Electrical engineering

Physics

Osmosis

Nanotechnology

Reversed electrodialysis

Energy conversion efficiency

Process engineering

Membrane

Nanofluidics

Pressure-retarded osmosis

Forward osmosis

Osmotic pressure

Reverse osmosis

Energy transformation

Engineering

Osmotic power

Chemistry

Renewable energy

Materials science

Desalination

Electrodialysis

Optoelectronics

Biochemistry

Thermodynamics

Nature Reviews Materials

The osmotic pressure difference between river water and seawater is a promising source of renewable energy. However, current osmotic energy conversion processes show limited power output, mainly owing to the low performance of commercial ion-exchange membranes. Nanofluidic channels with tailored ion transport dynamics enable high-performance reverse electrodialysis to efficiently harvest renewable osmotic energy. In this Review, we discuss ion diffusion through nanofluidic channels and investigate the rational design and optimization of advanced membrane architectures. We highlight how the structure and charge distribution can be tailored to minimize resistance and promote energy conversion, and examine the possibility of integrating nanofluidic osmotic energy conversion with other technologies, such as desalination and water splitting. Finally, we give an outlook to future applications and discuss challenges that need to be overcome to enable large-scale, real-world applications. Osmotic energy conversion is a promising renewable energy source. This Review discusses nanofluidics-based osmotic energy conversion systems, investigating the principles of ion diffusion in nanofluidic systems, optimization of membrane architectures to increase energy conversion and possible integration with other technologies, such as water splitting.

Nanofluidics for osmotic energy conversion