Novel modular stack design for high PREssure PEM

water elecTrolyZer tEchnoLogy with wide operation range and reduced cost (PRETZEL)

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Green hydrogen produced

by electrolysis might become a key energy carrier for the implementation of renewable energy as a cross-sectional connection between the energy sector, industry and mobility. Proton exchange membrane (PEM) electrolysis is the preferred technology for this purpose, yet large facilities can hardly achieve FCH-JU key performance indicators (KPI) in terms of cost, efficiency, lifetime and operability. Consequently, a game changer in the technology is necessary.

PRETZEL has been nominated for FCH JU award!

PROJECT

Innovation

The overall goal of PRETZEL is to develop an innovative polymer electrolyte membrane electrolyzer (PEMEL) that provides significant increases in efficiency and operability to satisfy emerging market demands.

Such electrolyzers are urgently needed in the context of the increased demands of the grid balancing market. PRETZEL is offering a break-through in becoming game changers in the field of water electrolyzers.

Pretzel

The project PRETZEL will innovate in the following areas:

INNOVATIONSTARGETS
Reduction of precious metalsIncreases availability, decreases CAPEX
Production of optimized current collectors with low cost coatings that will allow operation at high current densitiesIncrease of efficiency and reduction of operative costs; reduction of bipolar plates (BPP) production costs while taking over the water distribution; increasing the power density without mass transport limitation
Corrosion resistant (BPP) without flow fieldReduction of Ti and reduction of manufacturing costs
High pressure operation > 100 barReduction of compressor costs, increase of system efficiency
Innovative hydraulic concept for pressurizing and coolingIncreases life time and efficiency; enables high current density; enables durable large active area cells

The project PRETZEL

Concept and approach

Schematic drawing of a PEMEL system as container solution by iGas energy.

Recent developments in the field of polymer electrolyte membrane electrolyzers (PEMEL) strive towards the reduction of overall system costs in order to compete with state of the art alkaline electrolysis. Major optimization aspects refer to an increase in efficiency as well as the achievement of high-pressure electrolysis. Both issues concern the PEMEL stack, which needs to generate hydrogen with high production rates (high current density) at a reasonable cell voltage (efficiency) and high output pressure so that raw material deployment can be reduced (e.g. noble metals, proton conductive polymers and titanium) and balance of plant components can be omitted (especially, compressor stages).

 

Concept of PRETZEL project with component inputs and expected outcome.

Furthermore, the stack components such as the membrane electrode assemblies (MEA), the porous current distributor (PCD) and the bipolar plates (BPP) must be mass produced and designed with cost saving measures in mind in order to improve efficiency in use of expensive raw materials.

This concept addresses the above aspects to realize the next generation electrolyzer technology, whilst meeting the needs of industrial scale hydrogen production in the near future. Beyond these challenges, a significant increase of lifetime and improved operability will be achieved to cope with intermittent electricity supply from renewable energy sources.

This approach is encapsulated in the full title of the project: “Novel modular stack design for high PREssure PEM water elecTrolyZer tEchnoLogy’’ with wide operation range and reduced cost. This is shorted to the acronym: ‘’PRETZEL

Each of these innovations have already proven in a small laboratory scale and can be considered being in the range of TRL 3. Hence, the overall goal of this project is to prove the functionality of these proven technologies in a realistic environment in order to advance them to TRL 5. In practice, this means integrating them into a fully functioning 25 kW, 100 bar electrolyzer system that reflects the realistic and highly dynamic conditions required by the market.

Innovation

The overall goal of PRETZEL is to develop an innovative polymer electrolyte membrane electrolyzer (PEMEL) that provides significant increases in efficiency and operability to satisfy emerging market demands. Such electrolyzers are urgently needed in the context of the increased demands of the grid balancing market. PRETZEL is offering a break-through in becoming game changers in the field of water electrolyzers.

The project PRETZEL will innovate in the following areas:

InnovationsTargets
Reduction of precious metalsIncreases availability, decreases CAPEX
Production of optimized current collectors with low cost coatings that will allow operation at high current densitiesIncrease of efficiency and reduction of operative costs; reduction of bipolar plates (BPP) production costs while taking over the water distribution; increasing the power density without mass transport limitation
Corrosion resistant (BPP) without flow fieldReduction of Ti and reduction of manufacturing costs
High pressure operation > 100 barReduction of compressor costs, increase of system efficiency
Innovative hydraulic concept for pressurizing and coolingIncreases life time and efficiency; enables high current density; enables durable large active area cells

 

 

Objectives

The project PRETZEL has the following objectives:

  1. Develop and manufacture high pressure polymer electrolyte membrane electrolyzer (PEMEL) to operate at increased temperatures.
  2. Develop and manufacture the high pressure PEMEL stack based on the novel principle of hydraulic compression.
  3. Set-up and undertake continuous procedures to evaluate the development process through all phases against PRETZEL specifications.
  4. Integrate the innovative PEMEL stack into a high pressure PEMEL test facility and validate the overall performance and operational criteria.
  5. Disseminate and exploit the innovations in PRETZEL in order to prepare the market penetration of this new technology.

A central objective of this project is the development of a novel PEMEL system with a maximum 25 kW electrical power consumption that generates 4.5 mh-1 H2 at rated power, at an output pressure of 100 bar and feed water temperature of maximum 90 °C.

At the system level, the specific energy demand at rated production rate will be below 25 kWh kg-1 H2 and 70 % on the basis of higher heating value (HHV). Furthermore, this system will be able to operate in overload mode referring to a production rate as high as 6.8 mh-1 H2 (1.5 times overload). Rapid response of 1 second for a hot start and 10 seconds for a cold start are the operating targets of the system.

At the stack level, the project will implement a patented design approach based on hydraulic cell compression. This design allows for large planar cell components, which is required for future mass production, and effective cooling at very high production rates and temperature levels. Regarding sufficient stack conditioning, a cooling system will be developed for voltages of maximum 2.0 V per cell at rated power and of 2.3 V per cell in overload modus. Additionally, the target of PRETZEL is the development of a high pressure PEMEL stack, which opens a perspective for specific stack costs of below 500 € kW-1. As for the production at 100 bar, an additional compressor is omitted, for the targeted system specific systems costs are possible in the range of 750 € kW-1.

Facts and figures

General Information

  • PROJECT FULL NAME: Novel modular stack design for high PREssure PEM water elecTrolyZer tEchnoLogy with wide operation range and reduced cost
  • ACRONYM: PRETZEL
  • PROJECT REFERENCE: 779478
  • TOPIC: FCH-02-1-2017: Game changer Water Electrolysers
  • DURATION: 36 months
  • START DATE: January 1st 2018
  • END DATE: December 31st 2020
  • PROJECT FUNDING: € 1,999,088.75
  • COORDINATOR: Deutsches Zentrum für Luft – und Raumfahrt (DLR) (Germany)
  • PARTICIPATING ORGANIZATIONS: PRETZEL comprises a consortium of 9 partners from 5 European countries

Performance Targets

The main performance targets of the project PRETZEL are the development of a novel polymer electrolyte membrane electrolyzer (PEMEL) system with the following benefits:

  • High system efficiency by 70 %
  • H2 output pressure of 100 bar
  • Rapid response of below 1 second for a hot start and below 10 seconds for a cold start
  • Dynamic operation range between 4 and 6 A cm-2, ability for 1.5 times overload
  • Water temperature of 90°C
  • Higher than 2000 h operation

Work packages

Work package structure of PRETZEL project

The project PRETZEL is divided into the following seven work packages:

WORK PACKAGE 1 – Coordination

This work package is concerned with the general activity of coordination and steering of the activities in view of the time-schedule, project finances and the quality of the results.

WORK PACKAGE 2 – Definition of Specifications and Requirements

This work package will validate the component development tasks. Here the requirements and specifications on the new developed components such as catalysts, membrane electrode assembly (MEA), current collectors, macroporous layers (MPL), bipolar plates (BPP) and especially the design and tolerances will be defined. Also the measurement protocols will be determined and defined in collaboration with the existing standardization activities of the FCH JU and JRC.

This of course implies that WP 3 and 4 which will run in parallel in order to guarantee a deep communication between the component development of WP 3 followed by characterization and testing (WP 4).

WORK PACKAGE 3 – Component Manufacture

This work package is the heart of the project and the basis for reaching the FCH2 JU impacts in WP 5 and 6.

In collaboration between the Westfälische Hochschule, GKN Sinter Metals Filters GmbH (GKN) and the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), two approaches will be developed. These are the realizing sufficient and the totally dense coatings for the highly conductive, flexible and low cost bipolar plate. These approaches are necessary in order to prevent corrosion and potentially destructive pin holes.

Additionally, GKN and DLR are working on a new current collector approach, which combines the structural benefits of graded porous structures overtaking the mass transport and water distribution function from the bipolar plate. It also optimizes the performance at high current densities by applying MPL in contact to the electrodes. This development supports the gas removal at high gas production rates.

In a further collaboration, ARMINES and Soluciones Catalíticas IBERCAT S.L. are developing support materials and catalysts for improved activities, respectively. DLR will help to characterize those materials in terms of activity and stability. Those high performance materials will be used by ADAMANT in order to develop the electrodes used by the Centre for Research and Technology-Hellas (CERTH) producing the membrane electrode assembly.

WORK PACKAGE 4 – Compliance Testing and Characterization

This work package is responsible for the pre-qualification, characterization and testing of all developed and adjusted materials and components from Work Package 3. Universitatea Politehnica Timisoara (UPT), CERTH and DLR are responsible for electrochemical and physical characterization.

WORK PACKAGE 5 – High Pressure Stack

In this work package, the design of the cell frames developed in a currently running project at WHS will be adjusted to suit the cell components developed in Work Package 3. Major tasks will be the integration of the bipolar plates (BPPs) and the porous current distributors (PCDs) in combination with an adequate process media and hydraulic medium conduction. This is crucial in order to guarantee a homogeneous media transport through the single cells as well as a homogeneous temperature distribution. Therefore, the respective flow channels will be designed according to the specifications of the inner cell components (BPPs and PCDs).

Following the validation of the functionality of the component and cell design, a 25 kW stack will be constructed. This includes the modification of the existing high-pressure housing to fulfil the requirements concerning media and current conduction. The stack will be integrated into the test system at WHS.

WORK PACKAGE 6 – 25 kW System Integration

In this work package, the constructed stack from WP5 will be integrated in an existing test facility for test runs with the operating parameters. The system integration comprises, among other things, the elevated temperature and pressure. The engineering for this upgrade will be done by iGas Energy. Finally, long-term testing will provide information on the efficiency and cost reduction potential of the newly developed 25 kW high-pressure electrolysis system.

WORK PACKAGE 7 – Dissemination and Exploitation

This work package will disseminate the project progress and results so that non-participating organisations will be adequately informed of progress and recommendations arising from the work undertaken. This will be achieved in the following ways:

  • One internal scientific workshop open to participants and invited stakeholders
  • One public scientific workshop open to a wider community
  • Publication of the results in scientific journals
  • Quarterly project fact sheets
  • Internet website

Consortium

Our Partners

DLR w-hs Armines UPT Adamant Composites GKN CERTH IberCats Igas Energy

NEWS

Our Latest News

July 16, 2019 PDF

2019 Semiannual Meeting of PRETZEL project at Ibercat, Parque Científico of Madrid

On February 28th and March 1st 2019, project partner IBERCAT, located at the Parque Científico of Madrid (FPCM), hosted the latest official meeting of PRETZEL project.

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January 3, 2019 PDF

2018 Semiannual Meeting of PRETZEL Project at Universitatea Politehnica Timisoara (UPT)

On September 25th 2018, the Universitatea Politehnica Timișoara (UPT) hosted the official Semiannual meeting of PRETZEL project at the Faculty of Industrial Chemistry and Environmental Engineering.

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September 27, 2018 PDF

08/2018 D2.2 deliverable – Compliance test protocols and analytics

In August 2018, the PRETZEL consortium published the deliverable D2.2 entitled: Compliance test protocols and analytics.

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June 27, 2018 PDF

2018 Q1 newsletter – Successful Kickoff Meeting of the PRETZEL Project

In January 2018, the German Aerospace Center (DLR) hosted the official project start of the project entitled:

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CONTACT

German Aerospace Center Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)

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