Reverse electrodialysis: A validated process model for design and optimization

Abstract Reverse electrodialysis (RED) is a technology to generate electricity using the entropy of the mixing of sea and river water. A model is made of the RED process and validated experimentally. The model is used to design and optimize the RED process. It predicts very small differences between counter- and co-current operation. It was decided to focus on co-current design because co-current operation causes smaller local pressure differences between the river and seawater compartments—hence smaller risk of leakages and the possibility to use very thin membranes with high fluxes and very open spacer structures with low hydrodynamic resistance. Segmentation of the electrodes proved to increase the power density by about 15% under realistic operational conditions. The model shows that with smaller systems – in terms of length of the flow path – higher power densities are possible. This effect is rather dramatical and poses a challenge for designing improved RED stacks on large commercial scale. It is suggested to reduce the flow path length by applying a fractal structure design of the spacers. Such structures can be made by profiling the membrane.

[1]  Matthias Wessling,et al.  Practical potential of reverse electrodialysis as process for sustainable energy generation. , 2009, Environmental science & technology.

[2]  G. J. Harmsen,et al.  Reverse electrodialysis : Performance of a stack with 50 cells on the mixing of sea and river water , 2009 .

[3]  E. Brauns,et al.  Salinity gradient power by reverse electrodialysis: effect of model parameters on electrical power output , 2009 .

[4]  J. Weinstein,et al.  Electric Power from Differences in Salinity: The Dialytic Battery , 1976, Science.

[5]  J. Veerman,et al.  Reducing power losses caused by ionic shortcut currents in reverse electrodialysis stacks by a validated model , 2008 .

[6]  Electric power produced from two solutions of unequal salinity by reverse electrodialysis , 1992 .

[7]  R. Audinos,et al.  Electrodialyse inverse. Etude de l'energie electrique obtenue a partir de deux solutions de salinites differentes , 1983 .

[8]  Joseph Jagur-Grodzinski,et al.  Novel process for direct conversion of free energy of mixing into electric power , 1986 .

[9]  Hubertus V. M. Hamelers,et al.  Towards implementation of reverse electrodialysis for power generation from salinity gradients , 2010 .

[10]  R. Lacey.  Energy by reverse electrodialysis , 1980 .

[11]  Matthias Wessling,et al.  On the resistances of membrane, diffusion boundary layer and double layer in ion exchange membrane transport , 2010 .

[12]  Matthias Wessling,et al.  Ion conductive spacers for increased power generation in reverse electrodialysis , 2010 .

[13]  Matthias Wessling,et al.  Current status of ion exchange membranes for power generation from salinity gradients , 2008 .

[14]  R. E. Pattle.  Production of Electric Power by mixing Fresh and Salt Water in the Hydroelectric Pile , 1954, Nature.

[15]  J. Post,et al.  Energy recovery from controlled mixing salt and fresh water with a reverse electrodialysis system. , 2008, Environmental science & technology.

[16]  G Jan Harmsen,et al.  Electrical power from sea and river water by reverse electrodialysis: a first step from the laboratory to a real power plant. , 2010, Environmental science & technology.

[17]  J. Post,et al.  Salinity-gradient power : Evaluation of pressure-retarded osmosis and reverse electrodialysis , 2007 .

[18]  Marian Turek,et al.  Renewable energy by reverse electrodialysis , 2007 .

[19]  G. J. Harmsen,et al.  Reverse electrodialysis: Comparison of six commercial membrane pairs on the thermodynamic efficiency and power density , 2009 .

[20]  Matthias Wessling,et al.  Transport limitations in ion exchange membranes at low salt concentrations , 2010 .

[21]  F. Suda,et al.  Transient changes in the power output from the concentration difference cell (dialytic battery) between seawater and river water , 2007 .