WO2010088919A1 - Réservoir d'énergie osmotique - Google Patents

Réservoir d'énergie osmotique Download PDF

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Publication number
WO2010088919A1
WO2010088919A1 PCT/EG2009/000020 EG2009000020W WO2010088919A1 WO 2010088919 A1 WO2010088919 A1 WO 2010088919A1 EG 2009000020 W EG2009000020 W EG 2009000020W WO 2010088919 A1 WO2010088919 A1 WO 2010088919A1
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Prior art keywords
solution
pressure
membrane
energy
reservoir
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PCT/EG2009/000020
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English (en)
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Ahmed Aly Fahmy Elsaid
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Ahmed Aly Fahmy Elsaid
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Priority to PCT/EG2009/000020 priority Critical patent/WO2010088919A1/fr
Publication of WO2010088919A1 publication Critical patent/WO2010088919A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/025—Reverse osmosis; Hyperfiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/002—Forward osmosis or direct osmosis
    • B01D61/005—Osmotic agents; Draw solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/025—Reverse osmosis; Hyperfiltration
    • B01D61/026—Reverse osmosis; Hyperfiltration comprising multiple reverse osmosis steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/06—Energy recovery
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2313/00—Details relating to membrane modules or apparatus
    • B01D2313/24—Specific pressurizing or depressurizing means
    • B01D2313/246—Energy recovery means

Definitions

  • the present invention relates to the technical field of energy storage and, in particular, to a method and apparatus for converting and storing electrical and/or mechanical energy in the form of osmotic energy.
  • the stored osmotic energy is converted into electrical and/or mechanical energy when required.
  • the source of the energy is the excess available energy, such as solar energy and wind energy, during the periods of low demand.
  • Storing energy in quantities high enough to compensate the shortage of energy source for several days is a perfect solution to increase the reliability of renewable energy, such as solar energy and wind energy, so increases its capability for high penetration in a power grid.
  • Storing energy means storing electrical and/or mechanical energy during the periods of low demand, and at the same time, high availability of the intermittent energy source, then converting stored energy back into electrical energy during periods of no or low availability of the intermittent energy source.
  • Storing energy in batteries in the form of electrochemical energy is one of the used methods for storing energy. During low demand periods the excess energy is used to charge the batteries that will supply energy when required. Batteries are not convenient for large scale storage systems because of its high cost.
  • the capacity factor of the power plant is 25%
  • number of days that the batteries will supply the load without additional energy input is 10 days
  • batteries used are led-acid batteries 200 Ah 12 Volt
  • the minimum allowable state of charge of the batteries is 25%
  • the actual capacity of the battery is 80% of the nominal capacity
  • the head at which the pumps and the turbines operate depends on the geography of the location of the system. Some locations have as low as 100 meters head; others have more than 700 meters head. As the energy density is in linear relationship with the head, locations with low head are inconvenient for several days' storage capacity; this makes the convenient locations rarer. Therefore, a need exists for a novel method that uses cheap and common materials as energy storage medium and, also, this novel method can be implemented in locations where there are no such requirements for the site characteristic.
  • the method disclosed in the present invention stores the energy in the form of osmotic energy, and then when required, converts it into electric energy.
  • the method comprises two phases: “reverse osmosis phase”, during this phase the energy storage process takes place, and the other phase is “osmosis phase”, during this phase process of converting stored energy into electric energy takes place.
  • Pressure exchanger array comprises a large number of pressure exchanger units. Each pressure exchanger unit is a positive displacement device; its function is to transfer pressure from a high pressure fluid to a low pressure fluid.
  • the high pressure solution enters the pressure exchanger at point 9 and leaves at point 10 where its pressure drops.
  • the low pressure solution enters the pressure exchanger unit at point 4 and leaves at point 6 where it gains its pressure.
  • the pressure at point 6 - P6 is less than P9 and PlO is less than P4.
  • a medium concentration aqueous solution exits reservoir Rl at point 1 where it splits into two portions, one is withdrawn at point 2 by the high pressure pump HP and pressurized to point 5 and the other is withdrawn at point 3 by the booster pump BPl then by the pressure exchanger array PX and pressurized at point 6, the pressure at point 6 - P6 is equal to P5.
  • the function of BPl is to compensate part of the pressure losses in the pressure exchanger array PX.
  • the solution delivered by pressure exchanger array PX and the solution delivered by the high pressure pump HP are mixed again together at point 7, which has the same pressure as points 6 and 5, where the solution enters the membrane array M.
  • a reverse osmosis process takes place in the membrane array and due to this process the entering solution at point 7 is split into two portions, one exits at point 8, the pressure at point 8 P8 is slightly less than P7— this pressure drop is due to the pressure losses along the membrane surface— while the concentration of the solution at point 8 is high, therefore the osmotic pressure at point 8 is also high— higher than that at point 7.
  • the other portion of the solution, called the permeate passes through the membrane then it exits the membrane array at point 11.
  • the pressure at point 11 is atmospheric pressure, while the concentration of the solution at point 11 is low, therefore the osmotic pressure at point 11 is also low. This low osmotic pressure solution flows to reservoir R2 where it is stored.
  • the high osmotic pressure solution at point 8 which is also high static pressure solution, gains more pressure by the booster pump BP2 and leaves the pump at point 9, this slight pressure increase in BP2 is required to compensate the pressure losses along the membrane surface and part of the pressure losses in the pressure exchanger array.
  • the high osmotic pressure solution loses its static pressure and leaves the pressure exchanger array, at atmospheric pressure, and flows to reservoir R3, at point 10, where it is stored.
  • the permeate flows from the high osmotic pressure side to the low osmotic pressure side if the following condition is satisfied: (P8 - P11) - ( ⁇ 8 - 7ill) > 0 Or P8 > ( ⁇ 8 - ⁇ ll) + Pll (1)
  • the excess available energy of a power plant which is the input of this phase, is employed., mainly, to operate the high pressure pump HP and the booster pumps BPl and BP2.
  • the output of this phase is that two bodies of different concentration solution have been provided.
  • osmotic potential which is capable of producing energy in a later phase, has been created.
  • osmosis phase The main components of osmosis phase are illustrated in Fig. 2, these components are: medium concentration reservoir Rl, low concentration reservoir R2, high concentration reservoir R3, hydraulic turbine T, three booster pumps BP3, BP4 and BP5, membrane array M and pressure exchanger array PX.
  • osmosis phase takes place to generate required electric energy to feed the load.
  • a high concentration solution therefore it is also a high osmotic pressure solution— exits reservoir R3 at point 10 where its static pressure increases by means of three devices.
  • First device is booster pump BP3 where the solution gains a slight static pressure increase, at point 12, to compensate part of the pressure losses in the pressure exchanger array PX.
  • Second device is pressure exchanger PX where it gains most of its pressure at point 13.
  • Third device is booster pump BP4 where the solution gains a slight pressure increase, at point 14, to compensate the pressure losses along the membrane surface and part of the pressure losses in the pressure exchanger array. Then the solution enters the membrane M at point 14.
  • a low concentration solution therefore it is also a low osmotic pressure solution —exits reservoir R2 at point 11 where its static pressure is atmospheric.
  • the solution is withdrawn by booster pump BP5 where the solution gains a slight pressure increase, at point 21, to compensate the pressure losses in the membrane array.
  • the low static pressure solution which is also low osmotic pressure solution, enters the membrane array M at point 21 where osmosis process takes place, and due to this process most of the entering solution at point 21— the permeate— passes through the membrane to the other side of the membrane where it mixes with the solution entering the membrane at point 14, then the solution exits the membrane array at point 15.
  • the osmotic pressure of the solution at point 15 is less than that at point 14, and that is because it mixes with the permeate which has a very low osmotic pressure.
  • the static pressure at point 15 is slightly less than that at point 14 due to pressure losses in the membrane array.
  • the permeate flows from the low osmotic pressure side to the high osmotic pressure side if the following condition is satisfied:
  • the solution at point 15 splits into two portions, one enters the pressure exchanger array at point 17 and exits at point 19 at atmospheric pressure, the other portion enters the turbine T at point 16 and exits at point 18 at atmospheric pressure.
  • the energy contained in the solution due to its high static pressure is converted, in the turbine, into mechanical energy, which usually will convert into electric energy.
  • Most of the energy generated by the turbine will supply the load with the required electric energy, while a small portion is used to operate BP3, BP4 and BP5.
  • Most of the solution at point 21 passes through the membrane to the other side of the membrane, while the rest of it exits the membrane at point 22.
  • the solution at point 22 is called the bleed, and it is important for keeping the concentration inside the membrane, at the low concentration side, at low limit.
  • the solution exiting the turbine and the solution exiting the pressure exchanger mix again at point 20 where it mix with the bleed where it returns to its concentration at point 1 and stored again in Rl.
  • Figure 1 is a schematic diagram illustrating the reverse osmosis phase of a single stage energy storage apparatus according to one embodiment of the present invention.
  • Figure 2 is a schematic diagram illustrating the osmosis phase of a single stage energy storage apparatus according to one embodiment of the present invention.
  • Figures 3A and 3B illustrate the operation of a pressure exchanger.
  • Figures 4A and 4B illustrate the usage of the pressure exchanger array in reverse osmosis phase and osmosis phase.
  • Figure 5 is a section in a pressure vessel of a membrane array.
  • Figures 6A and 6B are schematic diagrams illustrating an efficient use of the storage reservoirs in both reverse osmosis phase and osmosis phase.
  • Figure 7 shows a proposal for implementing the method of the present invention in a solar power plant.
  • Figures 8A and 8B are schematic diagrams illustrating a multistage energy storage apparatus according to the best mode of the invention in both reverse osmosis phase and osmosis phase.
  • Figures 9 and 10 are schematic diagrams illustrating the usage of medium pressure membranes with high osmotic pressure solution.
  • the pressure exchanger array comprises a large number of pressure exchanger units arranged in parallel; the pressure exchanger unit is a positive displacement device.
  • the rotary pressure exchanger is efficient and durable, but as its operation involves leakage between the two different concentration solutions, which causes a reduction in the osmotic potential, the preferred type is the reciprocation pressure exchanger.
  • each pressure exchanger unit consists of a cylinder 301, inside the cylinder a free piston 302 moving along the axis of the cylinder.
  • the flow of the liquids is controlled by electrically operated valves: the inlet valves 303a and 303d and outlet valves 303b and 303c.
  • the liquid A which is at high static pressure, enters cylinder 301 at point (a) through the open valve 303a.
  • valves 303c and 303d are closed, the flow of the liquid A pushes the piston 302 in the direction shown in figure 3a, and the piston pushes the liquid B to exit the cylinder through the open valve 303b.
  • Liquid B exits the cylinder, at point (b), at a pressure slightly less than the pressure of liquid A at point (a).
  • the difference between the pressure at point (a) and the pressure at point (b) is equal to the pressure losses due to the flow from point (a) to (b) and due to the friction between the piston and the cylinder.
  • the piston moves until it reaches the sensing element 304b—the sensing element might be photocell or limit switch.
  • the sensing element sends signal to valves 303a and 303b to close and to valves 303c and 303d to open.
  • the liquids inside the piston are isolated from the high pressure at points (a) and (b), and pressure equalization takes place between the liquids inside the cylinder and the points (c) and (d).
  • the pressure at point (d) is low and it is slightly lower at point (c), the fluid B enters cylinder 301 at point (d) through the open valve 303d.
  • valves 303a and 303b are closed, the flow of the liquid B pushes the piston 302 in the direction shown in figure 3B, and the piston pushes the liquid A to exit the cylinder through the open valve 303c.
  • Liquid A exits the cylinder, at point (c), at a pressure slightly less than the pressure of liquid B at point (d). the difference between the pressure at point (d) and the pressure at point (c) is equal to the pressure losses due to the flow from point (d) to (c) and due to the friction between the piston and the cylinder.
  • the piston moves until it reaches the sensing element 304a, as shown in figure 3A the sensing element sends signal to valves 303c and 303d to close and to valves 303a and 303b to open to start new cycle.
  • the pressure exchanger array is a common component between both phases of the invention. In other words, there is no need to add a pressure exchanger array in each phase, as both phases will not work simultaneously.
  • the designated maximum flow rate of the pressure exchanger array is equal to that of the highest maximum flow rate of the two phases. Using the same pressure exchanger array with the phase of the lower maximum flow rate does not affect the performance, in contrary, the losses are less as the liquids' velocities are less.
  • FIG. 4A illustrates the pressure exchanger array when it is used in the reverse osmosis phase, when the valves al, bl, cl, and dl are open and valves a2, b2, c2, and d2 are closed, the direction of flow will be as it is in figure 1. (reverse osmosis phase).
  • FIG 4B which illustrates the pressure exchanger array when used in the reverse osmosis phase, when the valves al, bl, cl, and dl are closed and valves a2, b2, c2, and d2 are open, the direction of flow will be as it is in figure 2. (osmosis phase).
  • the membrane array comprises a large number of pressure vessels arranged in parallel.
  • the pressure vessel PV in fig. 5 is a long cylindrical shaped vessel inside which a number of membrane elements are arranged in series.
  • the membrane element ME is of cylindrical shape which fits inside the pressure vessel. In the center of the membrane element a perforated tube PT.
  • aqueous solution enters the pressure vessel at point (e) and passes along the membrane elements where it exits at point (f).
  • the membrane layer allows only water to pass across the membrane layer, whereas it is impermeable to the solute of the solution. Although the membrane is impermeable to the solute, a small portion of the solute can pass across the membrane layer.
  • the measure of the ability of the membrane to reject the solute is the rejection coefficient.
  • the permeate collects in the perforated tube PT where it mixes with another solution entering the perforated tube at point (g), the solution that results from this mixing exits the perforated tube at point (h).
  • the permeate splits from the solution driving away the solvent (water) whereas most of the solutes remains, therefore the concentration of the solution at point (f) is higher than that at point (e). Also the solution at point (g) mixes with a lower concentration solution (the permeate), therefore the concentration of the resultant solution at point (h) is less than that at point (g).
  • the volume of solution enters the membrane at point (e) equals to the sum of the volumes exit the membrane (the solution that exits at point (f) and the volume of the permeate), So:
  • V e Vp err neate + V f (4) Also, the volume of solution exits the perforated tube at point (h) equals to the sum of the volumes enter the perforated tube (the solution that enters at point (g) and the volume of the permeate), So:
  • V h V permeate + V g (5)
  • the concentration of the entering solution at (e) is higher than the concentration of the entering solution at (g).
  • the reverse osmosis process takes place when the following condition is satisfied:
  • the concentration of the entering solution at (e) is less than the concentration of the entering solution at (g).
  • the osmosis process takes place when the following condition is satisfied:
  • the membrane array is a common component between both phases of the invention.
  • Two valves at each of the four points (e), (f), (g), and (h) are connected. Each valve is connected, from the other side, to the proper component of the apparatus. One valve is open during the reverse osmosis phase and the other is closed, and vice versa.
  • E ro is the total input energy in the reverse osmosis phase
  • E 0 is the net output energy produced in the osmosis phase. More specifically, and referring back to figuresl and 2, E ro is the energy required to split a solution of volume Vl that occupies the reservoir Rl in figure 1, into two solutions of volumes VIl and VlO that occupy the reservoirs R2 and R3 respectively, and E 0 is the energy produced by joining two solutions of volumes VIl and VlO that occupy the reservoirs R2 and R3 respectively in figure 2, into one solution of volume Vl that occupies the reservoir Rl. When estimating these energies, we are dealing with energy and volume— not power and volume flow rate.
  • E BPljn , E BP2 i n , E BP3in , E BP4in , E B p 5in are the energy consumed by booster pumps BPl, BP2, BP3, BP4, BP5
  • E HP i n is the energy consumed by high pressure pump HP
  • E T o ut is the energy produced by hydraulic turbine T. It is obvious that the efficiency increases with the term E TOut and it decreases with the increase of all other terms of equation (11).
  • the terms E BPljn , E B p 2 j n , E BP3in , E B p 4in , E BP5in are not the main terms which affect the efficiency of the method, as their values are small.
  • ⁇ ⁇ and ⁇ P are the turbine efficiency and the high pressure pump efficiency.
  • V per mea t ei the permeate volume in the reverse osmosis phase. Equation (14) means that the volume handled by the high pressure pump HP (V5) is equal to the volume of the permeate in the reverse osmosis phase.
  • V16 V permeate2 (15)
  • V permeate2 is the permeate volume in the osmosis phase. Equation (15) means that the volume handled by the turbine T (V16) is equal to the volume of the permeate in the osmosis phase.
  • V5 V16 + V22 (16)
  • V5 is the volume handled by the high pressure pump
  • V16 is the volume handled by the turbine
  • V22 is the volume of the bleed.
  • the bleed in the osmosis phase, is the necessary portion of the low concentration solution which should be allowed to exit the membrane in order to keep the concentration inside the membrane, in the low concentration side, at low limit. Equation (16) means that the volume handled by the high pressure pump HP is larger than the volume handled by the turbine T, and the difference equals to the volume of the bleed.
  • the bleed instead of mixing the bleed (represented by point 22) with the solution at point 20, the bleed is stored in a separate reservoir and will mix with the rest of the solution in a different way, thus the volume V5 will be reduced. This will be detailed when describing figures 8A and 8B which illustrates the best mode.
  • the concentration of the solution at point (f) is higher than that at point (e).
  • the increase of the concentration depends on the ratio of the volume of the permeate to the volume entering at point (e). In the reverse osmosis desalination plants, this ratio is called Recovery Ratio and this expression will be used hereafter.
  • the difference between the concentration at point 8 and the concentration at point 7 increases with the increase of the recovery ratio of the reverse osmosis phase.
  • the solution at point f flows to point 7 without mixing with solutions of other concentration, therefore the concentration at point 7 equals to the concentration at point 1.
  • the concentration at point 15 is equal to the concentration at point 20
  • the solution at point 20 mixes with the bleed (point 22) and composes the solution at point 1 but as the volume of the bleed is small compared to the volume of the solution at point 20, therefore the concentration at point 20 is slightly higher than that at point 1. So the concentration at point 15 is slightly higher than that at point 7. So, we can conclude that the difference between the concentration at point 8 and the concentration at point 15 increases and decreases with the increase and decrease of the recovery ratio of the reverse osmosis phase.
  • the difference between the osmotic pressure at point 8 and the osmotic pressure at point 15 ( ⁇ 8 - ⁇ l5) increases and decreases with the increase and decrease of the recovery ratio of the reverse osmosis phase.
  • 0SS is the pressure losses in the membrane which is, approximately, equal to the pressure rise by the booster pump BP2.
  • P21 - PIl is equal to the pressure rise by the booster pump BP5.
  • 0SS and (P21 - PIl) are small compared to P7 min and P15 max , besides they are in opposite sides of the equation and have the same sign and there values are approximately equal, therefore the two terms can be neglected.
  • a high overall efficiency of the method requires a low recovery ratio of the reverse osmosis phase.
  • the storage medium is the solution which is stored in the reservoirs of the apparatus.
  • the preferred solution A) should be ionic solution with high solubility in order to have high osmotic potential; B) the viscosity of the solution should be low when it is in its highest concentration, to reduce the pressure losses arising from the flow of the solution in the different components of the apparatus; C) it should be common and cheap, therefore it should be aqueous solution and the solute is a common salt such as sodium chloride, but the preferred solution is concentrated sea water.
  • the source of the raw water from which the concentrated sea water is produced is a near sea, and it is produced in the last few months before the start up of a system constructed according to the present invention, and during the construction period.
  • the concentrated sea water is produced by the means of a multistage reverse osmosis plant, this plant is not part of the system, but it is part of the construction equipments. As the production of the solution can take several months, the size of this temporary RO plant is small. Still another smaller plant is required to be a permanent part of the system for the purposes of maintenance and to compensate any leakage might happen.
  • rejection coefficient is 100 % (it is more than 99% for commercial membranes)
  • the solution at point 11— which is stored in reservoir R2 in the reverse osmosis phase— in figure 1 is pure water (the concentration is zero ).
  • C15 V14 .
  • V14 V15 - V21 V15 .
  • C15 (V15 - V21) .
  • High energy density reduces the required volume of the storage medium, accordingly it also reduces the required volumetric capacity of the reservoirs that contain the storage medium.
  • the structure of the reservoirs is of reinforced concrete.
  • FIG. 6A and 6B illustrate an arrangement of the reservoirs where the volume of the reservoirs is only 120% of the volume of the storage medium i.e. the excess volume is 20%.
  • the reservoir R2 is divided into 12 equal sections (from R2-1 to R2-12), the volume of each section is 10% of the maximum volume of the solution at point 11 in figures 1 and 2 i.e. when the system is in full storage state.
  • Each of these sections is connected to the system through two valves: VIvIl and VIvI.
  • the reservoir R3 is divided into 12 equal sections (from R3-1 to R3-12), the volume of each section is 10% of the maximum volume of the solution at state 10 in figures 1 and 2 i.e. when the system is in full storage state.
  • Each of these sections is connected to the system through two valves: VIvIO and VIvI.
  • figure 6B illustrates the status of the valves and the directions of flow during the osmosis phase assuming that R2-12 and R3-12 are the source of the solutions at state 11 and 10 respectively and that R2-10 and R3-10 are the receivers of the solution at state 1.
  • FIG. 7 shows an example of a large photovoltaic array where the photovoltaic array is installed on the upper surface of the concrete reservoirs. In the middle of the reservoirs is the power plant. The power plant comprises all other components of both power generation system and energy storage system. The design in figure 7 does not require any additional area requirements for the energy storage system.
  • Membrane productivity is the power produced in the osmosis phase per unit area of the membrane.
  • the membrane array is a major component of the present invention, it is very important to have a high Membrane productivity, thus reducing the required size of the membrane array.
  • the solution used in the system is obtained through artificial process.
  • the purpose is to have the highest possible concentration—
  • the high concentration provides a high osmotic pressure— at point 14 in figure 2.
  • the osmotic pressure at point 15 is also high.
  • the static pressure at point 16 is high.
  • the pressure at point 16 is the inlet pressure of the turbine.
  • the flow rate of the turbine is equal to the flow rate of the permeate. Therefore the power generated by the turbine is higher than that the power generated in other methods using pressure lower than that at point 16 and having the same permeate flow. Therefore, the present method has membrane productivity higher than that used in other methods having the same permeate flow rate.
  • the present invention has another advantage regarding to the membrane maintenance.
  • the methods employing reverse osmosis or osmosis process use an open cycle i.e. the source of the solution is open such as seawater.
  • the solution of these sources has a high level of impurities and requires a costly process of filtration and treatment to maintain the membrane in good condition.
  • the present method is a closed cycle where the system will be charged once during the start up of the system, so this costly filtration and treatment is performed once at the start up. The ongoing filtration and treatment requirement is much less than the open cycle.
  • Figures 8A and 8B illustrate the schematic diagrams of the best mode.
  • the method comprises three stages— the number of stages is illustrative and the present invention is not limited to this number of stages.
  • reservoir R4 is added to store the bleed generated in the osmosis phases instead of mixing it with the rest of the solution in Rl, then in the osmosis phase it enters the membrane separately— the bleed has a small volume compared to the total volume of the solution.
  • the reservoirs R2 and R3 are divided into sections, a section of reservoir Rl is composed by connecting two sections from R2 and R3.
  • valves are added to the system in two groups, when the valves of one group are open the valves of the other group are closed, so there are two positions, in one position the system works in the reverse osmosis phase and in the other it works in the osmosis phase.
  • a medium concentration solution (at point 1 figure 8A) stored in the reservoirs R2-1 and R3-1 (which are connected together and acting as one section of reservoir Rl through two open valves) flows, exactly as previously described, through booster pump PBl-I, pressure exchanger PXl, high pressure pump HPl, and membrane array Ml where it splits into the permeate and a solution at point 23.
  • the solution at point 23 starts the second stage through PB1-2, HP2, PX2, and M2 where it splits into anther mount of the permeate and a solution at point 24.
  • the solution at point 24 starts the third stage through PB1-3, HP3, PX3, and M3 where it splits into anther mount of the permeate and a solution at point 25.
  • the solution at point 25 has a high osmotic pressure and a high static pressure; it gains slight pressure by booster pump BP2, then it flows to the reservoir R3-3 through the series of pressure exchangers where it exchanges its pressure.
  • a high concentration solution (at point 10 figure 8B) stored in the reservoirs R3-5 gains a high pressure through a series of booster pumps and pressure exchangers BP3-1, PXl, BP3-2, PX2, BP3-3, PX3, and BP4, then it enters the perforated tube of the membrane M3 of the third stage— at point 26— where it increases its volume by mixing with the permeate of this stage, then it flows through turbine T3 and pressure exchanger PX3 and collects at point 27.
  • the solution at point 27 enters the second stage through M2, T2 and PX2 and collects at point 28.
  • the solution at point 28 enters the third stage through M3, T3 and PX3 and collects at point 1 where it is stored in the reservoirs R2-7 and R3-7 (which are connected together and acting as one section of reservoir Rl through two open valves).
  • the solution at point 10 starts to flow from the reservoirs R3-5
  • another solution starts to flow from reservoir R2-5 at point 11 and enter the first stage through booster pump BP5-1 and the membrane array Ml.
  • the rest of the solution at point 29 starts second stage through BP5-2 and M2 where the permeate splits and the rest of the solution at point 30 starts third stage through BP5-3 and M3 where the permeate splits and the rest of the solution at point 22 (the bleed) is stored in reservoir R4.
  • V49 V52.
  • P52 . Vl . ⁇ ⁇ 0.271 .
  • T2 and T3 we can estimate the energy produced by T2 and T3. Therefore the energy produced according to the multistage option is:
  • E ⁇ ou tM (0.271 . P52 + 0.171 . (P53 - P52) + 0.081 . (P54 - P53)) . Vl . ⁇ ⁇ (22)
  • E TOu ts 0.1 . P54 . Vl . ⁇ ⁇ .
  • P54 P52 + (P53 - P52) + (P54 - P53), so;
  • the solution at point 65 enters at point 65 and exits the membrane at point 66 where it enters the pump P which delivers the solution at point 67 at a higher pressure.
  • the solution enters the membrane ML and exits at point 68 with the same osmotic pressure of point 65.
  • the pressure at point 68— which is, approximately, equals to the pressure delivered by the pump P— is:
  • the static pressure at points 63 and 64 is atmospheric while it is high at points 61 and 62.
  • the intermediate solution at points 65, 66, 67 and 68 is kept at intermediate static pressure.
  • the process in membrane ML is the same as the previous arrangement, whilst the static pressure at point 62 is very high— P62 > ( ⁇ 62 - ⁇ 63)— so that the reverse osmosis process takes place; This high static pressure applies high stresses on the membrane.
  • a bypass valve BV is required to control the concentration of the intermediate solution. The losses in this arrangement are low.
  • the ambient temperature has small effect on the efficiency of the method. As the ambient temperature varies along the hours of the day, the temperature of the solution varies. But the osmotic pressure of a solution is in linear relationship with its absolute temperature, therefore the required pressure to operate the high pressure pumps, when the solution is warmer, is higher. While the operating pressure of the turbines, when the solution is colder, is lower.
  • the effect of temperature on efficiency is very small for the following reasons: A) the fluctuation of the ambient temperature along the day is small compared to the average absolute temperature, B) the fluctuation of the temperature of the solution is less than the fluctuation of the ambient temperature, C) when using photovoltaic arrays as the source of energy, the difference between the average temperature of the solution during reverse osmosis phase (energy consuming phase) and the average temperature during osmosis phase (energy generating phase) is less than the fluctuation of the temperature of the solution.
  • the effect of the temperature is less when using wind farms as the source of energy.
  • the present invention is perfectly exploited when used as energy storage method for large scale renewable energy power plants that requires large storage capacity enough to supply the load for days.
  • the perfect storage system comprises several modules. Increasing the number of modules increases the average efficiency of the system as the pumps and turbines will work close to their optimum point on their performance curve.
  • Each module comprises the multistage apparatus described above, for example six stages. Therefore the system comprises a large number of turbines, high pressure pumps and booster pumps. The capacity of these turbines and pumps should be high, as small turbines and pumps have insufficient efficiency. So, this large number of high capacity equipments requires large scale power plants.
  • the cost of all other components of the system are not related to the storage capacity of the system, but they are related to the power plant capacity and the maximum demand load. Therefore the disclosed energy storage method becomes more feasible when it is required to have large storage capacity for a specific power plant capacity.

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  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Nanotechnology (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

La présente invention concerne un procédé et un appareil permettant de stocker de l''énergie pendant des périodes où on dispose d'un excédent de production d'une centrale électrique utilisant une source d'énergie renouvelable. On utilise l'énergie en excédant pour pressuriser une solution à concentration de milieu (1) dont la pression statique est supérieure à la pression osmotique, ce qui fait que lors de la présentation contre une membrane semi-perméable, la solution se sépare par osmose inverse en deux parties: une solution à haute concentration (10), et le perméat (11), chacune des deux parties étant mise en réserve dans un réservoir. Pendant les périodes de faible disponibilité de la source de production d'énergie, la solution (10) est pressurisée à une pression inférieure à sa pression osmotique, puis elle est introduite sur la membrane semi-perméable où son volume augmente en reprenant par osmose du perméat (11). La solution résultante est introduite à l'entrée d'une turbine de production d'énergie. Une partie de l'énergie produite est utilisée pour pressuriser la solution (10), le reste de l'énergie produite alimentant la charge.
PCT/EG2009/000020 2009-09-06 2009-09-06 Réservoir d'énergie osmotique WO2010088919A1 (fr)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013033082A1 (fr) * 2011-08-31 2013-03-07 Oasys Water, Inc. Moteur thermique osmotique
WO2016090216A1 (fr) * 2014-12-04 2016-06-09 Solutions Labs, Inc. Échangeur thermique et de pression hybride
US20200047125A1 (en) * 2018-08-13 2020-02-13 Pani Energy Inc. Fluid management system and method
US20220243695A1 (en) * 2018-05-11 2022-08-04 Innovator Energy, LLC Fluid displacement systems and methods
WO2022200288A1 (fr) * 2021-03-25 2022-09-29 Technische Universität Darmstadt Réservoir intermédiaire d'énergie pour installations de production d'électricité

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US3906250A (en) * 1973-07-03 1975-09-16 Univ Ben Gurion Method and apparatus for generating power utilizing pressure-retarded-osmosis
US4193267A (en) * 1977-02-25 1980-03-18 Ben-Gurion University Of The Negev Research & Development Authority Method and apparatus for generating power utilizing pressure-retarded osmosis
JPH01224500A (ja) * 1988-03-03 1989-09-07 Mitsubishi Electric Corp 揚水機
DE19742259A1 (de) * 1997-09-25 1999-04-01 Schmidt Luesmann Jochen Dr Ing Verfahren zur Energieerzeugung
EP1161981A2 (fr) * 1994-10-12 2001-12-12 Toray Industries, Inc. Appareil et procédé de séparation par osmose inverse à plusieurs étapes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3906250A (en) * 1973-07-03 1975-09-16 Univ Ben Gurion Method and apparatus for generating power utilizing pressure-retarded-osmosis
US4193267A (en) * 1977-02-25 1980-03-18 Ben-Gurion University Of The Negev Research & Development Authority Method and apparatus for generating power utilizing pressure-retarded osmosis
JPH01224500A (ja) * 1988-03-03 1989-09-07 Mitsubishi Electric Corp 揚水機
EP1161981A2 (fr) * 1994-10-12 2001-12-12 Toray Industries, Inc. Appareil et procédé de séparation par osmose inverse à plusieurs étapes
DE19742259A1 (de) * 1997-09-25 1999-04-01 Schmidt Luesmann Jochen Dr Ing Verfahren zur Energieerzeugung

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013033082A1 (fr) * 2011-08-31 2013-03-07 Oasys Water, Inc. Moteur thermique osmotique
WO2016090216A1 (fr) * 2014-12-04 2016-06-09 Solutions Labs, Inc. Échangeur thermique et de pression hybride
US10519985B2 (en) 2014-12-04 2019-12-31 Breakthrough Technologies, LLC Hybrid pressure and thermal exchanger
US11125251B2 (en) 2014-12-04 2021-09-21 Breakthrough Technologies, LLC Hybrid pressure and thermal exchanger
US20220243695A1 (en) * 2018-05-11 2022-08-04 Innovator Energy, LLC Fluid displacement systems and methods
US11981586B2 (en) * 2018-05-11 2024-05-14 Innovator Energy, LLC Fluid displacement energy storage with fluid power transfer
US20200047125A1 (en) * 2018-08-13 2020-02-13 Pani Energy Inc. Fluid management system and method
WO2022200288A1 (fr) * 2021-03-25 2022-09-29 Technische Universität Darmstadt Réservoir intermédiaire d'énergie pour installations de production d'électricité

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