A Short Review on Hydrogen, Biofuel, and Electricity Production Using Seawater as a Medium

Energy security coupled with the impact of greenhouse gas emissions have resulted in growing interest in investigating new technologies for renewable energy production as an alternative to fossil fuels. In this context, seawater is an inexhaustible and environmentally benign source for the production of clean energy. Natural seawater is the most convenient medium to produce energy, when compared to synthetic seawater or fresh water. To date, there have been no detailed reviews regarding energy conversion methods using seawater. The main aim of this review is to furnish the important features of energy production/conversion technologies using seawater as a medium. The basic principle, application and important finding of the available technologies such as photocatalysis, photoelectrochemical, microbial desalination, biochemical, electrolysis, reverse electrodialysis, capacitive mixing, pressure retarded osmosis, mixing entropy battery, and seawater batteries have been described in this review. Energy or energy carriers can be produced in the form of electricity, hydrogen (H-2), methane (CH4), and biodiesel. Relevant design and operating conditions that influence the energy production from seawater such as physicochemical properties of materials, reaction conditions, reactor design, and formation of byproducts are summarized briefly. We also found that most of the technologies have been evaluated only at the laboratory scale. To avoid the fouling problems, it is advised to use natural seawater after filtration.