Boosting Capacitive Blue-Energy and Desalination Devices with Waste Heat

Mathijs Janssen, Andreas Härtel, and René van Roij
Phys. Rev. Lett. 113, 268501 – Published 24 December 2014

Abstract

We show that sustainably harvesting “blue” energy from the spontaneous mixing process of fresh and salty water can be boosted by varying the water temperature during a capacitive mixing process. Our modified Poisson-Boltzmann calculations predict a strong temperature dependence of the electrostatic potential of a charged electrode in contact with an adjacent aqueous 1:1 electrolyte. We propose to exploit this dependence to boost the efficiency of capacitive blue engines, which are based on cyclically charging and discharging nanoporous supercapacitors immersed in salty and fresh water, respectively [D. Brogioli, Phys. Rev. Lett. 103, 058501 (2009)]. We show that the energy output of blue engines can be increased by a factor of order 2 if warm (waste-heated) fresh water is mixed with cold sea water. Moreover, the underlying physics can also be used to optimize the reverse process of capacitive desalination of water.

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  • Received 30 May 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.268501

© 2014 American Physical Society

Authors & Affiliations

Mathijs Janssen*, Andreas Härtel, and René van Roij

  • Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands

  • *M.A.Janssen1@uu.nl

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Vol. 113, Iss. 26 — 31 December 2014

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