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Novel MAterial and Process Design for ReVerse Electrodialysis-Water ELectrolysis Energy System

Periodic Reporting for period 1 - MARVEL (Novel MAterial and Process Design for ReVerse Electrodialysis-Water ELectrolysisEnergy System)

Reporting period: 2017-06-01 to 2019-05-31

The skyrocketing demand for energy across the globe has intensified the search for alternative clean and renewable energy technologies that are fundamental to sustainable socio-economic development, national security, and environmental safety. The MARVEL project was designed to implement high-quality research focusing on clean energy and hydrogen production technologies. The core objectives of MARVEL were to: i) design a monovalent ion-selective membrane for RED ii) develop novel, fully characterized membrane separators and polymer binders for APWEL iii) test RED-APWEL process with these new materials and iv) perform a techno-economic assessment for commercial feasibility. To achieve cutting-edge knowledge and expertise, the researcher (Dr. Ramato Ashu Tufa) was trained in a range of scientific, technical and industrial interdisciplinary training activities.
The multidisciplinary MARVEL project has led to several outcomes and innovations. Specifically, a new type of monovalent selective cation exchange membranes (CEMs) were designed for RED through chemical modification using composite solutions based on pyrrole (conducting polymer) and chitosan (biopolymer). The unique property of such membranes restricted the so-called ‘uphill transport’ which is a phenomenon resulting in the reduction of open-circuit voltage and the power density of RED under natural conditions. For the APWEL, a novel anion exchange membrane (AEM) based on Polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (PSEBS) base material functionalized with 1,4-diazabicyclo[2.2.2]octane (DABCO) were synthesized by solution casting, which is a potentially scalable approach for large-scale membrane fabrication. This AEM were combined with cheap, earth-abundant electrocatalysts such as NiCo2O4 and NiFe2O4 to form a catalyst-coated-membranes (CCMs) to design a more economical, high performing APWEL system. Generally, the development of high performance RED system and the use of novel CCMs in combination with electrocatalysts based on low-cost materials is a strategic route to design a more efficient, economically affordable RED driven APWEL system.
Only in the EU, the theoretical potential of SGP is estimated to be 2,109 TWh/year. Efficient exploitation of this energy represents a potential hydrogen production capacity of 33 Mt/year significantly enhancing the EU's capability to secure sustainable energy supplies, and transition to a decarbonized energy system. This advance substantially impacts the competitiveness of EU’s research on renewable energy technologies worldwide.
The project MARVEL promoted high-quality research training through excellence, innovation, mobility and diversity in inter/multidisciplinary investigation approaches. The main activities performed are listed below:
1. Training activities to strengthen scientific knowledge, research skills as well as complementary and transferable skills: The activities involved an in-depth practice on membrane fabrication and characterization techniques, teaching and supervision, attendance of summer schools, workshops, high-quality proposal development, public presentation skills etc.
2. Development of new membrane materials for RED and APWEL energy systems: For RED, a new type of CEM were prepared by chemical modification of commercial membranes using composite materials based on conducting polymers. These membranes exhibited a promising monovalent selectivity (Na+ vs Mg2+) with up to 3-fold improvement compared to pristine membranes. For APWEL, a new type of catalyst coated membranes (CCMs) were along with cheap and earth-abundant electrocatalysts. The CCM led to a significant reduction in catalyst loading compared to the traditional catalyst-coated electrodes.
3. Synthesis of binders and electrocatalysts for APWEL system: Platinum group-free catalysts based on NiCo2O4 for anode and NiFe2O4 for cathode were developed and used for CCM development. The use of PSEBS-CM-DABCO binder with the catalysts played a crucial role in the stability of the CCMs.
4. Hybrid RED-APWEL testing: Lab-scale RED unit equipped with the new monovalent selective CEMs resulted in a higher power density (more than 40 %) compared to the pristine counterparts. Moreover, the industrial-scale RED (200 cells) using sulfate-rich industrial effluents combined with a lab-scale APWEL unit (6 cells) resulted in a hydrogen production rate reaching 50 cm3/h.cm2 under the optimal conditions. This work marks a development towards large-scale renewable hydrogen production using industrial effluents.
5. Techno-economic assessment: Exergy analysis for RED in hybrid application with desalination technologies resulted in up to 16 % reduction specific energy consumption at the desalination stage. This principle was later extended to the application of RED in hydrogen technologies.
6. Dissemination plans for the project were developed, reviewed and updated to ensure its maximum visibility and impact. Some of the communication tools and strategies performed for the MARVEL project involve project websites, leaflets, public engagement activities, publication in high-quality peer-reviewed journals, presentations at international conferences etc.

The research outputs of MARVEL have been presented at more than 6 international conferences. Up to 6 research papers have been published in international peer-reviewed journals. Other publications are being prepared for submission, submitted or under review.
The availability of membranes mainly limits the practical implementation of RED at commercial scale. In particular, the current membranes at the market are prone to the impact of multivalent ions under natural feed conditions. The new type of IEMs based on conducting polymers represent a first attempt in designing unique CEMs for enhanced monovalent selectivity in RED. Even though the obtained performance parameters still needs some improvement, the strategy and materials employed to prepare the membranes indicated a possibility of further designing of a high performance IEMs for the practical implementation of RED.
On the other hand, the new type of CCM materials, which were exhaustively tested in APWEL for the first time, significantly reduced the catalyst loading compared to the traditionally used catalyst-coated substrates. This development contributes primarily to the reduction of the capital cost required for the implementation of the zero-gap APWEL on an industrial scale. Various other research outputs of the MARVEL related to industrial-scale RED operation using waste resources, and the development of new electrodes and electrocatalysts for APWEL have a huge contribution to the design and development of new energy technologies.
In general, the overall findings and achievements of MARVEL would enhance the research and industrial competence of EU worldwide, particularly, on the renewable energy sector, including the hydrogen market. Moreover, improvement in the efficiency of integrated RED-APWEL is a key for the commercial success a renewable hydrogen technology inline with 20-20-20 EU targets, ultimately ensuring a secure, environmentally sustainable and economically competitive EU energy supply for generations to come.
Active participation in a variety of research activities and secondments had a notable impact in developing the scientific know-how of the fellow along with complementary and transferable skills.
Performance of monovalent selective membranes for reverse electrodialysis
SEM images of catalyst coated membranes for alkaline water electrolysis
Characterization of catalysts coated membranes and electrodes for alkaline water electrolysis
SEM images of prisitne and modified membranes for reverse electrodialysis