Author(s): Cilia Swinkels; Sam Van Der Zwan; Arnout Bijlsma; Ivo Pothof
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Abstract: In the mixing process of water with different salinities a large amount of energy is released, which is normally converted into heat if fresh water rivers enter estuaries and seas. This energy, often referred to as Blue Energy, may be extracted by two different processes: Reversed Electrodialysis (RED) or Pressure Retarded Osmosis (PRO). The Netherlands has a number of locations where large fresh water flows enter saline water bodies via man-made structures, creating opportunities for Blue Energy applications. This paper investigates the hydrodynamic and mass transfer processes at two different scales, the estuarine scale and the membrane module scale, for a specific site in The Netherlands: IJmuiden. The physics at these two very different scales both play a role in the performance of a potential Blue Energy power plant. On the estuarine scale–the tidal and density driven hydrodynamic scale–the performance of a Blue Energy power plant depends primarily on the available salinity gradient. In many locations, natural mixing of saline and fresh water reduces the maximum exploitable salinity gradient. Therefore, an adequate intake and outfall layout is required to optimize the performance of a Blue Energy plant. Particulate matter content is another issue to be addressed: at present, the required pre-filtration would account for the largest energy losses in the Blue Energy process. A model at the module scale shows that delicate balances exist between most of the design parameters of a Blue Energy power plant and that for salinity gradients present in IJmuiden a net energy production in the order of 5 to 7 MW can be expected.
Year: 2010