlene Steward
November 16, 2009NREL/PR-560-47432
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.
NREL Wind2H2 RD&D Project
• The National Renewable Energy Laboratory in partnership with Xcel Energy and DOE has designed, operates, and continues to perform testing on the wind-to-hydrogen (Wind2H2) project at the National Wind Technology Center in Boulder
• The Wind2H2 project integrates wind turbines, PV arrays and electrolyzers to produce from renewable energy
National Renewable Energy Laboratory 2 Innovation for Our Energy Future
Sustainable Paths to Hydrogen
Solar Energy
Heat
Hydrogen
Thermolysis
Mechanical Energy
Electricity
Electrolysis
Biomass
Thermo-Chemical & Biological
ConversionPhotolysis
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Hydrogen Potential from Sustainable Resources
Wind Biomass
Solar
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20% Wind Energy by 2030 Scenario
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ulat
ive
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alle
d C
apac
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W) Offshore
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2008
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How Much Wind is Available in the U.S.?
- 200 400 600 800 1,0000
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Quantity Available, GW
Leve
lized
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t of E
nerg
y, $
/MW
h
Onshore
Class 6
Class 4
Class 7
Class 5
Class 3
Offshore
Class 6
Class 4
Class 7
Class 5
Class 3
10% of Existing Transmission Capacity Available to Wind
2010 Costs w/o PTC, $1,600/MW-mile, w/o Integration costs Source: Black & Veatch/NREL
20% Goal
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Technology Challenges to Meet 20% Goal
• Massive growth in installations – 8 GW installed in 2008– ~29 GW total as of 2009 – Over 300GW by 2030
• Widely distributed across the nation– Many high wind sites– Substantial installation in
moderate resource areas– Some offshore is needed
• Performance is critical– Capital cost– Capacity Factor– O&M
• Every 1 ¢/kWh of cost reduction saves the nation over $10 billion per year at 20% penetration
National Renewable Energy Laboratory 7 Innovation for Our Energy Future
Wind2H2 Project – Overall Goal
• Provide RD&D to help DOE achieve it cost target for hydrogen production from wind-based water electrolysis of $4.80/gge by 2012 and to <$3.00/gge by 2017
Challenges• Reduce capital costs of electrolysis
system through improved designs and lower cost materials
• Develop low-cost hydrogen production from electrolysis through integration with renewable electricity sources
• Develop strategies for low cost hydrogen production from electrolysis through utility coordination
National Renewable Energy Laboratory 8 Innovation for Our Energy Future
Wind2H2 Project – Main Objectives
• Research the cost and capability of “time shifting” wind and PV energy through utility-scale hydrogen-based energy storage
• Research optimal wind/hydrogen through systems engineering
• Characterize and control wind turbine/PV and H2-producing stack
• Evaluate synergies from co-production of electricity and hydrogen
• Compare response and performance of alkaline and PEM electrolyzer technologies
• Realize efficiency gains though simplified and integrated power controllers
• Working towards ‘ideal’ wind to hydrogen – Simplifying PE, common controls, closely
coupling wind input to stack, electricity regulation
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Wind2H2 System Operating Modes
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PV Configuration Testing
Direct connect versus various input voltages (Ein) through power controller
65% -90%
100%
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PV Powered Electrolysis
• Onboard power electronics account for 15 to 30% of the overall electrolyzer system cost
• Minimize redundant components• Test data illustrates improvement in energy capture
to stack when using MPPT power electronics• Testing showed a 10% – 20% increase in energy
capture
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9:18 9:38 9:59 10:19 10:39 10:59 11:19 11:39 11:59
Time of Day
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k Po
wer [
W]
E-130 connected through MPPT
power electronics
E-120 direct connect to PV
Direct connect
MPPT power electronics
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10kW Wind Turbine Powered Electrolysis
• Initial tests with third generation power electronics, wind speed measurement and control algorithm indicate further improved energy capture of wind electricity into hydrogen production
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er (W
atts
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Gen 2 – DC Power Gen 1 – DC Power
Planned increased energy capture from
Gen 2 to Gen 3
Increased energy capture from Gen 1
to Gen 2
Available wind power= Preliminary results
showing increased energy capture with new TSR algorithm. Algorithm is currently being tuned for stability.
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100kW Wind Turbine Powered Electrolysis
• Instrumented power signal from 100 kW wind turbine to drive 33 kW alkaline stack current to follow power available from turbine
020406080
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urre
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roge
n Fl
ow [N
m^3
Stack Current [A]H2 Flow [Nm^3/hr]
Grid AC
Power Data
Varying Stack Current
100 kWWind
Turbine
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Electrolyzer System Efficiency
• Wind2H2 system used to assess electrolyzer performance • Stack and system efficiency of alkaline (33 kW stack, 40 kW system)
and PEM-based (6 kW stack, 7 kW system) measured
Efficiency PEM Electrolyzer Alkaline Electrolyzer
LHV HHV LHV HHV
Stack Efficiency
Low Current 80% (5A) 95% (5A) 78% (30A) 92% (30A)
Rated Current 63% (135A) 75% (135A) 59% (220A) 70% (220A)
System Efficiency
Low Current 0% (15A) 0% (15A) 0% (35A) 0% (35A)
Rated Current 49% (135A) 57% (135A) 35% (220A) 41% (220A)
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Cost Analysis
• Cost analysis performed based on NREL’s power electronics optimization and testing and on our electrolyzer cost analysis study
• Large centralized system capable of 50,000 kg per day production
• Optimized power conversion system due to a closer coupling of the wind turbine to the electrolyzer stack can reduce the total cost of hydrogen by 7%.
Capital Component (uninstalled) Baseline System
Optimized System
1.5 MW Wind Turbine
Rotor $248,000 $248,000
Drive Train $1,280,000 $1,180,000
including power electronics $100,000 $0
Control System $10,000 $10,000
Tower $184,000 $184,000
Balance of Station $262,000 $262,000
2.33 MW Electrolyzer $1,570,000 $1,350,000
including power electronics $220,000 $0
New Power Electronics Interface $0 $70,000
Resulting Hydrogen Cost ($/kg) $6.25 $5.83
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350 bar Vehicle Fueling System
• Outdoor rated compressor• 400 bar tank (18 kg)• 350 bar non-communication fill
dispenser• 1.8 kg (110 mile range) Mercedes-
Benz FC vehicle
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Key Findings from Wind2H2 RD&D
System Efficiency (HHV): At rated stack current…– The PEM electrolyzer system efficiency of 57% – The alkaline system had a system efficiency of 41%
• H2 production about 20% lower than the manufacturer’s rated flow rate• 50% system efficiency would be realized if rated flow were achieved
Cost Reductions from Power Electronics Optimization:– Analysis showed a potential 7% reduction in cost per kg of
hydrogen based on capital cost improvement• Projected cost of hydrogen falling to $5.83/kg from a baseline of
$6.25/kg
Energy Transfer Improvements: PV configuration testing compared direct-connection to the electrolyzer stack with a connection through power electronics– The MPPT power electronics system captured between 10% and
20% more energy than the direct-connect configuration
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Hydrogen-Based Energy Storage Cost Analysis
Project Objective:• Evaluate the economic viability of the use of hydrogen for
medium- to large-scale energy storage applications in comparison with other electricity storage technologies
Project Background:• FY2009 study builds upon and expands on an initial scoping
study of hydrogen-based energy storage conducted in FY2008• Benchmarking against competing technologies (batteries,
pumped hydro, CAES)• Expanded analysis of PEM fuel cells and hydrogen combustion
turbine• Analysis of production of excess hydrogen for vehicles• Preliminary analysis of environmental impactsNational Renewable Energy Laboratory 19 Innovation for Our Energy Future
Energy Storage Scenario
Nominal storage volume is 300 MWh (50 MW, 6 hours)– Electricity is produced from the storage system during 6 peak hours
(1 to 7 pm) on weekdays– Electricity is purchased during off peak hours to charge the system
Electricity source: excess wind / off peak grid electricity – Assumed steady and unlimited supply during off peak hours (18 hours
on weekdays and 24 hours on weekends)– Assumed fixed purchase price of 3.8¢/kWh with sensitivities run at
2.5¢/kWh and 6¢/kWhNational Renewable Energy Laboratory 20 Innovation for Our Energy Future
Analysis Framework
Major Assumptions• No taxes or transmission charges are included in the analysis• The supply of off peak and/or renewable electricity is unlimited• Costs are presented in $2008Timeframes• High cost or “current” technology • Mid range cost
– Some installations exist – Some cost reductions for bulk manufacturing and system integration have
been realized– Installations are assumed in the near future; 3 to 5 years.
• Low range cost – Estimates for fully mature technologies and facility experience
Cost analysis performed using the HOMER model– Results are presented as levelized cost of energy; $/kWh or $/kg for hydrogen
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Energy Storage Study Findings
0.0
20.0
40.0
60.0
80.0
100.0
120.0
FC/ abo
vegro
und
FC/ geo
logic
Hydrog
en ex
pans
ion/co
mbusti
on tu
rbine
NiCd batt
ery
NaS ba
ttery
Vanad
ium re
dox b
attery
Pumpe
d hyd
roCAESLe
veliz
ed c
ost o
f out
put e
lect
ricity
(¢/K
Wh)
28 24 19
83
25 28
13 10
Comparison of hydrogen and competing technologiesNational Renewable Energy Laboratory 22 Innovation for Our Energy Future
Analysis Results - Hydrogen
Hydrogen fuel cell with geologic storage
0.14 0.18 0.22 0.26 0.3 0.34 0.38 0.42 0.46 0.5 0.54 0.58
Electrolyzer capital cost
Geologic storage capital cost
Fixed O&M
Electrolyzer efficiency
Fuel cell capital cost
Electricity price
HIGH-COST CASE
Electrolyzer capital cost
Geologic storage capital cost
Fixed O&M
Electrolyzer efficiency
Fuel cell capital cost
Electricity price
MID-RANGE CASE
Electrolyzer capital cost
Geologic storage capital cost
Fixed O&M
Electrolyzer efficiency
Fuel cell capital cost
Electricity price
LOW-COST CASE
Cost of Energy ($/kWh)
$0.24
$0.50
$0.18
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Analysis Results - Hydrogen
Hydrogen gas turbine with geologic storage
0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.3 0.32 0.34
Steel Tank capital cost
Fixed O&M
Electrolyzer capital cost
Combustion Turbine capital cost
Electrolyzer efficiency
Electricity price
HIGH-COST CASE
Geologic Storage capital cost
Fixed O&M
Electrolyzer capital cost
Combustion Turbine capital cost
Electrolyzer efficiency
Electricity price
MID-RANGE CASE
Geologic Storage capital cost
Fixed O&M
Electrolyzer capital cost
Combustion Turbine capital cost
Electrolyzer efficiency
Electricity price
LOW-COST CASE
Cost of Energy ($/kWh)
$0.17
$0.19
$0.26
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Recent Publications
Technical ReportNREL/TP-581-44082April 2009
Technical ReportNREL/TP-TP-550-44103December 2008
http://www.nrel.gov/hydrogen/proj_wind_hydrogen.html
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Acknowledgments
Xcel Energy– Frank Novachek– Vicki McCarl– Brad Hollenbaugh
DOE– Roxanne Garland– Richard Farmer– Monterey Gardiner
Contractors– John Cornish (EPC)– Marc Mann (Spectrum)
NREL– Kevin Harrison– Greg Martin– Keith Wipke– George Sverdrup– Robert Remick– Genevieve Saur– Bill Kramer– Ben Kroposki– Mike Stewart
National Renewable Energy Laboratory 26 Innovation for Our Energy Future