Scalability of nanopore osmotic energy conversion

Achieving scalability remains a pivotal hurdle in the realm of osmotic power generation utilizing nanoporous membranes. This study addresses this challenge by introducing a scaling law that facilitates the estimation of the maximum membrane area and porosity achievable without compromising permselectivity due to inter-pore electrostatic couplings.

Abstract:

Artificial nanofluidic networks are emerging systems for blue energy conversion that leverages surface charge-derived permselectivity to induce voltage from diffusive ion transport under salinity difference. Here the pivotal significance of electrostatic inter-channel couplings in multi-nanopore membranes, which impose constraints on porosity and subsequently influence the generation of large osmotic power outputs, is illustrated. Constructive interference is observed between two 20 nm nanopores of 30 nm spacing that renders enhanced permselectivity to osmotic power output via the recovered electroneutrality. On contrary, the interference is revealed as destructive in two-dimensional arrays causing significant deteriorations of the ion selectivity even for the nanopores sparsely distributed at an order of magnitude larger spacing than the Dukhin length. Most importantly, a scaling law is provided for deducing the maximal membrane area and porosity to avoid the selectivity loss via the inter-pore electrostatic coupling. As the electric crosstalk is inevitable in any fluidic network, the present findings can be a useful guide to design nanoporous membranes for scalable osmotic power generations.

Author list:

Makusu Tsutsui*, Wei-Lun Hsu, Kazumichi Yokota, Iat Wai Leong, Hirofumi Daiguji, Tomoji Kawai*

How to cite:

M. Tsutsui, W.-L. Hsu, K. Yokota, I. W. Leong, H. Daiguji, T. Kawai, Exploration 2024, 20220110.
https://doi.org/10.1002/EXP.20220110