Pressure Retarded Osmosis

Renewable Energy Generation and Recovery

Khaled Touati, Fernando Tadeo, Joon Ha Kim, Oscar Andres Alvarez Silva, Sung Ho Chae

• Publisher: Academic Press
• Year: 2017
• Print ISBN:
  9780128121030
• eBook ISBN:
  9780128123157
• Topic: Physical Sciences
• Subtopic: Energy

Pressure Retarded Osmosis: Renewable Energy Generation and Recovery offers the first comprehensive resource on this method of generating renewable energy. Dr. Khaled Touati and the team of editors combine their expertise with contributions from other leaders in the field to create this well-rounded resource, which discusses and analyses this novel method of creating a controllable renewable energy. The promises of the PRO technique are first clearly presented and explained, and the authors then provide a comprehensive analysis of the issues that remain such as Concentration Polarization, Membrane Deformation, and Reverse Salt Diffusion. Possible solutions to these issues which often restrict industrial implementation are then discussed to mitigate these detrimental effects, and there is also an emphasis on the recovery of energy from desalination processes using PRO, which is able to reduce energy consumption and make it more economically and environmentally efficient. - Combines research with experience to deliver a complete resource on Pressure Retarded Osmosis - Discusses all areas of PRO in detail - Offers solutions to problems commonly experienced and summarizes each method with a clear and concise conclusion - Includes case studies from the Great Salt Lake (U.S.A) and Dead Sea (Asia), as well as other rivers from America, Europe, and Asia

Chapter One

Pressure Retarded Osmosis as Renewable Energy Source

Khaled Touati¹, and Fernando Tadeo^{2 1}Technopark Borj Cedria, Soliman, Tunisia ²University of Valladolid, Valladolid, Spain

Abstract

This chapter presents a novel renewable energy source (pressure retarded osmosis), which uses the energy generated by differences in salt concentrations between two fluids, commonly freshwater and saltwater. Compared with other renewable energy sources, it has the advantage of controllability. An overview of the state of the art of this technique is presented, discussing also its basic operation principles and main challenges.

Keywords

Draw solution; Energy cost; Environmental impact; Feed solution; Membrane permeability; Osmotic power; Pressure-retarded osmosis; Renewable energies; Reverse salt diffusion; Salinity gradient energy

Contents

1. Introduction

2. Salinity Gradient Energy

2.1 Free Energy of Mixing

3. Pressure Retarded Osmosis

3.1 Osmotic Processes

3.1.1 Reverse Osmosis

3.1.2 Forward Osmosis

3.1.3 Pressure Retarded Osmosis

3.2 Reversible Mixing in Pressure Retarded Osmosis

3.3 Nonreversible Mixing in Pressure Retarded Osmosis (Pressure Retarded Osmosis Under Constant Applied Pressure)

3.4 Basic Concept of Pressure Retarded Osmosis

3.5 Water and Salt Fluxes Across a Pressure Retarded Osmosis Membrane in Ideal and Real Cases

3.5.1 Ideal Membrane With Perfect Hydrodynamics

3.5.2 Realistic Membrane With Reverse Salt Flux and Concentration Polarization

3.5.3 Concentration Polarization in Pressure Retarded Osmosis

3.6 Pressure Retarded Osmosis Power Density

4. Development of Pressure Retarded Osmosis

4.1 Chronological Evolution of the Pressure Retarded Osmosis Process

4.2 Pressure Retarded Osmosis Models' Progress

4.2.1 Loeb Model

4.2.2 Lee Model

4.2.3 Achilli Model

4.2.4 Yip Model

4.2.5 Sivertsen Model for a Hollow Fiber Pressure Retarded Osmosis Membrane

4.2.6 Touati Model

4.3 Pressure Retarded Osmosis Membranes Development

4.3.1 Flat-Sheet Membrane Development

4.3.2 Hollow Fiber Pressure Retarded Osmosis Membrane

5. Integration of Pressure Retarded Osmosis With Desalination Processes

6. Pressure Retarded Osmosis Limitations and Suggested Solutions

6.1 Membrane Fouling

6.2 Membrane Scaling

6.3 Concentration Polarization

6.4 Membrane Deformation

7. Pressure Retarded Osmosis Energy Cost

8. Environmental Impact

9. Final Considerations and Conclusions

References

Further Reading

1. Introduction

Energy demand is increasing worldwide, following economic development and population growth [1]. In fact, primary energy demand has more than doubled since 1971, which mainly relies on fossil fuels [2]. The world is thus facing unprecedented challenges for energy supply because of the decrease in the availability of inexpensive fossil fuels [3], and the detrimental effects of the emissions of greenhouse gases (GHGs) [4], which generate climate change [5].

These concerns should provide sufficient motivation for drastically reducing the use of fossil fuels: providing affordable, clean, secure, and adequate energy sources remains one of the world's biggest challenges. The need for renewable energy sources to meet world energy demand and progressively divert fossil energy sources is on the increase [6]. Thus, many research efforts are concentrating on developing efficient alternative energy sources [7]: solar, wind, tidal, wave, and biomass are being extensively studied to provide secure and sustainable energy sources. Nonetheless, the uneven availability of energy sources, complex logistics, or high installation costs are still preventing them from being widely used.

This book concentrates on pressure retarded osmosis (PRO), which is an alternative source of renewable energy currently in development: it is part of the so-called osmotic power or salinity gradient energy (SGE) sources, which use the energy generated by differences in salt concentrations between two fluids, commonly freshwater and saltwater. When a river runs into a sea, spontaneous mixing of freshwater and saltwater occurs: if the mixing is done reversibly (at least partially), work can be obtained from the mixing process [7...

Table of contents

• Cover image
• Title page
• Table of Contents
• Dedication
• Copyright
• Preface
• Acknowledgments
• Introduction
• Chapter One. Pressure Retarded Osmosis as Renewable Energy Source
• Chapter Two. Water and Salt Fluxes in Pressure Retarded Osmosis
• Chapter Three. Effects of the Temperatures on PRO
• Chapter Four. Integration of PRO into Desalination Processes
• Chapter Five. Implementing Salinity Gradient Energy at River Mouths
• Index