Reverse electrodialysis, design and optimization by modelling and experimentation

PhD ceremony: Mr. J. Veerman, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Reverse electrodialysis, design and optimization by modelling and experimentation

Promotor(s): prof. G.J. Harmsen

Faculty: Mathematics and Natural Sciences

One of the potential clean and renewable energy resources is salinity gradient power, generated from the reversible mixing of seawater with river water. The global potential is estimated to be 2.6 terawatt, more than the current electricity consumption. It was found that reverse electrodialysis (RED) is a promising technique to convert this potential energy into useful electricity. This technique is commonly known as Blue Energy and is one of the research topics of Wetsus, centre for sustainable water technology, in Leeuwarden.

A RED generator consists of a stack of ion exchange membranes and water compartments and is terminated on both sides by electrodes. An inventory was made for all aspects of electrode systems in terms of technical feasibility, SHE (safety, health and environment) and economics. All known as well as some novel own developed electrode systems were evaluated. The iron based systems with inert electrodes have the best opportunities for use in commercial RED power plants.

For optimal performance, three response parameters were investigated: power density, energy efficiency and net power. With short flow paths, high power densities can be obtained. A patent has been applied for a more effective fractal solution: an integration of membranes with a branched system of flow channels.

The RED process was modeled and this model was validated. The model predicts the effect of stack configuration and operational parameters. With this model, upscaling is possible in a number of steps; an idea is a Blue Energy power plant of 200 Megawatt in the Afsluitdijk.

Read also the press release