Electrically-conductive firebrick system

Abstract

To provide an improved energy storage system and apparatus which store electric power in a power grid.SOLUTION: A firebrick system 803 serving as a thermal energy storage system includes a firebrick checkerwork 804 and an electrode 802, 806. The firebrick checkerwork includes one or more conductive firebrick layers, each including a plurality of electrically-conductive doped metal oxide firebricks with one or more airflow vents. The electrode includes one or more electrode firebrick layers, each layer including a plurality of electrode firebricks. The firebrick checkerwork is heated due to application of electric power to the electrode. Air flowing through the firebrick checkerwork is then heated for use in an industrial application, commercial application, residential application, transportation application, etc., which are heat-related applications, some of which is heated for use in other applications which are related to electricity production or which are related to other purposes that are unrelated to electricity production and require heat.SELECTED DRAWING: Figure 8C

Description

Technical Field

[0001]

[0001] One or more embodiments described herein relate to managing energy storage.

Background Art

[0002]

[0002] Modern energy generation and distribution networks (“power grids”) include many different power sources. Some generators (e.g., conventional power plants such as coal, oil, natural gas, nuclear power, etc.) can operate with a relatively continuous output, while other power sources such as solar thermal or wind power can have variable generating capacity, e.g., based on environmental factors. As more and more solar thermal and wind power generators come online to reduce greenhouse gas emissions, the variability of the output power may need to be considered with the expansion of the power grid's energy storage capacity. However, current battery technology has proven to be insufficient and very costly to implement. Attempts have been made to use other types of energy storage systems such as pumped hydro storage. However, these other systems are location-limited and not readily available or deployable.

Summary of the Invention

Means for Solving the Problems

[0003]

[0003] One or more embodiments described herein provide improved energy storage systems and methods that can be used for various applications, and particularly importantly, include storing power in a power grid.

[0004]

[0004] These and / or other embodiments provide an energy storage system and method for controlling power storage to offset variability in the output of one or more power sources of a grid, including, but not limited to, variability in the output power of solar thermal generators, wind turbines, and other power sources that are affected by inconsistent operation due to environmental and / or other factors.

[0005]

[0005] These and / or other embodiments provide an improved energy storage system and method that can be easily deployed in various contexts.

[0006]

[0006] These and / or other embodiments provide an improved energy storage system and method that are economical to implement.

[0007]

[0007] According to one or more embodiments, a thermal energy storage system includes a refractory brick latticework comprising one or more conductive refractory brick layers, each conductive refractory brick layer comprising a plurality of conductive doped metal oxide refractory bricks having one or more ventilation holes to enable an air flow through the refractory brick latticework, a first electrode comprising one or more electrode refractory brick layers, each electrode refractory brick layer comprising a plurality of electrode refractory bricks, the first electrode being configured to receive power from a power source, and the refractory brick latticework is heated due to the application of the received power. In such a configuration, the air flowing through the refractory brick latticework can be heated by the refractory brick latticework to provide heat for various uses including, but not limited to, residential heat use, industrial heat use, commercial heat use, transportation use, and / or electricity production (which may occur in any or all of residential, industrial, commercial, and transportation environments). The concepts described herein can be utilized in both the high-temperature heat market and the electricity market. Thus, after reading the description provided herein, one of ordinary skill in the art will understand the present It is to be understood that the thermal storage systems and other embodiments described in the specification can provide heat for all types of heat users and heat-related applications (e.g., industrial applications, commercial applications, residential applications, transportation applications, etc.). It is further to be understood that some of these applications may be related to electricity production, while other applications may be related to other purposes that require heat not related to heat production. Thus, one or more embodiments can, in some cases, function as an effective alternative to a battery, while other embodiments can be used in a variety of other contexts, such as providing heat for virtually any purpose.

[0008]

[0008] According to one or more embodiments, the apparatus comprises a first electrode, a second electrode, and a conductive refractory brick, the conductive refractory brick being disposed in a predetermined pattern between the first electrode and the second electrode, and each of the conductive refractory bricks comprising a doped metal oxide material configured to generate heat based on a potential applied between the first electrode and the second electrode.

[0009]

[0009] The foregoing and other objects, features, and advantages will become apparent from the following more particular description of the embodiments, as illustrated in the accompanying drawings, in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; rather, emphasis is placed on illustrating the principles of the embodiments.

Brief Description of the Drawings

[0010]

Figure 1

[0010] FIG. is a block diagram of an exemplary industrial system using a conductive refractory brick system according to the described embodiments.

Figure 2A

[0011] FIG. is a plot of material conductivity versus temperature for refractory bricks of various materials according to the described embodiments.

Figure 2B

[0012] FIG. is a plot of electron concentration versus temperature for doped semiconductor refractory bricks according to the described embodiments.

Figure 2C

[0013] A plot of electron concentration and resistivity versus temperature for doped semiconductor refractory bricks according to the described embodiments.

Figure 2D

[0014] A block diagram of an exemplary electric heating thermal energy storage (E-TES) system using conductive refractory bricks according to the described embodiments.

Figure 3

[0015] A diagram of an exemplary container system including an E-TES system according to the described embodiments.

Figure 4

[0016] A diagram of an exemplary E-TES system using conductive refractory bricks according to the described embodiments.

Figure 5

[0017] A schematic diagram of an exemplary Y (wye) configuration electrical connection of electrodes of an E-TES system according to the described embodiments.

Figure 6

[0018] A schematic diagram of an exemplary Y (wye) configuration electrical connection of electrodes of an E-TES system according to the described embodiments.

Figure 7A

[0019] A diagram showing an image of an exemplary refractory brick system according to the described embodiments.

Figure 7B

[0020] A diagram showing an image of an exemplary refractory brick system according to the described embodiments.

Figure 8A

[0021] A perspective view of an exemplary electrode and conductive refractory brick layout for an E-TES system in a delta configuration according to the described embodiments.

Figure 8B

[0022] A perspective view of an exemplary electrode and conductive refractory brick layout for an E-TES system in a Y (wye) configuration according to the described embodiments.

Figure 8C

[0023] A perspective view of another exemplary electrode and conductive refractory brick layout for an E-TES system in a Y (wye) configuration according to the described embodiments.

Figure 9

[0024] Block diagram of an exemplary energy distribution and storage grid using an E-TES system according to the described embodiment.

Figure 10

[0025] Block diagram of an exemplary concrete kiln system using an E-TES system according to the described embodiment.

Figure 11

[0026] Block diagram of an exemplary natural gas power system using an E-TES system according to the described embodiment.

Figure 12

[0027] Block diagram of an exemplary nuclear power system using an E-TES system according to the described embodiment.

Figure 13

[0028] Pair of plots of resistivity versus temperature of refractory bricks using doped chromium oxide according to the described embodiment. **DETAILED DESCRIPTION OF THE INVENTION**

[0011]

[0029] One or more embodiments described herein provide systems and methods for implementing electric heating thermal energy storage (E-TES). Such systems and methods may be useful for decarbonization for a variety of applications, including but not limited to those related to power grids or industrial systems. As an increasing number of renewable energy generators are deployed within the power grid, there is a desire for abundant and inexpensive energy storage technologies to cover cycles in power generation, such as solar thermal or wind energy generation. Embodiments of E-TES described herein may meet these goals. Furthermore, these and / or other embodiments may be used in various industrial processes that generate and / or consume heat, such as furnaces, kilns, refineries, nuclear power plants, etc. As described herein, some embodiments of E-TES may use electrically heated refractory bricks to store thermal energy for use as heat or conversion to electricity.

[0012]

[0030] Figure 1 shows an exemplary deployment embodiment of an E-TES system using heated refractory bricks in a power grid or industrial system. As shown in Figure 1, the heated refractory brick E-TES system 108 can receive an electrical input 104 to heat the refractory bricks and can also receive an air input 102. For example, the air input 102 can be "cold" air, ambient temperature air, exhaust from an industrial process, etc. The input air can be heated by the heated refractory brick 108 and output as hot air 110. In some embodiments, the temperature of the output hot air 110 can be adjusted by a temperature regulator 114 that can include air provided by an air bypass 106 from the input air 102. For example, the temperature of the output air can be adjusted by providing cooler air (e.g., via bypass 106) when the temperature of the heated refractory brick 108 is higher than the desired temperature for the output hot air 110 provided to the output user 112, which can be a kiln or furnace, for example. Alternatively, when the temperature of the heated refractory brick 108 is lower than the desired temperature for the output air 110, additional fuel such as natural gas can be provided via the temperature regulator 114 to raise the temperature of the output hot air 110.

[0013]

[0031] In some embodiments, the output user 112 can be a natural gas power cycle plant. According to one or more embodiments, a default efficiency, e.g., a round-trip electrical efficiency of 55 - 60%, can be achieved. In other embodiments, the output user 112 can be a nuclear power plant (e.g., a fourth-generation nuclear reactor), and the E-TES system can achieve a round-trip electrical efficiency of, for example, 65 - 70%. In one embodiment, the E-TES system (e.g., the refractory brick 108) can be located in close proximity to the user 112.

[0014]

[0032] However, existing systems do not achieve a sufficiently high temperature range and / or suffer from a dramatically short lifespan due to the high temperatures required. For example, existing heaters have a limited temperature range (e.g., Tpeak of the heater < Tpeak of the refractory brick), a limited charging rate (e.g., limited ability to transport heat from the heater to the refractory brick due to the surface wattage load of the heater and / or the temperature gradient and thermal stress of the refractory brick), and a heater lifespan that is dramatically shortened by high temperatures that can incur high replacement costs.

[0015]

[0033] Therefore, one or more embodiments provide direct resistance heating of the refractory brick 108. For example, one or more embodiments can electrically heat an insulated mass of refractory brick to a very high temperature (e.g., from about 1000 °C to about 2000 °C, however, higher temperature ranges are possible). The heat stored in the refractory brick 108 can be delivered as output air 110 by blowing air into passages within the hot refractory brick to deliver the stored heat for industrial heat applications (e.g., kilns, furnaces, refineries) or for electric power generation applications (e.g., power plants).

[0016]

[0034] Direct resistance heating (DRH) of the refractory brick 108 eliminates the drawbacks in commercially available heaters, where the temperature is limited only by the properties of the refractory brick, enabling higher temperature applications, increased energy density, and a higher charging rate. Further, the refractory brick system removes the wattage load constraints of existing heaters, and designing the refractory brick to provide substantially uniform heat generation throughout the refractory brick system reduces stress on the system, which reduces repair costs and results in a more reliable operation. Therefore, according to one or more embodiments, there is provided a conductive brick that can be mass-produced to form a stable stackable electrical circuit for Joule heat that can be cycled daily within a given range (e.g., approximately 1000 °C to approximately 1800 °C, or another range) over a long time period, e.g., for years.

[0017]

[0035] The described embodiments provide refractory bricks made of a suitable material having conductivity to provide desired heating characteristics. A progressive resistivity-temperature trend governed by carrier mobility can be a characteristic of refractory bricks.

[0018]

[0036] FIG. 2A shows a plot providing examples of the conductivity of different materials versus temperature. The conductivity of a material can be determined, for example, by Equation (1):

Number

[0019]

[0037] The carrier mobility μ c can be estimated based on Equation (2),

Number

[0020]

[0038] As shown in FIG. 2A, in a metal, electrons have a continuum of allowable energies (e.g., Nc≈constant), whereby heating is overall stable, and any non-uniform heating is corrected by the conductivity in the hotter region being lower and the colder region having a higher current than the warmer region. Thus, the conductivity can be estimated as σ∝T-3 / 2.

[0021]

[0039] In a semiconductor refractory brick, the intrinsic conductivity of the semiconductor has a band gap between the conduction band and the valence band, whereby electrons are localized and cannot jump levels without thermal activation. Thus, the intrinsic conductivity is

Equation

[0022]

[0040] In the case of extrinsic conductivity of a semiconductor, when an element having one more or one less valence electron than the substituted element is doped into the semiconductor, electron donor or acceptor sites can be formed. The activation energy Ea associated with "donating" or "accepting" electrons may be smaller than the semiconductor band gap energy Eg. Thus, the intrinsic conductivity is

Equation

[0023]

[0041] Accordingly, according to one or more embodiments, "metallic" behavior can be achieved in high temperature ceramics in a highly oxidizing environment. Doping a semiconductor material to achieve a period of "consumption" before the exponential trend becomes dominant allows for the formation of three distinct conductive regions: intrinsic, extrinsic (or "consumption"), and ionization (or "freeze-out"), such as shown in the plot in FIG. 2B. As shown in FIG. 2B, in the extrinsic region, Nc(T) is constant and thus exhibits performance like that of a metal. As shown in FIG. 2C, in the unstable region, extrinsic carriers are activated ( [Number] ), and when all carriers are activated, carrier activation levels off, resulting in a decrease in mobility and an increase in metal-like behavior, where conductivity is constant over temperature (e.g., σ ∝ T-3 / 2). As the temperature continues to rise, intrinsic carriers are activated and eventually exceed the extrinsic carriers, entering the unstable region ( [Number] ).

[0024]

[0042] FIGS. 2B and 2C show an example where upper and lower temperature boundaries TU and TL can be selected by modifying the material and dopant levels, thus setting the desired temperature range of operation where the conductivity of the refractory brick material is approximately constant (e.g., the consumption region). The temperatures TU and TL depend on the semiconductor bandgap energy Eg, which is the bandgap energy (eV ) of the refractory bulk material, the activation energy (eV) of the dopant sites due to the interaction between the dopant material and the bulk material, Ea, and the density of the added dopant material (per cm 3 ), Na. Generally, the consumption region shifts to higher temperatures as doping is increased.

[0025]

[0043] Figure 2C shows a doped SiC ceramic heater, which is also a common refractory brick material, where TL is approximately 800 °C and TU is approximately 1600 °C. Doped SiC is generally not suitable for E-TES because it oxidizes, and the oxidation hinders the electrical current flow between the refractory bricks and ultimately destroys the bulk properties of the material.

[0026]

[0044] Thus, according to one or more embodiments, a refractory bulk material based on a metal oxide such as chromium oxide (Cr2C3) can be selected with a given semiconductor bandgap energy Eg. A dopant material having a relatively low Ea can be used to dope with Na to achieve the desired temperature range from TL to TU. The goal of the selection is to achieve a low TL (below about 700 °C), a high TU (above about 1800 °C), a large temperature range (e.g., a depletion range of about 1000 °C or more), and a high Na (e.g., highly doped) such that impurities can be ignored (above about 1020 / cm3).

[0027]

[0045] Figure 2D shows an example where a stable stackable semiconductor refractory can be provided according to one or more embodiments, and this refractory can achieve metallic conductive behavior for use in an electric heating type thermal energy storage (E-TES) system. As shown in Figure 2D, the E-TES system 200 can include an "upper" electrode 202 and a "lower" electrode 204. Between the electrodes 202 and 204 is a layer of refractory shown as refractory layer 206. The refractory layer 206 includes a plurality of stackable refractories 208, and the refractories 208 can be at different levels, for example, in an overlapping relationship with each other. In another embodiment, the refractories 208 can all be at the same level. Since the refractories 208 can be freely stacked, the plurality of stackable refractories 208 can form an air passage 210 between adjacent pairs of individual refractories (which also allows for thermal expansion of the refractories). Generally, the air flow can be in at least one given direction. An example of the direction is shown by the dashed line 212.

[0028]

[0046] Figure 3 shows a diagram of an exemplary heat exchanger vessel that can be used to contain a refractory brick E-TES system as shown in Figure 2D. As shown in Figure 3, the vessel system 300 can include an air inlet 310, a lower plenum 308, a body 312, an upper plenum 304, and a hot air outlet 302. Collectively, the plenums 304 and 308 and the body 312 can form a vessel 314. Generally, the vessel 314 can be a insulated steel vessel disposed in an industrial facility or a power plant. In some embodiments having a higher air pressure, the vessel 314 can be prestressed concrete. As shown, the vessel 314 can include a predefined pattern (e.g., a latticework) of refractory bricks, shown as refractory bricks 306, such as those shown with respect to Figure 2D, that can be implemented.

[0029]

[0047] As shown, the lower plenum 308 is a hemispherical inlet for the air flow into the vessel 314, and the upper plenum 304 is a hemispherical outlet for the air flow through the vessel 314. The air flow is provided from the inlet 310 and flows through the refractory bricks 306 as shown by the dashed arrow 316 and then exits through the hot air outlet 302. In some embodiments, the lower plenum 308 includes a support structure (e.g., corrosion-resistant steel, ceramic archway, dome structure, etc.) for the vessel 314 to support the vessel 314 as an upright structure. Additionally, in some embodiments, the lower plenum 308 can be maintained at a lower temperature than the remainder of the vessel 314 by using a thermal insulation layer between the lower plenum 308 and the refractory brick latticework 306 and / or by using one or both of passive and active cooling. Although shown as generally cylindrical in Figure 3, the vessel 314 has specific sizes and shapes that vary based on its use and application.

[0030]

[0048] As described, the vessel 314 can have a large electrical input (e.g., as three-phase AC power or as DC power), and in one embodiment, the refractory brick latticework 306 can be implemented to have three isolated conductive refractory brick regions in a given configuration. Examples include a delta configuration, a Y (wye) configuration, or another configuration. In one embodiment, three-phase power can be provided by electrical penetrations into the refractory brick latticework and / or conductive electrodes that withstand a high-temperature oxidizing environment.

[0031]

[0049] FIG. 4 shows an embodiment of the refractory brick latticework 306 that can be included within the heat exchanger vessel of FIG. 3. As shown in FIG. 4, the refractory brick latticework 306 can include multiple layers or regions of chimney-shaped lattice refractory bricks having different conductivities and / or functions.

[0032]

[0050] As shown in FIG. 4, an illustrative embodiment can use three general types of refractory bricks: insulating refractory bricks 402, 410, 412, and 414, electrode refractory bricks 404 and 408, and conductive refractory bricks 406. The insulating refractory bricks are electrically insulating and can be implemented using a given combination of materials. An example combination is alumina / magnesia / silica. The electrode refractory bricks are highly conductive and result in low heat generation, being highly doped (~about 10 21 / cm 3 ) metal oxide refractory bricks (e.g., the electrode refractory bricks do not require a small temperature coefficient of resistance). The conductive refractory bricks are approximately 10 times more resistive than the electrode refractory bricks and have a small temperature coefficient of resistance, being carefully mixed and doped (~about 10 20 / cm 3 ) metal oxide refractory bricks.

[0033]

[0051] As shown in FIG. 4, the top layer of insulating refractory bricks shown as the upper insulating layer 402 electrically insulates the upper electrode 404 from the structure of the container 314 and provides thermal mass and weight for good electrical contact between the upper electrode 404 and the conductive refractory brick latticework 406. In some embodiments, the upper electrode 404 may be composed of a plurality of regions of electrode refractory bricks, shown as electrode regions 404a-n. In some embodiments, for example, there may be three electrode regions of the upper electrode 404 to isolate the individual phases of a three-phase power input. Each of the electrode regions 404a-n may be separated by one or more regions of insulating refractory bricks shown as insulating regions 414. In another embodiment, a different number of regions may be included.

[0034]

[0052] The conductive refractory brick latticework 406 may also include a plurality of regions of conductive refractory bricks shown as conductive regions 406a-n, which in some embodiments may be generally aligned with and correspond to the electrode regions 404a-n for three-phase power. The conductive refractory brick latticework 406 is a location for heat generation and storage within the E-TES system. The lower electrode 408 is also composed of electrode refractory bricks. In embodiments using a Y (wye) configuration three-phase power, the lower electrode 408 is a single region and forms the neutral point of contact for a three-phase Y (wye) configuration as shown in FIG. 4. In embodiments using a delta configuration three-phase power, the lower electrode 408 may be separated into a plurality of conductive regions to transfer electricity through the latticework 406 to provide an impedance load between phases. The lower insulating layer 410 is made of insulating refractory bricks and electrically and thermally insulates the lower electrode 408 from the container 314. In another embodiment, a different number of conductive regions may be included.

[0035]

[0053] FIG. 5 shows, for example, a Y (wye) configuration three-phase power where introducing electricity only at the upper electrode 404 allows the container penetration for the electrode to be at the top of the container 314 An embodiment of the E-TES system 500 using force is shown. As shown, the line source 502 generates three-phase electricity, and a single phase is provided to the corresponding one of the upper electrode regions 404a-c. As shown in FIG. 5, each electrode region 404a-c may have one or more electrical penetrations of the container 314, shown as electrical connections 504. The illustrative embodiment shown in FIG. 5 may include electrical connections 504 only at the top of the container 314. For example, in an embodiment where the upper electrode 404 has a power connection only at the top of the container 314, maintenance or replacement of components may be easier by removing only the upper insulating layer 402. Other embodiments may alternatively or additionally use connections at the bottom of the container 314, which may be more difficult to access for maintenance, but may benefit from lower temperatures due to the airflow through the E-TES system. In some embodiments, the electrical penetrations 504 may be temperature and / or pressure controlled, for example, by an annular container sleeve, to maintain a reliable ceramic / metal interface between the electrical penetrations 504 and the electrode refractory brick region 406.

[0036]

[0054] FIG. 6 shows an illustrative electrical schematic of an embodiment of the Y (wye) configuration of the E-TES system 500. In this embodiment, each region of the upper electrode 404 corresponds to a given phase supplied by the generator 502, and the lower electrode 408 can be used to provide a neutral point, optionally having a neutral connection 602.

[0037]

[0055] As described herein, embodiments provide a conductive refractory made of a doped metal oxide. The doped metal oxide refractory provides a high-temperature operating range (about 1800 °C), is conductive, electrically stable (exhibiting a nearly constant resistivity above 400 °C), thermally cyclable over many cycles, physically stackable with a low contact resistance (about 0.1 Ω-cm2 at 5 PSI), and is inexpensive.

[0038]

[0056] Figure 7A shows an exemplary embodiment of a refractory brick latticework 700. The latticework 700 may include a plurality of layers (or levels) of refractory bricks 702 stacked on top of each other, shown as layers 710a - n. As shown, each refractory brick 702 may be implemented as a chimney - type brick having one or more chimney ventilation holes 708 passing through the refractory brick along the axis of the refractory brick (e.g., vertically from bottom to top). For example, as shown, each refractory brick 702 includes seven chimney ventilation holes 708, each of which has a substantially hexagonal cross - sectional shape. The overall shape of each refractory brick 702 is selected to be substantially symmetric to enable easy stacking and placement within a latticework containing a plurality of refractory bricks, and also to enable ease of manufacture. For example, as shown in FIG. 7, the refractory brick 702 may also be substantially hexagonal and may include one or more ridges 706 and / or teeth 704 around the outer edge or perimeter of the refractory brick. The outer ridges and teeth may facilitate the placement of a plurality of refractory bricks into the latticework and may facilitate the connection of the refractory bricks to each other. Further, the shape of the refractory brick 702 and the ridges 706 and teeth 704 may facilitate the deployment of the refractory brick 702 into containers of different shapes (e.g., the container 314 of FIG. 3) without modifying the refractory brick. Similarly, one side (e.g., the top) of each refractory brick 702 may include a recess 712, and the opposite side (e.g., the bottom) may have a corresponding protrusion (not shown) to fit within the recess, further facilitating the stacking and connection of the refractory bricks.

[0039]

[0057] Figure 7B shows another exemplary embodiment of a refractory brick latticework, shown as a refractory brick latticework 720. As shown, each refractory brick 722 may include one or more chimney ventilation holes 728. As shown, each chimney ventilation hole may have a substantially square cross - section and may pass through the refractory brick along the axis of the refractory brick (e.g., vertically from bottom to top). The edges of each refractory brick 722 are angled, as shown as edges 724 and 726, to facilitate placement within the latticework and / or deployment within containers of different shapes It can be made square or rounded. Some embodiments may include one or more lateral cutouts 730 to facilitate connection between refractory bricks.

[0040]

[0058] The refractory brick embodiments shown in FIGS. 7A and 7B may allow the bricks to expand and contract as the temperature changes, without requiring any material between the bricks that can be damaged by expansion and contraction and / or extreme temperatures. This deformability allows the conductive refractory bricks to maintain a good electrical connection even as the material deforms over temperature changes.

[0041]

[0059] Thus, the refractory bricks described are made by mixing a bulk material in powder form (e.g., chromium oxide) with a desired amount of dopant material (e.g., nickel oxide). In some embodiments, the dopant material can be approximately 2% - 5% of the mixture. The mixture is then mechanically pressed into bricks having the desired size, shape, and shape factor, and including one or more chimney vents to allow air flow through the refractory bricks. The refractory bricks are then temperature / pressure sintered into bricks.

[0042]

[0060] In the described embodiments, the refractory bricks can be nickel-doped chromium oxide, magnesium-doped chromium oxide, lithium-doped nickel oxide, copper-doped nickel oxide, aluminum-doped zinc oxide, cerium-doped stabilized zirconium oxide, niobium-doped titanium oxide, or other high-temperature metal oxides doped with metals of different valences, which can be mixed with an electrically inert oxide such as alumina, magnesia, or silica. For example, in some embodiments, some alumina (e.g., aluminum oxide) can be mixed with nickel-doped chromia (e.g., chromium oxide), which can make the refractory bricks less expensive and / or stronger without significantly changing the electrical properties of the refractory bricks.

[0043]

[0061] FIG. 8A shows an exemplary embodiment of a refractory brick system 800 that can be an implementation form of the system shown in FIG. 4. As shown, the upper electrode 802 can include one or more insulating regions 822 such that the insulating region 822 divides the upper electrode 802 into a plurality of conductive regions 820. Similarly, the refractory brick latticework portion 804 can also include one or more insulating regions 818 such that the insulating region 818 divides the refractory brick latticework 804 into a plurality of conductive regions 816. The lower electrode 806 can also include one or more insulating regions 812 such that the insulating region 812 divides the lower electrode 806 into a plurality of conductive regions 810. As described herein, each of the upper electrode 802, the lower electrode 806, and the refractory brick latticework 804 can include a plurality of layers of refractory bricks, and the insulating regions and conductive regions of each layer overlap and are generally aligned with each other such that the plurality of layers form the entire multilayer. Thus, each of the upper electrode 802, the lower electrode 806, and the refractory brick latticework 804 can have a plurality of multi-refractory brick layer electrical isolation portions.

[0044]

[0062] In some embodiments, the geometries of the conductive portions 820, 816, and 810 can be arranged such that the various conductive portions overlap each other, thereby forming an electrical connection and forming a path for electricity to conduct through the refractory brick system 800. For example, as shown in FIG. 8A, the line 808 shows an exemplary electrical path of the system 800 based on the arranged overlap of the conductive portions 820, 816, and 810.

[0045]

[0063] Thus, one or more embodiments provide a conductive refractory brick that can form a conductive medium that is stable and stackable in air, and the manner of stacking the refractory bricks can form a desired electrical flow path throughout the system 800. As described herein, the refractory brick latticework 804 is a location of heat generation. Generally, the refractory brick latticework 804 and the upper electrode 802 are electrically isolated from a plurality of (e.g., three) It is divided into the phase parts obtained and can receive each phase of three-phase power. Further, each phase part can be further partitioned to form a "meandering" electrical path 808 in order to achieve the desired system resistance and charge behavior and to ensure the passive charge stability of the system 800. For simplicity, line 808 shows the electrical path for a single electrical phase of the system 800, and the electrical paths for other phases can have a similar configuration.

[0046]

[0064] As shown, the conductive refractory bricks are separated by insulating refractory bricks to form a meandering electrical path indicated by line 808 passing through the upper electrode 802, the refractory brick latticework 804, and the lower electrode 806. The upper electrode 802 and the lower electrode 806 are separated by insulating refractory bricks in a pattern different from that of the refractory brick latticework 804, but the patterns can overlap each other to connect vertical electrical paths as indicated by line 808.

[0047]

[0065] In some embodiments, both the "beginning" and the "end" of the electrical path 808 are at the upper electrode 802, thus avoiding the need to provide any electrical through-holes at the bottom of the container, for example, as described with respect to FIG. 5. However, as described herein, other embodiments can alternatively or additionally use electrical through-holes at the bottom of the container. For example, the latticework pattern of the illustrative embodiments described herein (such as those shown in FIGS. 8A, 8B, and 8C) can be reversed if it is desired to place the power connection at the bottom rather than the top of the container.

[0048]

[0066] As shown in FIG. 8A, the electrical system operates in a delta configuration. The number of serpentine paths desired in the system determines the operating configuration such that the electrical through-section is at the top of the system. When the number of serpentine paths is even, the system has a delta configuration, and when the number of serpentine paths is odd, the system has a Y (wye) configuration. FIG. 8A shows an illustrative "6-pass delta configuration" system. Further, although generally described herein as using three-phase AC power, some embodiments may use DC power when powered by a DC source such as, for example, a solar panel array or a rectifier. As described above, electrical path 808 is a serpentine electrical path for a single phase of a three-phase system, and thus, the three-phase system will use three separate electrical paths. In a DC system, the same serpentine configuration of electrical path 808 used in a delta configuration may be used, but the three electrical paths of the three-phase system are instead connected in series between two nodes of the DC source.

[0049]

[0067] According to one or more embodiments, the widths of the insulating regions 822, 818, and 812 are at least two fire bricks to maintain isolation in an alternating pattern, although other embodiments may include wider insulating regions. As shown in FIG. 8A, the conductive regions 816 of the fire brick latticework 804 are sized such that electricity and heat are conducted quickly enough to avoid a runaway condition and result in a consistency in temperature throughout the fire brick latticework 804 (in some embodiments, a cross-section in the range of 0.25 m to 1.5 m). In some embodiments, the various conductive regions 816 are sized to be approximately the same such that the electrical current is symmetric between regions, resulting in a more consistent temperature distribution throughout the fire brick latticework 804. In some embodiments, the height of the fire brick latticework 804 (e.g., the conductive regions 816 and the insulating regions 818) is in the range of tens of meters (e.g., generally 20 to 40 m).

[0050]

[0068] Figures 8B and 8C illustrate exemplary embodiments of electrodes and conductive refractory brick layouts for an E-TES system in a Y (wye) configuration. For example, FIG. 8B shows an exemplary refractory brick system 801 using an electrical path 808 in a "3-pass" Y (wye) configuration. Similar to FIG. 8A, the electrical path 808 represents one of the electrical paths in a three-phase system. As described herein, in some embodiments, a given electrical path 808 may correspond to one of the phase legs of a three-phase system and may begin at a given one of the conductive regions 820 of the upper electrode 802. Each electrical path 808 may end at a Y (wye) node 821, and the electrical current flowing through the path 808 for one of the legs of the three-phase system flows in a reverse direction through the electrical paths for the other legs of the three-phase system. That is. As described herein, in some embodiments, a given electrical path 808 may correspond to one of the phase legs of a three-phase system and may begin at a given one of the conductive regions 820 of the upper electrode 802. Each electrical path 808 may end at a Y (wye) node 821, and the electrical current flowing through the path 808 for one of the legs of the three-phase system flows in a reverse direction through the electrical paths for the other legs of the three-phase system.

[0051]

[0069] FIG. 8B shows each meandering path 808 as having the same (or substantially similar) shape, but this is not required by the system. In one or more embodiments, the electrical paths 808 may be used with the same (or substantially similar) flow area to avoid bottlenecks in the current flow where overheating may occur. As shown in FIGS. 8A and 8B, each layer 802, 804, and 806 of the refractory brick system may have a predefined geometry (e.g., may be substantially hexagonal) to facilitate fitting within a container having a substantially circular cross-sectional shape, for example, but other shapes and configurations are possible.

[0052]

[0070] FIG. 8C shows an exemplary refractory brick system 803 using layers 802, 804, and 806 having a substantially square or rectangular cross-sectional shape, which can be advantageously used in containers of the same cross-sectional shape. As shown in FIG. 8C, an electrical path 808 in a “3-pass” Y (wye) configuration. Similar to FIG. 8A, the electrical path 808 represents one of the electrical paths in a three-phase system. As described herein, in some embodiments, a given electrical path 808 can correspond to one of the phase legs of a three-phase system and can originate at a given one of the conductive regions 820 of the upper electrode 802. Each electrical path 808 can terminate at a Y (wye) node 821, and the electrical current flowing through the path 808 for one of the legs of the three-phase system flows in a reverse direction through the electrical paths for the other legs of the three-phase system. Although each meandering path 808 is shown in FIG. 8C as having the same (or substantially similar) shape, this is not required by the system. Preferably, the described embodiments use electrical paths 808 having the same (or substantially similar) surface area (not necessarily the shape) such that the current flow is substantially the same in each path, thus avoiding bottlenecks in the higher resistance current flow where overheating can occur.

[0053]

[0071] Thus, an E-TES refractory brick system as described according to one or more embodiments can achieve heating systems of various sizes, shapes, and temperatures up to a certain limit, for example, about 2000° C., or another limit in air. The refractory brick system can have a modular design with respect to shape and size and can thus be adapted to various furnace or container shapes and sizes. Further, a refractory brick system as described herein can be compatible with a standard control system while operating with high stability over a longer heater life than other solutions and achieving higher temperatures than can be achieved by other systems.

[0054]

[0072] FIG. 9 shows an illustrative embodiment of an E-TES refractory brick system 912 within an exemplary electrical distribution grid 900. As shown in FIG. 9, the E-TES system 912 stores excess electricity as heat and uses existing power generation and storage technologies (e.g., power generation device 902, heater 904, synthetic fuel system 906, power cycle system 908, and conventional electrical energy storage system 910) to provide the stored energy as electricity to electricity consumers 914 or as heat to heat consumers 916.

[0055]

[0073] FIG. 10 shows an embodiment of an E-TES refractory brick system as described herein, for use, for example, in one or more cement kilns. As shown, the E-TES system can receive cold air from the grate cooler of a cement plant and then supply electrically heated air to one or both of a rotary kiln and / or a pre-kiln. This can result in significant carbon emissions reduction for the cement plant and , can result in significant energy cost savings (renewable energy surplus). Reduction in combustion gas use can result in easier cement firing. Finally, the E-TES system is estimated to be very cost-effective for a cement plant and is estimated to be approximately 5% of the total cement plant cost.

[0056]

[0074] FIG. 11 shows an embodiment of an E-TES system that can be used as a battery when coupled to a power plant, such as a natural gas power plant, shown as plant 1100. As shown, the E-TES system 1106 can be provided with air from a compressor 1104. The E-TES system 1106 is electrically heated to provide hot air to a turbine 1108, which hot air is provided to a heat recovery steam generator 1110 and a stack 1112. The turbine provides power to the compressor 1104 and the generator 1102. In one embodiment, natural gas can be injected to increase the heat to an even higher level. This system can achieve a given efficiency, e.g., a round-trip energy efficiency of 55-65%, or different ranges of efficiency.

[0057]

[0075] FIG. 12 shows an embodiment of an E-TES system that can be used with an air cycle system, such as a nuclear or solar thermal power plant. As shown, the power plant system 1200 can include an E-TES system 1206 that receives cold air from one or more salt-air heaters 1204 and provides heated air to a turbine 1202, which can drive a generator 1208 and / or a heat recovery steam generator 1212. Zero-carbon fuel can be added to the output of the E-TES system 1206 to raise the temperature to a desired range or otherwise condition it prior to input into the turbine. In one example implementation, this E-TES system can achieve a round-trip electrical efficiency of 65-70% or more, although different levels of efficiency may be obtained.

[0058]

[0076] FIG. 13 shows a first plot 1300 showing an example of the resistance of doped chromia refractory bricks versus temperature. Plot 1302 shows an enlarged view of the region of plot 1300 indicated by rectangle 1304. As shown, the doped chromia refractory bricks achieve a very low resistance (<0.5 Ω-cm) that is approximately linear between 900 and 1500 °C.

[0059]

[0077] Accordingly, according to one or more embodiments, an E-TES system is provided that may be useful for industrial and / or combined cycle plant applications operating at medium to high temperatures. These may be, for example, those using medium temperature heat (e.g., <500 °C), such as steam systems, chemical plants, paper mills, etc., and may also be useful for high temperature heat applications (e.g., about 800 - 2000 °C), such as steel, aluminum, cement, glass, and other high temperature industrial processes.

[0060]

[0078] After reading the description provided herein, it should thus be understood that the thermal energy storage systems and other embodiments described herein can provide heat for all kinds of heat users and heat-related applications (e.g., industrial applications, commercial applications, residential applications, transportation applications, etc.). Some of these applications may be related to electricity production, while other applications may be related to other purposes that require heat unrelated to heat production. Thus, one or more embodiments can, in some cases, function as an effective alternative to batteries and can be used in a variety of other contexts, such as, for example, to provide heat for virtually any purpose.

[0061]

[0079] As used herein, the term "metal oxide" generally refers to any polymer, molecule, or solid containing a metal or metalloid cation and an oxide anion. These include, but are not limited to, transition metal oxides, rare earth metal oxides, alkali metal oxides, and alkaline earth metal oxides. The structures include, but are not limited to, binary monoxide MO, dioxide MO2, trioxide M2O3, cuprite oxide M2O, as well as , spinel-type structures MN2O4, and perovskites MNO3, including but not limited to polymetal oxides, where M and N are different metal species.

[0062]

[0080] References in this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the claimed subject matter. The appearances of the phrase "in one embodiment" in various places in this specification are not necessarily all referring to the same embodiment, nor are they necessarily separate or alternative embodiments mutually exclusive of other embodiments. The same applies to the term "implementation form".

[0063]

[0081] To the extent that terms regarding directions are used in this specification and the claims (e.g., upward, downward, upper, lower, parallel, perpendicular, etc.), these terms are merely intended to assist in describing various embodiments and are not intended to limit the claims in any way. Such terms do not require strictness (e.g., strict perpendicularity or strict parallelism), but instead, general tolerances and ranges are intended to be applied. Similarly, unless otherwise explicitly stated, each numerical value and range should be interpreted as approximate as if the words "about", "substantially", or "approximately" preceded the value or values of the range.

[0064]

[0082] Also, for the purposes of this description, the terms "couple", "coupling", "coupled", "connect", "connecting", or "connected" refer to any manner in which energy is transferred between two or more elements.

[0065]

[0083] It should be understood that the steps of the exemplary methods described herein are not necessarily required to be performed in the order described. Similarly, additional steps may be included in such methods, and certain steps may be omitted or combined in ways consistent with various embodiments.

[0066]

[0084] It should be further understood that various changes in the details, materials, and arrangements of the parts described and illustrated in order to explain the nature of the described embodiments may be made by those skilled in the art without departing from the following claims.

Claims

**Claim 1** A refractory brick latticework comprising one or more conductive refractory brick layers, each conductive refractory brick layer comprising a plurality of conductive doped metal oxide refractory bricks having one or more ventilation holes to allow an air flow through the refractory brick latticework, and the refractory brick latticework, A first electrode comprising one or more electrode refractory brick layers, each electrode refractory brick layer comprising a plurality of electrode refractory bricks, the first electrode being configured to receive power from a power source, and the first electrode, Comprising, The refractory brick latticework is heated due to the application of the received power, and air flowing through the refractory brick latticework is heated by the refractory brick latticework, a thermal energy storage system. **Claim 2** A second electrode comprising one or more electrode refractory brick layers, each electrode refractory brick layer comprising a plurality of electrode refractory bricks, further comprising the second electrode, The refractory brick latticework comprises a plurality of electrically isolated latticework portions, the first electrode comprises a plurality of electrically isolated electrode portions, The second electrode is configured to be electrically coupled to two or more of the electrically isolated latticework portions of the refractory brick latticework to form an electrical transmission path through the refractory brick latticework, the system according to claim 1. **Claim 3** Each of the plurality of electrically isolated electrode portions is configured to receive an electrical phase isolated from the power source, the system according to claim 2. **Claim 4** The second electrode is configured to provide a neutral point for power provided as three-phase power, and the thermal energy storage system operates in a Y (wye) configuration, the system according to claim 2. **Claim 5** Further comprising one or more insulating layers, the insulating layers comprising one or more insulating refractory brick layers, each insulating refractory brick layer comprising a plurality of non-conductive refractory bricks having one or more ventilation holes to allow an air flow through the refractory bricks, the system according to claim 1. **Claim 6** The system according to claim 1, wherein the conductive doped metal oxide refractory brick contains one of chromium oxide doped with nickel, chromium oxide doped with magnesium, nickel oxide doped with lithium, nickel oxide doped with copper, zinc oxide doped with aluminum, stabilized zirconium oxide doped with cerium, and titanium oxide doped with niobium.

7. The conductive doped metal oxide refractory brick is doped at a concentration of approximately 10 ２０ / cm ３ The system according to claim 6, wherein the system is doped at a concentration of approximately 10

8. The system according to claim 1, wherein the electrode refractory brick contains one of chromium oxide doped with nickel, chromium oxide doped with magnesium, nickel oxide doped with lithium, nickel oxide doped with copper, zinc oxide doped with aluminum, stabilized zirconium oxide doped with cerium, or titanium oxide doped with niobium.

9. The electrode refractory brick is highly conductive and doped at a concentration of approximately 10 ２１ / cm ３ to result in low heat generation, for the system according to claim 8.

10. The system according to claim 5, wherein the non-conductive refractory brick contains one or more of alumina, magnesia, or silica.

11. The system according to claim 1, wherein the refractory brick latticework is heated to a temperature of 1000°C to 2000°C.

12. The second electrode includes a plurality of electrically isolated second electrode portions. The system according to claim 2, wherein the plurality of electrically isolated latticework portions, the plurality of electrically isolated electrode portions, and the plurality of electrically isolated second electrode portions are configured to provide an electrical path through each electrically isolated latticework portion.

13. The number of meandering portions of each electrical path is even for the thermal energy storage system to operate in a three-phase delta configuration, and the number of meandering portions of each electrical path is odd for the thermal energy storage system to operate in a three-phase Y (wye) configuration. The system according to claim 12.

14. The system according to claim 8, wherein the dopant mixture is approximately 2% to 5%.

15. The system according to claim 1, wherein the conductive doped metal oxide refractory brick contains a high-temperature metal oxide doped with metals of different valences.

16. The system according to claim 15, wherein the conductive doped metal oxide refractory brick further contains an electrically inert oxide.

17. The system according to claim 16, wherein the electrically inert oxide contains one of alumina, magnesia, or silica.

18. The first electrode The second electrode A device comprising a conductive refractory brick and wherein the conductive refractory brick is disposed in a predetermined pattern between the first electrode and the second electrode, and each of the conductive refractory bricks comprises a doped metal oxide material configured to generate heat based on a potential applied between the first electrode and the second electrode.

19. The predetermined pattern includes a plurality of overlapping layers of the conductive refractory brick, and the conductive refractory brick is spaced apart to form an air flow path. The device according to claim 18.

20. Each of the conductive refractory bricks includes a dopant concentration corresponding to the temperature of heat to be generated based on a potential applied between the first electrode and the second electrode. The device according to claim 18. ​

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