Kevin Harrison* 

Robert Remick*

Aaron Hoskin 

Gregory Martin*

World Hydrogen Energy 

Conference

Essen, Germany

May 19, 2010

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/PR-560-48269

Hydrogen Production: 

Fundamentals and Case 

Study Summaries 
20% Wind by 2030 Scenario

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2000 2006 2012 2018 2024 2030

Cumulative Installed Capacity (GW)

Offshore

Land-based

2010

As of December 31, 2009 - 34,863 MW of wind power 

have been installed across the United States. 











Challenges to 20%

• Growth in installations 

– 8 GW installed in 2008

– 9 GW installed in 2009

– Total 34 GW 2009 

• 50 GW offshore

– Cape Wind approved

– 130 wind turbines

– 420 MW

• Performance is critical

– Gearbox reliability

– Capital cost

– Capacity Factor

– O&M
Competitive Energy Storage 

Technologies

Source: Energy Storage Association
Solar Energy

Heat

Hydrogen

Thermolysis

Mechanical Energy

Electricity

Electrolysis

Biomass

ThermoChemical & 

Biological 

Conversion

Photolysis

Sustainable Paths to Hydrogen
Sustainable Hydrogen Potential

Wind Biomass

Solar
• Examine benefit to utility by time shifting wind and PV 

energy with hydrogen production

• Research optimal wind/hydrogen through systems 

engineering and power electronics integration

• Characterize and control wind turbine/PV and H2-

producing stack

• Evaluate synergies from co-production of electricity 

and hydrogen

NREL/Xcel Energy 

Wind to Hydrogen - Objectives
New Wind2H2 Configuration
PV Configuration Testing

Direct connect versus various input voltages 

(Ein) through power controller

85% -

92%

100%
Round I - PV Powered Electrolysis

• Onboard power electronics account for 15 – 30% of the 

overall electrolyzer system cost 

• The data illustrates improvement in energy capture to stack 

when using MPPT power electronics

• Testing showed a 10% – 20% increase in energy capture 

depending on input voltage to power electronics

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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

Stack Power [W]

E-130 connected 

through MPPT 

power electronics

E-120 direct Direct connect connect to PV 

MPPT power 

electronics
PV-to-Stack Optimization

• Installed 10-cell stack in 

series with existing 20-

cell stack to better align 

PV and stack operating 

points

• Improved PV-to-stack 

sizing enabled 2nd phase 

direct coupling versus 

MPPT power electronics
Impact of Shifting Operating Point

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Voltage (V)

Current (A)

PV Array IV 

20-cell stack Relocated with 10 

additional cells

PV array maximum 

power point
Solar Irradiance

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4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00

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Irradiance [W/m^2]

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Stack Power [W]

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Irradiance [W/m^2]

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Stack Power [W]

Electrolyzer 

Fault

Performed IV 

sweeps of PV 

array

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Irradiance [W/m^2]

% Time

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Irradiance [W/m^2]

% Time
Direct Coupling v. Power Electronics 

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Irradiance [W/m^2]

Ratio Stack Power/Irradiance

Power Electronics 

with MPPT Direct Coupling
General Electrolyzer System Data

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0.020

0.040

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Stack Current [A]

Hydrogen Flow [kg\h]

Although stack efficiency is higher at 

lower current the hydrogen flow (thus 

system efficiency) is zero at currents 

below 15 A

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Stack Current [A]

Stack Efficiency [%]

Electrolyzer consumes hydrogen to 

maintain the desiccant drying system

New techniques and incremental 

improvements in drying systems will 

improve system efficiency

Higher pressure electrolyzers will 

dissolve more hydrogen that is also 

wasted
350 bar Vehicle Fueling System

New System Components

• Storage tank, compressor and 

dispenser

– 18 kg @ 6000 psi

– 120 kg @ 3500 psi

• June 2010

– Additional 6000 psi storage

– Cascade filling

– Total 250 kg (including 3500 psi tanks)

• 9 months of refueling A-Class 

Mercedes (~2 kg, 110 miles)

• Proterra Fuel Cell Bus 

– March 2010, 20 kg

• Yesterday, Ford H2 ICE shuttle leased 

by NREL
Integrated Renewable Energy System

Integrated Systems

• 5 kW fuel cell (PEM)

• 5 kW to 10 kW PV array

• 10 kW wind turbine

TEST: Dynamic response (both 

DC and AC) of fuel cell with 

both PV and wind systems

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4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:0

Time of Day

Irradiance [W/m^2]

7.25 kWh / m2

1 minute → Increase 536 W/m2

→ Decrease 518 W/m2

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11:00 12:00 13:00

Time of Day

Irradiance [W/m^2]
Variable Stack Current Testing

Comparison Testing

PEM: 3-stack design with

Individual power supplies

Alkaline: New stack installation

Test: Long duration testing of 

stacks with highly variable 

(wind profile) current
WIND ENERGY & HYDROGEN 

INTEGRATION

International Energy Agency, Hydrogen 

Implementing Agreement, Annex 24

To explore in detail all possible issues 

(technical, economical, social, 

environmental, market and legal) related to 

hydrogen production using electrolysis with 

wind energy. 
National Renewable Energy Laboratory Innovation for Our Energy Future

Recent Publications

Technical Report

NREL/TP-581-44082

April 2009

Technical Report

NREL/TP-TP-550-44103

December 2008

http://www.nrel.gov/hydrogen/proj_wind_hydrogen.html
Thank you for your attention!

Questions?