Investigation of pressure retarded osmosis power production

Nikolaos Taousanidis,Konstantinos Gavros,L Slătineanu,A.M Mihalache,G Oancea,C.E Panait,M.I Ripanu,M Coteata,R Ibanescu,O Dodun,M Boca,P Kyratsis,V Merticaru,G Nagit

doi:10.1051/matecconf/201711210004

Abstract

A major source of energy exists where there is mixing between aqueous solutions of different salinities. This energy source is particularly concentrated where fresh water rivers flow on to the ocean. The power, represented by the osmotic pressure difference between fresh water and salt water, may be called salinity gradient power. In this study the pressure retarded osmosis method for the extraction of salinity gradients’ energy is investigated, main problems and difficulties are pointed out and finally the whole subject is justified with experimental results.

Highlights

After decades of anticipation we may be close to the ability to extract substantial amounts of energy from the sea
Membrane properties under pressure retarded osmosis (PRO) conditions can be calculated using a model taking into account concentration polarization
Required parameters - water permeation coefficient A, salt permeation coefficient B, and resistance to salt transport in the membrane substrate K - can be obtained from Reverse Osmosis (RO) and Direct Osmosis (DO) experiments

Summary

Introduction

After decades of anticipation we may be close to the ability to extract substantial amounts of energy from the sea. Some of the incident solar energy establishes and maintains thermal gradients. Water is evaporated, condensed and precipitated nonuniformly and establishes salinity differences. This energy source exists at the interface between waters of differing salinities and is concentrated where fresh water rivers flow on to the ocean. The power, represented by the osmotic pressure difference between fresh water and salt water, may be called salinity gradient power. Salinity power has certain features that make it attractive as a source of energy. Experiments indicate that the equivalent pressure head between 0.5 molar seawater and fresh water is about 24atm. In this study we deal with the pressure retarded osmosis (PRO) technique [1]

Principle of pressure retarded osmosis

Experiment

Conclusions