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
(H2), 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.