High-efficiency electrical energy storage system

Abstract

Electrical energy storage and hot water production system, characterized in that it comprises: - an air liquefaction unit (1) including an air compression unit, for producing liquefied air gases; - a storage unit (6) for the liquefied air gases produced; - an evaporator (7) for vaporizing the liquefied air gases from the storage unit (6) and producing compressed air; - a cogeneration unit integrated into a hot water production plant (4) for supplying a district heating network (9), the cogeneration unit comprising an air expansion turbine (2), an air compressor (5), said cogeneration unit being configured to operate in a mode in which it uses the heat generated during the liquefaction of the air to heat the water in the district heating network (9); - the turbine (2) being arranged to recover energy from the compressed air produced. Abbreviated figure: Fig. 1

Description

Title of the invention: High-efficiency electrical energy storage system

[0001] The invention belongs to the field of energy storage and production.

[0002] With the rise of intermittent renewable energies, the need to store electrical energy has emerged. Today, the only way to store large quantities of electrical energy over an average period is with a pumped-storage hydroelectricity (PSH) plant. This requires two water reservoirs at different altitudes. During off-peak hours, water is pumped from the lower reservoir to the upper reservoir. During peak hours, the reverse is done: the water is released through turbines as it flows downhill. This has significant advantages. The response time is very short. The recovery efficiency is good, on the order of 70 to 80%. These systems are almost always located in mountainous areas, often associated with dams. Consequently, their number is limited and they are often located far from energy consumers.

[0003] Storage requires a medium. Air is ubiquitous, free, and non-polluting. However, liquefying air requires significant amounts of energy. The invention thus proposes to replace water as a storage medium with air in a highly efficient manner, offering strong synergy.

[0004] The present invention relates to an innovative high-efficiency electrical energy storage system combined with hot water production. This system allows for the storage of surplus electrical energy, particularly from intermittent renewable sources, and its subsequent release with high efficiency. It is particularly well-suited to decentralized storage needs and integrates effectively with district heating systems. The improved cogeneration system maximizes energy utilization and minimizes fuel consumption.

[0005] The invention relates to an electrical energy storage and hot water production system, characterized in that it comprises: - an air liquefaction unit comprising an air compression unit to produce liquefied air gases; - a storage unit for the liquefied air gases produced; - an evaporator to vaporize the liquefied air gases from the storage unit and produce compressed air; - a cogeneration unit integrated into a hot water production plant intended for a district heating network, the cogeneration unit comprising an air expansion turbine, in particular a high-pressure air turbine, an air compressor and optionally a low-pressure air expansion turbine, said unit cogeneration being configured to operate in a mode in which it uses the heat generated during the liquefaction of air to heat the water in the district heating network; - the turbine, in particular high pressure, and where applicable the low pressure turbine, is arranged to recover the energy from the compressed air produced.

[0006] According to one embodiment, the system is configured to be used to store electrical energy from renewable sources.

[0007] According to one embodiment, the system includes a circuit for releasing a portion of the compressed air produced to the atmosphere, a system in which the low-pressure turbine is arranged to recover energy from said portion of the compressed air produced.

[0008] Figure 1 represents an embodiment of the system in energy storage mode. Figure 2 represents this embodiment in stored energy recovery mode.

[0009] The system represented comprises the following elements:

[0010] An air liquefaction unit 1: This unit uses a conventional liquefaction cycle, optimized to operate with air compression 11 by a compressor 8 driven by a motor (M) at an air intake temperature above 25°C. The heat 12 generated during the air liquefaction (particularly during air compression) is recovered to heat the water in the district heating network 9, thus improving the energy efficiency of the system.

[0011] A storage unit 6 for the liquefied air gases produced.

[0012] A cogeneration (cogen) unit: integrated into a hot water production plant 4, this unit comprises a high-pressure air turbine 2 and an air compressor 5. It produces electricity while recovering the heat generated by air compression to heat the water in the network 9. The cogeneration system according to the invention is distinguished by its increased efficiency.

[0013] An evaporator 7: this device vaporizes the stored liquid air by efficiently recovering the cold contained in the liquid. It uses compressors to recompress the air to a low temperature, thus minimizing energy consumption during the release of the stored energy.

[0014] A high-pressure (HP) turbine 2 and a low-pressure (LP) turbine 3: these turbines recover energy from the compressed air produced by the evaporator 7. The HP turbine 2 expands the air to a high temperature (approximately 550°C) to produce electricity during peak consumption. The LP turbine 3 expands the air to a low temperature, which is then released into the atmosphere.

[0015] The system operates as follows:

[0016] Energy storage: Excess electrical energy, for example from wind turbines during periods of high winds, is used to power the air liquefaction unit 1. The air is compressed, then cooled and liquefied. The heat generated by the air compression is recovered to heat the water in the district heating network 9.

[0017] Cogeneration: The cogeneration unit operates continuously to produce electricity and heat. In normal operating mode, the turbine 2 and the air compressor 5 operate synchronously to produce electricity and heat the network water 9.

[0018] Figure 1 represents the system in heat recovery mode. The turbine 2 drives a compressor 8 of the liquefaction unit 1, thereby compressing an additional flow of air. Recovering the heat generated by compression from the cogeneration unit limits the consumption of additional fuel 10 and thus saves fuel 10. Driving the compressor 8 of the liquefaction unit 1 with the turbine 2 allows for air liquefaction at a lower cost.

[0019] Figure 2 represents the system in energy recovery mode: when the electricity demand is high, the stored liquid air is vaporized in the evaporator 7, producing high-pressure compressed air. This high-pressure compressed air is then expanded in the 2 HP turbine to generate electricity. The air expanded by the 2 HP turbine is then cooled before being expanded in the 3 LP turbine.

[0020] The invention has the following advantages:

[0021] High energy recovery efficiency: The system allows for the storage and release of electrical energy with high efficiency, thanks to the optimization of the thermodynamic cycle and the efficient recovery of heat.

[0022] Integration with existing installations: The system can be easily integrated with existing district heating plants, thus optimizing the use of infrastructure and minimizing investment costs.

[0023] Flexibility and adaptability: The system is compatible with different energy sources, including renewable energies, and can be adapted to the specific needs of each installation.

[0024] Enhanced cogeneration: The energy from the turbine is transmitted to the compressor 8 of the liquefaction unit and the heat produced by the liquefaction of the air is used in cogeneration.

[0025] The invention is suitable for the following applications: - Large-scale electrical energy storage for power grids, - Decentralized energy production for isolated communities or industrial sites, - district and industrial heating, as a complement to or replacement for traditional heating systems, - integration of renewable energies, such as wind or solar energy, for more sustainable energy production.

[0026] Examples:

[0027] A city wishes to store the energy produced by an offshore wind farm for use during peak consumption periods. The system according to the invention can be installed in an existing district heating plant, allowing the excess energy to be stored in the form of liquefied air gases and released to produce electricity and heat for the district heating network.

[0028] An isolated industrial site, powered by solar panels, requires an energy storage system to ensure a stable power supply during periods of low sunlight. The system according to the invention can be used to store excess solar energy in the form of liquefied atmospheric gases and release it as needed, while also providing heat for industrial processes.

Claims

Demands

1. Electrical energy storage and hot water production system, characterized in that it comprises: - an air liquefaction unit (1) including an air compression unit, for producing liquefied air gases; - a storage unit (6) for the liquefied air gases produced; - an evaporator (7) for vaporizing the liquefied air gases from the storage unit (6) and producing compressed air; - a cogeneration unit integrated into a hot water production plant (4) for a district heating network (9), the cogeneration unit comprising an air expansion turbine (2), an air compressor (5), said cogeneration unit being configured to operate in a mode in which it uses the heat generated during the liquefaction of the air to heat the water in the district heating network (9); - the turbine (2) being arranged to recover energy from the compressed air produced.