MW-Scale PEM-Based Electrolyzers for
RES Applications
Cooperative Research and Development Final
Report
CRADA Number: CRD-18-00742
NREL Technical Contact: Kevin Harrison
NREL is a national laboratory of the U.S. Department of Energy Technical Report
Office of Energy Efficiency & Renewable Energy NREL/TP-5B00-79055
Operated by the Alliance for Sustainable Energy, LLC February 2021
This report is available at no cost from the National Renewable Energy
Laboratory (NREL) at www.nrel.gov/publications.
Contract No. DE-AC36-08GO28308
MW-Scale PEM-Based Electrolyzers for
RES Applications
Cooperative Research and Development Final
Report
CRADA Number: CRD-18-00742
NREL Technical Contact: Kevin Harrison
Suggested Citation
Harrison, Kevin. 2021. MW-Scale PEM-Based Electrolyzers for RES Applications:
Cooperative Research and Development Final Report, CRADA Number CRD-18-00742.
Golden, CO: National Renewable Energy Laboratory. NREL/TP-5B00-79055.
https://www.nrel.gov/docs/fy20osti/79055.pdf.
NREL is a national laboratory of the U.S. Department of Energy Technical Report
Office of Energy Efficiency & Renewable Energy NREL/TP-5B00-79055
Operated by the Alliance for Sustainable Energy, LLC February 2021
This report is available at no cost from the National Renewable Energy National Renewable Energy Laboratory
Laboratory (NREL) at www.nrel.gov/publications. 15013 Denver West Parkway
Golden, CO 80401
Contract No. DE-AC36-08GO28308 303-275-3000 • www.nrel.gov
NOTICE
This work was authored [in part] by the National Renewable Energy Laboratory, operated by Alliance for Sustainable
Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding
provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Hydrogen and Fuel Cell
Technologies Office. The views expressed herein do not necessarily represent the views of the DOE or the U.S.
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Cooperative Research and Development Final Report
Report Date: January 27, 2021
In accordance with requirements set forth in the terms of the CRADA agreement, this document
is the final CRADA report, including a list of subject inventions, to be forwarded to the DOE
Office of Scientific and Technical Information as part of the commitment to the public to
demonstrate results of federally funded research.
Parties to the Agreement: Giner ELX (Acquired by PlugPower in 2020)
CRADA Number: CRD-18-00742
CRADA Title: MW-Scale PEM-Based Electrolyzers for RES Applications
Responsible Technical Contact at Alliance/NREL:
Kevin Harrison | Kevin.Harrison@nrel.gov
Name and Email Address of POC at Company:
Monjid Hamdan | MHamdan@plugpower.com
Sponsoring DOE Program Office(s):
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Hydrogen and Fuel Cell
Technologies
Joint Work Statement Funding Table Showing DOE Commitment:
NREL
Estimated Costs Totals
Shared Resources
Year 1 $30,000.00 $30,000.00
TOTALS $30,000.00 $30,000.00
Executive Summary of CRADA Work:
Many nations are rapidly increasing electrical generation capacity from renewable energy
sources (RES) such as wind and solar. The wide penetration of RES requires an energy storage
solution which has come in the form of hydrogen generated via polymer exchange membrane
(PEM) electrolysis. A study of the current state-of-the-art PEM electrolysis indicates that the
largest PEM-based stacks range from 150 – 250kW and that a significant scale-up of the
technology is required to accommodate multi-Megawatt (MW) energy storage solutions in large-
scale RES applications.
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.
Summary of Research Results:
Statement of Work
To address critical aspects for the successful commercialization of Giner ELX’s MW PEM-based
electrolyzer stacks, three (3) tasks will be performed.
Task 1 the active area of the electrolyzer stack will be scaled-up from 290 centimeters squared
(cm2) (150 kW platform) to 1,250 cm2 (1 MW platform). In this task Giner ELX will assemble a
multi-cell stack based on their 1 MW stack platform having an active area of 1,250 cm2. The
number of cells will be determined based on the power capabilities at NREL's Energy Systems
Integration Facility (ESIF) test site. Future scale-up of the 1 MW stack technology to an active
area of 3,000 cm2 (5 MW platform) or greater is feasible.
Results: Task 1 was completed by Giner ELX when the (nominally) 225 kW electrolyzer stack
was delivered to NREL in July 2018. The PEM electrolyzer stack has the following capabilities;
• Cell Active Area: 1,250 cm2
• Stack contains 29 cells, but scalable to 100’s depending on hydrogen production required
• Operating Pressure: 40 bar, differential mode
• Operating Temperature: 70°C
• Nominal Operating Current: 3,750A (Current density 3A/cm2)
• Support stand includes fork-lift access for ease of movement
• CE compliant
Figure 1. 29-cell Allagash electrolyzer stack designed and built by Giner ELX prior to shipment to
NREL in July 2018
Task 2 includes integration, and operational testing, of the MW-stack platform at NREL’s ESIF
facility. The stack will be operated cyclically between a current density of 0 to 3,000 milliampere
(mA) mA/cm² over a 5,000-hour period. During operation, NREL will monitor individual cell
voltage, cross-cell leakage (percentage of hydrogen (H2) in oxygen (O2), and collect fluoride
samples. The fluoride samples will be delivered to Giner ELX and analyzed to determine
membrane/stack lifetimes.
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.
Results: This task was completed by NREL staff when the stack was installed, commissioned
and operated to over 4,900 hours. The initial 5,000 hour goal was not fully achieved by the time
this CRADA expired, but the lower goal was agreed by email from Monjid Hamdan on
September 23, 2019 – well before the CRADA end date in January 2020.
To accomplish this task staff at the Energy Systems Integration Facility (ESIF) completed the
following;
• Modified NREL’s electrolyzer stack test bed to accommodate ‘Allagash’ MW-platform
stack
• Installed sensors, power cables, pressure regulator, pumps, etc.
• Purchased and installed 2 new (4 total) 250 kW power supplies (AC/DC) to enable stack
currents up to 4,000A
o In current sharing mode, all 4 power supplies will provide the required current
(3,750A)
• Test stand is now capable of power up to a 1 MW PEM electrolyzer stack (250V, 4000A)
• Stack integrated into testbed and all alarms points verified prior to operations
which started in August of 2019 – 1 month after delivery
• A new stainless-steel water tank was designed and installed into the system in August
2019 – replacing the polypropylene tank installed in 2013
• A new cell voltage monitoring system was developed and all cell voltages stable and
within range
• As of September 2019, over 2,000 hours was achieved under attended mode of operation
and on track to complete operations by end of January 2020
• Completed over 4,900 hours of stack operations, including a significant portion of
hours under un-attended status, by the completion of the CRADA in January 2020
Figure 2. 29-cell Allagash electrolyzer stack fully installed and ready for operations at NREL's
ESIF in August 2018
Task 3 Data analysis will be conducted by Giner ELX and NREL to evaluate performance
(efficiency, durability, lifetime) of the stack. This includes the effect of the additive on voltage
performance and on the stability of the additive during extended operation (5,000 hours) at
current densities of 3,000 mA/cm2. Voltage performance data will also be used to determine the
effect on cell components and catalyst utilized in the MW stack platform.
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.
A final report will be prepared as part of Task 3. The final report from Giner ELX and NREL
will include a summary of the operational conditions, voltage-current curves as a function of
temperature and pressure, fluoride release data, time-series of the stack voltage and
histogram/summary tables of hours of stack current levels, cathode pressures and stack
temperatures over the 5,000 hours of operation. This operational data will be used to calculate
stack voltage efficiency, stack decay rate and predict lifetime based on stack current, fluoride
release rates, average stack temperature and anode/cathode pressures.
Results: The results from water sampling to obtain the fluoride release rate, cell voltage, cell
decay rate and the amount of hydrogen crossing over to the oxygen side of the stack are
presented here. In addition, a representative polarization scan is provided below showing a very
small variance on all cells of 30mV with the exception of cells 1 and 29, which were measured
on the current collectors and not representative of the actual cell voltage.
• Fluoride Release Rate measured: < 6 ppb (3 samples; control 5, 10, and 15 ppb)
o These results were obtained using water samples from the electrolyzer system and
sent out to a laboratory that analyzed for fluoride
• Low Voltage Degradation rate: < 1.5 uV per cell – hour after 8,500 hours and <1 µV
per cell - hr over 10,000 hour period of 7-cell operation at Giner ELX
• %H2 in O2: <10% LFL (Water from pressurized H2 phase separator drains into H2O/O2
reservoir
o These H2-in-O2 results were obtained from a combustible gas detector
continuously analyzing the presence of hydrogen in a slipstream of oxygen gas
being vented from the large de-ionized water tank that acts a gas/water phase
separator.
Figure 3. Polarization (voltage-current) scan showing < 2 V per cell in the shaded circle at
maximum current density of 3A/cm2
Figure 3 highlighting the PEM stack voltage of 58.1 V (< 2 V per cell) at full stack current
3,750A while holding cathode pressure at 40 bar and average stack temperature of 70°C.
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.
Figure 4. Snapshot of cell voltages at 3,750A with high anode water flow showing the shaded cells
running cooler (t = 300 hours).
Cell 29
Cell 1
Figure 5. Approximately 30mV variance of cell voltages at 3A/cm 2 with exception of end cells (1
and 29) being measured on the current collectors during a polarization scan
Error! Reference source not found. is a graph of all 29 cell voltages versus time during a
polarization scan. Excluding cells 1 and 29, due to their sense location on the large plates where
power wiring is connected (i.e., the current collectors), shows a very tight distribution of cell
voltages being less than 30 mV at full current density of 3A/cm2.
Summary Conclusion:
This is the final report required in Task 3 with details of the work described in Tasks 1 – 3.
Under this CRADA Giner ELX designed, built and delivered a 29-cell electrolyzer stack to
NREL in July 2018. NREL completed upgrades to the balance of plant and installed the 225 kW
electrolyzer stack in August 2018. Roughly 2,000 hours of attended operation were accumulated
within the next year before NREL was able to receive approval to run unattended 24/7. Over
4,900 hours of operation were completed by the CRADA end date in January 2020.
During this time water samples were captured at NREL, shipped to Giner ELX where an outside
lab performed analysis for fluoride that provides insight into how much the cells are degrading
over time. Electrolyzer stack test bed was continuously monitored for water flow, cathode
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.
pressure, average stack temperature and hydrogen cross-over to the anode side of the stack.
Periodically, NREL performed polarization scans, while maintaining cathode pressure and stack
temperature, where stack current was varied from roughly 375A up to 3,750A while monitoring
stack and cell voltages. The polarization scans, also called voltage-current scans, provide further
insight on how cell/stack voltages are performing over the full range of stack power.
Subject Inventions Listing:
None
ROI #:
None
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