GB2608390A - System for repurposing defunct nuclear power plant - Google Patents

Abstract

A system for repurposing a defunct nuclear power plant for storing excess renewable energy. The defunct nuclear power plant comprises a first accumulator for receiving a first fluid medium, such as water, at high pressure and a second accumulator for storing a second fluid medium, such as air. The system comprises a pump to transport the first fluid medium into the first accumulator, and a connection between the first and second accumulators for pressure transfer from the first fluid medium at high pressure in the first accumulator to the second fluid medium under a low pressure to get the second fluid medium to a higher pressure during an energy storage phase, and from the second fluid medium at the higher pressure in the second accumulator to the first fluid medium in the first accumulator during an energy recovery phase. The system further comprises a generator 118 including a connection to a public power grid, and at least one reaction turbine 126 in fluid communication with the first accumulator is coupled to the generator. The reaction turbine is connected in series with a constant pressure turbine 128 and the generator, wherein the constant pressure turbine is arranged between the reaction turbine and the generator.

Description

SYSTEM FOR REPURPOSING DEFUNCT NUCLEAR POWER PLANT TECHNICAL FIELD

The present disclosure relates to a system for energy storage and recovery; and more specifically to systems for repurposing a defunct 5 nuclear power plant for effectively utilizing excess energy from a renewable energy plant.

BACKGROUND

In recent times, developed as well as developing nations worldwide and in particular countries of the European Union are undergoing a fast and irreversible transition from nuclear energy to renewable sources of energy. Power supply from wind farms and solar panel parks enable vast growth rates and is paramount in replacing conventional sources of energy, such as non-renewable sources including nuclear energy, fossil fuels and so forth. Notably, such a transition is evident and bound to continue and gain amplitude as governments are further urged to comply with international treaties, agreements and national regulations with regard to climate change and fulfill or meet the renewable energy laws and directives.

However, the cost of such a transition is enormous as the existing infrastructure of power supply has been built as a centralized system of large-scale predictable and stable generation, transmission, storage and distribution of electric power; whereas renewable energy supply is decentralized, unstable and un-predictable due to the highly intermittent dependence on the forces of nature. For example, power generation by wind farms and solar panels is very decentralized, highly volatile and generally results in either a massive surplus amount of energy or a significant deficit, consequently jeopardizing both power supply and grid stability. Typically, such intermittency causes significant annual costs and a surplus of green energy is usually wasted and thus require conventional power generating plants, nuclear and coal to compensate for the shortages. Conventionally, to overcome the aforementioned drawbacks, the only solution is storing excessive power at peak generation times for consumption at a later point in time. However, traditional systems and methods are in-sufficient or in-capable of providing an environmentally friendly system that is stable and generates low-cost energy from renewable sources and thus a need for an efficient and sustainable energy storage technology is developed.

Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks and provide an improved system or method for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant.

SUMMARY

The present disclosure seeks to provide a system for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant. An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in prior art.

In one aspect, an embodiment of the present disclosure provides a system for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant, the defunct nuclear power plant comprising a first accumulator that is configured to receive a first fluid medium at a high pressure and a second accumulator 25 adapted to store a second fluid medium, the system comprising: a pump arrangement driven by the excess energy from the renewable energy plant, the pump arrangement configured to be driven to directly or indirectly transport the first fluid medium into the first accumulator; a connection disposed between the first accumulator and the second accumulator to allow for effective pressure transfer from the first fluid medium received at the high pressure in the first accumulator to the second fluid medium stored under a low pressure, to get the second fluid medium to a high pressure, during an energy storage phase, and from the second fluid medium at the high pressure in the second accumulator to the first fluid medium in the first accumulator, during an energy recovery phase; a generator including an interface for connection to a public power grid; and at least one turbine in fluid communication with the first accumulator and operatively coupled to the generator, with the at least one turbine in effective communication with the first accumulator in a reaction turbine, which is connected in series with a constant pressure turbine in such a manner that a drive shaft of the reaction turbine is connected to a drive shaft of the constant pressure turbine and a drive shaft of the generator, with the constant pressure turbine arranged between the reaction turbine and the generator.

Embodiments of the present disclosure substantially eliminate or at least partially address the aforementioned problems in the prior art and enable the system to provide a cheap, eco-friendly and sustainable system for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant.

Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments construed in conjunction with the appended claims that follow.

It will be appreciated that features of the present disclosure are 30 susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, as well as the following detailed description of 5 illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those skilled 10 in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein: FIG. 1 is an illustration of a block diagram of a system for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant, in accordance with an embodiment of the present disclosure; and FIG. 2 is an illustration of an arrangement of a reaction turbine, a constant pressure turbine and a generator in a system for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant, in accordance with various embodiment of the present disclosure.

In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practising the present disclosure are also possible.

In an aspect, an embodiment of the present disclosure provides a system for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant, the defunct nuclear power plant comprising a first accumulator that is configured to receive a first fluid medium at a high pressure and a second accumulator adapted to store a second fluid medium, the system comprising: a pump arrangement driven by the excess energy from the renewable energy plant, the pump arrangement configured to be driven to directly or indirectly transport the first fluid medium into the first accumulator; a connection disposed between the first accumulator and the zo second accumulator to allow for effective pressure transfer from the first fluid medium received at the high pressure in the first accumulator to the second fluid medium stored under a low pressure, to get the second fluid medium to a high pressure, during an energy storage phase, and from the second fluid medium at the high pressure in the second accumulator to the first fluid medium in the first accumulator, during an energy recovery phase; a generator including an interface for connection to a public power grid; and at least one turbine in fluid communication with the first accumulator and operatively coupled to the generator, with the at least one turbine in effective communication with the first accumulator in a reaction turbine, which is connected in series with a constant pressure turbine in such a manner that a drive shaft of the reaction turbine is connected to a drive shaft of the constant pressure turbine and a drive shaft of the generator, with the constant pressure turbine arranged between the reaction turbine and the generator.

The present disclosure provides a system for repurposing a defunct nuclear power plant for effectively utilizing excess energy from a renewable energy plant. The term "decommissioned or defunct" refers to the state of the nuclear power plants that are no longer available for nuclear energy generation and wherein a radioactivity clean-up and progressive dismantling of the power plant has taken place. Typically, the radioactive part of the nuclear reactor is removed, and the remaining infrastructure may be repurposed for other purposes, such as using excess energy from a renewable energy power plant. The renewable energy power plant configured to produce energy from renewable sources, such as, but not limited to, hydro, wind, geothermal, solar energy comprises a limitation with respect to energy storage. Currently, the energy storage devices are in-sufficient for storing the fluctuations caused by renewable energy power plants. Moreover, traditional energy storage systems such as pumped storage power plants or dams are insufficient and difficult to implement for environmental reasons. The system is configured to store and utilize excess energy produced by any renewable energy power plant by using the defunct power plant. The system may be referred to as a hydrodynamic storage system that may be implemented in any smart grid to buffer energy imbalances due to low energy generation levels from volatile energy sources (for example, solar cells, wind turbines and so forth) and peak power/energy demands (e.g. morning and evening peak power loads) in the power grid. Beneficially, the system may be implemented in a de-commissioned power plant (e.g. in the safety building, housing the de-commissioned nuclear reactor, or the turbine housing) or any other building, which features a sufficiently tight connection to the power grid, to feature an efficient energy transfer from and into the power grid. The stored energy is released in the reverse order to the storage. The storage medium is expanded using a PeIton turbine and the stored energy is recovered. Notably, due to the self-sufficient operation of the system, energy storage systems of such type have black start capabilities i.e. in the event of a grid failure, the power plant may be started without auxiliary energy and the public power grid may be easily rebuilt or repaired and due to the high flexibility and adaptability of the system, power failures are highly unlikely to occur.

The defunct nuclear power plant comprises a first accumulator that is configured to receive a first fluid medium at a high pressure. The "accumulator" refers to a pressure accumulator configured to store the first fluid and smooth out any pulsations or fluctuations. The stored fluid medium is available for instantaneous use, released upon demand at a rate higher than the rate supplied by the pump alone. Notably, the first fluid medium may also be referred to as "energy carrier" transported using a pump arrangement at high pressure. Herein, the first accumulator is configured to receive the first fluid medium at high pressure. The "fluid medium" refers to a substance, such as a liquid or gas, that can flow, has low viscosity and no fixed shape. For example, the first fluid medium may be water, heavy water, oxygen, nitrogen, carbon di-oxide or a combination of one or more first fluid mediums. The high pressure associated with the first fluid medium is generated by a pump arrangement coupled to the first accumulator for transferring the first fluid medium under high operating pressure. The operating pressure or high pressure ranges from 0.1 bar, 0.2 bar, 0.21 bar, 0.22 bar, 0.25 bar, 0.3 bar, 0.5 bar, 0.75 bar, 1 bar and 2 bar. In an exemplary scenario, the first fluid medium is transported at a high pressure of 2.23 nnWs a (meters of water column) or 0.2186 bar. Generally, accumulators are used with pressure-energy storage devices, however, conventional pressure-energy storage devices due to the energy conversion efficiency limitations are insufficient to effectively store the excess energy primarily 5 due to the pressure change of the fluid medium during transfer, leading to a temperature increase and associated energy loss. Beneficially, the first pressure accumulator utilizes a non-compressible fluid (such as water) instead of a compressible fluid to act as the fluid medium to avoid the adiabatic losses to a great extent and hence improve the overall 10 energy conversion efficiency and the economics of the system.

In an embodiment, when a plurality of first accumulators are provided, a connection line is present connecting the outlets of the first accumulators with one another, wherein the first accumulators are arranged in such a manner with respect to each other that the connection line has a gradient and has a sump at its lowest point, which is connected to an inlet of the turbine. Typically, when a plurality of first accumulators are used in combination, the outlet of each accumulator of the plurality of first accumulators is connected to the inlet of the next accumulator in the plurality of first accumulators. Notably, the first accumulators are arranged with respect to the operating conditions, such as the operating to pressure, to form the gradient (or pressure gradient) between the first and last accumulator of the plurality of first accumulators to allow for an efficient transfer of the first fluid medium without the need of external energy or help.

The defunct nuclear power plant further comprises a second accumulator adapted to store a second fluid medium. The second accumulator is configured to store the second fluid medium (that may or may not be different from the first fluid medium). Notably, the second fluid medium may act as a propellant medium. Typically, the second accounnator is a compressed fluid storage tank, such as a compressed air tank, configured to store the second fluid medium at a pressure lower than that of the first fluid medium. Generally, the second fluid medium is stored at atmospheric pressure. For example, the second fluid medium may be air, hydrogen, oxygen, carbon di-oxide, nitrogen or any other gas stored at atmospheric pressure and/or temperature.

In an embodiment, characterized in that the ratio of a volume of the first accumulator to a volume of the second accumulator is 1:1, 1:2, 1:3, or 1:4. Typically, the size or volume of the first accumulator may or may not be different from the second accumulator. Herein, the ratio of the volume of the first accumulator to the volume of the second accumulator is 1:1 (i.e. equal sizes), 1:2, 1:3, or 1:4. It will be appreciated that the size and ratio of sizes of the first and second accumulators may be varied without limiting the scope of the disclosure. Generally, the system works with operating pressures up to 500 bar. With the appropriate design of the pressure vessel (first accumulator, second accumulator), operating pressures of up to 1000 bar may be achieved and results in a high energy density that can be stored in the smallest of spaces. For example, energy outputs between 2 and 450 MW are achievable. By expanding, i.e. enlarging the first and second accumulators, any amount of energy can be stored much more cost-effectively than with previously known storage systems. For example, it is possible that the volume ratio between the first accumulator and the second accumulator is 1: 1, 1: 2, 1: 3 or 1: 4 and more.

The system for repurposing the defunct nuclear power plant comprises a pump arrangement driven by the excess energy from the renewable energy plant. The "pump arrangement" refers to an arrangement of one or more pumps arranged in a specified order (series and/or parallel), configured to transfer at least one fluid (such as the first fluid medium) to a desired location (such as the first accumulator). The pump arrangement is configured to be driven to directly or indirectly transport the first fluid medium into the first accumulator. Specifically, the pump arrangement is configured to transport the first fluid medium either directly or indirectly, i.e. after storage at a storage basin. Beneficially, the pump arrangement utilizes the excess energy from the renewable energy power plant to transport the first fluid medium, thereby increasing the overall efficiency of the system. The "storage basin" refers to a storage or tank configured to temporarily store the first fluid medium at a desired pressure and/or temperature. For example, the storage basin is an artificial storage tank located at a specific height and enabled with regulation and control systems. Beneficially, the storage basin enabled with regulation and control systems control the temperature and pressure of the stored first fluid medium before transferring into the first accumulator to achieve high inlet pressures at a later stage (such as for acheiving high inlet pressure in a connected turbine).

The system for repurposing the defunct nuclear power plant further comprises a connection disposed between the first accumulator and the second accumulator to allow for effective pressure transfer. The "connection" refers to a long hollow tubular structure configured to act as a connection between two or more operating system elements, such as the first accumulator, the second accumulator or the pump arrangement. In particular, a compressed air tank and a pressurized water tank are connected via exactly one pressure line which is designed to conduct compressed air from the pressurized water tank to the compressed air tank when energy is stored and compressed air from the compressed air tank to the pressurized water tank when energy is recovered. In energy recovery, this pressure line is used to ensure that compressed air can flow from the compressed air tank into the pressurized water tank without any loss of pressure. In the case of energy storage, this pressure line is used to ensure that compressed air can flow from the pressurized water tank into the compressed air tank without loss of pressure.

Notably, the connection may be referred to as the pipeline connecting any two system elements or the connector between the pipelines of the two or more system elements. Herein, the connection disposed between the first accumulator and the second accumulator is configured to allow for effective pressure transfer between the connected system elements. Typically, the connection allows the first accumulator or the second accumulator to decrease or increase, respectively, the operating pressure of the first and second fluid mediums. Typically, the connection enables the first and second pressure accumulators to efficiently equalize the pressure in the two accumulators without any external help. It will be appreciated that the effective pressure transfer between the first and second accumulators may be controlled using regulation and control systems based on the implementation without limiting the scope of the disclosure. Specifically, the connection allows the effective pressure transfer in two different phases for the first and second accumulators. Herein, the connection is configured to allow effective pressure transfer from the first fluid medium received at the high pressure in the first accumulator to the second fluid medium stored under a low pressure, to get the second fluid medium to a higher pressure, during an energy storage phase, and from the second fluid medium at the high pressure in the second accumulator to the first fluid medium in the first accumulator, during an energy recovery phase. Typically, the effective pressure transfer takes place in either the energy storage phase or the energy recovery phases. The energy storage phase comprises effective pressure transfer from the first fluid medium received at high pressure to the second fluid medium stored under a low pressure to increase the operating pressure of the second fluid medium, whereas the energy recovery phase comprises effective pressure transfer from the second fluid medium at the high pressure to the first fluid medium in the first accumulator, to increase the operating pressure of the fluid medium in the second accumulator. Alternatively stated, if there is an excess of energy, the energy carrier (or the first fluid medium) is withdrawn from the relaxation basin (of renewable energy power plant) and fed to the pressurized water storage tank (first accumulator) under high pressure with the aid of the high-pressure pump arrangement. The first fluid medium is pushed back into the first accumulator against the pressure of the second fluid medium. The height of fall (geodetic height) used in nature is artificially generated with the high pressure and the energy is stored in the energy carrier (first fluid medium) with the help of the second fluid medium. Further, if the energy is drawn i.e. during energy recovery phase, the physical process is reversed. Beneficially, such a simple and effective pressure transfer between the first and second accumulators or in other words the simple and efficient pressure handover from the second fluid medium to the first fluid medium allows for a simple and cheap construction and increases the overall system efficiency.

In an embodiment, the second accumulator is in a constant pressure equilibrium with the first accumulator, in such a manner that during energy storage and recovery the pressure in the second accumulator is equal to the pressure in the first accumulator. The second accumulator and the first accumulator are connected to one another in such a way that a constant pressure equalization takes place between the two tanks, such that the pressure in the first and second accumulators is always balanced during energy storage as well as during energy recovery phases, i.e. a pressure equilibrium is developed or maintained between the first and second accumulators. Typically, during energy storage phases, i.e. when the first fluid medium is fed into the second accumulator, the pressure of the total volume of the second accumulator on always increases, and the pressure of the total volume of the first accumulator is always identical to the pressure in the second accumulator. With energy recovery, i.e. the first fluid medium is transferred out of the first accumulator, the pressure of the total volume of the first accumulator always decreases, and the pressure of the total volume of the first accumulator is always identical to the pressure in the second accumulator.

In another embodiment, precisely one pressure line is present between an outlet of the second accumulator and an inlet of the first accumulator and is configured to conduct compressed second fluid medium from the first accumulator to the second accumulator during energy storage and to conduct the compressed second fluid medium from the second accumulator to the first accumulator during energy recovery. Typically, the one pressure line between the outlet of the second accumulator and the inlet of the first accumulator is configured to conduct the compressed second fluid medium from the first and second accumulators during energy storage and energy recovery phase, respectively to control and maintain the pressure in the first and second accumulators and accordingly maintain the energy storage.

In another embodiment, a stop device is arranged in the pressure line, which is configured to block the pressure line at a sudden pressure drop. Typically, the stop device is arranged in the pressure line and is configured to block the pressure line upon encountering a sudden pressure drop. Beneficially, such a stop device enables smooth operation of the system and prevents any interference in the working of the system elements. For example, the stop device may be a stopping valve configured to close upon experiencing a pressure drop.

The system for repurposing the defunct nuclear power plant further comprises a generator including an interface for connection to a public power grid. The "generator" refers to an electrical generator configured to transform or convert the excess energy developed from the renewable energy power plant into usable electrical energy or power through the interface for connection to an external circuit. The "interface" refers to a connection between the generator and public power grid. Typically, the interface is configured to receive or accept power or energy from any energy source (such as the generator) and convert the received power at a required voltage and/or frequency to be used by the public power grid. For example, the interface may be an external electrical circuit, power convertor, rectifier, regulator, diode rectifier and so forth. Herein, the generator is configured to convert the received energy from the generator into usable electrical energy with the help of the interface, wherein upon conversion, the electrical energy may be transferred via the interface for further implementation. Optionally, the generator may be coupled to a powerful high pressure (HP) pump by means of an automatic coupling on one side. Through this connection, in addition to a small, self-sufficient HP pump (of the pump arrangement), a large HP pump may be additionally driven by switching the generator to motor operation. In other words, when there is a high excess output or during energy recovery phase and outside normal operation, large outputs of energy may be generated and stored in a short time.

The system for repurposing the defunct nuclear power plant further comprises at least one turbine in fluid communication with the first accumulator and operatively coupled to the generator. The "turbine" refers to a rotary mechanical device configured to extract energy from a fluid flow and convert the extracted energy into useful work. Typically, the at least one turbine is in fluid communication with the first accumulator i.e. the at least one turbine is configured to receive the first fluid medium from the first accumulator to extract excess energy from the flow of the first fluid medium and thereby convert the extracted energy of the first fluid medium using the operatively coupled generator to generate electrical power to be used by the connected public power grid. Typically, the at least one turbine in effective communication with the first accumulator is a reaction turbine, which is connected in series with a constant pressure turbine in such a manner that a drive shaft of the reaction turbine is connected to a drive shaft of the constant pressure turbine and a drive shaft of the generator, with the constant pressure turbine arranged between the reaction turbine and the generator. The at least one turbine comprises rotating blades curved and arranged so as to develop torque from gradual decrease of fluid medium pressure and is mechanically and/or operatively coupled with the constant pressure turbine and the generator, wherein the constant pressure turbine is located between the at least one turbine and the generator.

In an embodiment, a compressed-air turbine is present between the second accumulator and the first accumulator. Beneficially, the compressed air turbine may be arranged between the first accumulator and the second accumulator, in particular in the connection between the first and second accumulators and is configured to transform energy from compressed air or fluid. As a result, additional or excess energy is obtained when compressed or pressurized fluid medium flows through the connecting line, thereby improving and increasing the efficiency of the system. The proposed system operates substantially with circulating water, which is released by the PeIton turbine or by the serial arrangement of the reaction turbine and constant-pressure turbine and pumped back by means of high pressure pump arrangement into the first accumulator. The system works with a small amount of make-up air or supplementary air that may be necessary due to leaks in the pressure system and can be topped up in the respective container if necessary. The required amount of supplementary air is determined during the operation of the proposed system via the control unit and supplied via the compressed air reservoir or turbine. By means of the compressor air turbine, the pressure in the first and second accumulators before starting the storage power plant operation depending on the system design is regulated to a pressure of 50, 100 or 200 bar is compressed up to 1000 bar. After the system has been commissioned, i.e. during the operating phase in which the system is used as a power plant for storing excess energy from renewable energy power plants, the compressed air turbine is used exclusively to feed compressed air into a compressed air reservoir, which is connected upstream of the second accumulator and only serves to replace leaked fluid. The system can thus be operated at pressures of 50, 100, 200 till up to 1000 bar.

In an embodiment, the drive shaft of the reaction turbine and the drive shaft of the constant pressure turbine form a common shaft, or the drive shaft of the reaction turbine and the drive shaft of the constant pressure turbine are coupled to each other via a rigid coupling. The "common shaft" refers to a single drive shaft formed between the reaction turbine and the constant pressure turbine and the "rigid coupling" refers to a type of shaft coupling used to connect the two shafts of the reaction and constant pressure turbines together at their ends for the purpose of transmitting power. Optionally, the drive shaft of the reaction turbine is connected to the drive shaft of the constant pressure turbine via a transmission, and that an outlet of the first accumulator is connected to an inlet of the reaction turbine and an outlet of the reaction turbine is connected to an inlet of the constant pressure turbine. The "transmission" refers to a transmission line configured to transmit the power between the reaction and constant pressure turbine. For example, the transmission may be a shaft, a power cable, a rod and so forth. In such cases, the outlet of the first accumulator is connected to the inlet of the reaction turbine and outlet of the reaction turbine is connected to the inlet of the constant pressure turbine forming a series formation. The outlet connected constant pressure turbine is then connected to the generator for power generation.

In another embodiment, a means for regulating a pressure of the inlet pressure of the constant pressure turbine is arranged between an outlet of the reaction turbine and an inlet of the constant pressure turbine. The "means for regulating pressure" refers to a pressure regulator or valve configured to control the pressure of the fluid medium to a desired value.

Optionally, the means for regulating pressure is an integrated device comprising a pressure setting, a restrictor and a sensor, or comprises of a separate pressure sensor, controller and flow valve. Beneficially, the means for regulating a pressure of the constant pressure turbine is installed in the supply line to the constant pressure turbine to prevent the loss of energy due to leaks during standstill and is configured to switch on or off when the turbine starts up or when the turbine is turned off, respectively.

In yet another embodiment, wherein a stop valve is provided at an inlet of the turbine, wherein the stop valve is configured to remain closed during inactivity. Beneficially, the stop valve is installed at the inlet of the turbine ( or at the supply line to the constant pressure turbine) to prevent the loss of energy due to leaks during standstill and is configured to switch off the turbine during periods of inactivity of the turbine.

In an embodiment, a process control unit is provided which is configured, as a function of the load on a public power grid, to drive the high-pressure pump with energy from the public power grid to pump first fluid medium from a first fluid medium reservoir into the first accumulator when there is a surplus of energy in the public power grid, or to conduct pressurized first fluid medium from the first accumulator to the at least one turbine and to feed the energy generated in the generator to the public power grid, when there is a demand for energy in the public power grid. The "process control unit" refers to a control system configured to monitor and adjust a process to provide a desired output to maintain quality and improve the performance of system. In an example, the process control unit is configured to switch the operation of the operating pump arrangement as a function of the load on the public power grid. Typically, the process control unit is configured to switch the power supply of the pump arrangement during energy generation and energy recovery phases. Specifically, during energy recovery phase, or when there is a surplus of energy in the public power grid, the process control unit is configured to drive the high-pressure pump with energy from the public power grid to pump the first fluid medium from the first fluid medium reservoir into the first accumulator, and during energy generation phases or when there is a demand for energy in the public power grid, the process control unit is configured to conduct the pressurized first fluid medium from the first accumulator to the at least one turbine and to feed the energy generated in the generator to the public power grid. If, during the energy storage, as will be described later, water is pumped via a high pressure pump from a water tank into the pressure fluid tank, whereby the high-pressure pump is operated by means of surplus energy from a public or non-public power grid. Due to the increasing amount of water in the pressurized water tank, the remaining compressed air in the pressurized water tank is displaced into the connected compressed air tank with a simultaneous pressure increase due to the constant volume of the tanks. Due to the pressure equalization between the pressurized water tank and the compressed air tank, the pressure in both tanks is always identical. As the amount of water in the pressurized water tank increases, this pressure rises continuously up to a predeternninable maximum value. In the energy recovery phase, water is fed from the first accumulator to the PeIton turbine or the reaction turbine and the constant pressure turbine connected to it. The generator, connected to the drive shaft of the PeIton turbine or to the common drive shaft of the reaction turbine and the constant pressure turbine, generates the energy fed to connected public or non-public power grid. Typically, the pressure in the first accumulator decreases due to the decreasing amount of water with a constant volume of the container. Due to the pressure equalization between the first and the second accumulators, the pressure in both accumulators is identical at all times. As the amount of water in the pressurized water tank and in the compressed air tank decreases, this pressure drops continuously down to a specifiable minimum value.

In another embodiment, in the case of energy recovery, the process control unit is configured to regulate the power generated by the at least one turbine by opening or closing of inlet nozzles connected to the turbine. The "inlet nozzle" refers to adjustable nozzles configured to adapt or adjust the power generated by the generated based on the requirement by the public power and to stabilize the fluctuations in the generated energy in the public power grid. The process control unit may be present, which is designed to control a function of the load of a connected or connected to the system, public or non-public power grid, the high-pressure pump by means of power from the public power grid in order to transfer water from a water reservoir to the first accumulator when there is excess energy in the utility grid. Pressurized fluid medium is fed from the first accumulator to the at least one turbine and the electricity generated in the generator connected to the turbine is fed into the public power grid when there is a demand for energy in the public power grid. With the proposed system, either excess energy can be stored, or the stored energy is made available with short reaction times. In this regard, the control unit is designed to control the regenerative power generated by the reaction turbine and/or the constant-pressure turbine by opening or closing the reaction turbine and/or the constant-pressure turbine connected fins via the fluid medium inlet nozzles. The outlet pressure from the overpressure turbine can be regulated by means of the control unit of the overpressure turbine in such a way that the outlet pressure from the overpressure turbine and thus the inlet pressure into the constant pressure turbine can be kept constant despite the variable system pressure in the pressurized water tank and thus the variable inlet pressure of the overpressure turbine. The output of the constant pressure turbine can be adapted to the required generator output via the adjustable inlet nozzles. By regulating the constant pressure turbine by means of the inlet, the fluid medium volume is adapted to the required output and thus the output of the overpressure turbine is indirectly adapted to the total output of the turbine combination by readjustment via the inlet nozzles.

In an embodiment, the process control unit is provided for comparing a current pressure in the first accumulator and a current pressure in the second accumulator and a current level of the first fluid medium in the first accumulator with a set pressure value, wherein the process control unit and a comparison unit is configured to feed compressed second fluid medium from a reservoir to the second accumulator as a function of the comparison result. The process control unit further comprises the comparison unit configured to compare the current pressures (at any point of time) of the first and second accumulators. Beneficially, such a comparison enables the process control unit via the comparison unit to make adjustments to the feed of the compressed second fluid medium based on the comparison result. The "set pressure value" refers to an optimum pressure value for the first fluid medium in the first accumulator, based on which the pressure in the first and/or second accumulator may be varied using the process control and comparison unit.

In another embodiment, the process control unit is further configured in such a manner that the compressed second fluid medium is fed from the reservoir to the second accumulator based on one or more operating parameters including at least one of a pre-pressure, turbine output and an energy requirement from the public power grid. The process control unit is configured to feed the compressed second fluid medium from the reservoir (or storage basin) to the second accumulator based on one or more operating parameters including at least one of a pre-pressure, turbine output and an energy requirement from the public power grid. Typically, upon analysis of at least the pre-pressure, turbine output and energy requirement from the public power grid, the process control unit is configured to adjust the volume, temperature and/or operating pressure of the second fluid medium based on analyzed requirements. The energy storage is invariably controlled by the process control unit by feeding back the circulating fluid medium with high-pressure pump arrangement into the accumulators. This process only takes place with excess energy from the public grid. The required compressed air is also only generated with excess energy from the public power grid. The system according to the invention can be run up from 0 to 100% in approximately 60-90 seconds. Beneficially, the high pressure pumps can be designed in such a way that they can be run from the still sand to 100% power for approximately 20-30 seconds. The volume of the first and the second accumulators can be designed such that the system according to the invention can deliver the full design output over a period of up to 4 hours.

In an embodiment, wherein at least one of the turbine and the generator are coupled to an idle drive unit configured to keep operating the at least one of the turbine and the generator at least at an idle speed. In order to reduce the start phase to a few seconds, the at least one turbine and the generator are configured to be maintained at a constant speed using an idle drive unit. The during the delivery time during idle phases, thereby considerably shortening the start phase. Typically, at least one of the turbine and the generator are coupled to the idle drive unit, wherein the idle drive unit is configured to keep operating the at least one of the turbine and the generator at least at an idle speed. Further optionally, when the at least one turbine is at a standstill, an electronic start ramp is initially run up in a high-speed phase and then adjusted to the desired output with a fine-tuning phase.

The system is a hydro-dynamic energy storage system that works on the principle of energy storage in power plants located in the mountains (i.e. exploiting advantage of height). The system is characterized by its simple 30 and robust construction and depending on the voltage, the system may be employed with a transformer to achieve power amplification and increased efficiency. Further, the system is configured in order to achieve a high economic efficiency, and thereby the system components with a high degree of efficiency selected during implementation. The system comprising the at least one turbine is a PeIton turbine (or a francis turbine) that have a high efficincy of upto 94%. Moreover, the system comprising the generator and pump arrangement are high-voltage generators and high-pressure pumps (HP pumps) results in a high level of development i.e. reflected in the high efficiency of the system components used, of up to 94%. Only the usual storage basins were replaced by artificial pressure storage tanks. The system is supplemented by a sophisticated regulation and control technology. Further, the system employs an artificial storage at a desired height to acheive high inlet pressures to the at least one turbine. Furthermore, the closed circuit configuration of the system enables the storage system to work reliably and independently over long periods of time without consuming any additional resources. Furthermore, the constant alternation between excess energy (recovery phase) and energy demand (generation phase) can be operated with the sytem over long periods of time without encountering any problems and to easily manage the energy fluctuations. Typically, the system is enabled to generate high power plant outputs of up to 400 megawatts (MW) and due to the compact design of the system, high performances are achieved in an eco-friendly manner in a smaller area as compared to conventional systems without impairing or affecting the external surroundings. To enable the compact design of the system, the storage basin is built under the turbine housing of the at least one turbine and solve two existing problems concurrently i.e. the storage basin forms the foundation for the turbine housing and the turbine housing causes a sufficient load to create a buoyancy effect in the storage basin in an event, wherein the site has a high groundwater level and the storage basin is increasingly buoyant as a result.

Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a nonexclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, illustrated is a block diagram of a system 100 for repurposing a defunct nuclear power plant 102 for effectively utilizing excess energy from a renewable energy plant 104, in accordance with an embodiment of the present disclosure. As shown in FIG. 1, the system 100 comprises the defunct nuclear power plant 102 for effectively utilizing excess energy from the renewable energy plant 104. The defunct nuclear power plant 102 comprises a first accumulator 106 that is configured to receive a first fluid medium 108 at a high pressure and a second accumulator 110 adapted to store a second fluid medium 112. The system 100 for repurposing the defunct nuclear power plant 102 comprises a pump arrangement 114 driven by the excess energy from the renewable energy plant 104, wherein the pump arrangement 114 configured to be driven to directly or indirectly transport the first fluid medium 108 into the first accumulator 106. Further, the system 100 comprises a connection 116 disposed between the first accumulator 106 and the second accumulator 110 to allow for effective pressure transfer from the first fluid medium 108 received at the high pressure in the first accumulator 106 to the second fluid medium 112 stored under a low pressure, to get the second fluid medium 112 to a high pressure, during an energy storage phase, and from the second fluid medium 112 at the high pressure in the second accumulator 110 to the first fluid medium 108 in the first accumulator 106, during an energy recovery phase. The system 100 further comprises a generator 118 including an interface 120 for connection to a public power grid 122 and at least one turbine 124 in fluid communication with the first accumulator 106 and operatively coupled to the generator 118, with the at least one turbine 124 in effective communication with the first accumulator 106 is a reaction turbine 126, which is connected in series with a constant pressure turbine 128 in such a manner that a drive shaft 130 of the reaction turbine 126 is connected to a drive shaft 132 of the constant pressure turbine 128 and a drive shaft 134 of the generator 118, with the constant pressure turbine 128 arranged between the reaction turbine 126 and the generator 118.

Referring to FIG. 2, illustrated is an arrangement of a reaction turbine 126, a constant pressure turbine 128 and a generator 118 in a system 100 for repurposing a defunct nuclear power plant 102 for effectively utilizing excess energy from a renewable energy plant 104, in accordance with various embodiments of the present disclosure. It will be appreciated that for the sake of simplicity and for better illustration, FIG. 2 does not illustrate other components of the system 100 of FIG. 1. As shown, the arrangement of the reaction turbine 126, the constant-pressure turbine 128 and the generator 118 in a novel system 100 is done in a uniform or aligned manner. The reaction turbine 126, for example, a Francis turbine has an inlet 202 and an outlet 204. The inlet 202 is connected to the first accumulator 106 (not shown) via a connection 116. The outlet 204 of the reaction turbine 126 is connected to an inlet 206 of the constant pressure turbine 128, for example a PeIton turbine. Further shown, the at least one turbine 124 in fluid communication with the first accumulator 106 and operatively coupled to the generator 118, with the at least one turbine 124 in effective communication with the first accumulator 106 is a reaction turbine 126, which is connected in series with a constant pressure turbine 128 in such a manner that a drive shaft of the reaction turbine 126 is connected to a drive shaft 132 of the constant pressure turbine 128 and a drive shaft 134 of the generator 118, with the constant pressure turbine 128 arranged between the reaction turbine 126 and the generator 118. The drive shaft 132 is guided essentially centrally through the constant pressure turbine 128. In particular, the drive shafts 130, 132 form a single-piece drive shaft or a common drive shaft. However, the drive shafts 130, 132, 134 may also be aligned to form the common drive shaft. Notably, further shown with arrows, the direction of flow of the fluid medium (such as the first fluid medium) as indicated by the connection 116 to the inlet 202 of the reaction turbine 126, between the reaction turbine 126 and the constant-pressure turbine 128.

Claims (15)

1. CLAIMS1. A system (100) for repurposing a defunct nuclear power plant (102) for effectively utilizing excess energy from a renewable energy plant (104), the defunct nuclear power plant comprising a first accumulator (106) that is configured to receive a first fluid medium (108) at a high pressure and a second accumulator (110) adapted to store a second fluid medium (112), the system comprising: a pump arrangement (114) driven by the excess energy from the renewable energy plant, the pump arrangement configured to be driven 10 to directly or indirectly transport the first fluid medium into the first accumulator; a connection (116) disposed between the first accumulator and the second accumulator to allow for effective pressure transfer from the first fluid medium received at the high pressure in the first accumulator to the second fluid medium stored under a low pressure, to get the second fluid medium to a higher pressure, during an energy storage phase, and from the second fluid medium at the high pressure in the second accumulator to the first fluid medium in the first accumulator, during an energy recovery phase; a generator (118) including an interface (120) for connection to a public power grid (122); and at least one turbine (124) in fluid communication with the first accumulator and operatively coupled to the generator, with the at least one turbine in effective communication with the first accumulator is a reaction turbine (126), which is connected in series with a constant pressure turbine (128) in such a manner that a drive shaft (130) of the reaction turbine is connected to a drive shaft (132) of the constant pressure turbine and a drive shaft (134) of the generator, with the constant pressure turbine arranged between the reaction turbine and the generator.
2. 2. The system (100) according to claim 1, characterized in that the drive shaft (130) of the reaction turbine (126) and the drive shaft (132) of the constant pressure turbine (128) form a common shaft, or the drive shaft of the reaction turbine and the drive shaft of the constant pressure 5 turbine are coupled to each other via a rigid coupling, or the drive shaft of the reaction turbine is connected to the drive shaft of the constant pressure turbine via a transmission, and that an outlet of the first accumulator (106) is connected to an inlet (202) of the reaction turbine and an outlet (204) of the reaction turbine is connected to an inlet (206) 10 of the constant pressure turbine.
3. 3. The system (100) according to claim 2, characterized in that a means for regulating a pressure of the inlet pressure of the constant pressure turbine (128) is arranged between an outlet (204) of the reaction turbine (126) and an inlet (206) of the constant pressure turbine.
4. 4. The system (100) according to any one of the preceding claims, characterized in that when a plurality of first accumulators (106) are provided, a connection line (116) is present connecting the outlets of the first accumulators with one another, wherein the first accumulators are arranged in such a manner with respect to each other that the connection line has a gradient and has a sump at its lowest point, which is connected to an inlet of the turbine (124).
5. 5. The system (100) according to any one of the preceding claims, characterized in that wherein a stop valve is provided at an inlet (202) of the turbine (124), wherein the stop valve is configured to remain closed 25 during inactivity.
6. 6. The system (100) according to any one of the preceding claims, characterized in that the second accumulator (110) is in a constant pressure equilibrium with the first accumulator (106), in such a manner that during energy storage and recovery the pressure in the second accumulator is equal to the pressure in the first accumulator.
7. 7. The system (100) according to any one of the preceding claims, characterized in that a compressed-air turbine is present between the 5 second accumulator (108) and the first accumulator (106).
8. 8. The system (100) according to any one of the preceding claims, characterized in that precisely one pressure line is present between an outlet of the second accumulator (110) and an inlet of the first accumulator (106) and is configured to conduct compressed second fluid medium (112) from the first accumulator to the second accumulator during energy storage and to conduct the compressed second fluid medium from the second accumulator to the first accumulator during energy recovery.
9. 9. The system (100) according to claim 8, characterized in that a stop device is arranged in the pressure line, which is configured to block the pressure line at a sudden pressure drop.
10. 10. The system (100) according to any one of the preceding claims, characterized in that the ratio of a volume of the first accumulator (106) to a volume of the second accumulator (110) is 1:1, 1:2, 1:3, or 1:4.
11. 11. The system (100) according to any one of the preceding claims, characterized in that a process control unit is provided which is configured, as a function of the load on a public power grid (122), to drive the high-pressure pump (114) with energy from the public power grid to pump first fluid medium (108) from a first fluid medium reservoir into the first accumulator (106) when there is a surplus of energy in the public power grid, or to conduct pressurized first fluid medium from the first accumulator to the at least one turbine (124) and to feed the energy generated in the generator (118) to the public power grid, when there is a demand for energy in the public power grid.
12. 12. The system (100) according to claim 11, characterized in that, in the case of energy recovery, the process control unit is configured to 5 regulate the power generated by the at least one turbine (124) by opening or closing of inlet nozzles connected to the turbine.
13. 13. The system (100) according to any one of claims 11 to 12, characterized in that the process control unit is provided for comparing a current pressure in the first accumulator (106) and a current pressure in the second accumulator (110) and a current level of the first fluid medium (108) in the first accumulator with a set pressure value, wherein the control and the comparison unit is configured to feed compressed second fluid medium (112) from a reservoir to the second accumulator as a function of the comparison result.
14. 14. The system according to claim 13, characterized in that the process control unit is further configured in such a manner that the compressed second fluid medium (112) is fed from the reservoir to the second accumulator (110) based on one or more operating parameters including at least one of a pre-pressure, turbine output and an energy requirement from the public power grid (122).
15. 15. The system (100) according to any of preceding claims, wherein at least one of the turbine (124) and the generator (118) are coupled to an idle drive unit configured to keep operating the at least one of the turbine and the generator at least at an idle speed.