초록 ▼

Embodiments provide systems and methods for taking power from an electric power grid and converting it into higher-pressure natural gas for temporary storage. After temporary storage, the higher-pressure natural gas may be expanded through an expansion engine to drive a generator that converts energ

Embodiments provide systems and methods for taking power from an electric power grid and converting it into higher-pressure natural gas for temporary storage. After temporary storage, the higher-pressure natural gas may be expanded through an expansion engine to drive a generator that converts energy from the expanding natural gas into electrical power, which may then be returned to the electric power grid. In this way, the disclosed systems and methods may provide ways to temporarily store, and then return stored power from the electric power grid. Preferably, the components of the system are co-located at the same natural gas storage facility. This allows natural gas storage, electrical energy storage, and electrical energy generation to take place at the same facility.

대표청구항 ▼

1. A system at a natural gas storage facility, the system comprising: natural gas received from a natural gas pipeline system;a compressor configured to receive the natural gas and to compress the natural gas from a pipeline pressure to a reservoir pressure to form high-pressure natural gas and wast

1. A system at a natural gas storage facility, the system comprising: natural gas received from a natural gas pipeline system;a compressor configured to receive the natural gas and to compress the natural gas from a pipeline pressure to a reservoir pressure to form high-pressure natural gas and waste heat of compression;a controllable reservoir configured to receive the high-pressure natural gas from the compressor, temporarily store the high-pressure natural gas, and release the high-pressure natural gas after storage;an expansion engine configured to receive the high-pressure natural gas from the reservoir, expand the high-pressure natural gas from the reservoir pressure to the pipeline pressure, and produce useful power;a heat exchanger at the expansion engine configured to heat the high-pressure natural gas from the reservoir prior to expansion;a heat exchanger at the compressor configured to heat a thermal transfer fluid from the waste heat of compression;a thermal storage system configured to temporarily store thermal energy, the thermal storage system including: a hot tank configured to receive the thermal transfer fluid from the heat exchanger at the compressor and to temporarily store the thermal transfer fluid, in which the heat exchanger at the expansion engine is further configured to receive the thermal transfer fluid from the hot tank; anda cold tank configured to receive the thermal transfer fluid from the heat exchanger at the expansion engine and to temporarily store the thermal transfer fluid, in which the heat exchanger at the compressor is further configured to receive the thermal transfer fluid from the cold tank;an electric generator co-located at the natural gas storage facility with the compressor, the reservoir, the expansion engine, and the heat exchanger at the expansion engine, the generator configured to be driven by the useful power produced by the expansion engine; anda system outlet configured to receive the natural gas from the expansion engine and to return the natural gas to the natural gas pipeline system. 2. The system of claim 1, in which the compressor is an electric drive compressor. 3. The system of claim 1, in which the reservoir is a depleted gas reservoir. 4. The system of claim 1, further comprising a gearbox between the expansion engine and the generator, in which the gearbox is configured to change a rotational speed of the expansion engine to a required rotational speed of the generator. 5. The system of claim 1, in which the compressor is a multi-stage compressor and the expansion engine is a multi-stage expansion engine. 6. The system of claim 1, in which the thermal storage system further includes a cooling heat exchanger between the cold tank and the heat exchanger at the compressor, the cooling heat exchanger being configured to cool the thermal storage medium from a cold tank temperature. 7. A system at a natural gas storage facility, the system comprising: natural gas received from a natural gas pipeline system;a compressor configured to receive the natural gas and to compress the natural gas from a pipeline pressure to a reservoir pressure to form high-pressure natural gas and waste heat of compression;a controllable reservoir configured to receive the high-pressure natural gas from the compressor, temporarily store the high-pressure natural gas, and release the high-pressure natural gas after storage;a multi-stage expansion engine configured to receive the high-pressure natural gas from the reservoir, expand the high-pressure natural gas from the reservoir pressure to the pipeline pressure, and produce useful power;a heat exchanger at the expansion engine configured to heat the high-pressure natural gas from the reservoir prior to expansion;a prime mover configured to generate electric power;a heat exchanger at the prime mover configured to capture waste heat energy from the prime mover and to transfer the heat energy to a thermal transfer fluid, in which the heat exchanger at the expansion engine is further configured to receive the thermal transfer fluid from the heat exchanger at the prime mover to heat the high-pressure natural gas from the reservoir prior to each stage of expansion; andan electric generator co-located at the natural gas storage facility with the compressor, the reservoir, the expansion engine, and the heat exchanger at the expansion engine, the generator configured to be driven by the useful power produced by the expansion engine; anda system outlet configured to receive the natural gas from the expansion engine and to return the natural gas to the natural gas pipeline system. 8. The system of claim 7, in which the heat exchanger at the expansion engine includes a preheater before a first stage of the expansion engine and a reheater before each subsequent stage of the expansion engine. 9. The system of claim 7, in which the heat exchanger at the prime mover includes: a waste heat recovery unit configured to capture the waste heat energy from the prime mover and to use the waste heat energy to generate hot fluid; anda heater configured to receive the generated hot fluid from the waste heat recovery unit and to heat the thermal transfer fluid. 10. The system of claim 7, in which the heat exchanger at the expansion engine includes a liquid-bath heat exchanger. 11. The system of claim 7, in which the system outlet further comprises a dehydration unit configured remove moisture from the natural gas. 12. The system of claim 7, in which the compressor is an electric drive compressor. 13. The system of claim 7, in which the reservoir is a depleted gas reservoir.