Reverse osmosis

Marketing

Membrane distillation

Engineering

Brine

Petroleum engineering

Power (physics)

Biochemistry

Salinity

Computer science

Geology

Business

Reversed electrodialysis

Oceanography

Electrodialysis

Waste management

Environmental engineering

Thermodynamics

Physics

Organic chemistry

Membrane

Renewable energy

Desalination

Energy storage

Process engineering

Environmental science

Chemistry

Forward osmosis

Osmotic power

Commercialization

Electrical engineering

Applied Energy

Salinity gradient energy is currently attracting growing attention among the scientific community as a renewable energy source. In particular, Reverse Electrodialysis (RED) is emerging as one of the most promising membrane-based technologies for renewable energy generation by mixing two solutions of different salinity. This work presents a critical review of the most significant achievements in RED, focusing on membrane development, stack design, fluid dynamics, process optimization, fouling and potential applications. Although RED technology is mainly investigated for energy generation from river water/seawater, the opportunities for the use of concentrated brine are considered as well, driven by benefits in terms of higher power density and mitigation of adverse environmental effects related to brine disposal. Interesting extensions of the applicability of RED for sustainable production of water and hydrogen when complemented by reverse osmosis, membrane distillation, bio-electrochemical systems and water electrolysis technologies are also discussed, along with the possibility to use it as an energy storage device. The main hurdles to market implementation, predominantly related to unavailability of high performance, stable and low-cost membrane materials, are outlined. A techno-economic analysis based on the available literature data is also performed and critical research directions to facilitate commercialization of RED are identified.

Progress and prospects in reverse electrodialysis for salinity gradient energy conversion and storage