Osmotic power,
salinity gradient power or
blue energy is the energy available from the difference in the salt concentration between
seawater and
river water. Two practical methods for this are
reverse electrodialysis (RED) and
pressure retarded osmosis (PRO). Both processes rely on
osmosis with ion specific
membranes. The key waste product is
brackish water. This byproduct is the result of natural forces that are being harnessed: the flow of fresh water into seas that are made up of salt water.