GB2599199A

GB2599199A - System and method of energy storage

Info

Publication number: GB2599199A
Application number: GB2109099.8A
Authority: GB
Inventors: Alexander Lindsay James
Original assignee: Lind Ltd
Current assignee: Lind Ltd
Priority date: 2020-09-17
Filing date: 2021-06-24
Publication date: 2022-03-30
Anticipated expiration: 2041-06-24
Also published as: GB202109099D0; GB2599199B; WO2022058462A1; GB202014659D0; EP4233111A1

Abstract

A combined heating and energy storage system 1 and a method of providing an energy storage system, the combined system comprising a wet heating system 10 with at least one heat source 12, at least one emitter 14 and a distribution circuit 16. The system also features an energy storage system 20 comprising a cell 22 with a current collector having first 26 and second 27 electrodes, a body between the electrodes that defines first 23 and second 24 flow chambers, first 18a and second 18b flow loops in fluid communication with the first and second flow chambers for directing positive electrolyte and negative electrolyte through the cell respectively. The first and second flow loops are part of the heating system distribution circuit and the heat transfer fluid comprises at least one of the positive or negative electrolytes.

Description

SYSTEM AND METHOD OF ENERGY STORAGE

Field of Invention

The present invention relates to methods of energy storage and a combined heating and energy storage system.

Background

In order to support increased and efficient use of renewable energy sources there is a need for energy storage systems. Such systems may enable surplus power to be locally accumulated during periods of peak generation (for example when wind or solar availability is high) and utilised during periods when demand exceeds available generation. Energy storage may be used to maximise self-consumption and/or to time-shift load requirements. As such, systems have been proposed in which storage batteries are installed in domestic or commercial properties.

To provide maximum usefulness any such storage systems should be efficient in both charging and discharging. A larger storage capacity is generally desirable but, for example when seeking to install a storage system in an existing property, the capacity may need to be balanced with the system space requirements.

Accordingly, there is a desire for an improved energy storage systems and methods which may provide efficient storage and enable relatively high storage capacity with a relatively low system space footprint. It is particularly desirable to provide an energy storage system with low cost per capacity (cost per kWhr) for example in comparison to existing technologies such as lithium-ion cells.

Summary of Invention

According to a first aspect of the invention, there is provided a. combined heating and energy storage system. The system comprises: a wet heating system comprising: at least one heat source; at least one emitter, positioned remotely from the heat source; and a distribution circuit for directing a heat transfer fluid between the at least one heat source and the at least one emitter. The system further comprising an energy storage system comprising: a cell including a current collector having first and second electrodes, a body between the electrodes, the body defining first and second flow chambers; a first flow loop in flow communication with the first flow chamber for directing positive electrolyte through the cell; a second flow loop in flow communication with the second flow chamber for directing negative electrolyte through the cell. The at least one of the first and second flow loops is part of the heating system distribution circuit such that, in use, the heat transfer fluid comprises at least one of the positive or negative electrolytes.

It may be appreciated that the cell arrangement of embodiments provides a flow battery. For example, the energy cell may be a redox flow battery. Flow batteries operate by ion exchange occurring between the positive and negative electrolytes in the cell as the electrolytes pass through their respective flow chambers. The cell may further comprise a membrane separating the first and second flow chambers (and the ion exchange between the electrolytes may occur through the membrane). It will be appreciated that flow batteries provide a reversable storage of energy wherein energy may be stored by applying a current to the electrodes of the cell and energy may be extracted through the electrodes by flowing the electrolyte through the cell.

According to a second aspect of the invention, there is provided a method of providing an energy storage system comprising: providing an electrolyte in the heat transfer fluid of a wet heating system providing a flow battery in fluid communication with the wet heating system; applying an electric current to the flow battery when energy storage is required; and pumping electrolyte around the wet heating system and through the flow battery when energy extraction is required. Energy extraction may, for example, be required based upon household demands such as cooling or refrigeration or charging of an Electric Vehicle.

An advantage of embodiments of the invention is that the use of a flow battery for electrical storage decouples the energy storage capacity and power rating of the energy storage system -the energy capacity is a function of the volume of electrolyte whereas the power rating is determined by the current collector (for example by the anode surface area). This provides increased flexibility when designing a storage system in accordance with embodiments.

It may be appreciated that, advantageously, embodiments of the invention utilise the volume of the heating system to provide a convenient storage capacity for electrolyte of an energy storage system. Thus, embodiments provide a flow battery without requiring dedicated storage volumes (typically tanks) for both positive and negative electrolyte. Embodiments utilise the same fluid used for heat transfer to also provide at least one of the electrolytes. This enables embodiments to leverage the existing volume of the heating system to reduce or remove the need for additional electrolyte storage. In embodiments the heating system components (such as the piping and emitters) may provide an integrated or hidden volume for storage of electrolyte which may enable the use of a flow battery energy storage system in situations where it might otherwise by impractical. In addition to reduction of space requirements it will be appreciated that embodiments may also advantageously reduce the installation costs in comparison to dedicated energy storage systems. The flow battery of embodiments also provides advantages in that the overall cost of storage is relatively low. Advantageously, a flow battery based energy storage system of embodiments may have a long lifespan (for example 20 years or more) and may be fully recyclable at the end of its life.

In some embodiments one of the first or second flow loops is part of the heating system distribution circuit and the other of the second or first flow loops is independent of the heating system. The other of the second or first flow loops may comprise an electrolyte storage tank. In such an embodiment, the heating system provides one side of the energy storage system. This may for example simplify installation in some applications. Further, when using such a single sided approach it may be possible to minimise the volume of the non-heating system side by utilising an electrolyte of higher concentration so as to minimise the storage tank volume required.

In other embodiments the first and second flow loops may each be formed by distinct parts of the heating system distribution circuit. For example, the first and second flow loops may each formed by separate loops of the heating system distribution circuit. In such an embodiment each loop of the distribution circuit comprises at least one emitter. The separate loops of the heating system distribution circuit may for example define separate heating zones. Each loop of the heating system distribution circuit may further comprise a pump to provide a motive force to the heat transfer fluid. Arrangement in which both loops of the flow battery are provided within the heating system may for example be useful in larger installations such as large domestic or commercial premises where the heating system has substantial total volume.

Embodiments of the invention may be used with a variety of possible types of heat source. In some embodiments a plurality of heat sources may be provided for example to enable different heating depending upon the available energy source. Heat sources could include heat pumps (for example an air to water heat pump), solar, boilers (including, for example, oil, gas, hydrogen, electric, fusion). In some embodiments a heat source may be an electric heater selectively powered by the energy cell. In a system with multiple heat sources at least one heat exchanger may be provided to transfer heat energy between the source(s) and the heat transfer fluid.

The at least one emitter may comprise a radiator or an underfloor heating system. In embodiments the at least one emitter may comprise a plurality of distributed emitters connected by the heating system distribution circuit. For example, the heating system may be a central heating system. It may be appreciated that embodiments may be particularly advantageous in arrangements with a plurality of distributed emitters since the available volume of the heating system distribution circuit (including the volume of the emitters themselves) will enable an increased volume of electrolyte and therefore a higher capacity storage system.

In embodiments the system may further comprise a renewable energy generator.

The renewable energy generator may for example be a solar system or a wind generator. The renewable energy generator may produce electrical energy which can be stored using the energy storage system and/or used to provide power to a heat source. In some embodiments the system may be a hybrid system in which, for example, heating may be selectively provided by either renewable or conventional (e.g. gas or electricity supplied from a source such as a national supply grid) depending upon availability at any particular time.

According to an aspect of the invention, there is provided a domestic heating system comprising the combined heating and energy storage system according to embodiments. Since many domestic properties include existing wet central heating systems including for example radiators or underfloor heating distributed around the property embodiments of the invention may advantageously be retro-fitted to utilise existing infrastructure. This may for example greatly reduce the space required to install an energy storage system in comparison to a similar capacity conventional battery system (whether that be a polymer or flow battery). In embodiments, the distributed components of the heating system (for example the piping forming the distribution circuit and the radiators and/or underfloor heating providing the emitters) may be unmodified with only the heat transfer fluid needing to be replaced or provided with additives to enable it to be an electrolyte for the storage system.

According to another aspect of the invention, there is provided an industrial heating system comprising the combined heating and energy storage system according to embodiments. Such a system may for example be of particular use in light industrial applications where an existing centralised heating system is already installed.

Industrial systems may for example be used in agriculture (including for example glass houses), industrial estates (including for example manufacturing and distribution units) and brewing or distillation facilities.

According to another aspect of the invention, there is provided a mobile building or residence comprising the combined heating and energy storage system in accordance with an embodiment. Mobile buildings or residences may for example include caravans, campervans and portable or transportable building (such as prefabricated modular building units). Such mobile buildings or residences often have significant space restrictions such that methods and systems in accordance with embodiments may be particularly advantageous.

A combined heating and storage system in accordance with an embodiment may also have applications in vehicles, for example, an electrical vehicle with a heating system (for example for passenger comfort) could utilise embodiments to provide additional storage for electrical energy. Such embodiments could, for example, be used to provide range extending storage capacity.

Methods in accordance with embodiments of the invention may include the steps of forming two separate loops in the wet heating system. For example when converting an existing heating system a modification may be made to separate the system into two separate zones. The method may further comprise providing a positive electrolyte in a first loop and providing a negative electrolyte in a second loop.

Methods of embodiments may comprise providing a renewable energy generator; and storing excess energy created by the energy generator by applying electric current to the flow battery.

Whilst the invention has been described above, it extends to any inventive combination of the features set out above or in the following description or drawings.

Unless otherwise stated, each of the integers described may be used in combination with any other integer as would be understood by the person skilled in the art.

Further, although all aspects of the invention preferably "comprise" the features described in relation to that aspect, it is specifically envisaged that they may "consist" or "consist essentially" of those features outlined in the claims. In addition, all terms, unless specifically defined herein, are intended to be given their commonly understood meaning in the art.

Description of the Drawings

Embodiments of the invention may be performed in various ways, and embodiments thereof will now be described by way of example only, reference being made to the accompanying drawings, in which: Figure 1 shows a combined heating and energy storage system in accordance with an embodiment; Figure 2 shows a further embodiment having a hybrid heat source; Figure 3 shows an alternate embodiment having a single sided heating system; and Figure 4 shows a method of energy storage in accordance with an embodiment

Detail Description of Embodiments

A combined heating and energy storage system 1 in accordance with an embodiment is shown schematically in figure 1. The system 1 is based around a conventional wet central heating system 10 such that it can be conveniently installed in applications which currently utilise such systems. The system 1 may, therefore, be particularly suitable for retro-fitting to an in-situ heating system 10 (but is not exclusively as such and could also be used in a new build system).

The heating system 10 includes a heat source 12 which may for example be a conventional central heating boiler or an air-to-liquid heat pump, a plurality of heat emitters 14a, 14b, 14c and 14d and a distribution circuit comprising a series of pipes 16 connecting the emitters 14 to the heat source 12. The system 10 contains a heat transfer fluid (which may be water with various additives, for example one or more anti-corrosion chemical) which can be heated by the heat source 12 and transported through the distribution circuit to heat the emitters 14 such that they can provide heat to a local areas. The emitters 14 may for example be radiators or underfloor heating. In the example of figure 1, the heat emitters are in two zones 18a, 18b with each zone being a closed loop with the respective emitters of each zone 14a, 14b and 14c, 14d being simply connected in series. It will be appreciated that this series loop configuration is shown for simplicity, but other configurations (for example parallel connected emitters) may be possible. The heating system 10, also includes pumps 17a and 17b in the distribution system to provide motive force to the heat transfer fluid (which is also energy storage fluid in accordance with embodiments). As may be noted in the figure, since the heating is in two zones 18a, 18b a pump 17a, 17b may be provided for each respective zone. It will be appreciated that numerous modifications may be made to the heating system 10 without departing from the scope of the invention, particularly since embodiments are intended to be used with existing systems which may include unusual or legacy configurations due to a building specific configuration. The heating system 10 may for example include one or more storage tank for heat transfer fluid and may include one or more control devices such as temperature sensors and controllers or timers.

In accordance with embodiments of the invention the heating system 10 is integrated with an energy storage system 20. The energy storage system 20 is in the form of a flow battery such as a redox flow battery. The energy storage system includes a cell 22 comprising a pair of chambers 23, 24 separated by a membrane 25.

The chambers 23, 24 are each in fluid communication with one of the loops 18a 18b of the distribution circuit 16 of the heating system. The cell 22 further comprises a current collector comprising first 26 and second 27 electrodes associated with the chambers 23 and 24. The current collector is connected to a power circuit 30 which may include at least one input 32 and output 34 to allow electrical energy to be provided to or extracted from the energy storage system 20. As will be explained further below, in order to allow the operation of the flow battery of the energy storage system 20, additives are provided to the heat transfer fluid of the heating system 10 such that the heat transfer fluid comprises an electrolyte.

Figure 2 shows an alternate embodiment of the invention in which the heat source 12 of the heating system 10 is provided with multiple sources 13a, 13b. For example, the heat source 12 could be a heating tank and the multiple sources 13a, 13b could provide heat via a heat exchange arrangement such as a coil passing through the heating tank. One source 13a may, for example, be a conventional gas boiler. The other source 13b may be electrically powered. For example, the source 13b may be a heat pump (such as a ground source or air source heat pump) which provide the advantages of low running costs and reduced carbon emissions. Advantageously, the electrically powered heat source 13b may be directly or indirectly coupled to the output 34 of the energy storage system 20 such that stored energy can be selectively used to power the heating system 10.

The embodiment of figure 2 also provides an example of a controller 40 for the heating and energy storage system (which it will be appreciated could be provided in other embodiments). The controller 40 includes a user interface 42 which may for example be a touchscreen display to both provide information (for example energy status and costs) and to accept control inputs. The controller 40 has connections (which may for example be wired or wireless) 43, 44, 45, 46 to the different components of the apparatus 1. The controller 40 is connected to the heating system 10 via a connection 45 and to the heating sources 13 by connection 46. A connection 43 is provided between the controller 40 and the power circuit 30. A connection 44 is provided between the energy storage system 20 and the controller 40. Other connections may also be provided for example the controller 40 could be integrated or connected to individual heat controls in the heating system 10 or power generators such as the solar panel 35 (shown in figure 1). Thus, it will be appreciated that the controller can monitor the different aspects of the combined heating and energy storage system to ensure optimised and efficient operation including for example anticipation of expected future demands. The user can view the status on the display of the user interface 42.

In order to maximise the flexibility of the system, an alternative embodiment is shown in figure 3. In contrast to the arrangement of figures 1 and 2, which may be considered dual sided, the embodiment of figure 3 is a single sided system as the heating system 310 provides only one of the flow loops of the energy storage system 320. The heating system 310 includes a heat source 312, a plurality of heat emitters 314a, 314b, a distribution circuit comprising a series of pipes 316 connecting the emitters 314 to the heat source 312 and a pump 317 for providing motive force to the heat transfer fluid. The system 310 contains a heat transfer fluid (which may be water with various additives) which can be heated by the boiler 312 and transported through the distribution circuit to heat the emitters 314 such that they can provide heat to a local area. The emitters 314 may for example be radiators or underfloor heating. Whilst the illustrated embodiment includes only a single series loop of emitters 314 it will be appreciated that the heating system may have any convenient configuration and may for example include multiple zones even on a single sided embodiment.

As the heating system 320 of the single sided embodiment of figure 3 provides only one loop of the flow battery the heat transfer fluid will be either a positive or negative electrolyte only. In the illustrated example the heating circuit is in fluid communication with the negative side flow chamber 324 of the cell 320 and, therefore, the heat transfer fluid is a negative electrolyte (but this arrangement may be reversed). In this embodiment the other side of the flow battery (in the example the positive electrolyte circuit) is formed by a dedicated circulation loop 350 which comprises a tank 352 and a flow pump 354 which are in fluid communication with the positive flow chamber 323 of the cell 320.

Operation of embodiments of the invention will now be described with reference to the flow diagram of Figure 4. Whether the system is to be a new install or a retro-fit the method starts by modifying a wet heating system by providing electrolyte in the heat transfer fluid (block 410) and providing a flow battery in fluid communication with the heating system (block 420). If the wet heating system is water based, then the electrolyte may be simply provided by dissolving or suspending appropriate substances in the heat transfer fluid. It will be appreciated that the specific chemical make up of the electrolyte will depend on the type of flow battery provided by the cell. The configuration of the system may be selected based upon the specific constraints for any application (for example, the space availability, the capacity requirements and/or any existing heating system infrastructure) and therefore the step of providing the flow battery in communication with the heating system may optionally further comprise either arranging two separate loops in the heating system (as in Figures 1 and 2) or providing a dedicated flow loop with a storage tank (as in Figure 3).

When storage of electricity is required, as shown in block 430, a current is applied to the cell 22 via the electrodes 26, 27. The current may be provided to the power circuit 30 via an input 32 and may for example be the output from a renewable generator such as a wind or solar generator, as shown in the example of figure 1 by the solar panel 35. The current applied to the electrodes 26, 27 is stored by conversion of the electrical energy into chemical energy in the electrolytes in the cell 22 (via ion exchange through the membrane 25). Thus, energy can be stored in the flow battery during peak generation or when off peak electricity is available. A potential advantage of the flow battery provided in embodiments may be enabling energy storage from a source (such as the solar panel 35) without requiring any DC to AC conversion, such that system efficiency is enhanced.

As shown in block 440, when electricity demand is high or heat is required the electrolyte in the two loops of the storage 18a and 18b/310 and 350 is pumped through the chambers 23, 24/ 323, 324 of the cell 25/325. Through ion exchange at the membrane 25 current is produced at the electrodes 26,27 of the cell 22. The electric power produced may be output from the power circuit 30 (via output 34). When heating is required the electric output from the energy storage system 20 may be used to run the pump 17 and heat source 13b of the heating system 10. Thus, during peak energy times and/or when renewable energy generation is unavailable or limited stored energy may be drawn from the energy storage system 20 to provide heating through the heating system 10. Such an arrangement may help reduce a user's fuel costs (thereby helping reduce or alleviate fuel poverty) and/or increase their ability to utilise green energy.

Although the invention has been described above with reference to preferred embodiments, it will be appreciated that various changes or modification may be made without departing from the scope of the invention as defined in the appended claims. For example, it is worth noting that whilst embodiments of the invention provide a combined heating and energy storage infrastructure a user may not always require heat generation (for example in summer months) and as such the apparatus and methods of the invention may selectively be operated in a non-heating configuration without departing from the scope of the invention (for example the system being used purely for energy storage/load balancing).

Several forms of flow battery are available and may be used in embodiments of the invention. Further an advantage of embodiments of the invention is that it may be used to provide a highly flexible system which can readily be tailored to the specific requirements of a particular application by the system installer or designer. Thus, for example, the specific configuration of the heating system is not an essential feature of embodiments of the invention as any system including at least one loop for circulation of heat transfer fluid may be utilised.

Depending upon the electrolyte and flow battery type, in some embodiments the cell of the energy storage system may operate most efficiently in a specific heat range. As such, embodiments may include a temperature optimisations arrangement for controlling the temperature of the combined electrolyte/heat transfer fluid prior to entry to the cell. The temperature optimisation arrangement may include features such as a heat exchanger and/or a storage tank and an associated control system configured to ensure that electrolyte passing through the heating system is at an optimum temperature (for example 40 to Sot). Particularly in a single-sided system, such a temperature optimisation arrangement could include a heat exchanger between the two loops of the flow battery.

It will be appreciated that the embodiments described above have primarily been described in the context of a simple domestic (or light industrial) type combined heating and energy storage system. However, embodiments may be suitable for use in a variety of applications and may, for example, be used for short or longer term energy balancing. For example, in an agricultural application it may be advantageous to use an embodiment of the invention for seasonal based energy storage. For example, solar electricity generated in a summer season could be stored by the flow battery of an embodiment and utilised for heating or light during winter seasons.

Claims

Claims 1 A combined heating and energy storage system, comprising: a wet heating system comprising: at least one heat source; at least one emitter, positioned remotely from the heat source; and a distribution circuit for directing a heat transfer fluid between the at least one heat source and the at least one emitter; an energy storage system comprising: a cell including a current collector having first and second electrodes, a body between the electrodes, the body defining first and second flow chambers; a first flow loop in flow communication with the first flow chamber for directing positive electrolyte through the cell; and a second flow loop in flow communication with the second flow chamber for directing negative electrolyte through the cell; wherein at least one of the first and second flow loops is part of the heating system distribution circuit such that, in use, the heat transfer fluid comprises at least one of the positive or negative electrolytes.
2. The combined heating and energy storage system of claim 1, wherein one of the first or second flow loops is part of the heating system distribution circuit and the other of the second or first flow loops is independent of the heating system.
3 The combined heating and energy storage system of claim 2, wherein the other of the second or first flow loops further comprises an electrolyte storage tank.
4 The combined heating and energy storage system of claim 1, wherein the first and second flow loops are each formed by separate loops of the heating system distribution circuit.
5 The combined heating and energy storage system of claim 4, wherein each loop of the distribution circuit comprises at least one emitter and the separate loops of the heating system distribution circuit define separate heating zones.
6 The combined heating and energy storage system of claim 4 or 5, wherein each loop of the heating system distribution circuit further comprises a pump to provide a motive force to the heat transfer fluid.
7. The combined heating and energy storage system of any preceding claim, wherein the energy cell is a redox flow battery.
8 The combined heating and energy storage system of any preceding claim, wherein the heat source is an electric heater selectively powered by the energy cell.
9. The combined heating and energy storage system of any preceding claim, wherein the at least one heater comprises a radiator or an underfloor heating system.
10. The combined heating and energy storage system of any preceding claim, further comprising a renewal energy generator.
11. A domestic heating system comprising the combined heating and energy storage system of any preceding claim.
12. An industrial heating system comprising the combined heating and energy storage system of any of claims 1 to 10.
13. A mobile building or residence comprising the combined heating and energy storage system of any of claims 1 to 10.
14. A method of providing an energy storage system comprising: providing an electrolyte in the heat transfer fluid of a wet heating system providing a flow battery in fluid communication with the wet heating system; applying an electric current to the flow battery when energy storage is required; and pumping electrolyte around the wet heating system and through the flow battery when energy extraction is required.
15. The method of claim 14, further comprising: forming two separate loops in the wet heating system, and providing a positive electrolyte in a first loop and providing a negative electrolyte in a second loop.
16. The method of claim 14 or 15, further comprising: providing a renewable energy generator; and storing excess energy created by the energy generator by applying electric current to the flow battery.