Abstract:
A highly efficient, utility scale energy storage system employs large masses transported uphill to store energy and downhill to release energy. An electric powered cable winch or chain drive shuttles the masses between two storage yards of different elevations separated by a steep incline on rail vehicles supported by track and operated by an automated control system.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of U.S. provisional application Ser. No. 62/301,466 having a filing date of Feb. 29, 2016 entitled RIDGELINE CABLE DRIVE ELECTRIC ENERGY STORAGE SYSTEM having a common assignee as the present application, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND 
     Field 
       [0002]    The present invention relates generally to electric power storage and generation. More particularly, the present invention provides a system for gravitational potential energy storage employing electrically driven rail consists carrying off loadable masses between lower and upper storage yards. Potential energy is stored by employing electrical grid power for transport of the masses from the lower to upper storage facility using motor powered winch sets. Potential energy is recovered and returned to the electrical grid by generator operation of the winch set motors during transport of the masses from the upper to lower storage yards. The invention allows for grid load shifting as well the full range of ancillary services including regulation, spin, non-spin, replacement reserves, blackstart, VAR and heavy inertia to the grid. 
       Related Art 
       [0003]    The electric power grid is increasingly complex and the matching of power usage with power generation capabilities is a critical element in maintaining stability in operation. This issue is becoming more complicated with the addition of alternative energy generation sources such as wind power and solar power, which have inherent issues with consistency of power production. The need for utility scale energy storage as a portion of the power supply grid is driven by requirements for daily load shifting and power quality services including frequency regulation, voltage control, spinning reserve, non-spinning reserve and black start. It is presently estimated that requirements in the US will approach 85,000 MW for load shifting and 7,137 MW for power quality while global requirements will approach 450,000 MW for load shifting and 37,828 MW for power quality. 
         [0004]    Electrical energy storage may be accomplished using battery technologies, capacitor storage systems, kinetic energy storage systems such as flywheels or potential energy storage systems. Battery technology for Lithium ion batteries, flow batteries and Rechargeable Sodium-Sulfur batteries (NaS) are improving but typically will provide estimated capability only in the range of 10 megawatts or less. Similarly, capacitive storage systems on reasonable scale only provide between 1-10 megawatts of capability. Flywheel storage systems are also typically limited to less than 10 megawatts due to physical size and structural materials constraints. 
         [0005]    Conventional gravitational potential energy storage devices consist of mechanical lifting devices raising weights against the force of gravity and Pumped Storage Hydro, a method that stores energy in the form of water pumped uphill against the force of gravity. Mechanical lifting devices are limited in their height to a few hundred feet and therefore require large amounts of mass to store a significant amount of electric energy. This results in a very large cost, making these devices expensive and uneconomical. In Pumped Storage Hydro, water is pumped from a lower elevation reservoir to a higher elevation; the stored water is then released through turbines to convert the stored energy into electricity upon demand. The energy losses are typically greater than 20% of the amount stored and the difficulties in permitting, constructing and operating makes pumped storage hydro difficult to implement. It can take more than a decade to construct such a system. 
         [0006]    Rail based energy storage systems have been disclosed for use in utility scale energy storage in U.S. Pat. No. 8,593,012 issued on Nov. 26, 2013, which provide very efficient electric energy storage. However, such systems are designed to operate on steep conventional rail grades with larger storage yards available at each end of the system. In certain geographic areas those steep conventional grade features may not be available. 
         [0007]    It is therefore desirable to provide potential energy storage with capability in the range of 10-1,000 megawatts of power with high efficiency and reduced installation and capital investment requirements, which is operable with limited horizontal storage space on steeper than conventional rail inclines. 
       SUMMARY 
       [0008]    The embodiments disclosed herein provide a highly efficient, utility scale energy storage system which incorporates a power controller responsive to a utility grid and at least one module having tracks running from a bottom storage yard to a top storage yard and a winch set having a motor generator which simultaneously drives a first consist and a second consist in opposite directions on the tracks on grade. The first and second consist each incorporate at least one shuttle having a lifting mechanism to engage a mass stored in the bottom storage yard or top storage yard. The module is operable under control of the power controller in a charging mode with the winch set receiving in a motor electrical power from a utility grid to drive a first cycle with the first consist loading a mass in the bottom storage yard and ascending to the upper storage yard and unloading the mass and said second consist descending from the upper storage yard to the lower storage yard empty followed by a reversal of the winch set to drive a second cycle with the first consist descending form the upper storage yard to the lower storage yard empty and the second consist loading a mass in the bottom storage yard and ascending to the upper storage yard and unloading the mass thereby storing excess electrical energy available on the utility grid. The module is operable under control of the power controller in a generating mode with the winch set motor reversed to generate electrical power to the utility grid in a third cycle with the first consist loading a mass in the upper storage yard and descending to the lower storage yard and unloading the mass and said second consist ascending from the lower storage yard to the upper storage yard empty followed by a reversal of the winch set to generate in a fourth cycle with the first consist ascending from the lower storage yard to the upper storage yard empty and the second consist loading a mass in the upper storage yard and descending to the lower storage yard and unloading the mass thereby providing electrical energy to the utility grid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective overview of an embodiment of the Ridgeline cable drive electric energy storage system; 
           [0010]      FIG. 2  is a detailed perspective view of operating elements of the first exemplary embodiment as disclosed in  FIG. 1 ; 
           [0011]      FIG. 3  is a perspective overview of a second embodiment of the ridgeline cable drive electric energy storage system with bypass tracks; 
           [0012]      FIG. 4A  is a perspective view of the exemplary shuttle unit with a mass engaged; 
           [0013]      FIG. 4B  is a perspective view of the exemplary shuttle unit showing the wheel bogies and an embodiment of a mass support structure; 
           [0014]      FIG. 4C  is a perspective view of an exemplary mass; 
           [0015]      FIG. 5A  is a perspective view, with a portion of the ground cut away, of a track construction configuration for the ridgeline cable drive electric energy storage system; 
           [0016]      FIG. 5B  is an end view of the track construction configuration of  FIG. 5A   
           [0017]      FIG. 5C  is an end view of an alternative track construction configuration; 
           [0018]      FIG. 5D  is an exemplary configuration for a track support system with a concrete mass for a top anchoring of the track or track rail; 
           [0019]      FIG. 5E  is an exemplary configuration for a tie system used on conjunction with a track support as shown in  FIG. 5D  with lateral positioning support but longitudinal freedom for rail thermal expansion and contraction; 
           [0020]      FIG. 5F  is a detailed view of the rail engagement portion of the tie system of FIG.  FIG. 5E ; 
           [0021]      FIG. 5G  is a detailed view of a vertical adjustment wedge for use with the tie system of  FIG. 5E ; 
           [0022]      FIG. 5H  is an exemplary configuration for a track support system with a top mass and intermediate masses to constrain the track rails from longitudinal expansion and contraction while avoiding downslope migration; 
           [0023]      FIGS. 6AA-6AW  show a progression of shuttle positions and configurations for engagement of masses with a first exemplary mass engagement mechanism in the lower storage yard and disengagement of masses in the upper storage yard during system charging; 
           [0024]      FIGS. 6BA -BQ show a progression of shuttle positions and configurations for engagement of masses in the upper storage yard and disengagement of masses in the lower storage yard during system generation; 
           [0025]      FIGS. 7A-7N  show a progression of shuttle positions and configurations for engagement and disengagement of masses with a second exemplary mass engagement mechanism; 
           [0026]      FIG. 8  is a detailed representation of the winch drive elements; 
           [0027]      FIGS. 9A-9D  are a schematic representation of module winch operational sequencing with a switched variable frequency drive (VFD); 
           [0028]      FIG. 9E  is a timing diagram of the operational sequence for control of module winches by the VFD; 
           [0029]      FIG. 10A  is a representation of a mass storage configuration for storage yards with reduced grade; 
           [0030]      FIG. 10B  is a representation of mass storage configurations for storage yards on a common grade with the module track mainline; 
           [0031]      FIG. 10C  is a detailed representation of a method that allows for the standing of masses on a steep grade that prevents the masses from sliding down hill and minimizes the clearance height the mass must be raised to clear the mass foundation; and, 
           [0032]      FIGS. 11A-11I  show a progression of shuttle positions and configurations for engagement and disengagement of masses during system generation with a third exemplary mass engagement mechanism. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    A exemplary embodiment of the ridgeline cable drive electric energy storage system is made up of a number of individual modules. In this manner, the system can effectively be varied in size from 10 to several hundred-megawatt power and the output can be finitely controlled to perform ancillary services. Referring to the drawings, a typical system layout is shown in  FIG. 1 . A transmission line  10  provides connection to a utility grid to receive excess power as input to the system storage or transmit power from the system on demand from the utility. An electric substation  12  connects the transmission line  10  to a power control system  14  and winch sets  16 , which will be described in greater detail subsequently. The power control system  14  is responsive to the utility grid to store excess electrical power and to generate electrical power upon demand employing the system elements described herein. A number of funicular track sets carry consists  20   a ,  20   b  comprised of one or more shuttles (described in greater detail subsequently) which carry masses  22  between a lower storage yard  24  and an upper storage yard  26 . Each track set provides a cable drive gravity power module  18   a ,  18   b . Two modules are provided for the exemplary embodiment in  FIG. 1 . The consists  20  are connected to the winch sets  16  which simultaneously drive one consist upgrade and one consist downgrade with cables  15 . For storage of electric power when the grid has an excess, referred to herein as charging, the masses are loaded by the consists at the lower storage yard  24  and power from the grid is controlled by the control system  14  to be used by motors in the winch sets to move the consists to the upper storage yard where the masses are unloaded thereby storing the excess electrical power as potential energy in the elevated masses. The paired track sets allow a first cycle with a loaded consist to move upgrade to be unloaded while an empty consist moves downgrade to be loaded followed by reversal of the winch sets with a second cycle with the newly loaded consist moving upgrade and the unloaded consist moving downgrade. The process is therefore substantially continuous. Use of multiple track sets multiplies the power storage and generation capability and by relative staggering of the operational positioning of the consists along the track length for the various track sets provides greater continuity of charging or generation. When electricity generation is required, the process is reversed with the motors in the winch sets operating as generators converting the potential energy of the masses raised elevation back into electricity by regeneratively braking the consists motion during mass transport from the upper storage yard back to the lower storage yard with the generated electricity routed by the control system  14  to the power grid  10 . Use of multiple modules increases the power generation capability of the energy storage facility and by relative staggering of the operational positioning of the consists along the track length for the various track sets provides greater continuity of charging or generation. The addition of tracksets by using multiple modules defines the power output of the system and that the energy capacity (e.g hours of output at full power) is a function of the number of masses and the elevation change of the tracksets. Additionally, motor drive sharing may be employed between tracks via across the line powering of tracks that are not loading or unloading as will be described subsequently. As seen in  FIG. 2 , the winch sets  16  each employ two interconnected winch drums,  28   a  and  28   b  which rotate in opposite directions with gearing and both cables exiting off the bottom of the winch drums to simultaneously wind and unwind. In alternative embodiments discussed below the cable is wound in opposite directions on the drums and the drums are turned in the same directions. An exemplary consist  20   a  connected to winch drum  28   a  is shown carrying a mass  22  while consist  20   b  connected to winch drum  28   b  is unloaded and in transit. Shuttles may be joined to configure consists with a desired maximum loading or may be used individually in various system embodiments. The weight of consist  20   a  on track  32   a  of the module  18  is counterbalanced by the weight of consist  20   b  operating on track  32   b  thereby providing high efficiency, as the power from the unloaded shuttle is directly transmitted to the loaded shuttle, in operation for both charging and generating in the system with the weight of mass  22  substantially determining the charging or generating power of the track set. 
         [0034]    The modules may be configured as switchless with two complete tracks extending from the upper to lower storage yard in each module. Alternatively as shown in  FIG. 3  a single track may be employed in each module with a switched siding  34  along the track to allow the ascending consist  20   a  and descending consist  20   b  to pass. 
         [0035]    As seen in  FIGS. 4A-4C , each shuttle  30  incorporates multiple wheeled bogies  36  carrying a support frame  38  on which the mass  22  is carried. The wheeled bogies engage the track  32 . As best seen in  FIG. 4B , the support frame  38  includes a lifting platform  40 . The system for lifting the platform  40  may be mechanical, hydraulic or electric in various embodiments. However, an automated system for engagement and lifting or depositing the masses is desirable as will be described subsequently. The mass  22  as seen in  FIGS. 4A and 4C  has outer leg portions  42  separated by a bight portion  44  in an inverted “U” shape to straddle the width of the track  32 . The shape provides a low polar inertia reducing both rotational tendency or side to side rocking of the mass during transit up the steep grade. Reduction in side to side rocking enhances effective wheel to track loading. While shown with rounded edges on the upper corners the corners may be square. The leg portions have substantially flat bottoms  46  to rest on the ground straddling the track at the upper and lower storage yard allowing the masses to be freestanding. The lifting system  40  of the shuttle engages the bight portion  44  to raise the mass  22  clearing the flat bottoms  46  of the leg portions sufficiently for grade changes in the track. This configuration allows the shuttle to transit beneath the mass in the storage yard, engage and raise the mass and then proceed on the track without an external crane or lifting mechanism to place the mass on the shuttle. 
         [0036]    Tracks for the modules may be provided on the grade using one of several techniques. As shown in  FIGS. 5A and 5B , the tracks  32  may be anchored at the top of the grade with a concrete mass  50  with rail alignment pilings  52  inserted at spaced intervals on the grade. Ties or connectors  54  are engaged by the rails  56   a  and  56   b  of the track to maintain separation forming a “ladder track”. The “ladder track is supported on the grade on rock ballast  57  or similar material. Alternatively as shown in  FIG. 5C , ties  58  may be anchored directly to the earth on grade  60  in the grade with distributed soil anchors  70 . Rails  56   a  and  56   b  are then secured to the ties. 
         [0037]    To accommodate thermal expansion and contraction in the rails, an alternative configuration as shown in  FIG. 5D  may be employed. The top connection of the track is accomplished with a concrete mass  50  as in the configuration of  FIG. 5A . However, the rails  56   a  and  56   b  of track  32  are supported in ties  72  supported in a conventional manner on grade  60 . As seen in  FIGS. 5E and 5F , each tie  72  has a longitudinal relief  74  to receive each rail. Lateral sides  76  of the relief constrain the tracks laterally. However, the tracks are free to expand and contract longitudinally within the reliefs. Vertical adjustment of the tracks in the reliefs  74  may be accomplished with a slidable wedge  78  as seen in  FIG. 5G , which is received in a lateral relief  80  seen in  FIG. 5F . The wedge  78  incorporates a slot  82  received over a threaded pin  84  and may be constrained in position once adjusted by a nut  86  (seen in  FIG. 5E ) engaged on the pin. 
         [0038]    The rails of the track  32  may alternatively be constrained with regard to longitudinal expansion and contraction by placement of additional concrete masses  51  spaced on grade  60  to preclude migration of the track downslope induced by cyclical expansion and contraction as seen in  FIG. 5H . 
         [0039]    As previously discussed, lifting and depositing of masses on the shuttles (alone or connected in consists) in the upper and lower storage yards during operations for charging or generating without stopping the shuttles is highly desirable. A first exemplary lifting system is demonstrated in  FIGS. 6AA-6BQ . As seen in  FIG. 6AA  two shuttles  30   a  and  30   b  connected in a consist  20   a  active on a module  18   a  as described with respect to  FIG. 1  are lowered by the associated winch  16  to approach the lower storage yard  24  in which a number of masses  22   a - 22   d  are stored. 
         [0040]    Each shuttle has a rotatable lifting frame  100  pivotally attached at pins  102   a  and  102   b  to the support frame  38 . For this exemplary embodiment, the lifting mechanism is hydromechanical and a hydraulic piston/damper  104  is engaged to the rotatable frame  100 . A spring element may also be employed in combination with the hydraulic piston/damper for energy recovery during motion of the lifting frame as subsequently described. A hydraulic pump  106  mechanically driven by a geared connection to the wheels in the bogies  36  of the shuttle may be connected to drive the piston/damper  104  as will be described subsequently. Use of the mechanical geared drive through the shuttle wheels allows entirely independent operation of the lifting mechanism powered solely by motion of the shuttle. No separate electrical connection to the shuttle is required. One or more sensors  108  are positioned on the shuttle to detect relative position of the shuttle with respect to the end mass ( 22   a  initially) in the storage yard. Position of the sensor in the drawing is representative only. The sensor is mechanically actuated by contact through a feeler or similar mechanical element with the mass. In alternative embodiments where electrical power is available on the shuttle, optical or electronic sensors may be employed. 
         [0041]    As seen in  FIG. 6AB  as the shuttle  30   a  proceeds under the end mass  22   a  the sensor detects the mass and releases the frame  100  for rotation by the hydraulic piston/damper. As seen in  FIG. 6AC , the arms  110   a ,  110   b  of frame  100  rotate clockwise, constrained for parallel motion by center bar  111 , collapsing the frame to allow clearance of engagement stubs  112   a  and  112   b  under the masses. As seen in  FIG. 6AD , the consist with shuttles  30   a  and  30   b  continues to descend under the masses. As the second shuttle  30   b  approaches the end mass  22   a , as seen in  FIG. 6AE , the sensor detects the mass and releases the frame  100  for rotation by the hydraulic piston/damper. As seen in  FIG. 6AE , the arms  110   a ,  110   b  of frame  100  on shuttle  30   b  rotate clockwise, constrained for parallel motion by center bar  111 , collapsing the frame to allow clearance of engagement stubs  112   a  and  112   b  under the masses as seen in  FIG. 6AF . The consist continues to a reversal point as shown in  FIG. 6AG  and the winch  16  then reverses to draw the consist upgrade. As seen in  FIG. 6AH  as shuttle  30   b  approaches alignment with the end mass  22   a  the sensor detects the position and engages hydraulic piston/damper  104  to begin rotation of the frame counter clockwise to engage stubs  112   a  and  112   b  in receiving reliefs  114   a  and  114   b , respectively, in the lower surface of mass  22   a . Continuing upgrade motion of the shuttle  30   b  employs mechanical advantage provided by the arms  110   a  and  100   b  with rotation of engagement stubs  112   a  and  112   b  in the reliefs  114   a  and  114   b  to raise the mass  22   a  with the arms locking at the vertical as seen in  FIG. 6AI . The consist continues upgrade with shuttle  30   b  carrying mass  22   a  as shuttle  30   a  approaches mass  22   b  which is now the end mass in the storage row as seen in  FIG. 6AJ . As shuttle  30   a  approaches mass  22   b  the sensor detects the position and engages hydraulic piston/damper  104  on shuttle  30   a  to begin rotation of the frame to engage stubs  112   a  and  112   b  in receiving reliefs  114   a  and  114   b , respectively, in the lower surface of mass  22   a . Continuing upgrade motion of the shuttle  30   b  employs mechanical advantage provided by the arms  110   a  and  110   b  with rotation of engagement stubs  112   a  and  112   b  in the reliefs  114   a  and  114   b  to raise the mass  22   a  with the arms locking at the vertical as seen in  FIG. 6AK . The consist continues upgrade with shuttle  30   b  carrying mass  22   a  and shuttle  30   a  carry mass  22   b  as seen in  FIG. 6AL . 
         [0042]    As the consist approaches the upper storage yard  26  as shown in  FIG. 6AM , shuttle  30   b  proceeds beneath previously stored masses  22   e  and  22   f  (or if masses are not yet present in the upper storage yard an appropriate fixed and arch). As seen in  FIG. 6AN , the sensor detects the relative position of mass  22   e  and releases the vertical lock on shuttle  30   b  allowing the frame to begin to rotate counter clockwise with rotation damped by the piston/damper  104 . As the mass  22   a  engages mass  22   e , the frame completes rotation as shown in  FIG. 6AO  disengaging stubs  112   a  and  112   b  from the reliefs  114   a  and  114   b . A mass interlock  116  may be employed to engage the mass  22   a  to the mass  22   e  to enhance rotational stability. Resilient bumpers  118  may be employed on the vertical surfaces of the masses to facilitate engagement and reduce impact. The consist continues upgrade with shuttle  30   b  proceeding under the stored masses as shown in  FIG. 6AP . 
         [0043]    As seen in  FIG. 6AQ , the sensor on shuttle  30   a  detects the relative position of mass  22   a , previously deposited by shuttle  30   b , and releases the vertical lock on shuttle  30   a  allowing the frame to begin to rotate counter clockwise with rotation damped by the piston/damper  104  as shown in  FIG. 6AR . As the mass  22   b  engages mass  22   a , the frame completes rotation as shown in  FIG. 6AS . A mass interlock  116  may similarly be employed to engage the mass  22   b  to the mass  22   a  to enhance rotational stability. 
         [0044]    The direction of the consist is then reversed with the winch  16  allowing the consist to descend downgrade as shown in  FIG. 6AT . As shuttle  30   a  clears the last stored mass  22   b  as seen in  FIG. 6AU , the sensor detects the position and engages piston/damper  104  to rotate the frame clockwise to bring arms  110   a  and  110   b  upright engaging the vertical lock as show in  FIG. 6AV . Similarly, as shuttle  30   b  emerges from under the last stored mass  22   b , the sensor detects the position and engages piston/damper  104  to rotate the frame clockwise to bring arms  110   a  and  110   b  upright engaging the vertical lock as show in  FIG. 6AW . The consist then proceeds downgrade to repeat the steps beginning with  FIG. 6AA  as long the system is charging. 
         [0045]    When generating is required, each module operates as shown in  FIG. 6BA through 6BQ  (a reversal of the steps of  FIGS. 6AA-6AW  reiterated with slight abbreviation). As seen in  FIG. 6BA  two shuttles  30   a  and  30   b  connected in a consist  20   a  active on a module  18   a  as described with respect to  FIG. 1  are raised by the associated winch  16  to approach the upper storage yard  26  in which a number of masses are stored. As seen in  FIG. 6BB  as the shuttle  30   b  proceeds under the end mass  22   b  the sensor detects the mass and releases the frame  100  for rotation by the hydraulic piston/damper. The arms  110   a ,  110   b  of frame  100  rotate counter clockwise, constrained for parallel motion by center bar  111 , collapsing the frame to allow clearance of engagement stubs  112   a  and  112   b  under the masses. As seen in  FIG. 6BC , the consist with shuttles  30   a  and  30   b  continues to ascend under the masses. As the second shuttle  30   a  approaches the end mass  22   b  the sensor detects the mass and releases the frame  100  for rotation by the hydraulic piston/damper. The arms  110   a ,  110   b  of frame  100  on shuttle  30   a  rotate clockwise, constrained for parallel motion by center bar  111 , collapsing the frame to allow clearance of engagement stubs  112   a  and  112   b  under the masses as seen in  FIG. 6BD . The consist continues to a reversal point as shown in and the winch  16  then reverses to allow the consist to descend downgrade. As seen in  FIG. 6BE  as shuttle  30   a  approaches alignment with the end mass  22   b  the sensor detects the position and engages hydraulic piston/damper  104  to begin rotation of the frame clockwise to engage stubs  112   a  and  112   b  in receiving reliefs  114   a  and  114   b , respectively, in the lower surface of mass  22   b . Continuing downgrade motion of the shuttle  30   a  employs mechanical advantage provided by the arms  110   a  and  100   b  with rotation of engagement stubs  112   a  and  112   b  in the reliefs  114   a  and  114   b  to raise the mass  22   b  with the arms locking at the vertical as seen in  FIG. 6BF . The consist continues downgrade with shuttle  30   a  carrying mass  22   b  as shuttle  30   b  approaches mass  22   a  which is now the end mass in the storage row as seen in  FIG. 6BG . As shuttle  30   b  approaches mass  22   a  the sensor detects the position and engages hydraulic piston/damper  104  on shuttle  30   b  to begin rotation clockwise of the frame to engage stubs  112   a  and  112   b  in receiving reliefs  114   a  and  114   b , respectively, in the lower surface of mass  22   a . Continuing down grade motion of the shuttle  30   b  employs mechanical advantage provided by the arms  110   a  and  110   b  with rotation of engagement stubs  112   a  and  112   b  in the reliefs  114   a  and  114   b  to raise the mass  22   a  with the arms locking at the vertical as seen in  FIG. 6BH . The consist continues downgrade with shuttle  30   b  carrying mass  22   a  and shuttle  30   a  carry mass  22   b  as seen in  FIG. 6BI . 
         [0046]    As the consist approaches the lower storage yard  24  as shown in  FIG. 6BJ , shuttle  30   b  proceeds beneath previously stored masses  22   e  and  22   f  (or if masses are not yet present in the lower storage yard an appropriate fixed end arch or mechanical stop). As seen in  FIG. 6BK , the sensor detects the relative position of mass  22   c  and releases the vertical lock on shuttle  30   a  allowing the frame to begin to rotate clockwise with rotation damped by the piston/damper  104 . As the mass  22   a  engages mass  22   e , the frame completes rotation as shown in  FIG. 6BL  disengaging stubs  112   a  and  112   b  from the reliefs  114   a  and  114   b . The resilient bumpers  118  may be employed on the vertical surfaces of the masses to facilitate engagement and reduce impact. The consist continues down grade with shuttle  30   a  proceeding under the stored masses as shown in  FIG. 6BM . 
         [0047]    As seen in  FIG. 6BM , the sensor on shuttle  30   a  detects the relative position of mass  22   b , previously deposited by shuttle  30   a , and releases the vertical lock on shuttle  30   b  allowing the frame to begin to rotate counter clockwise with rotation damped by the piston/damper  104  as shown in  FIG. 6BN . As the mass  22   b  engages mass  22   a , the frame completes rotation as shown in  FIG. 6BO . 
         [0048]    The direction of the consist is then reversed with the winch  16  drawing the consist to ascend upgrade as shown in  FIG. 6BP . As shuttle  30   b  clears the last stored mass  22   a  as seen in  FIG. 6BP , the sensor detects the position and engages piston/damper  104  to rotate the frame counter clockwise to bring arms  110   a  and  110   b  upright engaging the vertical lock as show in FIG.  6 AV. Similarly, as shuttle  30   a  emerges from under the last stored mass  22   a , the sensor detects the position and engages piston/damper  104  to rotate the frame clockwise to bring arms  110   a  and  110   b  upright engaging the vertical lock as show in  FIG. 6BQ . The consist then proceeds upgrade to repeat the steps beginning with  FIG. 6BA  as long the system is generating. 
         [0049]    A second embodiment for the lifting system, also relying on mechanical advantage and motion of the shuttles to provide lifting of the masses while the shuttles are in motion, is shown in  FIGS. 7A-7N . While the operation of the second lifting system is described with respect to a single shuttle, a consist with two or more shuttles may be employed as described with respect to the first embodiment. A shuttle  30  having a structural frame  38  supports a ramp  120  with an apex  121  oriented in a first direction on the shuttle. A first roller system  122  is operatively carried on an upper surface of the ramp  120 . A first triangle element  124  engages the first roller system on a bottom surface with an apex  125  oriented oppositely from the ramp apex, A second roller system  126  is operatively carried on an upper surface of the triangle element  124 . The first and second roller systems are lockable and may employ pneumatic, mechanical or hydraulic systems for locking with required pressure provided by a pump  125  operatively geared to the wheels on bogies  36  of the shuttle as in the prior embodiment to avoid any requirement for electrical connection to the shuttle unit. A second triangle element  128  having an apex  129  oriented oppositely form the first triangle apex engages the second roller system  126  on a bottom surface and provides a top engagement surface  130 . An exemplary roller system which may be employed for the first and second rollers is a Superail system by Darnell-Rose Caster LLC, City of Industry, CA. 
         [0050]    In operation, as shown in  FIG. 7A , in an initial position, the first triangle element  124  is locked at a maximum divergent position from the apex of the ramp. The second triangle element  128  is carried at a minimum divergent position from the apex  125  of the first triangle element  124  allowing the shuttle  30  to transit underneath the masses  22   a - 22   c  present in a storage yard  24 . As the associated winch  16 , as described with respect to  FIG. 1 , draws the shuttle  30  along the track  32  the shuttle approaches the end mass  22   a  as seen in  FIG. 7B . Upon reaching the centerpoint of the mass  22   a , the top engagement surface  130  of the second triangle element  128  engages the bottom surface  132  of the bight  44  of mass  22   a  as seen in  FIG. 7C . As the shuttle continues upgrade, as seen in  FIG. 7D , the second triangle element, engaged to the mass  22   a , is drawn upward along the second roller system  126  lifting the mass  22   a . Upon reaching a maximum divergent position from the apex  125  of the first triangle element  124 , the second triangle element  128  is then locked on the second roller system  126  as seen in  FIG. 7E . The shuttle  30  with the loaded mass  22   a  is then drawn upgrade by the winch, as seen in  FIG. 7F  to approach the upper storage yard  26  as seen in  FIG. 7G . 
         [0051]    Upon approaching the first stored mass  22   d  in the upper storage yard  26  as seen in  FIG. 7H , the first triangle element  124  is unlocked on the first roller system  122 . Upon contact with the first stored mass  22   d  as seen in  FIG. 7I , the first triangle element  124  begins to descend on the first roller system  122  lowering the mass  22   a  as seen in  FIG. 7J . When the first triangle element  124  reaches the apex  121  of the ramp element  120  it is held by gravity, or may be locked in place and the shuttle  30  is free to transit beneath the stored masses  22   a  and  22   d  as shown in  FIG. 7K . Upon reversal of direction by the winch  16  the shuttle  30  exits the stored masses,  FIG. 7L , and begins to descend down grade as shown in  FIG. 7M . The first triangle element  124  is then driven hydraulically or pneumatically up first roller element  122  to the maximum divergent position from apex  121  of ramp element  120  as shown in  FIG. 7N  during transit. The second triangle element  128  is unlocked and allowed to travel down second roller system  124  to the apex  125  of second triangle element  124 , thereby assuming the initial position as shown in  FIG. 7A . The process is then repeated as long as the system remains charging. For generating, the process is reversed beginning at the top storage yard. 
         [0052]    As seen in  FIG. 8 , the winch drive sets  16  incorporate two drums  28   a ,  28   b  which rotate to draw their respective cables in opposite directions to oppositely raise or lower shuttles/consists on the track pairs in the module. The embodiment described with respect to  FIG. 2  and the embodiment of  FIG. 8  accommodates this requirement in alternative forms. Various embodiments may employ cable direction reversal by inner and outer bull gears, opposite cable winding on drums and opposite rotating spur gears by the addition of a reversal gear stage in one of the gearheads. For the embodiment of  FIG. 8 , the motor/generator  80  incorporates a fixed gear head  82  and a rotatable gear head  84  engaged to the motor with a rotating gear head mount  86 . Both gear heads rotate in the same direction. A first drum  28   a , incorporates an inner gear  88  engaging the rotatable hear head  84  while a second drum  28   b  incorporates and outer gear  90  engaging the fixed gear head  82  thereby providing the necessary opposite rotation. As masses are loaded and moved from the lower storage yard to the upper storage yard in the charging condition, the location of the next mass to be retrieved in the lower storage yard moves toward the distal end of the lower storage yard relative to the winch set. Shuttles therefor require greater cable length from the associated drum to reach the next available mass. Similarly, at the upper storage yard as masses accumulate the shuttle is not drawn as far toward the proximal end of the upper storage yard by a comparable cable length. As masses are moved from the upper storage yard to the lower storage yard in the generating condition, relative cable length is reduced. To accommodate this requirement, a differential motor  92  is engaged to the rotatable gear head  84  to adjust the cable length on the drums. The differential motor  92  is engaged to play out cable at each shuttle or consist transit during charging and take in cable at each shuttle or consist transit during generation. This provides increased accuracy in shuttle placement for mass loading and unloading. 
         [0053]    As previously described, driving the winch motors may be accomplished with across the line direct to grid synchronization between the various modules. As a consist is accelerated to speed after being loaded, the frequency of the winch motor(s) is matched to that of the electric grid. The winch motor(s) are then switched from being driven by the motor drive to being driven directly from the electric grid at a fixed speed. The winch motor drive is then available for use on another track module for the purpose of loading or unloading masses. In this way the number of winch motor drives can be reduced, the efficiency of the system can be increased and the inertia of the modules is linked directly to the frequency of the electric grid thereby stabilizing it. As seen in  FIGS. 9A-D  and  9 E a pair of variable frequency drives (VFD)  910   a ,  910   b  acting as the motor drive are employed. At a time=0, seen in  FIG. 9A , module  905  has consists approaching the upper storage yard and lower storage yard. Winch  915  is needed under VFD control to load and unload the masses as previously described. To accomplish this, the VFD  910   b  catches winch  915  from across-the-line at full power at point A in  FIG. 9E . Winches  911 - 913  are across-the-line traveling at full speed. Winch  914  is being accelerated by VFD  910   a . The VFD  910   b  decelerates winch  915  as seen in segment B of  FIG. 9E . The VFD then reverses direction of the winch  915  at point C. The VFD then operates the winch  915  at slow speed to load and unload the masses in segment D. The VFD then accelerates the winch  915  to full speed, segment E. Winch  915  is then bypassed from the VFD and operates across-the-line, segment F, and the VFD  910   a  then prepares to catch winch  914 , segment H. As represented in  FIG. 9B , the VFD  910   a  engages winch  914  to operate under VFD control while winches  911 - 912  and  915  operate across the line traveling at full speed and VFD  910   b  has been switched to winch  913  Two VFD&#39;s are needed so that while one track set is accelerating to 60 Hz the next one approaching the yards can be decelerated. In this way the sum of the power from both VFD&#39;s  910  a &amp; b is always equal to 1 track set The process is repeated as represented in  FIGS. 9C and 9D  for modules  904  and  903  as the consists in each module approach the upper and lower storage yards. The process is continued for modules  902  and  901  and then repeats. 
         [0054]    Regulation of the utility grid can be accomplished by the cable drive electric energy storage system both during charging/generation or when no other supply or demand on the system is present from the grid. During either charging or generation, operation by the VFD to increase or decrease consist speed on the currently controlled module may be employed for trim to regulate up (Reg-UP) or regulate down (Reg-Down). Regulation when the system is not operating in charging or generation may be accomplished by controlling the stopping position from either charging or generating to configure a loaded consist at mid-elevation or alternating consist position on grade to allow every other module to provide either instant Reg-Up or Reg-Down without the time delay required by mass loading. 
         [0055]    The lower storage yard  24  and upper storage yard  26  may be accommodated flat on grade as shown in  FIG. 10A  where the grade may be reduced from the steep grade of the track main line portions  33 . In exemplary embodiments a main line grade of 38% or higher may be employed and reduced grades of 7% or lower may be employed in the storage yards. Where storage must be accommodated on the same grade as the main line track portion as shown in  FIG. 10B , the storage yards may be implemented with respective concrete mass landing foundations,  53  in lower storage yard  24  and  55  in upper storage yard  26 . As shown in detail in  FIG. 10C , the concrete mass landing foundations  53 ,  55  are provided with a stair step bottom  150  to enhance support of the stored masses  20  on grade without downslope migration of the concrete masses. Similarly, the masses  20  are provided with a stair step bottom  154  on the outer leg portions of the masses mating with a stair step upper surface  152  on the concrete mass landing foundations  53 ,  55  to provide upright storage for the masses. Alternatively, the stair step upper surface  154  may employ steps equal in width to the bottoms  46  of the outer leg portions on the masses as previously described with respect to  FIG. 4D . 
         [0056]    An third alternative lifting system comparable to the shuttle disclosed in  FIG. 4B  and also relying on mechanical advantage and motion of the shuttles to provide lifting of the masses while the shuttles are in motion, is shown in  FIGS. 11A-11I . While the operation of the third lifting system is described with respect to a single shuttle, a consist with two or more shuttles may be employed as described with respect to the first embodiment. A shuttle  30  having a structural frame as in prior embodiments supports at least one rail  145  mounted at an angle complimentary to the angle of the track  32  providing a substantially horizontal running surface with the shuttle  30  mounted on the track. Multiple rails,  145   a ,  145   b  as depicted in  FIG. 4B , may be employed to allow a longer lifting platform  40  to be accommodated within the dimensions of the shuttle. The lifting platform  40  is supported by wheels  144  engaged to the rails  145  allowing reciprocation of the lifting platform horizontally. A lockable drive  141 , which for the embodiment shown comprises a clutched pulley engaged to one (or a pair) of the wheels on bogies  36 , is connected either to the lifting platform  40  or the wheels  144  to move the lifting platform on the rails. In alternative embodiments, the drive may be a hydraulic, electrical or other drive system. At the upper and lower storage yard, positions of the stored masses  22   a ,  22   b , et seq. are indicated with a track marker  140   a ,  140   b ,  140   c . A track marker sensor  142  is associated with the lifting platform  40  to detect proximity of the lifting platform to a mass associated with a track marker. The track marker sensor is interconnected to the lockable drive  141  to engage the drive upon alignment of the track marker sensor  142  with the track marker  140   a ,  140   b ,  140   c . As shown in  FIG. 11A , with the lifting platform  40  translated to a first end of the rails  145  designated by a first end stop sensor  146   a , the lifting platform is in a retraced position with respect to the shuttle  30  allowing the shuttle to be moved up or down the track under the stored masses. 
         [0057]    As seen in  FIG. 11B  for operation of the system in a charging mode, as shuttle  30  is pulled uphill by winch  16  sensor  42  engages marker  140   a  and drive  141  is lightly engaged driving lifting platform  40  from the first end stop sensor  147  toward an opposite end stop sensor  146   b . As shuttle  30  continues uphill, as seen in  FIG. 11C , drive  141  moves lifting platform  40  along rail  145  and spring roller  150  engages a lower surface  132  of the bight portion  44  of mass  22   a . As seen in  FIG. 11D , shuttle  30  continues uphill. Drive  141  may be placed in a slipping mode allowing spring rollers  150  to roll against lower surface  132  until a mass end sensor  147  on the lifting platform  40  engages a stop  148  on the mass  22   a . The engagement of sensor  147  commands drive  141  to full power. As seen in  FIG. 11E , shuttle  30  continues uphill as drive  141  now moves lifting platform  40  along rails  145 , displacing spring roller  150  which engages lower surface  132  of bight portion  44  with an upper surface  151  of the lifting platform  40 . The upper surface  151  of the lifting platform translates relative to the shuttle perpendicular to the track angle. Mass  22   a  is lifted directly vertically with horizontal motion (vector −H) of the lifting platform  40  on the rails  145  coordinated to oppositely match the horizontal component H of the motion vector M of the shuttle  30  as it proceeds up the hill. When lifting platform  40  engages opposite end stop  146   b  drive  141  is responsively stopped and locked. While a multispeed/power drive is described in this embodiment, under certain conditions a constant speed drive, engaged by sensor  142  providing a matching of the horizontal motion of the lifting platform  40  on the rails  145  opposite to the horizontal component of the motion vector of the shuttle  30  and disengaged and locked by end stop  146   b , may be employed. Shuttle  30  is then accelerated by the VFD as previously described and continues uphill with mass  22   a  engaged on lifting platform  40  as seen in  FIG. 11F . 
         [0058]    Shuttle  30  continues uphill and is decelerated by the VFD, as previously described, as sensor  142  approaches track marker  140   e  designating a desired position for unloading of the mass  22   a  in the upper storage yard as shown in  FIG. 11G . Shuttle  30  is stopped as sensor  142  engages track marker  140   e  and drive  141  is engaged. Shuttle  30  is rolled downhill by winch  16  and drive  141  move the lifting platform  40  from opposite end stop sensor  146   b  toward the end stop sensor  146   a  along rails  145 . Mass  22   a  is lowered directly vertically with motion of the lifting platform  40  on the rails  145  coordinated to match the horizontal component of the motion vector of the shuttle  30  as it proceeds down the hill thereby lower mass  22   a  on the ground until end stop sensor  146   a  is reached disengaging drive  141  as represented in  FIG. 11H . Shuttle  30  may then transition beneath the mass  22   a  to begin transiting downhill as shown in  FIG. 11I  to retrieve the next mass in the lower storage yard. 
         [0059]    Functioning of the system in generating mode operates identically in reverse order to that described, loading massed in the upper storage yard and unloading them in the lower storage yard. 
         [0060]    The various embodiments disclosed herein provide a method for storing electrical energy by first controlling a module with a power controller in a charging mode in which electrical power from a utility grid is received in a motor of a winch set, the winch set simultaneously driving a first consist and a second consist in opposite directions on tracks on grade. The winch set drives a first cycle which includes loading the first consist with a first of a plurality of masses in a bottom storage yard, causing the first consist to ascend to an upper storage yard, unloading the first of the plurality of masses, and simultaneously causing the second consist to descend from the upper storage yard to the lower storage yard. The winch set is then reversed to drive a second cycle which includes causing the first consist to descend from the upper storage yard to the lower storage yard empty and simultaneously loading the second consist with a second one of the plurality of masses in the bottom storage yard, causing the second consist to ascend to the upper storage yard and unloading the second one of the plurality of masses thereby storing excess electrical energy available on the utility grid. The power controller is also controllable in a generating mode with the winch set motor reversed to generate electrical power in which electrical power generated from the winch set motor is transferred to the utility grid in a third cycle which includes loading the first consist with the second of the plurality of masses in the upper storage yard, causing the first consist to descend to the lower storage yard, unloading the second of the plurality of masses and simultaneously causing the second consist to ascend from the lower storage yard to the upper storage yard empty. The winch set is then reversed to generate in a fourth cycle including causing the first consist to ascend from the lower storage yard to the upper storage yard empty and loading the second consist with the first of the plurality of masses in the upper storage yard, descending to the lower storage yard and unloading the first of the plurality of masses thereby providing electrical energy to the utility grid. 
         [0061]    While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention is therefore not limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.