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Title: Extracting energy from ocean thermal and salinity gradients to power unmanned underwater vehicles: State of the art, current limitations, and future outlook

Journal Article · · Renewable and Sustainable Energy Reviews

Thermal gradient energy-generation technologies for powering unmanned underwater vehicles (UUVs) or autonomous sensing systems in the ocean are mainly in the research development phase or commercially available at a limited scale, and salinity-gradient energy-generation technologies have not been adequately researched yet. The demand for self-powered UUVs suitable for long-term deployments has been growing, and further research related to small-scale ocean gradient energy systems is needed. In this study, we conducted a comprehensive review about harvesting energy from ocean thermal or salinity gradients for powering UUVs, focusing on gliders and profiling floats. Thermal gradient energy systems for UUVs based on phase change materials (PCM) cannot provide the energy required for powering autonomous sensing systems because of the systems’ low energy conversion efficiency. Besides reducing energy consumption by developing more efficient electrical-mechanical systems, enhancing the thermal conductivity of the PCMs may help address this challenge by increasing the power generation rate of the UUVs. Several other emerging technologies, such as thermoelectric generators, shape memory alloys, and small-scale thermodynamic cycle systems, have shown potential for powering UUVs, but they are still only at the laboratory testing or conceptual design phase. The most advanced power generation technologies based on salinity gradients, reverse electrodialysis and pressure-retarded osmosis, are still not economically viable for large-scale deployment, mainly because of the high cost of the components required to operate in harsh saline environments. Our feasibility evaluation showed that existing salinity gradient power generation technologies are not directly feasible for powering UUVs in the open ocean.

Research Organization:
National Renewable Energy Lab. (NREL), Golden, CO (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Water Power Technologies Office (EE-4W); USDOE
Grant/Contract Number:
AC36-08GO28308; AC05-76RL01830
OSTI ID:
1856207
Alternate ID(s):
OSTI ID: 1860249
Report Number(s):
NREL/JA-5700-80980; PNNL-SA-163771; MainId:79756; UUID:77d08fa1-ed51-47cb-9f5b-9d85b4866bf2; MainAdminID:63911
Journal Information:
Renewable and Sustainable Energy Reviews, Vol. 160; ISSN 1364-0321
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (98)

Limits of power production due to finite membrane area in pressure retarded osmosis journal October 2014
Deep SOLO: A Full-Depth Profiling Float for the Argo Program journal October 2019
Polyelectrolyte‐Coated Copper Hexacyanoferrate and Bismuth Oxychloride Electrodes for Efficient Salinity Gradient Energy Recovery in Capacitive Mixing journal September 2019
A thermal conductive composite phase change material with enhanced volume resistivity by introducing silicon carbide for battery thermal management journal November 2018
Preparation of nitrogen-doped graphene/palmitic acid shape stabilized composite phase change material with remarkable thermal properties for thermal energy storage journal December 2014
Charge-doped electrodes for power production using the salinity gradient in CapMix journal December 2020
Hydrogen production from inexhaustible supplies of fresh and salt water using microbial reverse-electrodialysis electrolysis cells journal September 2011
Design and testing of a shape memory alloy buoyancy engine for unmanned underwater vehicles journal October 2015
Microbial Reverse Electrodialysis Cells for Synergistically Enhanced Power Production journal June 2011
Osmotic power with Pressure Retarded Osmosis: Theory, performance and trends – A review journal March 2014
Dynamic modeling and endurance enhancement analysis of deep-sea gliders with a hybrid buoyancy regulating system journal December 2020
Extraction of Salinity-Gradient Energy by a Hybrid Capacitive-Mixing System journal March 2017
Energy Recovery from Solutions with Different Salinities Based on Swelling and Shrinking of Hydrogels journal May 2014
Experimental investigation of solidification and melting characteristics of composite PCMs for building heating application journal October 2014
Highly thermally conductive and flexible phase change composites enabled by polymer/graphite nanoplatelet-based dual networks for efficient thermal management journal January 2020
Experimental studies on a closed cycle demonstration OTEC plant working on small temperature difference journal March 2013
Underwater Gliders for Ocean Research journal June 2004
Preparation, modification and characterization of polymeric hollow fiber membranes for pressure-retarded osmosis journal January 2014
Pressure retarded osmosis: From the vision of Sidney Loeb to the first prototype installation — Review journal October 2010
Thermal conductivity enhancement of treated petroleum waxes, as phase change material, by α nano alumina: Energy storage journal April 2017
Field-test of a solar low delta-T Stirling engine journal June 2012
Salinity Gradient Energy from Expansion and Contraction of Poly(allylamine hydrochloride) Hydrogels journal June 2018
Hybrid desalination processes for beneficial use of reverse osmosis brine: Current status and future prospects journal March 2019
A review of shape memory alloy research, applications and opportunities journal April 2014
Comparison of Energy Efficiency and Power Density in Pressure Retarded Osmosis and Reverse Electrodialysis journal August 2014
Recent developments in pressure retarded osmosis for desalination and power generation journal March 2021
Alternative power sources for remote sensors: A review journal January 2014
Preparation and thermal properties of n–octadecane/stearic acid eutectic mixtures with hexagonal boron nitride as phase change materials for thermal energy storage journal November 2016
Thermal properties of n-pentadecane, n-heptadecane and n-nonadecane in the solid/liquid phase change region journal August 2015
Highly conductive phase change composites enabled by vertically-aligned reticulated graphite nanoplatelets for high-temperature solar photo/electro-thermal energy conversion, harvesting and storage journal November 2021
A novel solar-powered active low temperature differential Stirling pump journal September 2015
Harvesting blue energy with carbon electrodes of asymmetric nanopore distributions journal April 2021
Form-stable phase change composites: Preparation, performance, and applications for thermal energy conversion, storage and management journal November 2021
Osmotic Engine: Translating Osmotic Pressure into Macroscopic Mechanical Force via Poly(Acrylic Acid) Based Hydrogels journal May 2017
Sensitivity analysis and parameter optimization of energy consumption for underwater gliders journal January 2020
Improving thermal characteristics and stability of phase change material containing TiO2 nanoparticles after thermal cycles for energy storage journal September 2017
High performance thin film composite pressure retarded osmosis (PRO) membranes for renewable salinity-gradient energy generation journal August 2013
Powering the Blue Economy: Progress Exploring Marine Renewable Energy Integration With Ocean Observations journal November 2020
Introduction of organic-organic eutectic PCM in mesoporous N-doped carbons for enhanced thermal conductivity and energy storage capacity journal February 2018
Temperature-dependent thermal properties of solid/liquid phase change even-numbered n-alkanes: n-Hexadecane, n-octadecane and n-eicosane journal April 2015
Thermal conductivity enhancement on phase change materials for thermal energy storage: A review journal March 2020
Ocean thermal energy application technologies for unmanned underwater vehicles: A comprehensive review journal November 2020
Review of metallic phase change materials for high heat flux transient thermal management applications journal January 2020
A review of shape memory alloy based filtration devices journal June 2020
Investigations of inorganic and organic fouling behaviors, antifouling and cleaning strategies for pressure retarded osmosis (PRO) membrane using seawater desalination brine and wastewater journal October 2016
Energy Lost in a Hydrogel Osmotic Engine Due to a Pressure Drop journal August 2021
Lifetime prediction of thermoelectric devices under thermal cycling journal October 2019
Polyzwitterionic Hydrogels in Engines Based on the Antipolyelectrolyte Effect and Driven by the Salinity Gradient journal June 2019
Salinity Gradients for Sustainable Energy: Primer, Progress, and Prospects journal October 2016
State-of-the-Art Reviews and Analyses of Emerging Research Findings and Achievements of Thermoelectric Materials over the Past Years journal December 2018
n -Alkane Binary Molecular Alloys journal March 2004
Synthesis of “graphene-like” mesoporous carbons for shape-stabilized phase change materials with high loading capacity and improved latent heat journal January 2017
Organic Rankine cycle saves energy and reduces gas emissions for cement production journal June 2015
Experimental investigation on an ammonia-water based ocean thermal energy conversion system journal November 2013
A BGC-Argo Guide: Planning, Deployment, Data Handling and Usage journal August 2019
Improved performance of latent heat energy storage systems utilizing high thermal conductivity fins: A review journal May 2017
A revised ocean glider concept to realize Stommel's vision and supplement Argo floats journal January 2020
Profiling Floats in SOCCOM: Technical Capabilities for Studying the Southern Ocean journal June 2018
Nanoconfinement effects of N-doped hierarchical carbon on thermal behaviors of organic phase change materials journal March 2019
Construction of CNT@Cr-MIL-101-NH2 hybrid composite for shape-stabilized phase change materials with enhanced thermal conductivity journal October 2018
A review of car waste heat recovery systems utilising thermoelectric generators and heat pipes journal May 2016
A comprehensive review of the feasibility of pressure retarded osmosis: Recent technological advances and industrial efforts towards commercialization journal October 2020
Waste heat recovery from thermo-electric generators (TEGs) journal February 2020
Energy Capture from Thermolytic Solutions in Microbial Reverse-Electrodialysis Cells journal March 2012
Effect of carbon nanotube interfacial geometry on thermal transport in solid–liquid phase change materials journal September 2015
An innovative Organic Rankine Cycle (ORC) based Ocean Thermal Energy Conversion (OTEC) system with performance simulation and multi-objective optimization journal December 2018
The forward osmosis-pressure retarded osmosis (FO-PRO) hybrid system: A new process to mitigate membrane fouling for sustainable osmotic power generation journal August 2018
Conceptual design of a 5 MW OTEC power plant in the Oman Sea journal November 2016
A thermal engine for underwater glider driven by ocean thermal energy journal April 2016
Acceleration of Heat Transfer and Melting Rate of a Phase Change Material by Nanoparticles Addition at Low Concentrations journal March 2021
Towards the optimal operation of a thermal-recharging float in the ocean journal May 2018
Experimentally obtainable energy from mixing river water, seawater or brines with reverse electrodialysis journal April 2014
Thermal conductivity enhancement of phase change materials for thermal energy storage: A review journal January 2011
Progress and prospects in reverse electrodialysis for salinity gradient energy conversion and storage journal September 2018
Analysis of the high-efficiency EP-OTEC cycle using R152a journal May 2017
A review of solar-powered Stirling engines and low temperature differential Stirling engines journal April 2003
Protection and thermal management of thermoelectric generator system using phase change materials: An experimental investigation journal August 2018
Experimental investigation on copper foam/hydrated salt composite phase change material for thermal energy storage journal December 2017
SLOCUM: an underwater glider propelled by environmental energy journal January 2001
Enhancement of heat transfer for thermal energy storage application using stearic acid nanocomposite with multi-walled carbon nanotubes journal June 2013
Harvesting environmental thermal energy using solid/liquid phase change materials journal November 2017
Recovered Energy from Salinity Gradients Utilizing Various Poly(Acrylic Acid)-Based Hydrogels journal February 2021
Efficiency analysis and experimental validation of the ocean thermal energy conversion with phase change material for underwater vehicle journal August 2019
Capacitive Mixing for Harvesting the Free Energy of Solutions at Different Concentrations journal April 2013
Reverse electrodialysis in bilayer nanochannels: salinity gradient-driven power generation journal January 2018
Buoyancy engine developed for underwater gliders journal January 2016
Microbial Reverse-Electrodialysis Electrolysis and Chemical-Production Cell for H 2 Production and CO 2 Sequestration journal March 2014
High‐Performance Thermally Conductive Phase Change Composites by Large‐Size Oriented Graphite Sheets for Scalable Thermal Energy Harvesting journal October 2019
A review on shape memory alloys with applications to morphing aircraft journal April 2014
Characterization of Alkanes and Paraffin Waxes for Application as Phase Change Energy Storage Medium journal January 1994
Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III journal January 1996
Finite time thermodynamic analysis of endoreversible Stirling heat engine with regenerative losses journal October 2000
Model and simulation of the energy retrieved by thermoelectric generators in an underwater glider journal May 2018
A comparison of mono- and multi-valent ions as stack feed solutions in microbial reverse-electrodialysis electrolysis cells and their effects on hydrogen generation journal September 2016
Reducing pumping energy by using different flow rates of high and low concentration solutions in reverse electrodialysis cells journal July 2015
High performance asymmetric capacitive mixing with oppositely charged carbon electrodes for energy production from salinity differences journal January 2017
Recent developments and future perspectives of reverse electrodialysis technology: A review journal January 2018
Membrane Distillation and Reverse Electrodialysis for Near-Zero Liquid Discharge and low energy seawater desalination journal December 2015