Renewable energy from seawater
In reverse electrodialysis, ion exchange membranes are placed in an alternating way between two water solutions with a different salinity. The salt concentration difference creates a potential that in turn causes an electrical current to flow to electrodes connected to the electrical load. Before the REAPOWER (Reverse electrodialysis alternative power production) project, research focused on the combination of fresh water as the low salinity concentration solution and seawater as the high salinity concentration solution. This approach is suitable for very large-scale applications, but faces challenges as the conductivity of freshwater is limited. To overcome existing limitations, researchers used seawater as the low salinity concentration solution and brine as the high salinity concentration solution. Theoretical calculations showed that the energy content of brine available in a typical industrial facility could result in electrical power output of 450 kW at a very attractive cost. Researchers therefore started working closely together to develop the necessary components and materials tailored to the requirements of such reverse electrodialysis applications. Their efforts centred on manufacturing low-cost membranes with reduced electrical resistance. Adhesives were used for gluing membranes and spacers together to produce a leak-free replaceable stack. The stack was tested in the laboratory under different operating conditions. Computational fluid dynamics was also used to investigate the effect of different parameters on the process efficiency. Project partners developed mathematical models based on the basic principles behind the stack operation. The simulations predictions were compared with experimental data to validate the operation of the laboratory-scale reverse electrodialysis stack. REAPOWER went beyond the state of the art by showing the versatility of the reverse electrodialysis stack fed with real brine from a salt pond. The new technology has the potential to produce cheap electricity from brine and seawater and contribute to the development of this clean energy sector. A YouTube video clearly explains the technology and REAPOWER research that has made this a reality.
Keywords
Renewable energy, seawater, reverse electrodialysis, brine, REAPOWER