Reduction of SEC (specific energy consumption) is the field with the most specific technical research focus and effort in SWRO (seawater reverse osmosis) plants. For existing installations with energy recovery systems consisting in Pelton turbines, the most significant challenge is how to reduce energy costs. The highest efficient isobaric ERD (energy recovery devices) are used in order to produce major savings in energy consumption in the desalination process and/or to increase the freshwater capacity of the installations, by taking full advantage of the plant equipment. This paper gives a brief overview of the technology used to recover the energy from brine stream in large desalination plants, with a description of the modifications required if the recovery system with Pelton turbines is to be replaced by systems based on isobaric-chamber devices. All possibilities analysed are deeply justified technically and thermoeconomically within an exhaustive assessment (C) 2010 Elsevier Ltd. All rights reserved.