Reverse electro dialysis (RED) is an attractive technology for the production of energy from the mixing of fresh and salt water, since it does not produce environmental harmful substances. Fouling, with its various types, is one of the most severe problems within RED applications, dramatically decreasing the overall effective power output, mostly when using real waters. Thus, this project aims at identifying the effect of individual fouling compounds upon the RED performance and revealing the mode of action of the main one(s) when natural feed waters are used. Reasonable process modifications shall be proposed and tested including foremost pre-treatment schemes enabling a sustainable energy production.