Energy storage system and method
An energy storage system includes a crane and a plurality of blocks, where the crane is operable to move blocks from a lower elevation to a higher elevation (via stacking of the blocks) to store electrical energy as potential energy of the blocks, and then operable to move blocks from a higher elevation to a lower elevation (via unstacking of the blocks) to generate electricity based on the kinetic energy of the block when lowered (e.g., by gravity). The energy storage system can, for example, store electricity generated from solar power as potential energy in the stacked blocks during daytime hours when solar power is available, and can convert the potential energy in the stacked blocks into electricity during nighttime hours when solar energy is not available, and deliver the converted electricity to the power grid.
1. A block for use in an energy storage and generation system, comprising:
a body comprising concrete having a rectangular shape with a length greater than a width, the width being greater than a depth of the body, a planar facet interconnecting adjacent sides of the body, and one or more recesses on a bottom surface of the body; and
a metal plate attached to the one or more recesses to inhibit wear on the block during movement of the block,
wherein the block comprises a top portion that defines a top surface of the block, a middle portion that defines a peripheral surface of the block, and a bottom portion that defines a bottom surface of the block, the top and bottom portions comprising high performance concrete with a relatively higher compression strength and the middle portion comprising a low grade concrete having a relatively lower compression strength.
2. The block of claim 1 , wherein the body has an aspect ratio for the length to width to depth of 4:2:1.
3. The block of claim 1 , wherein the body has an aspect ratio for the length to width to depth of 3:2:1.
4. The block of claim 1 , wherein the body has a length of approximately 4 m.
5. The block of claim 1 , wherein the planar facet extends at 45 degrees relative to the adjacent sides of the body.
6. The block of claim 1 , wherein the body weighs between 20 tons and 55 tons.
7. The block of claim 1 , wherein the body is symmetrical along a first central plane through the width of the block and a second central plane through the depth of the block.
8. The block of claim 1 , wherein the body has one or more bores that extend through the length of the block from one or more proximal openings at a top end of the block to one or more distal openings at a bottom end of the block, the distal openings aligning with the one or more recesses on the bottom surface of the body.
9. The block of claim 8 , wherein the one or more bores are a pair of spaced apart bores that extend through the length of the block and are centered along the width and depth of the block.
10. The block of claim 8 , wherein the one or more proximal openings have a conical shape.
11. The block of claim 8 , wherein the one or more distal openings are stepped, at least a portion of the metal plate defining at least one of the one or more distal openings.
12. The block of claim 8 , further comprising a metal plate embedded in the block about the one or more proximal openings, at least a portion of the metal plate defining a tapered surface of the one or more proximal openings.
13. The block of claim 1 , wherein the body comprises an outer shell of concrete that encloses a ballast mass of a different material.
14. The block of claim 1 , wherein the block comprises rebar embedded in the concrete.
15. The block of claim 1 , wherein the high performance concrete has a compression strength of 10 to 60 MPa and the low grade concrete has a compression strength of 3 to 8 MPa.
16. The block of claim 1 , further comprising one or more reinforcement layers located in one or more of the top portion, middle portion and bottom portion of the block.
17. The block of claim 16 , wherein the one or more reinforcement layers are structural steel.
18. A block for use in an energy storage and generation system, comprising: a body comprising concrete having a rectangular shape with a length greater than a width, the width being greater than a depth of the body, a planar facet interconnecting adjacent sides of the body, and one or more recesses on a bottom surface of the body; and a metal plate attached to the one or more recesses to inhibit wear on the block during movement of the block; and a second metal plate embedded in the block about one or more proximal openings, at least a portion of the second metal plate defining a tapered surface of the one or more proximal openings, wherein the body has one or more bores that extend through the length of the block from one or more proximal openings at a top end of the block to one or more distal openings at a bottom end of the block, the distal openings aligning with the one or more recesses on the bottom surface of the body.
19. The block of claim 18 , wherein the one or more bores are a pair of spaced apart bores that extend through the length of the block and are centered along the width and depth of the block.