6.13 Novel electrochemical cell concepts for generating salinity gradient energy
There is a great societal need for clean and renewable energy, like Salinity Gradient Energy (SGE). SGE is the energy released when two flows of water with different salinity are mixed e.g. river and sea water. Reversed Electro Dialysis (RED) is a potentially very attractive technology for the production of SGE. In RED, a concentrated salt solution and a less concentrated salt solution are brought into contact through an alternating series of anion exchange membranes (AEM) and cation exchange membranes (CEM). The membranes separate the concentrated solution from the diluted solution and only ions can pass through the ion selective membranes. The difference in chemical potential between both solutions is the driving force for this process. At the electrodes a redox couple is used to convert the ion flow into an electron flow.
The RED system is not only capable of harvesting the salinity gradient energy, but also can play an important role in energy storage and electricity production from waste heat.
Although the RED technology is still a young technology it has already been proven to work on pilot scale. To advance the technology further, this project will develop breakthrough cell concepts. A first important focus will be redox-free cell concepts. Although current RED cells recycle the redox components, on longer term there is still an inactivation and the redox component needs to be replenished regularly. A system without chemicals would be both more sustainable and economical. A second focus will be cells with locally optimized current distributions. By varying the current distribution within the system, improved efficiencies can be achieved. A third focus is the optimal process operation in view of the presence of divalent ions. Divalent ions tend to lower the performance of the RED cells. This issue has in part been solved by developing new types of membranes, nevertheless it remains to be investigated whether optimal conditions have been selected for operation with these new types of membranes.
New cell concepts will not be only investigated for saline gradient energy generation but also applications for battery operation will be considered. A combined experimental and modeling research approach will be used.
We are looking for a candidate with an MSc degree in the field of process engineering; environmental engineering; membrane technology with both modelling and experimental skills.
The research project is part of the Wetsus research theme Blue Energy.
The following companies are part of the theme: A. Hak Construction (www.ahak.nl), Alliander (www.alliander.com), AquaBattery (www.aquabattery.nl), Fujifilm (www.fujifilm.eu), Landustrie/Desah (www.landustrie.nl), REDstack (www.redstack.nl) and W&F Technologies (www.magneto.nl).
Promotor: Prof.dr.ir. Cees Buisman (Wageningen University, Environmental Technology)
Co-promotor: Dr. Annemiek ter Heijne (Wageningen University)
Wetsus supervisor: dr. Michel Saakes
For more information contact:
Wetsus, Leeuwarden, The Netherlands