Osmotic power

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Osmotic power, salinity gradient power or blue energy is the energy available from the difference in the salt concentration between seawater and river water. Two practical methods for this are reverse electrodialysis (RED) and pressure retarded osmosis (PRO). Both processes rely on osmosis with membranes. The key waste product is brackish water. This byproduct is the result of natural forces that are being harnessed: the flow of fresh water into seas that are made up of salt water.

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In 1954, Pattle [1] suggested that there was an untapped source of power when a river mixes with the sea, in terms of the lost osmotic pressure, however it was not until the mid ‘70s where a practical method of harnessing it using selectively permeable membranes by Loeb [2] was outlined.

The method of generating power by pressure retarded osmosis was invented by Prof. Sidney Loeb in 1973 at the Ben-Gurion University of the Negev, Beersheba, Israel. [3] The idea came to Prof. Loeb, in part, as he observed the Jordan River flowing into the Dead Sea. He wanted to harvest the energy of mixing of the two aqueous solutions (the Jordan River being one and the Dead Sea being the other) that was going to waste in this natural mixing process. [4] In 1977 Prof. Loeb invented a method of producing power by a reverse electrodialysis heat engine. [5]

The technologies have been confirmed in laboratory conditions. They are being developed into commercial use in the Netherlands (RED) and Norway (PRO). The cost of the membrane has been an obstacle. A new, lower cost membrane, based on an electrically modified polyethylene plastic, made it fit for potential commercial use. [6] Other methods have been proposed and are currently under development. Among them, a method based on electric double-layer capacitor technology [7] and a method based on vapor pressure difference. [8]

Basics of salinity gradient power

Pressure-retarded osmosis Blue energy mechanism.svg
Pressure-retarded osmosis

Salinity gradient power is a specific renewable energy alternative that creates renewable and sustainable power by using naturally occurring processes. This practice does not contaminate or release carbon dioxide (CO2) emissions (vapor pressure methods will release dissolved air containing CO2 at low pressures—these non-condensable gases can be re-dissolved of course, but with an energy penalty). Also as stated by Jones and Finley within their article “Recent Development in Salinity Gradient Power”, there is basically no fuel cost.

Salinity gradient energy is based on using the resources of “osmotic pressure difference between fresh water and sea water.” [9] All energy that is proposed to use salinity gradient technology relies on the evaporation to separate water from salt. Osmotic pressure is the "chemical potential of concentrated and dilute solutions of salt". [10] When looking at relations between high osmotic pressure and low, solutions with higher concentrations of salt have higher pressure.

Differing salinity gradient power generations exist but one of the most commonly discussed is pressure-retarded osmosis (PRO). Within PRO seawater is pumped into a pressure chamber where the pressure is lower than the difference between fresh and salt water pressure. Fresh water moves in a semipermeable membrane and increases its volume in the chamber. As the pressure in the chamber is compensated a turbine spins to generate electricity. In Braun's article he states that this process is easy to understand in a more broken down manner. Two solutions, A being salt water and B being fresh water are separated by a membrane. He states "only water molecules can pass the semipermeable membrane. As a result of the osmotic pressure difference between both solutions, the water from solution B thus will diffuse through the membrane in order to dilute solution A". [11] The pressure drives the turbines and power the generator that produces the electrical energy. Osmosis might be used directly to "pump" fresh water out of The Netherlands into the sea. This is currently done using electric pumps.

Efficiency

A 2012 study on efficiency from Yale University concluded that the highest extractable work in constant-pressure PRO with a seawater draw solution and river water feed solution is 0.75 kWh/m3 (2.7 kJ/L) while the free energy of mixing is 0.81 kWh/m3 (2.9 kJ/L) — a thermodynamic extraction efficiency of 91.0%. [12]

Methods

While the mechanics and concepts of salinity gradient power are still being studied, the power source has been implemented in several different locations. Most of these are experimental, but thus far they have been predominantly successful. The various companies that have utilized this power have also done so in many different ways as there are several concepts and processes that harness the power from salinity gradient.

Pressure-retarded osmosis

Simple PRO power generation scheme Simplistic pressure retarded osmosis power generation diagram.jpg
Simple PRO power generation scheme
Osmotic Power Prototype at Tofte (Hurum), Norway Hurum osmosis power 02.JPG
Osmotic Power Prototype at Tofte (Hurum), Norway

One method to utilize salinity gradient energy is called pressure-retarded osmosis. [13] In this method, seawater is pumped into a pressure chamber that is at a pressure lower than the difference between the pressures of saline water and fresh water. Freshwater is also pumped into the pressure chamber through a membrane, which increase both the volume and pressure of the chamber. As the pressure differences are compensated, a turbine is spun, providing kinetic energy. This method is being specifically studied by the Norwegian utility Statkraft, which has calculated that up to 2.85 GW would be available from this process in Norway. [14] Statkraft has built the world's first prototype PRO power plant on the Oslo fjord which was opened by Princess Mette-Marit of Norway [15] on November 24, 2009. It aimed to produce enough electricity to light and heat a small town within five years by osmosis. At first, it did produce a minuscule 4 kilowatts – enough to heat a large electric kettle, but by 2015 the target was 25 megawatts – the same as a small wind farm. [16] In January 2014 however Statkraft announced not to continue this pilot. [17] Statkraft found that with existing technology, the salt gradient was not high enough to be economic, which other studies have agreed on. [18] Higher salt gradients can be found in geothermal brines and desalination plant brines, [19] and SaltPower, a Danish company, is now building its first commercial plant with high salinity brine. [20] There is perhaps more potential in integrating Pressure Retarded Osmosis as an operating mode of reverse osmosis, rather than a stand-alone technology. [21]

Reversed electrodialysis

RED-prototype of REDstack at the Afsluitdijk in The Netherlands RED-proefinstallatie afsluitdijk.JPG
RED-prototype of REDstack at the Afsluitdijk in The Netherlands

A second method being developed and studied is reversed electrodialysis or reverse dialysis, which is essentially the creation of a salt battery. This method was described by Weinstein and Leitz as “an array of alternating anion and cation exchange membranes can be used to generate electric power from the free energy of river and sea water.”

The technology related to this type of power is still in its infant stages, even though the principle was discovered in the 1950s. Standards and a complete understanding of all the ways salinity gradients can be utilized are important goals to strive for in order to make this clean energy source more viable in the future.

Capacitive method

A third method is Doriano Brogioli's [7] capacitive method, which is relatively new and has so far only been tested on lab scale. With this method energy can be extracted out of the mixing of saline water and freshwater by cyclically charging up electrodes in contact with saline water, followed by a discharge in freshwater. Since the amount of electrical energy which is needed during the charging step is less than one gets out during the discharge step, each completed cycle effectively produces energy. An intuitive explanation of this effect is that the great number of ions in the saline water efficiently neutralizes the charge on each electrode by forming a thin layer of opposite charge very close to the electrode surface, known as an electric double layer. Therefore, the voltage over the electrodes remains low during the charge step and charging is relatively easy. In between the charge and discharge step, the electrodes are brought in contact with freshwater. After this, there are less ions available to neutralize the charge on each electrode such that the voltage over the electrodes increases. The discharge step which follows is therefore able to deliver a relatively high amount of energy. A physical explanation is that on an electrically charged capacitor, there is a mutually attractive electric force between the electric charge on the electrode, and the ionic charge in the liquid. In order to pull ions away from the charged electrode, osmotic pressure must do work. This work done increases the electrical potential energy in the capacitor. An electronic explanation is that capacitance is a function of ion density. By introducing a salinity gradient and allowing some of the ions to diffuse out of the capacitor, this reduces the capacitance, and so the voltage must increase, since the voltage equals the ratio of charge to capacitance.

Vapor pressure differences: open cycle and absorption refrigeration cycle (closed cycle)

Both of these methods do not rely on membranes, so filtration requirements are not as important as they are in the PRO & RED schemes.

Open cycle

Similar to the open cycle in ocean thermal energy conversion (OTEC). The disadvantage of this cycle is the cumbersome problem of a large diameter turbine (75 meters +) operating at below atmospheric pressure to extract the power between the water with less salinity & the water with greater salinity.

Absorption refrigeration cycle (closed cycle)

For the purpose of dehumidifying air, in a water-spray absorption refrigeration system, water vapor is dissolved into a deliquescent salt water mixture using osmotic power as an intermediary. The primary power source originates from a thermal difference, as part of a thermodynamic heat engine cycle.

Solar pond

At the Eddy Potash Mine in New Mexico, a technology called "salinity gradient solar pond" (SGSP) is being utilized to provide the energy needed by the mine. This method does not harness osmotic power, only solar power (see: solar pond). Sunlight reaching the bottom of the saltwater pond is absorbed as heat. The effect of natural convection, wherein "heat rises", is blocked using density differences between the three layers that make up the pond, in order to trap heat. The upper convection zone is the uppermost zone, followed by the stable gradient zone, then the bottom thermal zone. The stable gradient zone is the most important. The saltwater in this layer can not rise to the higher zone because the saltwater above has lower salinity and is therefore less-dense and more buoyant; and it can not sink to the lower level because that saltwater is denser. This middle zone, the stable gradient zone, effectively becomes an "insulator" for the bottom layer (although the main purpose is to block natural convection, since water is a poor insulator). This water from the lower layer, the storage zone, is pumped out and the heat is used to produce energy, usually by turbine in an organic Rankine cycle. [22]

In theory a solar pond could be used to generate osmotic power if evaporation from solar heat is used to create a salinity gradient, and the potential energy in this salinity gradient is harnessed directly using one of the first three methods above, such as the capacitive method.

Boron nitride nanotubes

A research team built an experimental system using boron nitride that produced much greater power than the Statkraft prototype. It used an impermeable and electrically insulating membrane that was pierced by a single boron nitride nanotube with an external diameter of a few dozen nanometers. With this membrane separating a salt water reservoir and a fresh water reservoir, the team measured the electric current passing through the membrane using two electrodes immersed in the fluid either side of the nanotube.

The results showed the device was able to generate an electric current on the order of a nanoampere. The researchers claim this is 1,000 times the yield of other known techniques for harvesting osmotic energy and makes boron nitride nanotubes an extremely efficient solution for harvesting the energy of salinity gradients for usable electrical power.

The team claimed that a 1 square metre (11 sq ft) membrane could generate around 4 kW and be capable of generating up to 30 MWh per year. [23]

At the 2019 fall meeting of the Materials Research Society a team from Rutgers University reported creating a membrane that contained around 10 million BNNTs per cubic centimeter. [24] [25]

Using low caloric waste energy by regenerate a high solution ammonium bicarbonate in a solution with a low salinity

At Pennsylvania State University, Dr. Logan tries to use waste heat with low calority using the fact that ammonium bicarbonate decomposes into NH3 and CO2 in warm water to form ammonium bicarbonate again in cold water. So in a RED energy producing closed system the two different gradients of salinity are kept. [26]

Possible negative environmental impact

Marine and river environments have obvious differences in water quality, namely salinity. Each species of aquatic plant and animal is adapted to survive in either marine, brackish, or freshwater environments. There are species that can tolerate both, but these species usually thrive best in a specific water environment. The main waste product of salinity gradient technology is brackish water. The discharge of brackish water into the surrounding waters, if done in large quantities and with any regularity, will cause salinity fluctuations. While some variation in salinity is usual, particularly where fresh water (rivers) empties into an ocean or sea anyway, these variations become less important for both bodies of water with the addition of brackish waste waters. Extreme salinity changes in an aquatic environment may result in findings of low densities of both animals and plants due to intolerance of sudden severe salinity drops or spikes. [27] According to the prevailing environmentalist opinions, the possibility of these negative effects should be considered by the operators of future large blue energy establishments.

The impact of brackish water on ecosystems can be minimized by pumping it out to sea and releasing it into the mid-layer, away from the surface and bottom ecosystems.

Impingement and entrainment at intake structures are a concern due to large volumes of both river and sea water utilized in both PRO and RED schemes. Intake construction permits must meet strict environmental regulations and desalination plants and power plants that utilize surface water are sometimes involved with various local, state and federal agencies to obtain permission that can take upwards to 18 months.

See also

Related Research Articles

<span class="mw-page-title-main">Brine</span> Concentrated solution of salt in water

Brine is water with a high-concentration solution of salt. In diverse contexts, brine may refer to the salt solutions ranging from about 3.5% up to about 26%. Brine forms naturally due to evaporation of ground saline water but it is also generated in the mining of sodium chloride. Brine is used for food processing and cooking, for de-icing of roads and other structures, and in a number of technological processes. It is also a by-product of many industrial processes, such as desalination, so it requires wastewater treatment for proper disposal or further utilization.

<span class="mw-page-title-main">Desalination</span> Removal of salts from water

Desalination is a process that takes away mineral components from saline water. More generally, desalination is the removal of salts and minerals from a target substance, as in soil desalination, which is an issue for agriculture. Saltwater is desalinated to produce water suitable for human consumption or irrigation. The by-product of the desalination process is brine. Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on cost-effective provision of fresh water for human use. Along with recycled wastewater, it is one of the few rainfall-independent water resources.

<span class="mw-page-title-main">Dialysis (chemistry)</span> Process of separating molecules

In chemistry, dialysis is the process of separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane, such as dialysis tubing.

<span class="mw-page-title-main">Forward osmosis</span> Water purification process

Forward osmosis (FO) is an osmotic process that, like reverse osmosis (RO), uses a semi-permeable membrane to effect separation of water from dissolved solutes. The driving force for this separation is an osmotic pressure gradient, such that a "draw" solution of high concentration, is used to induce a net flow of water through the membrane into the draw solution, thus effectively separating the feed water from its solutes. In contrast, the reverse osmosis process uses hydraulic pressure as the driving force for separation, which serves to counteract the osmotic pressure gradient that would otherwise favor water flux from the permeate to the feed. Hence significantly more energy is required for reverse osmosis compared to forward osmosis.

Solar desalination is a desalination technique powered by solar energy. The two common methods are direct (thermal) and indirect (photovoltaic).

<span class="mw-page-title-main">Solar pond</span> Solar thermal energy

A solar pond is a pool of saltwater which collects and stores solar thermal energy. The saltwater naturally forms a vertical salinity gradient also known as a "halocline", in which low-salinity water floats on top of high-salinity water. The layers of salt solutions increase in concentration with depth. Below a certain depth, the solution has a uniformly high salt concentration.

<span class="mw-page-title-main">Electrodialysis</span> Applied electric potential transport of salt ions.

Electrodialysis (ED) is used to transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference. This is done in a configuration called an electrodialysis cell. The cell consists of a feed (dilute) compartment and a concentrate (brine) compartment formed by an anion exchange membrane and a cation exchange membrane placed between two electrodes. In almost all practical electrodialysis processes, multiple electrodialysis cells are arranged into a configuration called an electrodialysis stack, with alternating anion and cation-exchange membranes forming the multiple electrodialysis cells. Electrodialysis processes are different from distillation techniques and other membrane based processes in that dissolved species are moved away from the feed stream, whereas other processes move away the water from the remaining substances. Because the quantity of dissolved species in the feed stream is far less than that of the fluid, electrodialysis offers the practical advantage of much higher feed recovery in many applications.

A solar-powered desalination unit produces potable water from saline water through direct or indirect methods of desalination powered by sunlight. Solar energy is the most promising renewable energy source due to its ability to drive the more popular thermal desalination systems directly through solar collectors and to drive physical and chemical desalination systems indirectly through photovoltaic cells.

Reverse electrodialysis (RED) is the salinity gradient energy retrieved from the difference in the salt concentration between seawater and river water. A method of utilizing the energy produced by this process by means of a heat engine was invented by Prof. Sidney Loeb in 1977 at the Ben-Gurion University of the Negev. --United States Patent US4171409

Sidney Loeb (1917–2008) was an American-Israeli chemical engineer. Loeb made reverse osmosis (RO) practical by developing, together with Srinivasa Sourirajan, semi-permeable anisotropic membranes. The invention of the practical reverse osmosis membrane revolutionized water desalination. Loeb invented the power generating process pressure retarded osmosis (PRO)--making accessible a rich previously unknown source of green energy, and a method of producing power by a reverse electrodialysis (RED) heat engine, among other inventions in related fields. The production of energy by PRO and RED, among others, is sometimes called "osmotic power."

Reverse osmosis (RO) is a water purification process that uses a semi-permeable membrane to separate water molecules from other substances. RO applies pressure to overcome osmotic pressure that favors even distributions. RO can remove dissolved or suspended chemical species as well as biological substances, and is used in industrial processes and the production of potable water. RO retains the solute on the pressurized side of the membrane and the purified solvent passes to the other side. It relies on the relative sizes of the various molecules to decide what passes through. "Selective" membranes reject large molecules, while accepting smaller molecules.

<span class="mw-page-title-main">Osmosis</span> Chemical process

Osmosis is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential to a region of low water potential, in the direction that tends to equalize the solute concentrations on the two sides. It may also be used to describe a physical process in which any solvent moves across a selectively permeable membrane separating two solutions of different concentrations. Osmosis can be made to do work. Osmotic pressure is defined as the external pressure required to be applied so that there is no net movement of solvent across the membrane. Osmotic pressure is a colligative property, meaning that the osmotic pressure depends on the molar concentration of the solute but not on its identity.

<span class="mw-page-title-main">Pressure-retarded osmosis</span>

Pressure retarded osmosis (PRO) is a technique to separate a solvent from a solution that is more concentrated and also pressurized. A semipermeable membrane allows the solvent to pass to the concentrated solution side by osmosis. The technique can be used to generate power from the salinity gradient energy resulting from the difference in the salt concentration between sea and river water.

<span class="mw-page-title-main">Marine energy</span> Energy stored in the waters of oceans

Marine energy or marine power refers to the energy carried by ocean waves, tides, salinity, and ocean temperature differences. The movement of water in the world's oceans creates a vast store of kinetic energy, or energy in motion. Some of this energy can be harnessed to generate electricity to power homes, transport and industries.

<span class="mw-page-title-main">Capacitive deionization</span>

Capacitive deionization (CDI) is a technology to deionize water by applying an electrical potential difference over two electrodes, which are often made of porous carbon. In other words, CDI is an electro-sorption method using a combination of a sorption media and an electrical field to separate ions and charged particles. Anions, ions with a negative charge, are removed from the water and are stored in the positively polarized electrode. Likewise, cations are stored in the cathode, which is the negatively polarized electrode.

<span class="mw-page-title-main">Seawater desalination in Australia</span>

Australia is the driest habitable continent on Earth and its installed desalination capacity has been increasing. Until a few decades ago, Australia met its demands for water by drawing freshwater from dams and water catchments. As a result of the water supply crisis during the severe 1997–2009 drought, state governments began building desalination plants that purify seawater using reverse osmosis technology. Approximately one percent of the world's drinkable water originates from desalination plants.

<span class="mw-page-title-main">Statkraft osmotic power prototype in Hurum</span>

Statkraft osmotic power prototype is the world's first osmotic power plant, based on the energy of osmosis. The power plant is run by Statkraft. The power plant is located at Tofte in Hurum, Norway, with rooms at the factory area at Södra Cell Tofte cellulose factory. The power plant uses the osmotic gradient that occurs when fresh water and salt water meet, separated by a permeable membrane. The salt water pulls fresh water through the membrane and the pressure increases on the salt water side; this pressure increase can be used to produce electrical power with the use of a normal hydroelectric turbine/generator setup.

Osmosis is the movement of molecules through a membrane.

Concentration polarization is a term used in the scientific fields of electrochemistry and membrane science.

A microbial desalination cell (MDC) is a biological electrochemical system that implements the use of electro-active bacteria to power desalination of water in situ, resourcing the natural anode and cathode gradient of the electro-active bacteria and thus creating an internal supercapacitor. Available water supply has become a worldwide endemic as only .3% of the Earth's water supply is usable for human consumption, while over 99% is sequestered by oceans, glaciers, brackish waters, and biomass. Current applications in electrocoagulation, such as microbial desalination cells, are able to desalinate and sterilize formerly unavailable water to render it suitable for safe water supply. Microbial desalination cells stem from microbial fuel cells, deviating by no longer requiring the use of a mediator and instead relying on the charged components of the internal sludge to power the desalination process. Microbial desalination cells therefore do not require additional bacteria to mediate the catabolism of the substrate during biofilm oxidation on the anodic side of the capacitor. MDCs and other bio-electrical systems are favored over reverse osmosis, nanofiltration and other desalination systems due to lower costs, energy and environmental impacts associated with bio-electrical systems.

References

  1. ↑ R.E. Pattle (2 October 1954). "Production of electric power by mixing fresh and salt water in the hydroelectric pile". Nature. 174 (4431): 660. Bibcode:1954Natur.174..660P. doi:10.1038/174660a0. S2CID   4144672.
  2. ↑ S. Loeb (22 August 1975). "Osmotic power plants". Science. 189 (4203): 654–655. Bibcode:1975Sci...189..654L. doi:10.1126/science.189.4203.654. PMID   17838753.
  3. ↑ ^ Israel Patent Application 42658 of July 3, 1973. (see also US 3906250 Erroneously shows Israel priority as 1974 instead of 1973 US 3906250
  4. ↑ ^ Weintraub, Bob. "Sidney Loeb," Bulletin of the Israel Chemical Society, Dec. 2001, issue 8, page 8-9. https://drive.google.com/file/d/1hpgY6dd0Qtb4M6xnNXhutP4pMxidq_jqG962VzWt_W7-hssGnSxSzjTY8RvW/edit
  5. ↑ United States Patent US4171409 Archived 2016-04-06 at the Wayback Machine
  6. ↑ History of osmotic power (PDF) at archive.org
  7. 1 2 Brogioli, Doriano (2009-07-29). "Extracting Renewable Energy from a Salinity Difference Using a Capacitor". Physical Review Letters. 103 (5). American Physical Society (APS): 058501. Bibcode:2009PhRvL.103e8501B. doi:10.1103/physrevlett.103.058501. ISSN   0031-9007. PMID   19792539.
  8. ↑ Olsson, M.; Wick, G. L.; Isaacs, J. D. (1979-10-26). "Salinity Gradient Power: Utilizing Vapor Pressure Differences". Science. 206 (4417). American Association for the Advancement of Science (AAAS): 452–454. Bibcode:1979Sci...206..452O. doi:10.1126/science.206.4417.452. ISSN   0036-8075. PMID   17809370. S2CID   45143260.
  9. ↑ (Jones, A.T., W. Finley. “Recent developments in salinity gradient power”. Oceans. 2003. 2284-2287.)
  10. ↑ (Brauns, E. “Toward a worldwide sustainable and simultaneous large-scale production of renewable energy and potable water trough salinity gradient power by combining reversed electrodialysis and solar power?” Environmental Process and Technology. Jan 2007. 312-323.)
  11. ↑ (Brauns, E. “Toward a worldwide sustainable and simultaneous large-scale production of renewable energy and potable water through salinity gradient power by combining reversed electrodialysis and solar power?.” Environmental Process and Technology. Jan 2007. 312-323.)
  12. ↑ Yin Yip, Ngai; Elimelech, Menachem (2012). "Thermodynamic and Energy Efficiency Analysis of Power Generation from Natural Salinity Gradients by Pressure Retarded Osmosis". Environmental Science & Technology. 46 (9): 5230–5239. Bibcode:2012EnST...46.5230Y. doi:10.1021/es300060m. PMID   22463483. S2CID   206955094.
  13. ↑ Salinity-gradient power: Evaluation of pressure-retarded osmosis and reverse electrodialysis
  14. ↑ Recent Developments in Salinity Gradient Power Archived 2011-09-01 at the Wayback Machine
  15. ↑ "The world's first osmotic power plant from Statkraft". 27 November 2009. Archived from the original on 2011-08-12. Retrieved 2009-11-27. Statkraft-osmotic-power
  16. ↑ BBC News Norway's Statkraft opens first osmotic power plant
  17. ↑ "Is PRO economically feasible? Not according to Statkraft | ForwardOsmosisTech". 22 January 2014. Archived from the original on 2017-01-18. Retrieved 2017-01-18.
  18. ↑ Straub, Anthony P.; Deshmukh, Akshay; Elimelech, Menachem (2016). "Pressure-retarded osmosis for power generation from salinity gradients: is it viable?". Energy & Environmental Science. 9 (1). Royal Society of Chemistry (RSC): 31–48. doi:10.1039/c5ee02985f. ISSN   1754-5692.
  19. ↑ Chung, Hyung Won; Swaminathan, Jaichander; Banchik, Leonardo D.; Lienhard, John H. (2018). "Economic framework for net power density and levelized cost of electricity in pressure-retarded osmosis". Desalination. 448. Elsevier BV: 13–20. doi:10.1016/j.desal.2018.09.007. hdl: 1721.1/118349 . ISSN   0011-9164. S2CID   105934538.
  20. ↑ Saltpower
  21. ↑ Rao, Akshay K.; Li, Owen R; Wrede, Luke; Coan, Stephen M.; Elias, George; Cordoba, Sandra; Roggenberg, Michael; Castillo, Luciano; Warsinger, David M. (2021). "A framework for blue energy enabled energy storage in reverse osmosis processes". Desalination. 511. Elsevier BV: 115088. doi:10.1016/j.desal.2021.115088. ISSN   0011-9164.
  22. ↑ Salinity Gradient Solar Pond Technology Applied to Potash Solution Mining
  23. ↑ "Nanotubes boost potential of salinity power as a renewable energy source". Gizmag.com. 13 March 2013. Archived from the original on 2013-10-28. Retrieved 2013-03-15.
  24. ↑ Service, Robert F. (2019-12-04). "Rivers could generate thousands of nuclear power plants worth of energy, thanks to a new 'blue' membrane". Science | AAAS. Archived from the original on 2019-12-06. Retrieved 2019-12-06.
  25. ↑ "Symposium Sessions | 2019 MRS Fall Meeting | Boston". www.mrs.org. Archived from the original on 2019-11-29. Retrieved 2019-12-06.
  26. ↑ "Energy from Water". Archived from the original on 2017-02-02. Retrieved 2017-01-28.
  27. ↑ Montague, C., Ley, J. A Possible Effect of Salinity Fluctuation on Abundance of Benthic Vegetation and Associated Fauna in Northeastern Florida Bay. Estuaries and Coasts. 1993. Springer New York. Vol.15 No. 4. Pg. 703-717
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