Thermo-osmotic energy conversion and storage by nanochannels

Abstract

This work reports the conversion and storage of thermo-osmotic energy from combined salinity and temperature gradients using ultrasmall silica nanochannels (SNCs). Thanks to the high permselectivity of SNCs, the power output of osmotic energy conversion from a salinity gradient (0.5 M/0.01 M NaCl) was appealing, with a maximum output power density of 1.0 W m⁻² and a current density of 34.7 A m⁻². An additional temperature gradient of 10 K increases this output power by 40.4%. Moreover, under a salinity gradient, the open-circuit potential remained more than 80% after ten days, thus confirming the ability for energy storage. The mechanism of energy storage using nanochannels was then confirmed via finite element simulations. We believe that energy conversion from combined salinity and temperature gradients is a high-potential approach for harvesting clean energy.