TECHNICAL FIELD

[0001] The present disclosure generally relates to the field of hybrid energy storage systems for storing mechanical and electrical energy.

BACKGROUND

[0002] Free energy from various sources is available in abundance quantities in nature. However, the availability of free energy may change, periodically or chaotically, depending on the nature of the specific energy source.

[0003] Likewise, the amounts of energy demanded by consumers, may change periodically or chaotically.

[0004] It is therefore may be of interest to store energy at availability times, for supplying to consumers later in time, upon demand.

[0005] While only small fractions of Earth's free energy are harnessed by humanity, certain amounts of human efforts and recourses, are invested in generating energy artificially for addressing real-time demands, i.e. for immediate consumption.

[0006] The situation hints that the costs involved in storing energy for later use on- demand, are sometimes higher than the costs involved in generating energy artificially.

[0007] The nominal peek-power capability of an energy generating facility is commonly adapted to the maximal expected consumption from the facility. Most of the time, however, the consumed power may be way below the maximal. In such circumstances it may be of interest to produce more power than necessary in real-time (i.e. more power than the real-time consumption), and to store the surplus power for later use at times when the consumption increases. For justification of such surplus energy production, the costs involved in energy storage should be sufficiently low.

[0008] It is among the object of the presently disclosed subject matter to improve the efficiency of energy storage systems, _^ thereby making stored energy more competitive with respect to artificially generated energy and/or with respect to energy to be generated in real-time in response to temporal increase in consumption. BRIEF SUMMARY

[0009] A first broad aspect of the disclosed subject matter is a system for storing energy for outputting on demand, comprising at least one rotatable body of a predetermined mass constituting a flywheel, said flywheel constitutes a spinning mass upon rotation thereof; at least one energy exchanging arrangement configured to convert a predetermined form of energy into angular momentum of the spinning mass, and to retrieve kinetic energy from the spinning mass; a rechargeable electrical storage device having a predetermined mass, wherein the mass of the electrical storage device constitutes a portion of the mass of the rotatable body; and a control system for administering energy flow into and out of the flywheel and of the electrical storage device; whereby when the flywheel spins at a given angular velocity and the electrical storage device is both spinning as part of the flywheel and electrically charged to a predetermined degree, the density of extractable energy stored in the electrical storage device for outputting under control of the control system is greater than the density of energy stored by a non-rotatable electrical storage device of a similar mass and charged to a similar degree, by the amount of extractable kinetic energy stored in the mass of the electrical storage device due to its spinning.

[0010] In various embodiments of the disclosed subject matter, the at least one energy exchanging arrangement is or includes an electrical motor-generator in a single unit, functioning as a motor when the control system directs electrical energy into it from either an external source or from the electrical storage device, and functioning as a generator when the control system directs electrical energy from it into either the electrical storage device or an external energy consumer.

[0011] In various embodiments of the disclosed subject matter, the energy exchanging arrangement comprises both a motor and a generator separated from the motor, each having a rotor coaxially arranged about an axis of rotation of the flywheel.

[0012] In various embodiments of the disclosed subject matter, the rotor of the motor and the rotor of the generator are longitudinally separated along the flywheel's axis of rotation.

[0013] In various embodiments of the disclosed subject matter, the system for storing energy for outputting on demand is further comprising an onboard DC to AC converter having a predetermined mass, the mass of the DC to AC converter constituting a portion of the mass of the rotatable body. [0014] In various embodiments of the disclosed subject matter, the system for storing energy for outputting on demand comprises an AC generator and an AC output, wherein an AC generated by the generator is of a frequency in correlation with a rotation frequency of the spinning mass and is outputted to an external consumer through the AC output of the system, the system further comprises an onboard DC to AC converter configured to extract DC energy from the electrical storage device, upon demand, for conversion into AC energy and supply it through the AC output of the system.

[0015] In various embodiments of the disclosed subject matter, the DC to AC converter is configured to dynamically synchronize with the frequency of the AC generated by the generator while the DC to AC converter extracts DC from the electrical storage device, such that an electrical energy supplied trough the AC output of the system and having a given momentary AC frequency, includes energy extracted simultaneously from both the electrical storage device and the angular momentum of the spinning mass.

[0016] In various embodiments of the disclosed subject matter, the control system is configured to regulate DC from the electrical storage device to the motor for maintaining the rotation frequency of the spinning mass unchanged for time periods starting when a first condition is met and ending when a second condition is met.

[0017] In various embodiments of the disclosed subject matter, the electrical storage device is a capacitor, an ultracapacitor, a rechargeable battery, or a combination thereof.

[0018] In the context of the present disclosure amounts or percentages specified in integer numbers are to be considered inclusive of fractions of such amounts or percentages smaller than 0.5 from above what is specified and equal or greater than 0.5 from below what is specified.

[0019] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes at least 50% of the rotatable mass.

[0020] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes between 40% - 60% of the rotatable mass.

[0021] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes at least 70% of the mass of the rotatable body.

[0022] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes between 61% - 80% of the mass of the rotatable body.

[0023] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes at least 90% of the mass of the rotatable body. [0024] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes between 81% - 95% of the mass of the rotatable body.

[0025] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes between 11% - 95% of the rotatable mass, wherein a mass of a motor constituting the at least one of a motor and a generator, constitutes at least 4% of the rotatable mass.

[0026] In various embodiments of the disclosed subject matter, the mass of the electrical storage device constitutes between 11% - 95% of the rotatable mass, wherein a mass of a generator constituting the at least one of a motor and a generator, constitutes at least 4% of the rotatable mass.

[0027] In various embodiments of the disclosed subject matter, the electrical storage device comprises a plurality of cylindrical coaxially arranged material layers, each of a different predetermined radius whereby a layer having a radius smaller from the radius of another is enveloped within the another, whereby the layers are free to stretch individually under centrifugal forces generated by the spinning.

[0028] In various embodiments of the disclosed subject matter, the electrical storage device comprises a plurality of material layers, each constituting a separate constructional member of the rotatable body.

[0029] In various embodiments of the disclosed subject matter, the electrical storage device comprises an array of a predetermined number of coaxially arranged electrodes of a first material type intermittently arranged with a respective predetermined number of coaxially arranged electrodes of a second material type.

[0030] In various embodiments of the disclosed subject matter, the system is further comprising a slip-ring (either contact-based or wireless slipring), wherein the control system is in communication with a circuitry of the electrical storage device through the slip-ring.

[0031] In various embodiments of the disclosed subject matter, the control system and a circuitry of the electrical storage device are configured to mutually communicate wirelessly.

[0032] In various embodiments of the disclosed subject matter, a circuitry comprising at least one current line or coil on the rotatable body, is configured to collect energy for charging the electrical storage device by electromagnetic conduction, taking advantage of the spinning of the rotatable body as a means for the current line or coil for cutting magnetic lines produced outside the spinning body by energy extracted from an external source of electrical energy.

[0033] In various embodiments of the disclosed subject matter, a circuitry comprising at least one current line or coil on the rotatable body, is configured to produce a magnetic field by electrical energy extracted from the electrical storage device, said magnetic field is spinning with the spinning of the rotatable body thereby inducing electrical currents in at least current line or coil located outside of the rotatable body thus outputting electrical energy from the electrical storage device.

[0034] In various embodiments of the disclosed subject matter, the system for storing energy for outputting on demand is further comprising at least one photo-voltaic panel mounted as a part of the rotatable body and configured to electrically charge the electrical storage device by solar energy, the photo-voltaic panel is of a predetermined mass, the mass of the photovoltaic panel constitutes a part of the mass of the rotatable body.

[0035] A second broad aspect of the disclosed subject matter is method for increasing energy storage density of combined flywheel and electrical storage devices, the method comprising; providing at least one rotatable body of a predetermined mass constituting a flywheel, said flywheel constitutes a spinning mass upon rotation thereof and having a given maximal storage density of rotational kinetic energy per mass unit; providing as an onboard constituent of the mass of the rotatable body a rechargeable electrical storage device having a predetermined mass and a given maximal storage density of electrical energy per mass unit; thereby increasing the maximal amount of energy that can be carried by the rotatable body for outputting on demand, without increasing the mass of the rotatable body.

BRIEF DESCRIPTION OF THE FIGURES

[0036] The present disclosed subject matter will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which corresponding or like numerals or characters indicate corresponding or like components. Unless indicated otherwise, the drawings provide exemplary embodiments or aspects of the disclosure and do not limit the scope of the disclosure. In the drawings:

[0037] Fig. 1A illustrates schematics of a first exemplifying embodiment of a system for storing energy for outputting portions thereof on demand, according to the presently disclosed subject matter.

[0038] Fig. 1B illustrates schematics of a second exemplifying embodiment of a system for storing energy for outputting portions thereof on demand, according to the presently disclosed subject matter.

[0039] 1C illustrates a schematics of a third exemplifying embodiment of a system for storing energy for outputting portions thereof on demand, wherein the system comprises two coaxial separately rotatable flywheels.

[0040] Fig. 2A illustrates schematics of a fourth exemplifying embodiment of a system for storing energy for outputting portions thereof on demand, according to the presently disclosed subject matter, comprising a driving arrangement and an electrical generator in separate units.

[0041] Fig. 2B illustrates schematics of a variation of the embodiment of Fig. 2, with the motor and the generator located from opposite ends of the flywheel.

[0042] Fig. 2C illustrates schematics of a variation of the embodiment of Fig. 2, with the motor and the generator located one inside the other.

[0043] Fig. 2C illustrates schematics of a variation of the embodiment of Fig. 1B, with the M&G unit located inside the flywheel.

^' [0044] Fig. 3 illustrates a top view of a system for storing mechanical and electrical energy for outputting portions thereof on demand.

[0045] Fig. 4 illustrates a flow diagram of an example of a cycle of operation of a system according to the embodiment illustrated by Fig. 1A

[0046] Fig. 5 illustrates a flow diagram of an example of a cycle of operation of a system according to the embodiment illustrated by Fig. 1C DETAILED DESCRIPTION OF THE FIGURES

[0047] Fig. 1A illustrates schematics of an exemplifying embodiment of a system 100 for storing energy (mechanical and electrical) for outputting on demand, according to a first broad aspect of the presently disclosed subject matter.

[0048] The system 100 comprises (i) at least one rotatable body of a predetermined mass constituting a flywheel 101, said flywheel constitutes a spinning mass upon rotation thereof; (ii) a driving arrangement 102 (the driving arrangement may be anyone of a motor, a generator, a motor-generator, or a transmission system, according to the specific embodiment from a variety of possible embodiments and according to in site energy availability and demands) configured to exchange energy between one or more energy sources and one or more energy consumers wherein the spinning mass 101 being an energy source at times and an energy consumer at other times, with which the driving arrangement exchanges energy; (iii) a rechargeable electrical storage device 103 having a predetermined mass, wherein the mass of the electrical storage device 103 constitutes a portion of the rotatable mass 101 ; and (iv) a control system 104 for administering energy flow into and out of the electrical storage device 103 whereby when the flywheel spins at a given angular velocity and the electrical storage device is charged to a predetermined degree, the density of reusable energy stored in the electrical storage device 103 for outputting to the benefit of an external energy consumer is greater than the density of reusable energy stored by a non-spinning electrical storage device of a similar mass and carrying similar amount of reusable electrical charge, by the amount of reusable kinetic energy stored in the mass of the electrical storage device due to being spinning.

[0049] In various embodiments of the disclosed subject matter, the driving arrangement 102 is a transmission system (e.g. a gearbox, a transmission belt, a turbo, or the like) configured to deliver to the spinning mass mechanical energy retrievable from an external energy source.

[0050] In various embodiments of the disclosed subject matter, the driving arrangement 102 is a combustion-engine.

[0051] In various embodiments of the disclosed subject matter, the driving arrangement 102 is an electrical motor configured to convert electrical energy into angular momentum of the spinning mass.

[0052] In some embodiments of the disclosed subject matter the motor 102 includes a gearbox unit. [0053] In some embodiments of the disclosed subject matter the motor 102 includes a clutch. In various embodiments of the disclosed subject matter the clutch is electrical.

In some embodiments the electrical clutch comprises an electrical command port electrically coupled to the control unit, wherein the control unit 104 is configured to control the clutch for coupling and decoupling mechanical energy from the motor to the flywheel.

[0054] In some embodiments of the disclosed subject matter the control system is configured to route electrical energy from the rechargeable electrical storage device to the motor 102, upon detection of predetermined conditions. In various embodiments of the disclosed subject matter, the conditions include decrease in the angular velocity of the spinning mass to below a predetermined velocity value. In various embodiments of the disclosed subject matter the conditions include real-time retrieval of mechanical energy from the spinning mass by a mechanical energy consumer. The energy delivered from the spinning mass to the consumer tends to decrease the angular momentum of the spinning mass, while by routing electrical energy from the electrical storage device to the motor 102, the expected decrease in the angular momentum may be at least partially compensated for, by the electrical energy consumed. In various embodiments of the disclosed subject matter the conditions include availability of at least a predetermined amount of electrical energy in the electrical storage device (such that in case the electrical storage device had nearly run-out of electrical charge, further discharging is eliminated).

[0055] In the present embodiment the control system 104 and the electrical storage device communicate through a slipring 118.

[0056] In various embodiments of the disclosed subject matter at least one of the electrodes of the electrical storage device is configured to constitute, either alone or in combination with additional reinforcing materials, constructional reinforcement to other parts of the rotatable mass, said reinforcement increases the resistance of the rotatable mass against tearing or disintegrating under centrifugal forces, thus increases the max allowed spinning velocity of the rotatable mass.

[0057] In various embodiments of the disclosed subject matter, the additional reinforcing materials are or include carbon fibers.

[0058] In various embodiments of the disclosed subject matter, the additional reinforcing materials are or include composite materials. · [0059] The control system 104 may comprise electronic or electromechanically operable switches for directing electrical energy into the electrical storage device 103, and to extract energy therefrom on demand. In various embodiments of the disclosed subject matter the electromechanically operable switches are oriented on the spinning mass with movable contactor members thereof arranged to have their direction of motion parallel to the direction of spinning (i.e. perpendicularly to their radius of rotation), thereby eliminating centrifugal forces from affecting (or reducing the effect of such forces on) the operation of the switch.

[0060] Energy extracted from the electrical storage device 103 through the slipring 1 18 may be directed by the control system 104 either to the electrical energy outlet 151, or to the electrical motor 102.

[0061] Likewise, in case the embodiment includes a motor-generator (abbreviated MG or M&G) version (with the motor constituting the driving arrangement for propelling the flywheel to spin), electrical energy extracted from the MG may be directed by the control system 104 either through the slipring 118 to the electrical storage device 103 for recharging, or to the electrical energy outlet 151 , for use by an external consumer. In various embodiments of the system according to the presently disclosed subject matter, the control system may comprise at least one AC to DC converter and/or at least one DC to AC converter, and/or a pulsating DC to smooth DC converter. Depending on the embodiment's features, and on the requirements of the system's consumer/s, the MG may be an AC motor-generator or a DC motor generator, with the AC or DC supplied to and extracted from, manipulated by the control system 104 for satisfying the requirements of the destination device in terms of energy type, frequency, and voltage.

[0062] In various embodiments of the presently disclosed subject matter, the system comprises more than one rotatable mass, a first and a second of which, 101 and 141, respectively (shown in Fig. 1C), are rotatable coaxially.

[0063] In various embodiments of the presently disclosed subject matter in which the system comprises coaxially rotatable masses, said first and second rotatable masses may rotate each in an angular velocity differing from the angular velocity of the other, either in magnitude, direction (clockwise vs. counterclockwise), or both magnitude and direction.

[0064] In various embodiments according to the presently disclosed subject matter the system comprises coaxially rotatable masses, each of the rotatable masses is associated with a separate respective motor, wherein a stator unit of the motor is stationary and wherein a rotor unit of the motor constitute a part of the rotatable mass. In other various embodiments of the presently disclosed subject matter in which the system comprises coaxially rotatable masses, said first and second rotatable masses are associated with a common motor, wherein a first unit of the motor constituting a stator from view point of the second rotatable mass constitutes a part of the first rotatable mass, wherein a second unit of the motor constituting a rotor from view point of the second rotatable mass, constitutes a part of the first rotatable mass, wherein a rotation velocity of the motor is equal to the difference between the rotation velocities of the first and the second rotatable masses.

[0065] In various embodiments of the system according to the presently disclosed subject matter, the system comprises at least one rotatable mass having solar panels 101 s (especially useful for outer space missions with the flywheel spinning weightlessness in atmosphere-free environment and exposed to sunlight), wherein a mass of the solar panels constitutes a part of the rotatable mass and the panels are configured to convert solar energy into electrical energy useful for either boosting the motor or for recharging the electrical storage device. In various embodiments of the disclosed subject matter the solar panels lOls are arranged on the outer circumference of the flywheel 101. In some embodiments the solar panels are arranged on the top and bottom surfaces of the flywheel 101.

[0066] In various embodiments of the system according to the presently disclosed subject matter, the rotatable mass is maintained in a vacuumed environment for reducing loss of angular momentum due to interaction with ambient gas or air. In various embodiments of the presently disclosed subject matter the electrical storage device comprises sealed gas hydrogen containing compartments, wherein the gas confined in the compartments (e.g. hydrogen) constitutes an electrode of a rechargeable battery constituting the electrical storage device, wherein a mass of the hydrogen constitutes a part of the rotatable mass.

[0067] In various embodiments of the system according to the presently disclosed subject matter, the bearing system lOlb comprises magnetic bearings for avoiding loss of angular momentum due to friction.

[0068] In various embodiments of the system according to the presently disclosed subject matter, the bearing system lOlb comprises compressed gas bearings for minimizing loss of angular momentum due to friction. [0069] In a first broad aspect, the presently disclosed subject matter includes a disclosure of an ESS (energy storage system) embodiment, which is configured to store energy retrieved from an external source of electrical energy 210, for later providing it, upon demand, as a mechanical energy. Obviously, mechanical energy may be converted into electrical energy, but this first broad aspect includes a disclosure of a system that outputs mechanical energy, regardless of the utilization of such energy outside the system. Conversion of mechanical energy into electrical energy to be outputted by the system itself, is dealt with hereinafter as a second broad aspect of the presently disclosed subject matter.

[0070] Referring to a system 100 according to the first broad aspect, the control system 104 is configured to recognize the availability of electrical energy from the external source and to route the electrical energy retrieved, for energizing the motor which constitutes the driving arrangement) 102. The rotor part of the motor 102 thereby gains rotational momentum by conversion of electrical energy into kinetic energy. The rotatable mass 101 thus includes the mass of the rotor part of the motor, regardless whether the motor and the flywheel 101 are formed together or are separated along the shaft 108. The rotatable mass 101 includes (apart from the mass of the motor's rotor) the mass of the electrical storage device 103, and of any of electrical conductors, electronic circuitry, magnetic elements, electrical insulation elements and constructional constituents of the electrical storage device 103 and of the slipring 118, which together constitute the flywheel's rotatable mass 101.

[0071] The control system is further configured to distribute the available electrical energy between the motor (as described above) and the electrical storage device 102. As a matter of design, the distribution of electrical energy between the motor 102 and the electrical storage device 102 may be either simultaneous (as long as the electrical storage device 103 is not fully charged) or separate in time.

[0072] In case of simultaneous distribution, a predetermined percentage of the retrievable electrical energy is directed by the control system for charging the electrical storage device 103 to a desired charging degree in a desired charging rate, and a remaining percentage of the retrievable electrical energy is directed to energize the motor 102. This may continue until the flywheel 101 gains a desired angular momentum. [0073] In various embodiments of the presently disclosed subject matter a desired value of angular momentum of the flywheel may be the value associated with a maximal allowed spinning speed (accounting for a safety margin) beyond which the flywheel and/or constituents thereof are at risk of disintegration under centrifugal forces.

[0074] In case the distribution of electrical energy is separate in time, the control system may be programmed to route electrical energy to the motor 102 and to the electrical storage device at separate times (i.e. intermittently) for desired time periods. The order of distribution may be a function of real time conditions such as predictions concerning near future energy demands based on dynamically updated information sources. The control system may be designed to compute such predictions based on date stream from external sources (e.g. sensors, control systems associated with a consumer of the stored energy, internet, computer programs, or any other desired source).

[0075] In various embodiments of the disclosed subject matter the control system 104 may be associated with a sensing device 1 14 (e.g. electro-optical sensor) for retrieving the rotation velocity of the flywheel 101, for thereby calculating and deciding on how to distribute the energy between the components of the system and between the system and the external energy source and energy consumer.

[0076] Fig. 1B illustrates schematics of an exemplifying embodiment of a system 130 for storing mechanical and electrical energy for outputting on demand. The system 130 differs from the system 100 in that the slipring 118 is substituted by a wireless slipring, or by a transformer 128. The transformer 128 communicates with the electrical storage device 103, through a bidirectional AC-DC converter 138. While electrical energy flows through the transformer 128 wirelessly, in AC form, the AC-DC converter 138 allows for either charging the electrical storage device by electrical energy extracted externally through energy inlet 150, or internally, from MG, or for extracting DC energy from the electrical storage device 103 for the use of the motor 102, or of an external consumer, through the outlet 151.

[0077] It is noted that in various embodiments of the presently disclosed subject matter, the control system 104 may comprise an internal AC-DC and/or DC-AC converter, additionally to the bidirectional AC-DC converter 138. Accordingly, the form of electrical energy required for the operation of motor 102, as well as the form of energy supplied by the system or extracted by the system to/from external sources, may be independent of the form of electrical energy flowing through line l04sr (which in the embodiment illustrated by Fig. 1A may be DC, and in the embodiment illustrated by Fig. 1B is AC).

[0078] The system 130 further comprises a vacuum pump 133 for reducing air pressure inside the housing 110, for thereby reducing loss of momentum of the flywheel due to air drag. The vacuum pump 133 may be controlled by the control system 104, and may be energized by energy extracted either internally (e.g. from the electrical storage device 103, or e.g. from the MG 102), or from an external source of electrical energy.

[0079] Fig. 1C illustrates schematics of an exemplifying embodiment of a system 140 for storing mechanical and electrical energy for outputting on demand. The system 140 differs from both the system 130, and the system 100, in that it comprises two coaxially arranged flywheels 141 and 151, in substitution of the single flywheel 101 of systems 100 and 130.

[0080] Flywheel 141 is in the form of a hollow cylinder, enveloping the internal flywheel 151 (which in various embodiments may be a hollow cylinder as well).

[0081] The outer flywheel 141 is free to rotate about the shaft 108, irrespective of rotation of the shaft 108 itself, due to bearings 141b (e.g. conic bearings) which allow for free relative rotation between the shaft 108 and the flywheel 141. Flywheel 141 may be connected to bearing 14 lb by constructional elements, e.g. brackets 141 a and 141c.

[0082] The rotation direction of flywheel 141 may thus be controlled by the control system 104 to be either clockwise (as pointed by arrows 'c') or counterclockwise, independently of the rotation direction of the inner flywheel 151 (which occasionally is shown by the arrow 'cc' to be rotating counterclockwise). Moreover, either of both flywheels may be brought to a halt while the other is spinning.

[0083] In various embodiments of the presently disclosed subject matter the bearings l4lb are immovable longitudinally along the shaft 108, e.g. due to mutual protrusion and groove arrangements l08p between the shaft and the bearings at the locations of the bearings, by which the weight of flywheel 141 is transmitted to and supported by the shaft 108 in case the system is operated with the shaft 108 in vertical orientation.

[0084] In the illustrated embodiment the internal flywheel 151 , is connected to the shaft 108 and is driven to gain angular momentum by motor 102. The externally arranged flywheel 141 is configured to gain angular momentum through configuration comprising mutual motor parts 142 and 152 which together constitute an outrunner motor, between the two flywheels. [0085] Depending on the pattern of energy flow managed by the control system 104, the outrunner motor 142, 152

[0086] by Each of the flywheels 141 and 151, comprises a separate electrical storage device, 143 and 153, respectively, wherein the mass of the electrical storage device constitutes part of the rotatable mass of the respective flywheel.

[0087] In various embodiments of the presently disclosed subject matter the system may comprise a plurality of coaxially arranged flywheels, wherein at least one of the flywheels comprises an onboard electrical storage device.

[0088] In the illustrated embodiment, energy flow between the electrical storage device 143 onboard of the externally arranged flywheel 141 and the control system 104, is through a ring like transformer 148 (which extends al around the internally arranged flywheel 151) and through a bidirectional AC-DC converter 138.

[0089] The energy flow between the electrical storage device 153 onboard of the internally arranged flywheel 151 and the control system 104, is through a slipring 148.

[0090] In a second broad aspect illustrated by Fig. 2A, the presently disclosed subject matter includes a disclosure of an ESS embodiment 200 which is configured to store energy retrieved from an external source of electrical energy 210, for later releasing it, upon demand, as an electrical energy. The ESS 200 differs from the embodiment ESS 100 by the inclusion of a generator 212, the rotor part of which constitutes a part of the flywheel rotor 201. In various embodiments of the presently disclosed subject matter, the electrical energy stored in the electrical storage device 203 may be routed (by the control system 204) either directly to an electrical energy outlet 213 of the system, or through the motor 202, for thereby transforming the electrical energy into angular momentum of the rotor 201, which the generator 212 may then use for generating and outputting electrical energy.

[0091] In various embodiments of the presently disclosed subject matter the motor 202 and the generator 212 are separate parts, the rotors of which being each coaxially mounted with (i.e. sharing a common axis of rotation with) the flywheel 201. In such embodiments the motor 202 and the generator 212 may function simultaneously. Consequently, the rotation speed of the flywheel 201 can be maintained substantially unchanged (or even increased, if so desired) by powering the motor with electrical energy from the electrical storage device while electrical energy is generated by the generator 212 and consumed by an external consumer. [0092] In various embodiments of the presently disclosed subject matter, exemplified by ESS 240 of Fig. 2B, the motor 202 and the generator 212 are arranged serially, i.e. with longitudinal separation between their rotors along the flywheel's axis 20 la.

[0093] In other various embodiments of the presently disclosed subject matter exemplified by ESS 260 of Fig. 2C, the motor 202 and the generator 212 are arranged parallelly, interior cylindrical body enveloped within exterior cylindrical body, i.e. without (or with partial) longitudinal separation between their rotors along the flywheel's axis 20 la.

[0094] Referring now to Fig. 2D, another ESS embodiment 299 is disclosed, in which the motor 202 and the generator 212 are one and the same (referred to in the present disclosure a motor-generator unit), i.e. functioning part of the time as a motor, and part of the time as a generator. When being energized by electrical energy routed by the control unit 204, either from external electrical energy source or from the electrical storage device 203, the motor-generator 222 functions as a motor, i.e. converting the routed electrical energy into angular momentum of the flywheel 201. When being connected by the control unit 204 either to the electrical charging device 203 or to an external electricity consumer, the motor-generator 222 functions as a generator, i.e. converting the angular momentum of the flywheel 201 into electrical energy.

[0095] Fig. 3 illustrates schematics of a top view of an ESS embodiment 270 according to the disclosed subject matter. The ESS comprises a rotatable mass 201 constituting a flywheel, wherein a rechargeable battery 203 comprising a plurality of cylindrical intermittent layers (shown as black and white circles, functioning in pairs as positively and negatively rechargeable electrodes) constitutes part of the rotatable mass and of its constructional and skeletal arrangement. The rechargeable battery 203 is an electrical storage device in the essence of the disclosed subject matter.

[0096] The ESS further comprises a control system 204, a part of which 204a is mounted on the flywheel (e.g. within the most inner electrode layer of the battery 203).

[0097] The electrical storage device 203 is in electrical communication with the onboard part 204a of the control system 204. The onboard part 204a of the control system 204, may include any circuitry required for recharging the battery or for retrieving energy therefrom, e.g. alternating current rectifier, AC to DC converter, DC to AC and the like. The mass of the onboard part 204a of the control system 204 constitute a part of the rotatable mass, thus, . similarly to the battery itself, being capable of storing angular momentum for later use on demand. [0098] The ESS further comprises electrical inlet 251 couplable to an external source of electrical energy 210, and an electrical outlet 250 couplable to an external consumer 230 of electrical energy. At its outer end, the flywheel comprises a solar panel 20 ls, for recharging the battery

[0099] In various embodiments of the presently disclosed subject matter the rechargeable electrical storage device comprises a plurality of metallic layers, each arranged substantially equidistant from the axis of rotation of the spinning mass, the average distance (radii) of each layer from the axis differs from that of a neighboring layer by a thickness of a respective layer. In each pair of neighboring layers, one layer constitutes an electrochemical anode and the other constitutes an electrochemical cathode, of a rechargeable secondary electrical cell being or constituting a member of the electrical storage device.

[00100] In various embodiments of the disclosed subject matter, each layer is formed as an individual metal sheet closed on itself in the form of a cylindrical shell, wherein a plurality of layers functioning as electrochemical anodes are electrically connected to a common anode collector, wherein a plurality of layers functioning as electrochemical cathodes are electrically connected to a common anode collector. In various embodiments of the disclosed subject matter the common anode collector and the common cathode collector are in the form of a disc, which plane of the disks are oriented perpendicularly to the axis of rotation, one disk located at a first end of the cylindrical layers and the other disc at a second end thereof, opposite said first end.

[00101] In various embodiments of the disclosed subject matter the disc is punctured in a predetermined network-like pattern (and may include bent network segment) providing it with a degree of stretch-ability, whereby upon rotation at high spinning velocities the disc can deform under centrifugal forces, without disintegration.

[00102] In various embodiments of the disclosed subject matter, two adjacent layers of material are rolled together a predetermined number of rolls thereby forming about the axis of rotation a cylindrical shell, wherein a width of the shell is equal to the number of rolls times the average width of a roll.

[00103] In some embodiments of the disclosed subject matter, the electrochemical electrode sheets constituting the electrical storage device are composed with or reinforced by carbon fibers.

[00104] Fig. 4 illustrates a flow chart describing an example of operation procedure taken by a system for storing mechanical and electrical energy for outputting on demand, according to various embodiments of the disclosed subject matter. The system (e.g. of the embodiment illustrated in Fig. 1) comprises a flywheel which is couplable to a source of mechanical energy, wherein said source intends to supply mechanical energy to an external consumer, either directly or through the system. The external consumer may be for example the rotor of an electrical generator, the wheels or propellers of a vehicle, or any other device which makes use of mechanical energy. The source of mechanical energy may be a water fall, sea waves, wind, combustion engine, momentum of a vehicle (such as differential linear momentum that can be translated into rotational power during intentional deceleration of the vehicle), compressed gas, or any other available source of mechanical energy which may satisfactorily be coupled to the consumer.

[00105] The purpose of the system for storing energy, is to acquire mechanical energy from the source in amounts up to the maximal energy storage capacity of the system, whenever the amount of energy extractable from the source exceeds the amount of energy consumed by the consumer.

[00106] In a preceding process step, annotated 401, the consumer is coupled to the energy source and may then consume between zero and any predetermined percentage of energy that can be extracted from the source. The control system 104 of the system for energy storage 100 is fluently informed (i) of the real time amount of energy that can be extracted from the source; and (ii) of the real time amount consumed by the consumer; and/or (iii) of the real time difference between the amount of energy that can be extracted from the source and the actual amount of energy consumed by the consumer.

[00107] The control system 104 is configured, as represented in a process step annotated 406, to determine in real time whether said difference amount of energy exceeds one or more predefined threshold values. The system is further configured, as represented in a process step annotated 41 1 , to couple the energy source to the flywheel, upon detection that the threshold value/s has/have been met ("YES" result of step 406), thereby retrieving energy from the energy source and storing it as angular momentum of the rotatable mass. In case step 406 results with "NO", the control system repeats step 406.

[00108] In various embodiments of the disclosed subject matter, a first threshold value is, or may be adjusted to a desired value, e.g. between 0.1% and 50% of the real time amount of energy that can be extracted from the source. Another threshold value may be for example between 0.1% and 100% of the energy absorption capacity of the flywheel. The determination of threshold values may be a matter of design, taking into consideration variations in the worthwhileness of switching the system into energy storage mode. Worthwhileness may depend on amounts of retrievable energy (i.e. the differential between source energy and energy being consumed by the consumer), and on typical fluctuations which may occur in the amount of energy consumed by the consumer.

[00109] The control system is further configured as represented in a process step annotated 416, to determine whether the spinning velocity of the rotatable mass is, or exceeds, a predefined desired value. Upon detection that the desired velocity has been reached, the control system activates the electrical generator 102. In various embodiments of the disclosed subject matter the coupling is mechanical, involving mechanically coupling the axis of rotation of the generator to the axis of rotation of the spinning mass. In various embodiments of the disclosed subject matter the coupling is electrical, involving electrically coupling the electrical output of the generator to the rechargeable electrical storage device.

[001 10] Further in the process, the control system 104 detects the charging status of the electrical storage device 103, as represented in the process step annotated 426. In case the detection in step 426 finds the electrical storage-device is not fully charged (step 426 results with "NO" in the Fig.) the detection is continued. In case the detection in step 426 finds the electrical storage-device is fully charged (step 426 results with "YES" in the Fig.), the control system stops the charging and decouples the flywheel from the external source of mechanical energy, as represented by process step annotated 431.

[0011 1] The process further comprises a step (annotated 436) in which the control system monitors whether or not there is a demand for mechanical energy to be supplied by the system 100 to the consumer. Such demand is expected when the maximal real-time amount of mechanical energy retrievable from the external source is lesser than the amount of mechanical energy required by the consumer. Upon detection of a demand for mechanical energy (step 436 results with "YES" in the Fig.), the control system instruct coupling of the flywheel 101 to the consumer in process step 441. During consumption of energy from the flywheel, as well as on the long run of the flywheel (i.e. even when uncoupled to the consumer), the control system monitors the rotation speed of the flywheel as specified in process step 446. When the rotation speed decreases to below a preprogrammed value (step 446 results with "NO" to the question whether the flywheel runs at a desired velocity), the control system instructs energizing the motor 102 by electrical energy from the onboard electrical storage device 103. The motor then accelerates the flywheel until it returns to rotate in the desired speed.

[00112] In various embodiments the disclosed subject natter the control system is configured to regulate the current supplied from the electrical recharging device to the motor and maintaining it corresponding to the load coupled to the flywheel, for ^’ thereby maintaining the flywheel spinning in constant speed. This process may continue as long as the electrical energy storage device can supply electrical energy for compensating against the loss of angular momentum of the rotatable mass.

[00113] The amount of electrical energy stored in the electrical energy storage device is monitored in process step 456. Once the electrical energy storage device runs into shortage in energy (step 456 results with "YES" to the question "Electrical storage short in energy?") the rotation speed of the flywheel will decrease in time. As a matter of design, the control system may be configured to decouple the consumer from the flywheel at any desired moment, e.g. when the rotation speed decreases to below a predetermined value. In various embodiments of the disclosed subject matter the consumer is couplable to more than a single system for storing mechanical and electrical energy for outputting on demand, in which case when one of such systems runs into shortage in energy, the consumer may be coupled to another system, which is energy loaded.

[00114] The whole process can then be repeated, with the system for storing mechanical and electrical energy for outputting on demand returning to process step 406, while the energy consumer being recoupled to the external source of mechanical energy.

[00115] Fig. 5 illustrates a flow chart describing another example of operation procedure taken by a system for storing mechanical and electrical energy for outputting on demand, according to various embodiments of the disclosed subject matter. The system (e.g. of the embodiment illustrated in Fig. 1) comprises a flywheel which is couplable to a source of electrical energy, wherein said source intends to supply electrical energy to an external consumer, either directly or through the system. The external consumer may be for example an electrical motor, a plant comprising a plurality of electrical devices, or an electrical network which supply electricity to households. The source of electrical energy may be an electro-voltaic solar panel, a solar system comprising an array of solar electro-voltaic solar panel, generator operated by water fall, sea waves, wind, combustion engine, momentum of a vehicle (such as differential linear momentum that can be translated into rotational power during intentional deceleration of the vehicle), compressed gas, or any other available source of mechanical energy which may satisfactorily operate the generator.

[00116] In a preceding process step, annotated 501, the consumer is coupled to the energy source and may then consume between zero and any predetermined percentage of energy that can be extracted from the source. The control system 104 of the system for energy storage 100 is fluently informed (i) of the real time amount of energy that can be produced by the source; and (ii) of the real time amount consumed by the consumer; and/or (iii) of the real time difference between the amount of energy that can be produced by the source and the actual amount of energy consumed by the consumer.

[00117] The control system 104 is configured, as represented in a process step annotated 506, to determine whether a surplus electrical energy may be produced by the source for storage purposes (i.e. beyond what produced for satisfying the real-time requirements of the consumer) and whether said difference amount of energy exceeds one or more predefined threshold values. The system is further configured, as represented in a process step annotated 51 1 , to couple the energy source to the electrical motor 102, upon detection that the threshold value/s has/have been met ("YES" result of step 506), thereby retrieving electrical energy from the energy source and storing it as angular momentum of the rotatable mass. In case step 506 results with "NO", the control system repeats step 506.

[00118] In various embodiments of the disclosed subj ect matter, a first threshold value is, or may be adjusted to, a desired value, e.g. between 0.1% and 50% of the real time amount of energy that can be extracted from the source. Another threshold value may be for example between 0.1% and 100% of the energy absorption capacity of the electrical storage device, or of the electrical motor. The determination of threshold values may be a matter of design, taking into consideration variations in the worthwhileness of switching the system into energy storage mode. Worthwhileness may depend on amounts of retrievable energy (i.e. the differential between source energy and energy being consumed by the consumer), on typical fluctuations which may occur in the amount of energy consumed by the consumer and on characteristics of the electrical motor, e.g. its efficiency under different values of operation currents. [001 19] In various embodiments of the disclosed subject matter, the system is configured to take process step 521 in case a surplus amount of electrical energy may be produced by the source, regardless whether the threshold value/s has/have been met.

[00120] In some embodiments the system is configured to instruct coupling electrical energy from the source to the motor in case a first threshold value has been met, and to instruct coupling electrical energy from the source to the charging circuitry (taking process step 521), in case a second threshold value has been met. In various embodiments of the disclosed subject matter the second threshold value may be smaller than the first, per a specific detected characteristic. For example, the first threshold value may be 20% of the real time amount of energy that can be extracted from the source, and the second threshold value may be 0.5% of the real time amount of energy that can be extracted from the source. In such exemplary embodiment the control system 104 may be configured to (i) initiate electrical charging of the electrical storage device whenever the source can supply an extra amount of between 0.5%-20% of electrical energy; (ii) instruct energizing the electrical motor whenever the source can supply an extra amount of energy above 20% of electrical energy, while terminating a previously initiated electrical charging (thereby directing the entire surplus energy from the source to the electrical motor).

[00121] In various embodiments of the disclosed subj ect matter a third threshold value may be defined, and the control system may be further configured to split the surplus amount of source energy between the electrical motor (for storing a portion of the surplus energy as mechanical energy of the spinning mass) and between the electrical storage device (for charging it electrically by a remaining portion of the surplus energy). Referring to the above-mentioned example of two threshold values (0.5% surplus energy for energy storage by electrical charging, and 20% surplus energy for mechanical storage), the third threshold value may be for example 21% surplus energy amount. The control system may be configured such that whenever the surplus amount of energy that can be produced by the source is under 21%, the entire amount of surplus energy will be directed for energizing the motor (for storing the energy entirely as mechanical energy). Once the surplus energy reaches a value of 21% and up, the energy portion above 20% (e.g. 1% in case the surplus amount is equal to the third threshold value) the control system splits this differential energy for storage between the spinning mass and the electrical storage device. The splitting may be in equal parts (a surplus energy portion of 0.5% to be stored as electrical charge in the electrical charging device, and a remaining surplus energy portion 20.5% to be directed to the electrical motor for conversion into mechanical energy to be stored as kinetic energy of the spinning mass), or in different parts, as a matter of design.

[00122] In various embodiments of the disclosed subject matter the control system is configured to regulate the division of the energy available from the source between the electrical motor and the charging circuitry dynamically during simultaneous energy storage process, such that both the flywheel and the electrical storage device will reach their maximally allowed amount of stored energy nearly simultaneously.

[00123] The control system is further configured as represented in a process step annotated 516, to determine whether the spinning velocity of the rotatable mass is, or exceeds, a predefined desired value.

[00124] In various embodiments of the disclosed subj ect matter the desired value of the spinning velocity of the rotatable mass may be the maximal allowed velocity.

[00125] In various embodiments of the disclosed subject matter the desired value of the spinning velocity of the rotatable mass may be a value lower than the value of the maximal allowed velocity, which once reached may be further increased in a lower rate than before. Decreasing the acceleration of the spinning mass enables to direct part of the available electrical energy for charging the electrical storage device simultaneously with increasing the angular momentum of the flywheel.

[00126] Upon detection that the desired velocity has been reached ("YES" result of step 516), the control system instructs, in step 521, either disconnection of the electrical energy from the electrical motor or reduction in the electrical current through the motor 102 as well as connecting the electrical energy to the charging circuitry of the electrical storage device.

[00127] Further in the process, the control system 104 detects the charging status of the electrical storage device 103, as represented in the process step annotated 526. In case the detection in step 526 finds the electrical storage-device is not fully charged (step 526 results with "NO" in the Fig.) the detection is continued. In case the detection in step 526 finds the electrical storage-device is fully charged (step 526 results with "YES" in the Fig.), the control system stops the charging of the electrical storage device (as well as the electrical motor insofar not yet disconnected) from the external source of electrical energy, as represented by process step annotated 531. [00128] The process further comprises a step (annotated 536) in which the control system awaits a demand for mechanical energy to be supplied by the system 100 to the consumer. Such demand is expected when the maximal real-time amount of electrical energy retrievable from the external source is lesser than the amount of electrical energy required by the consumer. Upon detection of a demand for electrical energy (step 536 results with "YES" in the Fig.), the control system instructs activation of the generator 99 and coupling its outputted electrical energy to the consumer.

[00129] During consumption of energy from the flywheel, as well as on the long run of the flywheel (i.e. even when the generator 99 is off), the control system monitors the rotation speed of the flywheel as specified in process step 546. When the rotation speed decreases to below a preprogrammed value (step 546 results with "NO" to the question whether the flywheel runs at a desired velocity), the control system instructs energizing the motor 102 by electrical energy from the onboard electrical storage device 103. The motor then accelerates the flywheel until it returns to rotate in the desired speed.

[00130] In various embodiments of the disclosed subject matter the control system is configured to regulate the current supplied from the electrical recharging device to the motor and maintaining it in correspondence with the load coupled to the flywheel, for thereby maintaining the flywheel spinning at a constant speed. This process may continue as long as the electrical energy storage device can supply electrical energy for compensating against the loss of angular momentum of the rotatable mass.

[00131] The amount of electrical energy stored in the electrical energy storage device is monitored in process step 556. Once the electrical energy storage device runs into shortage in energy (step 556 results with "YES" to the question "Electrical storage short in energy?") the rotation speed of the flywheel will decrease in time. As a matter of design, the control system may be configured to decouple the consumer from the flywheel at any desired moment, e.g. when the rotation speed decreases to below a predetermined value. In various embodiments of the disclosed subject matter the consumer is couplable to more than a single system for storing mechanical and electrical energy for outputting on demand, in which case when one of such systems runs into shortage in energy, the consumer may be coupled to another system, which is energy loaded. [00132] The entire process can then be repeated, with the system for storing mechanical and electrical energy for outputting on demand 100, returning to its process step 506, while the energy consumer being recoupled to the external source of mechanical energy.

[00133] The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosed subject matter. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved.

[00134] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosed subject matter. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[00135] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosed subject matter has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosed subject matter in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosed subject matter. The embodiment was chosen and described in order to best explain the principles of the disclosed subject matter and the practical application, and to enable others of ordinary skill in the art to understand the disclosed subject matter for various embodiments with various modifications as are suited to the particular use contemplated.