Periodic Reporting for period 3 - NEXTAEC (MATERIALS FOR NEXT GENERATION ALKALINE ELECTROLYZER)
Reporting period: 2023-04-01 to 2024-03-31
The project NEXTAEC addresses a key technology in the green transition, electrolysis. Electrolysis is the dominating technology for conversion of electrical energy to chemical energy, i.e. fuels. In a future carbon neutral (or low emission) energy system based on renewable energy sources, a major part of the energy will be harvested from wind and sunshine and will be electrical. The intermittent nature of these sources calls for energy storage and chemical storage is the only realistic form at this scale. Moreover, some sectors, in particular parts of the transport sector, cannot be powered electrically and need fuel.
In the electrolysis process, water (H2O) is converted to hydrogen (H2) and oxygen (O2) by means of electrical energy. Hydrogen is a fuel and contains a major part of the original electrical energy as chemical energy. It can be stored or converted to other fuels, like hydrocarbons and alcohols.
There are three main types of electrolyzers (the device behind the process) each with its advantages and drawbacks, the alkaline electrolyzer (AEC), the PEM electrolyzer (PEMEC) and the solid oxide electrolyzer (SOEC). The AEC is the original state of art. It has been around for a century; it is robust and made from inexpensive materials, but it is bulky and needs much space. The PEMEC is much more compact and elegant with much higher production rates, but it suffers from high cost due to expensive materials including the scarce noble metal iridium. The SOEC is promising with the highest conversion efficiency of the three due to a very high working temperature, but large-scale devices are still under development. There will be a tremendous need for affordable electrolyzers at the multi-GW scale in the coming years. The EU Hydrogen Strategy of 2020 foresees 6 GW of hydrogen by electrolysis by 2024 increasing to 40 GW in 2030, just in the EU. BloombergNEF mentions 1.9 TW or electrolysis worldwide already in 2030 in their Green Scenario. Such numbers cannot be met by PEMEC because of the dependency of scarce elements, and it is questionable whether SOEC can be ready at scale for this first wave.
This has led to a renewed interest in the alkaline system that does not rely on strategic elements, and it is tempting to imagine that the AEC can be developed further to match the performance of the PEMEC without the use of expensive or scarce materials. A steady development has taken place over recent years, but the real game-changer would be to introduce a thin ion conducting membrane as separator and porous three-dimensional electrodes (both like the ones used in the PEMEC). This is what NEXAEC is about.
The project is formulated around a thin so-called ion-solvating membrane to separate the electrodes at which the electrochemical processes take place. This will lead to a lower internal resistance and allow for larger production rates. The concept of the ion-solvating membrane is different from the common approach of an ion-exchange membrane, like in the PEMEC. The big challenge for both concepts is stability in the alkaline environment.
The parallel development of electrodes is aiming at optimized three-dimensional structures which utilize the space available better and like the membrane contribute to higher production rates. Different advanced techniques are applied to manufacture these electrodes and to apply an active catalyst surface for the electrochemical reactions.
The objective of the project was to develop stable and highly conductive membranes as well as stable and highly active electrodes for the electrolyzer. These components would be scaled up and assembled in electrolyzer cells and tested in a full-size commercial electrolyzer stack (an assembly of many cells) with performance comparable to the PEMEC, but without the use of noble or strategic materials.
In the electrolysis process, water (H2O) is converted to hydrogen (H2) and oxygen (O2) by means of electrical energy. Hydrogen is a fuel and contains a major part of the original electrical energy as chemical energy. It can be stored or converted to other fuels, like hydrocarbons and alcohols.
There are three main types of electrolyzers (the device behind the process) each with its advantages and drawbacks, the alkaline electrolyzer (AEC), the PEM electrolyzer (PEMEC) and the solid oxide electrolyzer (SOEC). The AEC is the original state of art. It has been around for a century; it is robust and made from inexpensive materials, but it is bulky and needs much space. The PEMEC is much more compact and elegant with much higher production rates, but it suffers from high cost due to expensive materials including the scarce noble metal iridium. The SOEC is promising with the highest conversion efficiency of the three due to a very high working temperature, but large-scale devices are still under development. There will be a tremendous need for affordable electrolyzers at the multi-GW scale in the coming years. The EU Hydrogen Strategy of 2020 foresees 6 GW of hydrogen by electrolysis by 2024 increasing to 40 GW in 2030, just in the EU. BloombergNEF mentions 1.9 TW or electrolysis worldwide already in 2030 in their Green Scenario. Such numbers cannot be met by PEMEC because of the dependency of scarce elements, and it is questionable whether SOEC can be ready at scale for this first wave.
This has led to a renewed interest in the alkaline system that does not rely on strategic elements, and it is tempting to imagine that the AEC can be developed further to match the performance of the PEMEC without the use of expensive or scarce materials. A steady development has taken place over recent years, but the real game-changer would be to introduce a thin ion conducting membrane as separator and porous three-dimensional electrodes (both like the ones used in the PEMEC). This is what NEXAEC is about.
The project is formulated around a thin so-called ion-solvating membrane to separate the electrodes at which the electrochemical processes take place. This will lead to a lower internal resistance and allow for larger production rates. The concept of the ion-solvating membrane is different from the common approach of an ion-exchange membrane, like in the PEMEC. The big challenge for both concepts is stability in the alkaline environment.
The parallel development of electrodes is aiming at optimized three-dimensional structures which utilize the space available better and like the membrane contribute to higher production rates. Different advanced techniques are applied to manufacture these electrodes and to apply an active catalyst surface for the electrochemical reactions.
The objective of the project was to develop stable and highly conductive membranes as well as stable and highly active electrodes for the electrolyzer. These components would be scaled up and assembled in electrolyzer cells and tested in a full-size commercial electrolyzer stack (an assembly of many cells) with performance comparable to the PEMEC, but without the use of noble or strategic materials.
The main effort has been on the development of membranes and electrodes and to establish the required test infrastructure in the project. The membrane development started with fundamental polymer synthesis and polymer modification. Membranes with sufficiently high conductivity of 100 mS/cm and beyond have been manufactured and the alkaline stability is assessed. For the electrodes, several parallel approaches were followed including engineering the electrode structure and coating existing structures with catalytic layers. Cell performance significantly better than the common benchmark of 2 A/cm2 at 2 V has been obtained at 80 °C.
Selected membrane and electrode materials were integrated in a short stack. The membrane was of the ion-solvating class developed in the project and the electrodes were 3D structures likewise developed in the project.
Significant progress has been obtained in all areas addressed, but detailed results are only partly ready for publication. One patent application on membranes was filed.
With regard to dissemination,
• 422 followers were reached on Twitter/X
• In March 2024, a NEXTAEC Workshop was held within the Hydrogen Days 2024 in Prague.
• At the time of reporting, the project partners had published a total of 17 scientific papers with 7 more are planned and in progress, all fully or partly based on the project results.
• The consortium members collectively delivered a total of 62 oral and poster presentations at international conferences and workshops, with 6 more planned in 2024.
• The project was exhibited at the Hannover Fair in 2022.
• A total of 108 acts of dissemination were given including non-scientific communication.
Open access publications can be found at the project homepage at https://www.nextaec.eu/(opens in new window)
Selected membrane and electrode materials were integrated in a short stack. The membrane was of the ion-solvating class developed in the project and the electrodes were 3D structures likewise developed in the project.
Significant progress has been obtained in all areas addressed, but detailed results are only partly ready for publication. One patent application on membranes was filed.
With regard to dissemination,
• 422 followers were reached on Twitter/X
• In March 2024, a NEXTAEC Workshop was held within the Hydrogen Days 2024 in Prague.
• At the time of reporting, the project partners had published a total of 17 scientific papers with 7 more are planned and in progress, all fully or partly based on the project results.
• The consortium members collectively delivered a total of 62 oral and poster presentations at international conferences and workshops, with 6 more planned in 2024.
• The project was exhibited at the Hannover Fair in 2022.
• A total of 108 acts of dissemination were given including non-scientific communication.
Open access publications can be found at the project homepage at https://www.nextaec.eu/(opens in new window)
The ambitious targets for membranes and electrodes were all met during the project. The main commercial impact of the project activities is expected when the developed membranes and electrodes are verified on stack level on a larger scale showcasing a game changing technology that brings the next generation alkaline technology close to the present PEM based technology in terms of performance and compactness. PEM electrolyzers have gained a high popularity in recent years since they a capable of current densities of several amperes pr. cm2 in contrast to traditional alkaline counterparts with only 0.2 - 0.6 A cm-2.
Alkaline electrolyzers are already less expensive than PEM electrolyzers, but if the performance is increased 5 - 10 times, and if the cells are still as long-term stable, it will be a game changing break-through compared to the PEM technology. Capital cost-wise we will face a reduction of an order of magnitude as compared with PEM electrolyzers of today. Moreover, the scalability will not be limited the same way.
After meeting most of the individual targets on performance, we show an electrolyzer concept, which represents a significant step in the direction outlined above.
The concept of the ion-solvating membrane is gaining recognition as a third route to next generation electrolyzers along-side improved porous diaphragms and anion-exchange membranes. Prior to NEXTAEC, the ion-solvating membrane was much less mature. Now it is repeatedly mentioned together with anion-exchange membranes. We have made a solid effort to promote the idea at international conferences.
In a broad perspective, the interest in the alkaline alternative to PEM is growing fast for both cost and scalability reasons, and our progress with both membranes and electrode has contributed to accelerating this.
Alkaline electrolyzers are already less expensive than PEM electrolyzers, but if the performance is increased 5 - 10 times, and if the cells are still as long-term stable, it will be a game changing break-through compared to the PEM technology. Capital cost-wise we will face a reduction of an order of magnitude as compared with PEM electrolyzers of today. Moreover, the scalability will not be limited the same way.
After meeting most of the individual targets on performance, we show an electrolyzer concept, which represents a significant step in the direction outlined above.
The concept of the ion-solvating membrane is gaining recognition as a third route to next generation electrolyzers along-side improved porous diaphragms and anion-exchange membranes. Prior to NEXTAEC, the ion-solvating membrane was much less mature. Now it is repeatedly mentioned together with anion-exchange membranes. We have made a solid effort to promote the idea at international conferences.
In a broad perspective, the interest in the alkaline alternative to PEM is growing fast for both cost and scalability reasons, and our progress with both membranes and electrode has contributed to accelerating this.