Patent Publication Number: US-2023151799-A1

Title: Energy storage and delivery system with an elevator lift system and method of operating the same

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS 
     Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. 
     BACKGROUND 
     Field 
     The invention is directed to an energy storage and delivery system, and more particularly to an energy storage and delivery system that stores and releases energy via the vertical movement of blocks or bricks. 
     Description of the Related Art 
     Power generation from renewable energy sources (e.g., solar power, wind power, hydroelectric power, biomass, etc.) continues to grow. However, many of these renewable energy sources (e.g., solar power, wind power) are intermittent an unpredictable, limiting the amount of electricity that can be delivered to the grid from intermittent renewable energy sources. 
     SUMMARY 
     Accordingly, there is a need for improved system to capture electricity generated by renewable energy sources for predictable delivery to the electrical grid. As used herein, the electrical grid is an interconnected network for delivery of electricity from producers to consumers and spans a large geographical region, including cities, states and/or countries. 
     In accordance with another aspect of the disclosure, the energy storage and delivery system can in one example store solar power to produce off-hours electricity. The energy storage and delivery system can move a plurality of blocks from a lower elevation to a higher elevation to store solar energy as potential energy in the blocks during daylight hours when solar electricity is abundant. The energy storage system can then operate to move the blocks from the higher elevation to a lower elevation during nighttime to drive a generator to produce electricity for delivery to the power grid. In one implementation, the energy storage system can use a winch having one or more planetary gear assemblies and one or more brakes that advantageously allow for simplified control of the system to raise and lower blocks. 
     In accordance with another aspect of the disclosure a method for storing and generating electricity is provided. The method comprises operating an elevator on a tower to move a plurality of blocks from a lower elevation on the tower to a higher elevation on the tower to store energy in the blocks, each of the blocks storing an amount of energy corresponding to a potential energy amount of the block. The method also comprises operating the elevator to move the blocks from a higher elevation on the tower to a lower elevation on the tower (e.g., under a force of gravity), thereby generating an amount of electricity corresponding to a kinetic energy amount of said one or more blocks when moved from the higher elevation to the lower elevation. 
     In accordance with one aspect of the disclosure, an energy storage and delivery system is provided. The energy storage and delivery system comprises one or more modules. Each module comprises a plurality of blocks and a frame having a vertical height above a foundation. The frame includes a lower deck, an upper deck spaced vertically above the lower deck, an elevator shaft disposed between a left column and a right column of the frame that extend between the lower deck and the upper deck, and an elevator movably disposed in the elevator shaft and operatively coupled to an electric motor-generator. The elevator is sized to receive and support one or more blocks therein and operable to travel between a location above the lower deck and a location above the upper deck. The elevator is operable to raise one or more blocks from a location in the left column above the lower deck to a location above the upper deck over the left column, and to move one or more blocks from a location in the right column above the lower deck to a location above the upper deck over the right column to thereby store an amount of electrical energy corresponding to a potential energy amount of said one or more raised blocks. The elevator is operable to lower one or more blocks from a location above the upper deck over the left column to a location within the left column above the lower deck, and to move one or more blocks from a location above the upper deck over the right column to a location within the right column above the lower deck under a force of gravity to thereby generate an amount of electricity for each of the one or more lowered blocks via the electric motor-generator electrically coupled to the elevator. 
     In accordance with another aspect of the disclosure, a method for storing and generating electricity is provided. The method comprises operating an elevator along an elevator shaft between adjacent left and right columns to move a plurality of blocks between a location above a lower deck in the left or right columns to a location above an upper deck aligned with the left or right columns. Operating the elevator includes one or both of (a) lifting a block from the location above the lower deck in the left or right column, moving the block into the elevator shaft, raising the block to a location above the upper deck, moving the block out of the elevator shaft, and releasing the block to that it is aligned over its prior location in the left or right column to thereby store and amount of electrical energy corresponding to a potential energy amount of said block, and (b) lifting a block from the location above the upper deck and over the left or right column, moving the block into the elevator shaft, lowering the block to a location above the lower deck under a force of gravity, moving the block out of the elevator shaft, and releasing the block to that it is aligned below its prior location and within the left or right column to thereby generate an amount of electricity via an electric motor-generator electrically coupled to the elevator. 
     In accordance with another aspect of the disclosure, a block for use in an energy storage and generation system is provided. The block comprises a body made of one or more of concrete, steel and compacted dirt. The body has a rectangular shape with a planar top surface and a bottom surface having two or more protrusions that extend across a width of the body. A recess is defined between the two or more protrusions, the two or more protrusions and the recess extending across a width of the body. 
     In accordance with another aspect of the disclosure, an energy storage and delivery system is provided. The system comprises one or more modules. Each module comprises a plurality of blocks and a frame having a vertical height above a foundation. The frame includes an elevator shaft, and an elevator movably disposed in the elevator shaft, the elevator sized to receive and support one or more blocks therein and operable to move one or more of the plurality of blocks between a lower elevation and a higher elevation. A winch assembly is movably coupled to a cable that is coupled to the elevator, the winch assembly comprising one or more planetary gear assemblies, one or more brakes and a spool coupled to the cable. The one or more modules also comprises a motor-generator and a drive shaft having an end coupled to the motor-generator and an opposite end coupled to the winch assembly. At least one of the one or more brakes of the winch assembly is operable so that the spool rotates to reel-in the cable to raise the elevator to move one or more of the plurality of blocks from a lower elevation to a higher elevation to store energy or so that the spool rotates to reel-out the cable to lower the elevator to move one or more of the plurality of blocks from a higher elevation to a lower elevation to generate electricity. 
     In accordance with another aspect of the disclosure, a method for storing and generating electricity is provided. The method comprises operating an elevator along an elevator shaft to move a plurality of blocks between a lower elevation and a higher elevation, the elevator coupled to a cable that extends between the elevator and a spool of a winch assembly, the winch assembly comprising one or more planetary gear assemblies and one or more brakes. Operating the elevator includes operating a first brake of the winch assembly to disengage a brake disc of the winch assembly, operating a second brake of the winch assembly to disengage a first ring gear of a first planetary gear assembly and operating a third brake of the winch assembly to engage a second ring gear of a second planetary gear assembly to stop rotation of the spool. Operating the elevator also includes operating the first brake to engage the brake disc of the winch assembly, operating the second brake to disengage the first ring gear of the first planetary gear assembly and operating the third brake to disengage the second ring gear of the second planetary gear assembly to rotate the spool in a reverse direction to reel-out the cable to lower the elevator. Operating the elevator also includes operating the first brake to disengage the brake disc of the winch assembly, operating the second brake to engage the first ring gear of the first planetary gear assembly and operating the third brake to disengage the second ring gear of the second planetary gear assembly to rotate the spool in a forward direction to reel-in the cable to raise the elevator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, and in which: 
         FIG.  1    is a front elevational view of an energy storage system, in accordance with a first embodiment; 
         FIG.  2    is a front elevational view of an energy storage system, in accordance with a second embodiment; 
         FIG.  3    is a front elevational view of an energy storage system, in accordance with a third embodiment; 
         FIG.  4    is a side elevational view of an energy storage system, in accordance with the third embodiment; 
         FIG.  5    is a perspective view of an energy storage system, in accordance with the third embodiment; 
         FIG.  6    is a perspective view of an energy storage system, in accordance with the third embodiment; 
         FIG.  7    is a perspective view of a block, in accordance with one embodiment; 
         FIG.  8 A- 8 D  is a diagrammatic illustration of a block being moved onto an elevator, in accordance with one embodiment; 
         FIGS.  9 A- 9 B  are perspective views of a rotary energy storage system, in accordance with a fourth embodiment; 
         FIGS.  10 A- 10 B  are side views of a rotary energy storage system, in accordance with the fourth embodiment; 
         FIG.  11    is a top view of a rotary energy storage system, in accordance with the fourth embodiment; 
         FIGS.  12 A- 12 B  are perspective views of a rotary energy storage system, in accordance with the fourth embodiment; 
         FIG.  13    is a perspective views of a rotary energy storage system, in accordance with a fifth embodiment; 
         FIG.  14    is a diagrammatic illustration of a motor-generator coupled to a plurality of energy storage systems; 
         FIG.  15    is a diagrammatic illustration of a winch; and 
         FIG.  16    includes a table indicating winch performance based on brake activation. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is an energy storage system that can be operatively coupled to a large-scale electrical grid for stabilizing the electric grid and producing electricity for residential, commercial, and industrial consumers. The energy storage system draws electricity from the grid when supply is readily available, and inputs electricity back into the grid when demand is high. The energy storage system may also be operatively coupled to a solar power plant for purposes of storing electricity during daylight hours and outputting electricity to the grid during nighttime hours. The energy storage system can additionally or alternatively be operatively coupled to a wind power plant or other renewable energy generating plant. 
       FIG.  1    shows a schematic view of one implementation of an energy storage (ES) system  100 . The ES system  100  includes a frame  110 . In one implementation, the frame  110  can include a plurality of reinforced steel/concrete pillars, a plurality of cross members (not shown), a lower deck  112 , an upper deck  114 , at least one elevator  120  that travels in an elevator shaft  122 , a motor-generator  150 , and a plurality of ballast weights or blocks  130 . The blocks  130  are stacked and stored on the lower deck  112  and upper deck  114  (e.g., within a column  111   a  to the right and a column  111   b  to the right of the elevator shaft  122 ). The elevator  120  can be operated to move the blocks  130  between a stack on the lower deck  112  and a stack on the upper deck  114  via the elevator shaft  122 . The frame  110 , blocks  130 , elevator shaft  122  and elevator  120  form a module. In the illustrated implementation, the ES system  100  has one module. 
     To store electricity or other form of energy, a block  130  is lifted by the elevator  120  from the lower deck  112  to the upper deck  114 . To release energy and generate electricity, a block  130  is lowered from the upper deck  114  to the lower deck  112  (e.g., under force of gravity) by the elevator  120  (e.g., at a velocity of approximately 0.4 meter/second) and the force used to rotate the motor-generator  150  to generate electricity (e.g., based on the kinetic energy of the block  130  as it is lowered). 
     In one implementation, some blocks are confined to the upper deck  114  and lower deck  112  to the left of the elevator  120 , while other locks are confined to the upper deck  114  and lower deck  112  to the right of the elevator  120 . To the right, for example as shown in  FIG.  1   , there are a total of eight blocks including blocks  1 - 6  on the upper deck  114 , block  7  being moved by the elevator  120  upward to be stacked on block  6  on the right side, and block  8  on the lower deck  112 . To store additional energy, block  8  to the right may be raised and stacked on block  7  on the right side. Alternatively, to generate electricity, block  7  to the right may be lowered and stacked on top of block  8  to the right. The process may be repeated as long as there are blocks available to convert energy as required. Advantageously, the same elevator  120  can move blocks  130  on the right side of the elevator shaft  122  between the lower deck  112  and the upper deck  114 , and can move blocks  130  on the left side of the elevator shaft  122  between the lower deck  112  and the upper deck  114 . Blocks  130  on the left side of the elevator  120  are moved between the lower deck  112  on the left side of the elevator shaft  122  and the upper deck  114  on the left side of the elevator shaft  122 , and blocks  130  on the right side of the elevator  120  are moved between the lower deck  112  on the right side of the elevator shaft  122  and the upper deck  114  on the right side of the elevator shaft  122 . 
     Because each block  130  travels between a location at (or above) the lower deck  112  and a location at (or above) upper deck  114  so that the block  130  remains on the same side (e.g., to the left or right of the elevator shaft  122 ), each of the blocks  130  of the ES system  100  has a different vertical travel distance between the location above the lower deck  112  and the location about the upper deck  114 . For example, when all the blocks  130  are on the lower deck  112 , the top block  330  in the stack travels a shorter distance to the location above the upper deck  114  than the bottom block  130  in the stack, which must travel from the a location adjacent the bottom deck  112 , past the location of the upper deck  114  to a top of the stack on the upper deck  114 . Accordingly, each block  130  of the ES system  100  stores a different amount of energy when moved from the above the lower deck  112  to above the upper deck  114  (e.g., the top block  330  in the stack stores the least energy and the bottom block in the stack stores the most energy) and generates a different amount of electricity when moved from above the upper deck  114  to above the lower deck  112  (e.g., the top block  330  in the stack generates the most electricity and the bottom block  130  in the stack generates the least electricity). In one implementation, the elevator  120  can alternatively one block on the left side of the elevator shaft  122  between a position over the lower deck  112  and a position over the upper deck  114 , and move one block on the right side of the elevator shaft  122  between a position over the lower deck  112  and a position over the upper deck  114 , which can maintain the load on the lower deck  112  and upper deck  114  generally even between the left and right sides of the elevator shaft  122 , which can reduce a stress differential on the frame  110 . 
     In one implementation, each block  130  can be approximately 6 meters long, 6 meters wide, and 4 meters tall. However, the block  130  can have other suitable dimensions. The block  130  may be made of concrete, steel, and/or compacted dirt, for example. In one example, the total weight of a block  130  is between about 200 tons and about 300 tons (e.g., metric ton), such as approximately 288 tons (e.g., eight blocks  130  can have a total weight of between about 1600 tons and about 2400 tons, such as about 2304 tons). The height (h) of the upper deck  114  can in one implementation be approximately 88.5 meters, and the overall height (H) of the elevator shaft  122  can in one implementation be approximately 120.5 meters. However, the height (h) of the upper deck  114  and height (H) of the elevator shaft  122  can have other suitable values. The amount of energy storage of the ES system  100  can in one implementation be approximately 500 kWh (kilowatt hours). The amount of power generation provided by the ES system  100  can in one implementation be approximately 1.1 MW. In one implementation, the blocks  130  may weigh as much as 150 metric tons. 
       FIG.  2    shows a schematic view of a second implementation of an energy storage (ES) system  100 A. The ES system  100 A is similar to the ES system  100  illustrated in  FIG.  1    and described above. Therefore, the structure and description for the various features of the ES system  100  in  FIG.  1   , and the blocks  130  moved by the ES system  100 , are understood to also apply to the corresponding features of the ES system  100 A in  FIG.  2   , except as described below. The ES system  100 A differs from the ES system  100  in that it includes two elevators  120  instead of one. Each of the two elevators  120  moves along its corresponding elevator shaft  122  of the frame  210  and services a stack of blocks  130  to its immediate left and immediate right (e.g., blocks are within a column  111   a  to the right and a column  111   b  to the right of the elevator shaft  122 ). The frame  210  can have a width W. In one implementation, the width W can be between about 20 meters and about 40 meters, such as about 36 meters. The blocks  130  (on the immediate left and immediate right of each elevator  120 ) can be moved between the lower deck  112  and upper deck  114 . The ES system  100 A operates in the same manner as the ES system  100 , but the two elevators  120  of the ES system  100 A allow the ES system  100 A to store twice as much energy as the ES system  100  and to generated twice as much power (e.g. electricity) on demand as the ES system  100 . The frame  110 , blocks  130 , elevator shafts  122  and elevators  120  form a module. In the illustrated implementation, the ES system  100 A has one module. 
       FIGS.  3 - 6    illustrate a third implementation of an energy storage (ES) system  100 B. The ES system  100 B is similar to the ES system  100 A illustrated in  FIG.  2    and described above, which is similar to the ES system  100  illustrated in  FIG.  1    and described above. Therefore, the structure and description for the various features of the ES system  100 A in  FIG.  2   , and the blocks  130  moved by the ES system  100 A, are understood to also apply to the corresponding features of the ES system  100 C in  FIGS.  3 - 6   , except as described below. Like the ES system  100 A, the ES system  100 B includes a pair of elevators  320  that can each move blocks  330  in the same manner described above for the ES system  100  and  100 A (e.g., each elevator  320  can move blocks  330  immediately to the left or right side of the shaft of the elevator  320  between a lower deck  312  and an upper deck  314 ). For example, the blocks  330  are within a column  311   a  to the right and a column  311   b  to the right of the elevator shaft  322 . Unlike the ES system  100 A, the ES system  100 B includes five pairs of elevators standing side by side (e.g., in adjacent elevator shafts in a depth direction or into the page in  FIG.  3   , or as shown in  FIG.  4   ), thus producing a matrix of elevators  320  that is two elevators wide across the front (e.g., in the X direction in  FIG.  3   ) and five elevators deep (e.g., in the Y direction in  FIG.  4   ). However, the frame  310  can have any suitable number of elevators  320  across the front (e.g., in the X direction in  FIG.  3   ) and any suitable number of elevators  320  in a depth direction (e.g., in the Y direction in  FIG.  4   ). Each elevator  320  can have a stack of blocks  330  to the left and to the right of its associated elevator shaft  322 . The blocks  330  to the left and right can be stacked on the lower deck  312  or upper deck  314  and moved between the lower deck  312  and the upper deck  314 . The frame  310 , blocks  130 , elevator shafts  322  and elevators  320  in each vertical plane form a module. In the illustrated implementation, the ES system  100 B has five modules. 
     To store electricity or other form of energy, an elevator  320  descends an elevator shaft  322  to or near (e.g., above) the lower deck  312 , picks up a block  330  (e.g., from a stack of blocks  330  on the left side or right side of the elevator shaft  322 ), carries the block  330  to (or above) the upper deck  314 , and deposits the block on a stack of blocks  330  on the upper deck  314  (e.g., on the left side or right side, respectively, so that the block  330  on the upper deck  314  is on the same side it was when it was on the lower deck  312 , or above its original position). To release electricity or other form of energy, an elevator  320  ascends an elevator shaft  322  to or near (e.g., above) the upper deck  314 , picks up a block  330  (e.g., from a stack of blocks  330  on the left side or right side of the elevator shaft  322 ), carries the block  330  to (or above) the lower deck  312 , and deposits the block  330  on a stack of blocks  330  on the lower deck  312  (e.g., on the left side or right side of the elevator shaft  322 , respectively, so that the block  330  on the lower deck  312  is on the same side it was when it was on the upper deck  314 , or below its earlier position). The ES system  100 B, like the ES system  100 A,  100 , includes a motor-generator  350  (e.g., similar to the motor-generator  150  in  FIGS.  1 - 2   ) to lift and lower the blocks  330 . By moving the blocks  330  between a location at (or above) the lower deck  312  and a location at (or above) upper deck  314  so that the block  330  remains on the same side (e.g., to the left or right of the associated elevator shaft  322 ), the ES system  100 B, like the ES system  100 A,  100 , advantageously moves the blocks  330  so that the average load on the frame  310  (e.g., or foundation under the frame  310 ) is approximately constant during operation of the ES system, thereby inhibiting stresses on the system during operation. Additionally, because each block  330  travels between a location at (or above) the lower deck  312  and a location at (or above) upper deck  314  so that the block  330  remains on the same side (e.g., to the left or right of the associated elevator shaft  322 ), each of the blocks  330  of the ES system  100 B, like those of the ES system  100 A,  100 , have a different vertical travel distance between the location above the lower deck  312  and the location about the upper deck  314 . For example, when all the blocks  330  are on the lower deck  312 , the top block  330  in the stack travels a shorter distance to the location above the upper deck  314  than the bottom block  330  in the stack, which must travel from the a location adjacent the bottom deck  312 , past the location of the upper deck  314  to a top of the stack on the upper deck  314 . Accordingly, each block  330  of the ES system  100 B (as each block  130  of the ES system  100 ,  100 A) stores a different amount of energy when moved from the above the lower deck  312  to above the upper deck  314  and generates a different amount of electricity when moved from above the upper deck  314  to above the lower deck  312 . 
       FIG.  7    illustrates one implementation of a block  330 . In one implementation, the block  130  used with the ES system  100 ,  100 A in  FIGS.  1 - 2    can be similar (e.g., identical) to the block  330  in  FIG.  7   . In one implementation, the block  330  is rectangular and can optionally have a substantially smooth finish on an upper surface  330   a  (e.g. planar upper surface), a front side  330   b,  a back side  330   c,  a left side  330   d  and a right side  330   e  of the block  330 . Advantageously, the smooth surface can facilitate movement of a jack (such as the jack  810  described further below) over the upper surface  330   a.  The bottom surface  330   f,  in contrast, can in one implementation have a corrugated surface with two or more protrusions  740  and one or more recesses  742  along the length L of the block  330  that run the depth D of the block  330  from the front side  330   b  to the back side  330   c.  The protrusions  740  extend downward while the recesses  742  reside above the protrusions  740 . The protrusions  740  contact the ground, deck (e.g., lower deck  312 , upper deck,  314 ), other block  330 , or other surface on which the block  330  is placed, and the recesses  742  extend above said surface (e.g., extend approximately 10 to 30 centimeters above said surface). In one example, the protrusions  740  are 10 to 30 centimeters tall and define openings that extend across the depth D of the block  330 . In another implementation (shown in  FIGS.  3 - 6   ), the block  330  has two protrusions on the edges of the block  330  so there is one recess  742   a  (see  FIG.  5   ) between the two protrusions that defines a single opening that extends the depth of the block  330 . 
     In one implementation, each block  330  can be approximately 6 meters long, 6 meters wide, and 4 meters tall (e.g. have a volume of approximately 144 cubic meters). However, the block  330  can have other suitable dimensions. The block  330  may be made of concrete, or compacted dirt or soil, for example. In one example, the total weight of a block  330  is between about 200 tons and about 300 tons (e.g., metric ton), such as approximately 288 tons. The amount of energy storage of the ES system  100 B can in one implementation be approximately 500 kWh (kilowatt hours). The amount of power generation provided by the ES system  100 B can in one implementation be approximately 1.1 MW. 
       FIGS.  8 A- 8 D  show a block  330  with corrugated underside (e.g., corrugated bottom surface) and a wheeled jack operable to move the block  330 . The block  330  is moved from a deck  850  to the elevator  820  and then from the elevator  820  to a different deck  850 . The elevator  820  can in one implementation be similar to the elevator  120  in  FIGS.  1 - 2    for the ES system  100 ,  100 A and the elevator  320  in  FIGS.  3 - 6    for the ES system  100 B. The deck  850  can be the lower deck  112 ,  312  or upper deck  114 ,  314 . The jack  810 , which can be integrated into the elevator  820 , can slide under the block  330 , lift the block  330  (as described below), and then roll the block  330  back to the elevator  820 , or vice versa. For example, the jack  810  can have one or more fingers sized to extend in the one or more recesses  742  between protrusions  740  on the bottom side  300   f  of the block  330 . 
     The elevator  820  includes a platform  800  and the jack  810  is movable relative to the platform  800  (e.g., movably coupled or integrated with the elevator  820 ). The jack  810  includes a housing  811  with multiple wheels  812 , one or more (e.g., multiple) lift arms  814 , and upper surface  816 . The lift arms  814  can optionally be rotatably attached to the housing  811  (e.g., at the upper end of each arm  814 ). The lower end of each lift arm  814  is connected to one or more of the wheels  812 . The lift arms  814  can be rigidly affixed to a motor (e.g., electric motor) or actuator (not shown) that is operable to rotate the lift arms  814  between a vertical orientation and a non-vertical orientation. The overall height of the jack  810  is relatively low when the lift arms  814  are in the non-vertical orientation. When the motor/actuators are energized and the lift arms  814  rotated to the vertical orientation, the lift arms  814  raise the housing  811  and the overall height of the jack  810  is increased so that the upper surface  816  engages and lifts the block  330 , thereby allowing the jack  810  to move the block  330 . 
     In the process of removing a block  330 , the platform  800  can be aligned horizontally with the deck  850  (see  FIG.  8 A ). The jack  810  is rolled toward the block  330  with the lift arms  814  is the non-vertical orientation. The overall height of the jack  810  in this configuration is advantageously less than the height of a recess  742 ,  742   a  (e.g., of the corrugated bottom of the block  330 ). The jack  810  therefore slides under the block  330  between two protrusions  740  (see  FIG.  8 B ) and within one or more recesses  742 ,  742   a.  Once under the block  330 , the lift arms  814  are rotated to a vertical orientation which raises the jack  810  to an overall height greater than the height of the protrusions  740  and/or recesses  742 ,  742   a,  thereby lifting the block  330  off the deck  850  or off another block (see  FIG.  8 C ). Once lifted, the jack  810  is rolled back onto the elevator platform  800  (see  FIG.  8 D ) and the block  330  relocated to a deck  850  or stack at a different height. 
     To unload a block  330  from the deck  850 , the steps described immediately above are executed in reverse. 
       FIGS.  9 A- 12 B  illustrate a fourth implementation of an energy storage (ES) system  100 C. The ES system  100 C includes a frame  910 . In one implementation, the frame  910  can include a plurality of reinforced steel/concrete pillars with a lower deck  912 , an upper deck  914 , a plurality of elevator guides  920 , at least one elevator  922  (e.g., elevator grabber, elevator cage) operating within elevator shaft  924 , a motor-generator  950  with pulleys  926 , and a plurality of ballast weights or blocks  930 . The blocks  930  can be stacked and stored on the lower deck  912  and on the upper deck  914 . The elevator  922  is operable to move the blocks  930  between a stack on the lower deck  912  and a stack on the upper deck  914  via the elevator shaft  924 . The blocks  930  can have an arc shape  9  (e.g., be pie-shaped). The frame  910 , blocks  930 , elevator shaft  924  and elevator  922  form a module. In the illustrated implementation, the ES system  100 C has one module. 
     To store electricity or other form of energy, a block  930  is lifted by the elevator  922  (e.g., elevator grabber) from the lower deck  912  to the upper deck  914 . To release energy and generate electricity, a block  930  is lowered from the upper deck  914  to the lower deck  912  (e.g., under force of gravity) and the force used to rotate the motor-generator to generate electricity (e.g., based on the kinetic energy of the block  930  as it is lowered). 
     The blocks  930  are retrieved, for example, from a stack (e.g., on the lower deck  912  or upper deck  914 ) and returned to a stack (e.g., on the upper deck  914  or the lower deck  912 ) using a rotational motion (e.g., rotating the elevator  922  to the left or right relative to the elevator shaft  924  to retrieve or release blocks). If, for example, a block  930  is removed from above the lower deck  912  (e.g., removed from above a stack of blocks  930  on the lower deck  912 ), the elevator  922  (e.g., elevator grabber) securely grabs the block  930  (e.g., via a lip  925  of the elevator  922  that engages a shoulder  932  of the block  930 ), (optionally lifts and) rotates (e.g., by  90  degrees) the block  930  (e.g., in a first direction) from its position over the lower deck  912  to an angular position corresponding to the elevator shaft  924 , raises the block  930  to a point above the upper deck  914  (e.g., coinciding with the top of a stack of blocks  930  on the upper deck  914 ), rotates the block (e.g., in a second direction opposite the first direction) to a position directly over the stack of blocks  930 , and then releases the block  930  so that is rests on the top of the stack of blocks  930  on the upper deck  914 . Similar rotational motion is used by the elevator  922  (e.g., elevator grabber) to pick up a block  930  from above the upper deck  914  (e.g., from above a stack of blocks  930  on the upper deck  914 ) and place it over the lower deck  912  (e.g., place it at the top of a stack of blocks  930  on the lower deck  912 ). The rotational motion described herein refers to a rotation in a horizontal plane with respect to a vertical axis coinciding with a longitudinal axis running through the elevator guides  920  of the frame  910 . 
     In some embodiments, the motor-generator (not shown) resides on or near the ground and connects to the elevator (e.g., elevator grabber)  922  via the pulleys  926  mounted at the top of the tower guides  920 . 
       FIG.  13    illustrates a fifth implementation of an energy storage (ES) system  100 D. The ES system  100 D is similar to the ES system  100 C illustrated in  FIGS.  9 A- 12 B  and described above. Therefore, the structure and description for the various features of the ES system  100 C in  FIGS.  9 A- 12 B , and the blocks  930  moved by the ES system  100 C, are understood to also apply to the corresponding features of the ES system  100 D and blocks  1330  in  FIG.  13   , except as described below. The ES system  100 D differs from the ES system  100 C in that it includes five frames  1310 , each having a pair of elevators  1322 , instead of the two frames  910 , each having two elevators  922 , in  FIGS.  9 A- 12 B . The ES system  100 D can therefore store more energy than the ES system  100 C, and can generate more electricity than the ES system  100 C. Each of the five frames  1310  of the ES system  100 D can include a plurality of reinforced steel/concrete pillars with a plurality of lower decks  1312  and a plurality of upper decks  1314 , a plurality of elevator guides  1320 , a plurality of elevators (e.g., elevator grabbers)  1322 , a plurality of motor-generators  1050 , and a plurality of ballast weights or blocks  1330 . The ES system  100 D can operate in the same manner as the system  100 C to move blocks between the lower decks  1312  and the upper decks  1314  (e.g., by using rotational motion to remove a block  1330  from above a deck or stack of blocks on a deck, rotate the block in one direction to an elevator shaft, move the block to a different elevation, rotate the block in an opposite direction and place the block over a different deck or over a stack of blocks on said deck). Each frame  1310 , blocks  1330 , elevator shaft and elevator  1322  form a module. In the illustrated implementation, the ES system  100 D has five modules. 
       FIG.  14    is a diagrammatic illustration of a motor-generator  1460  coupled to a plurality of energy storage (and delivery) (ES) systems including a first ES system  1430  and second ES system  1440 . The ES systems  1430 ,  1440  are similar to the energy storage system  100 A,  100 B described above and blocks  1130  are similar to blocks  330 . Therefore, the structure and description for the various features of the ES system  100 A,  100 B and the blocks  330  in  FIGS.  2 - 6   , as well as their operation, are understood to also apply to the corresponding features of the ES system  1430 ,  1440  and block  1130 , except as described below. Though the illustrated embodiment shows the motor-generator  1460  as coupled to two energy storage systems  1430 ,  1440 , one of skill in the art will recognize that in other implementations the motor-generator  1460  can be coupled to only one energy storage system. In still another implementation, the motor-generator  1460  can be coupled to more than two energy storage systems (e.g., to four energy storage systems, six energy storage systems, eight energy storage systems). 
     The motor-generator  1460  can be operated to lift and/or lower blocks  1130  on a plurality of ES systems  1430 ,  1440  simultaneously. That is, the motor-generator  1460  is operable to lift a block  1130  along an elevator shaft  1124  in a column  1122  of one ES system  1430  (e.g., to a location above an upper deck  1114  of the frame  1110  of the ES system) while a block  1130  is lowered along an elevator shaft  1124  in a column  1122  on a different ES system  1440  (e.g., to a location above a lower deck  1112  of the frame  1110  of the ES system), thereby causing blocks  1130  in the ES systems  1430 ,  1440  to be lifted and lowered concurrently. 
     Each ES system  1430 ,  1440  includes a winch  1470 A,  1470 B coupled to the motor-generator  1460  via a drive shaft  1462  to lift and lower the blocks  1130 . Each ES system  1430 , 1440  further includes a cable  1450  that runs up the elevator shaft  1124 , over a pulley  1126 , and back down to an elevator (e.g., elevator grabber)  1120 . The cable  1450  may further include a damper  1452  and linear actuator  1454  mounted between the winch  1470 A,  1470 B and pulley  1126 . The damper  1452  can optionally be a hydraulic damper. In another implementation, the damper  1452  can be a pneumatic damper. In still another implementation, the damper  1452  can be a resilient damper (e.g., include a compressible material, such as rubber). The damper  1452  can advantageously absorb jerky motion in the cable  1450  and inhibit (e.g., prevent) excessive forces from damaging the cable  1450 . The linear actuator  1454  can expand or contract a small distance (e.g., less than several meters, such as less than 3 meters, less than 2 meters) to make fine adjustments in the vertical position of the elevator (e.g., elevator grabber)  1120  when in motion to pick-up or drop-off a block  1130 . 
     When a block  1130  is being lifted, the associated winch (e.g., winch  1470 A and/or  1470 B) draws power from the motor-generator  1460  via the drive shaft  1462 . When a block  1130  is being lowered, the winch (e.g., winch  1470 A and/or  1470 B) inputs power into the motor-generator via the drive shaft  1462 . The motor-generator  1460  is operable to output power to lift a block  1130  on one ES system (e.g., ES system  1430 ) while a receiving power when a block  1130  is lowered on a different ES system (e.g., ES system  1440 ), thereby causing the motor-generator  1460  to output power and receive power concurrently. Power received by the motor-generator  1460  can optionally be delivered to a power grid to which the motor-generator  1460  is electrically connected. 
       FIG.  15    is a diagrammatic illustration of a winch  1470 A. The winch  1470 A is substantially identical (e.g., identical) to the winch  1470 B, so the features illustrated in  FIG.  15    for winch  1470 A and described below are understood to apply to winch  1470 B. The winch  1470 A includes a plurality of planetary gears  1471 , a plurality of brakes  1475 , and a spool  1490  to reel in or reel out the cable  1450 . The plurality of planetary gears  1471  includes a first set of planetary gears  1471 ′ with a first sun gear  1474 , a first pair of planet gears  1476 , and a first ring gear  1478 , where the planet gears  1476  are arranged between the first sun gear  1474  and the first ring gear  1478 . The plurality of planetary gears  1471  also includes a second set of planetary gears  1471 ″ with a second sun gear  1480 , a second pair of planet gears  1482 , and a second ring gear  1484 , where the planet gears  1482  are arranged between the second sun gear  1480  and the second ring gear  1484 . The winch  1470 A further includes a brake disc  1472  that is concentric with the drive shaft  1462 . 
     The brake disc  1472  is affixed to the first pair of planet gears  1476  by one or more members  1473 , so that the brake disc  1472  rotates (e.g., about the first sun gear  1474 ) at the same speed as the first pair of planet gears  1476 . In addition, the first ring gear  1478  is affixed by one or more members  1477  to the second pair of planet gears  1482 , so that the first ring gear  1478  rotates (e.g., about the second sun gear  1480 ) at the same speed as the second pair of planet gears  1482 . 
     First brake A (e.g., brake pad(s) that selectively engage the disc  1472 ) is operable to slow or stop the rotation of the brake disc  1472  as well as the first pair of planet gears  1476 . Second brake B (e.g., brake pad(s) that selectively engage the first ring gear  1478 ) is operable to slow or stop the rotation of the first ring gear  1478  as well as the second pair of planet gears  1482 . Third brake C (e.g., brake pad(s) that selectively engage the second ring gear  1484 ) is operable to slow or stop the rotation of the second ring gear  1484 . In one implementation, one or more of the first brake A, second brake B and third brake C can be hydraulically operated brakes. In another implementation, one or more of the first brake A, second brake B and third brake C can be pneumatically operated brakes 
       FIG.  16    includes a table indicating the performance of a winch (e.g. winch  1470 A,  1470 B) based on activation of one or more of the first brake A, second brake B and/or third brake C. In the table, a “1” indicates that a brake force is actively braking while a “0” indicates that the brake is open and no braking force is applied. As indicated, the spool  1490  is stopped when brake C applies a brake force to the second ring gear  1484  while brakes A and B are open (e.g., no braking force is applied by brakes A and B). The spool  1490  operates in reverse when brake A applies a brake force to the brake disc  1472  while brakes B and C remain open (e.g., no braking force is applied by brakes B and C). When the spool  1490  operates in reverse, the elevator (e.g., elevator grabber)  1120  (and block  1130  carried by it) is lowered. The spool  1490  operates in the forward direct to lift the elevator (e.g., elevator grabber)  1120  (and block  1130  carried by it) when brake B applies a brake force to the first ring gear  1478  while brakes A and C remain open (e.g., no braking force is applied by brakes A and C). Advantageously, the plurality of planetary gears  1471  and brakes A, B, C allow the winch  1470 A (as well as the winch  1470 B) to operate to raise or lower the elevator  1120  without requiring complex motor controls, thereby providing a simplified and less costly control for raising and lowering the blocks  1130 . Though described in connection with the ES system  1430 ,  1440  above, the motor-generator  1460 , winch  1470 A,  1470 A and drive shafts  1462  in  FIGS.  14 - 15   , and operation mode in  FIG.  16   , can be implemented in any of the energy storage and delivery systems  100 - 100 D described above. 
     To convert the stored potential energy to electricity, the elevator  120 ,  320 ,  820 ,  922 ,  1322 ,  1120  can move one or more of the blocks  130 ,  330 ,  930 ,  1330 ,  1130  from a higher elevation to a lower elevation (e.g., vertically lower at least partially under the force of gravity) to drive the electric motor-generator  150 ,  350 ,  950 ,  1050 ,  1460  (via one or more cables or steel ribbons) to generate electricity, which can be delivered to a power grid to which the motor-generator  150 ,  350 ,  950 ,  1050 ,  1460  is electrically connected. Power in the form of electricity is generated each time a block  130 ,  330 ,  930 ,  1330 ,  1130  is lowered. 
     Advantageously, the energy storage and delivery system  100 - 100 D,  1430 ,  1440  can, for example, store electricity generated from solar power as potential energy in the raised blocks  130 ,  330 ,  930 ,  1330 ,  1130  during daytime hours when solar power is available, and can convert the potential energy in the blocks  130 ,  330 ,  930 ,  1330 ,  1130  into electricity during nighttime hours when solar energy is not available by lowering one or more blocks  130 ,  330 ,  930 ,  1330 ,  1130  and deliver the converted electricity to the power grid. 
     Described herein are examples of an energy storage and delivery system (e.g., the energy storage and delivery system  100 - 100 D,  1430 ,  1440 ) operable to convert electrical energy or electricity into potential energy for storage, and to convert potential energy into electrical energy or electricity, for example, for delivery to an electrical grid. Advantageously, the energy storage system requires little to no maintenance, and can operate decades (e.g., 30-50 years) with substantially no reduction in energy storage capacity. 
     In some implementations, the energy storage system described herein can store approximately 10 megawatts-hour (MWh) or more of energy (e.g., between 10 MWh and 100 MWh, such as 15 MWh, 20 MWh, 30 MWh, 50 MWh, 80 MWh, 90 MWh) and deliver approximately 10 MWh or more of energy (e.g., between 10 MWh and 100 MWh, such as 15 MWh, 20 MWh, 30 MWh, 50 MWh, 80 MWh, 90 MWh) to the electrical grid. The energy storage system described herein can deliver energy each hour (e.g., 1 MW up to 6 MW or more). However, in other implementations the energy storage and delivery system described herein can have other suitable energy storage and delivery capacities (e.g., 1 MWh, 3 MWh, 5 MWh, etc.). In one implementation, the energy storage and delivery system can optionally power approximately 1000 homes or more for a day. 
     The energy storage and delivery system described herein can advantageously be connected to a renewable energy (e.g., green energy) power generation system, such as, for example, a solar power energy system, a wind energy power system (e.g., wind turbines), etc. Advantageously, during operation of the renewable energy power generation system (e.g., operation of the solar energy system during daylight hours, operation of the wind power system during windy conditions), the energy storage and delivery system captures the electricity generated by the renewable energy power generation system. The energy storage and delivery system can later deliver the stored electricity to the electrical grid when the renewable energy power generation system is not operable (e.g., at night time, during windless conditions). Accordingly, the energy storage and delivery system operates like a battery for the renewable energy power generation system and can deliver off-hours electricity from a renewable energy power generation system to the electrical grid. 
     In implementations described above, the energy storage and delivery system  100 - 100 D,  1430 ,  1440  lifts blocks  130 ,  330 ,  930 ,  1330 ,  1130  to store electrical energy as potential energy and lowers blocks  130 ,  330 ,  930 ,  1330 ,  1130  to generate electricity. In one implementation, the elevator  120 ,  320 ,  820 ,  922 ,  1322 ,  1120  can be operated with excess power from an electricity grid. The amount of energy recovered by the energy storage system  100 - 100 D,  1430 ,  1440  for every unit of energy used to lift the blocks  130 ,  330 ,  930 ,  1330 ,  1130  can optionally be 80-90%. 
     Additional Embodiments 
     In embodiments of the present invention, an energy storage system, a method of operating the same, and a block for use with the same, may be in accordance with any of the following clauses: 
     Clause 1. An energy storage and delivery system, comprising:
         one or more modules, each module comprising
           a plurality of blocks, and   a frame having a vertical height above a foundation, the frame including an elevator shaft,
               an elevator movably disposed in the elevator shaft, the elevator sized to receive and support one or more blocks therein and operable to move one or more of the plurality of blocks between a lower elevation and a higher elevation, and   a winch assembly movably coupled to a cable that is coupled to the elevator, the winch assembly comprising one or more planetary gear assemblies, one or more brakes and a spool coupled to the cable;   
               
           a motor-generator; and   a drive shaft having an end coupled to the motor-generator and an opposite end coupled to the winch assembly,   wherein at least one of the one or more brakes of the winch assembly is operable so that the spool rotates to reel-in the cable to raise the elevator to move one or more of the plurality of blocks from a lower elevation to a higher elevation to store energy or so that the spool rotates to reel-out the cable to lower the elevator to move one or more of the plurality of blocks from a higher elevation to a lower elevation to generate electricity.       

     Clause 2. The system of clause 1, wherein the winch assembly comprises a brake disc concentric with the drive shaft and wherein the one or more planetary gear assemblies includes a first planetary gear assembly and a second planetary gear assembly, the first planetary gear assembly disposed axially between the brake disc and the second planetary gear assembly, the second planetary gear assembly disposed axially between the first planetary gear assembly and the spool, the first planetary gear assembly including a first sun gear, a first pair of planet gears, and a first ring gear, the second planetary gear assembly including a second sun gear, a second pair of planet gears and a second ring gear, the drive shaft fixedly coupled to the first sun gear, the second sun gear and the spool, the brake disc fixedly coupled to the first pair of planet gears, and the first ring gear fixedly coupled to the second pair of planet gears. 
     Clause 3. The system of clause 2, wherein the one or more brakes includes a first brake operable to selectively engage the brake disc, a second brake operable to selectively engage the first ring gear and a third brake operable to selectively engage the second ring gear. 
     Clause 4. The system of clause 3, wherein operating the first brake to disengage the brake disc, operating the second brake to disengage the first ring gear, and operating the third brake to engage the second ring gear stops rotation of the spool. 
     Clause 5. The system of any of clauses 3-4, wherein operating the first brake to engage the brake disc, operating the second brake to disengage the first ring gear, and operating the third brake to disengage the second ring gear rotates the spool in a reverse direction to reel-out the cable to lower the elevator. 
     Clause 6. The system of any of clauses 3-5, wherein operating the first brake to disengage the brake disc, operating the second brake to engage the first ring gear, and operating the third brake to disengage the second ring gear rotates the spool in a forward direction to reel-in the cable to raise the elevator. 
     Clause 7. The system of any preceding clause, further comprising a damper coupled to the cable, the damper configured to absorb at least a portion of a force applied to the cable. 
     Clause 8. The system of any preceding clause, further comprising a linear actuator coupled to the cable, the linear actuator configured to expand or contract to allow adjustment in a vertical position of the elevator to facilitate picking-up or dropping-off of the block. 
     Clause 9. The system of any preceding clause, wherein the one or more modules are two modules, and wherein the drive shaft couples to the winch of a first of the two modules and to the winch of the second of the two modules. 
     Clause 10. The system of clause 9, wherein the winch of the first module and the winch of the second module are operable to simultaneously lift a block in the first module and lower a block in the second module. 
     Clause 11. The system of any preceding clause, wherein the frame has a lower deck and an upper deck spaced vertically above the lower deck, and wherein the elevator shaft is disposed between a left column and a right column of the frame that extend between the lower deck and the upper deck. 
     Clause 12. The system of clause 11, wherein the elevator is operable to raise one or more blocks from a location in the left column above the lower deck to a location above the upper deck over the left column and to move one or more blocks from a location in the right column above the lower deck to a location above the upper deck over the right column to thereby store an amount of electrical energy corresponding to a potential energy amount of said one or more raised blocks, and wherein the elevator is operable to lower one or more blocks from a location above the upper deck over the left column to a location within the left column above the lower deck and to move one or more blocks from a location above the upper deck over the right column to a location within the right column above the lower deck under a force of gravity to thereby generate an amount of electricity for each of the one or more lowered blocks via the electric motor-generator electrically coupled to the elevator. 
     Clause 13. The system of clause 11, wherein the elevator is operable to move the plurality of blocks between the location above the lower deck and the location above the upper deck so that the average distribution of load on the frame or the foundation of the module remains substantially constant. 
     Clause 14. The system of any preceding clause, wherein the frame includes a plurality of columns of reinforced steel and concrete pillars. 
     Clause 15. A method for storing and generating electricity, comprising:
         operating an elevator along an elevator shaft to move a plurality of blocks between a lower elevation and a higher elevation, the elevator coupled to a cable that extends between the elevator and a spool of a winch assembly, the winch assembly comprising one or more planetary gear assemblies and one or more brakes,   wherein operating the elevator includes:
           operating a first brake of the winch assembly to disengage a brake disc of the winch assembly, operating a second brake of the winch assembly to disengage a first ring gear of a first planetary gear assembly and operating a third brake of the winch assembly to engage a second ring gear of a second planetary gear assembly to stop rotation of the spool,   operating the first brake to engage the brake disc of the winch assembly, operating the second brake to disengage the first ring gear of the first planetary gear assembly and operating the third brake to disengage the second ring gear of the second planetary gear assembly to rotate the spool in a reverse direction to reel-out the cable to lower the elevator, and   operating the first brake to disengage the brake disc of the winch assembly, operating the second brake to engage the first ring gear of the first planetary gear assembly and operating the third brake to disengage the second ring gear of the second planetary gear assembly to rotate the spool in a forward direction to reel-in the cable to raise the elevator.   
               

     Clause 16. The method of clause 15, wherein moving the blocks between the lower elevation and the higher elevation includes moving the blocks between a location above a lower deck in a left or a right column on either side of the elevator shaft to location above an upper deck aligned with the left or right columns. 
     Clause 17. The method of clause 16, wherein moving the one or more blocks between the location above the lower deck in the left or right columns and the location above the upper deck in the left or right columns includes positioning the blocks so that the average distribution of load on a foundation under the frame or on the frame remains substantially constant. 
     While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure. Accordingly, the scope of the present inventions is defined only by reference to the appended claims. 
     Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination. 
     Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. 
     For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment. 
     Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z. 
     Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount. As another example, in certain embodiments, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree. 
     The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.