초록 ▼

The present invention provides an energy storage device that utilizes a cold sink that undergoes cycles of freezing and thawing. The device converts electrical energy to stored thermal energy, and then re-converts the stored thermal energy to electrical energy, as needed or desired. The device can s

The present invention provides an energy storage device that utilizes a cold sink that undergoes cycles of freezing and thawing. The device converts electrical energy to stored thermal energy, and then re-converts the stored thermal energy to electrical energy, as needed or desired. The device can store energy on a large scale (e.g., on the order of megawatts or greater) and for an extended period of time (e.g., for at least 12 hours, or longer, as needed).

대표청구항 ▼

1. An energy storage system comprising: (a) a storage refrigerant circuit that receives input electric power and converts the electric power to stored thermal energy, the storage refrigerant circuit comprising: (i) a compressor that receives input electric energy and pumps a first refrigerant throug

1. An energy storage system comprising: (a) a storage refrigerant circuit that receives input electric power and converts the electric power to stored thermal energy, the storage refrigerant circuit comprising: (i) a compressor that receives input electric energy and pumps a first refrigerant through the circuit;(ii) a first condenser in fluid communication with the compressor and in thermal communication with a hot sink;(iii) a second condenser in fluid communication with the first condenser, wherein the second condenser releases heat sufficient to balance the energy around the hot sink;(iv) an expansion valve in fluid communication with the second condenser; and(v) an evaporator in fluid communication with the expansion valve and the compressor, and in thermal communication with a cold sink, wherein the cold sink is maintained at a temperature that is less than about 0° C. and that is at least about 20° C. cooler than the hot sink, wherein heat transfer from the cold sink to the evaporator causes the cold sink to freeze, wherein thermal energy from the cold sink is delivered through the storage refrigerant circuit to the hot sink, thereby converting the input electric power to thermal energy stored in the hot sink; and(b) a generation refrigerant circuit that receives stored thermal energy from the hot sink and converts the stored energy to output electric power, the generation refrigerant circuit comprising: (i) a pump that pumps a second refrigerant through the circuit;(ii) a vaporizer in fluid communication with the pump and in thermal communication with the hot sink;(iii) an expander in fluid communication with the vaporizer, wherein the expander produces output electric power; and(iv) a condenser in fluid communication with the expander and the pump, and in thermal communication with the cold sink, wherein thermal energy stored in the hot sink is delivered through the generation refrigerant circuit to the cold sink, driving the expander to produce output electric power, wherein heat transfer to the cold sink from the condenser causes the cold sink to melt, thereby converting the stored thermal energy to output electric power. 2. The energy storage device of claim 1, wherein the energy storage system can store at least about 1 megawatt (MW) of thermal energy. 3. The energy storage device of claim 1, wherein the theoretical efficiency is at least about 50%. 4. The energy storage device of claim 1, wherein the storage refrigerant circuit and the generation refrigerant circuit run synchronously. 5. The energy storage device of claim 1, wherein the storage refrigerant circuit and the generation refrigerant circuit run asynchronously. 6. The energy storage device of claim 5, wherein there is at least an 8 hour delay between the running of the storage refrigerant circuit and the running of the generation refrigerant circuit. 7. The energy storage device of claim 1, wherein the cold sink is at least about 30° C. cooler than the hot sink. 8. The energy storage device of claim 1, wherein the cold sink is maintained at about 0° C. and the hot sink is maintained at about 30° C. 9. The energy storage device of claim 1, wherein the cold sink is water. 10. The energy storage device of claim 9, wherein the cold sink is a brine. 11. The energy storage device of claim 1, wherein the hot sink is water. 12. The energy storage device of claim 11, wherein the hot sink is a natural aquifer. 13. The energy storage device of claim 1, wherein the first refrigerant is ammonia. 14. The energy storage device of claim 1, wherein the first refrigerant is pumped through the storage refrigerant circuit at flow rate between about 30,000 kg/hr to about 40,000 kg/hr. 15. The energy storage device of claim 1, wherein the second refrigerant is a lower alkyl hydrocarbon. 16. The energy storage device of claim 15, wherein the second refrigerant is selected from the group consisting of isobutane, propane, butane and dimethyl ether. 17. The energy storage device of claim 1, wherein the second refrigerant is pumped through the generation refrigerant circuit at a flow rate between about 100,000 kg/hr to about 125,000 kg/hr. 18. The energy storage device of claim 1, wherein the first refrigerant is ammonia and the second refrigerant is isobutane. 19. The energy storage device of claim 1, wherein the second condenser in the storage refrigerant circuit releases excess heat into the air. 20. The energy storage device of claim 1, wherein the second condenser in the storage refrigerant circuit releases excess heat into water. 21. The energy storage device of claim 1, wherein the compressor in the storage refrigerant circuit is in communication with a motor powered by an electricity generating source. 22. The energy storage device of claim 21, wherein the electricity generating source is one or more photovoltaic units. 23. The energy storage device of claim 21, wherein the electricity generating source is one or more wind turbines. 24. The energy storage device of claim 1, wherein the expander in the generation refrigerant circuit is in communication with a generator that is in communication with an electrical grid. 25. A method of storing electrical energy, comprising: (a) delivering electrical energy to a storage refrigerant circuit that receives input electric power and converts the electric power to stored thermal energy, the storage refrigerant circuit comprising: (i) a compressor that receives input electric energy and pumps a first refrigerant through the circuit;(ii) a first condenser in fluid communication with the compressor and in thermal communication with a hot sink;(iii) a second condenser in fluid communication with the first condenser, wherein the second condenser releases heat sufficient to balance the energy around the hot sink;(iv) an expansion valve in fluid communication with the second condenser; and(v) an evaporator in fluid communication with the expansion valve and the compressor, and in thermal communication with a cold sink, wherein the cold sink is maintained at a temperature that is less than about 0° C. and that is at least about 20° C. cooler than the hot sink, wherein heat transfer from the cold sink to the evaporator causes the cold sink to freeze, wherein thermal energy from the cold sink is delivered through the storage refrigerant circuit to the hot sink, thereby converting the input electric power to thermal energy stored in the hot sink; and(b) delivering the stored thermal energy in the hot sink to a generation refrigerant circuit that receives stored thermal energy from the hot sink and converts the stored energy to output electric power, the generation refrigerant circuit comprising: (i) a pump that pumps a second refrigerant through the circuit;(ii) a vaporizer in fluid communication with the pump and in thermal communication with the hot sink;(iii) an expander in fluid communication with the vaporizer, wherein the expander produces output electric power; and(iv) a condenser in fluid communication with the expander and the pump, and in thermal communication with the cold sink, wherein thermal energy stored in the hot sink is delivered through the generation refrigerant circuit to the cold sink, driving the expander to produce output electric power, wherein heat transfer to the cold sink from the condenser causes the cold sink to melt, thereby converting the stored thermal energy to output electric power. 26. The method of claim 25, wherein at least about 1 megawatt (MW) of thermal energy is stored in the hot sink. 27. The method of claim 25, wherein the theoretical efficiency is at least about 50%. 28. The method of claim 25, wherein the storage refrigerant circuit and the generation refrigerant circuit run synchronously. 29. The method of claim 25, wherein the storage refrigerant circuit and the generation refrigerant circuit run asynchronously. 30. The method of claim 29, wherein there is at least an 8 hour delay between the running of the storage refrigerant circuit and the running of the generation refrigerant circuit. 31. The method of claim 25, wherein the cold sink is at least about 30° C. cooler than the hot sink. 32. The method of claim 25, wherein the cold sink is maintained at about 0° C. and the hot sink is maintained at about 30° C. 33. The method of claim 25, wherein the cold sink is water. 34. The method of claim 33, wherein the cold sink is a brine. 35. The method of claim 25, wherein the hot sink is water. 36. The method of claim 35, wherein the hot sink is a natural aquifer. 37. The method of claim 25, wherein the first refrigerant is ammonia. 38. The method of claim 25, wherein the first refrigerant is pumped through the storage refrigerant circuit at flow rate between about 30,000 kg/hr to about 40,000 kg/hr. 39. The method of claim 25, wherein the second refrigerant is a lower alkyl hydrocarbon. 40. The method of claim 39, wherein the second refrigerant is selected from the group consisting of isobutane, propane, butane and dimethyl ether. 41. The method of claim 25, wherein the second refrigerant is pumped through the generation refrigerant circuit at a flow rate between about 100,000 kg/hr to about 125,000 kg/hr. 42. The method of claim 25, wherein the first refrigerant is ammonia and the second refrigerant is isobutane. 43. The method of claim 25, wherein the second condenser in the storage refrigerant circuit releases excess heat into the air. 44. The method of claim 25, wherein the second condenser in the storage refrigerant circuit releases excess heat into water. 45. The method of claim 25, wherein the compressor in the storage refrigerant circuit is in communication with a motor powered by an electricity generating source. 46. The method of claim 45, wherein the electricity generating source is one or more photovoltaic units. 47. The method of claim 45, wherein the electricity generating source is one or more wind turbines. 48. The method of claim 25, wherein the expander in the generation refrigerant circuit is in communication with a generator that is in communication with an electrical grid.