Patent Publication Number: US-11394035-B2

Title: Refuelable battery for the electric grid and method of using thereof

Description:
RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Patent Application 62/482,639 entitled “System and Method for a Refuelable Primary Battery for the Electric Grid” filed Apr. 6, 2017, the entire contents of which are hereby incorporated by reference for all purposes. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to the field of grid battery power, and more specifically to a new and useful system and method for a refuelable battery power grid solution. 
     BACKGROUND 
     There is much interest in finding and implementing energy solutions that move towards renewable energy and having a lower environmental impact. In recent years, renewable energy sources such as solar and wind have grown in usage. In many regions, initiatives are underway to move towards fully renewable in the future. However, there are still challenges to achieving fully renewable power supply in all regions. 
     Variability in supply is one challenge. Supply can vary by geography, weather, climate, and other factors. Many forms of renewable electricity production rely on the seasons to provide stored energy. For example, snowpack in the mountains in winter provides water in the summer which is used for hydropower. Additionally, renewable energy sources are often tied to the availability of energy sources for a particular region. Wind, solar, hydro, and/or other sources have different levels of applicability and various seasonal factors depending on the region. For example, solar in regions higher in the northern hemisphere or lower in the southern hemisphere will have seasonal trends. Technical solutions for seasonal variability currently don&#39;t exist. 
     Use of secondary batteries (i.e., batteries that are charged and discharge through a reversible electrochemical reaction) as temporary storage of power have received interest as a potential solution to variability of renewable energy. An often-cited use case is that of batteries being able to store power from solar during the day, and then supplying the grid with the power at night or times of low solar power supply. However, this fails to address larger periods of unpredictability. Secondary batteries are primarily designed to meet the needs of frequent discharge and charge cycles as is typical in daily usage cycles. Research has driven second batteries to be inexpensive over many cycles, but too costly to use in low cycle applications. Furthermore, secondary batteries, despite considerable research, often rely on materials that are not sufficiently earth abundant. 
     SUMMARY 
     Systems and methods of the various embodiments may provide a refuelable battery for the electric power grid and/or other power system to provide a sustainable, cost-effective, and/or operationally efficient solution to energy source variability and/or energy demand variability. In particular, the systems and methods of the various embodiments may provide a refuelable primary battery solution that addresses bulk seasonal energy storage needs, energy demand variation, and other challenges. 
     Systems and methods of the various embodiments may be employed in combination with a primary energy source connected to the power grid or other power requiring systems. The systems and methods of the various embodiments may utilize primary battery units within a battery power supply site. In various embodiments, the primary battery units may cycle through usage with a supply system supporting a “refueling process” on-site and/or offsite. In various embodiments, at the end of discharge, a primary battery unit may be decommissioned and the spent fuel (i.e., battery chemical materials) removed and new fuel added. In various embodiments, the refueling process may include the delivery, removal, and/or exchange of primary battery units and/or material components of the primary battery units. In various embodiments, the battery material components removed/exchanged in the primary battery units may include anodes of the primary battery units and/or cathodes of the primary battery units. 
     Various embodiments may provide a refuelable battery including a battery chamber configured to trap expended electrode material generated from electrode material of the battery while the battery is operating in a discharge mode. Expended electrode material may include oxidized anode material and/or reduced cathode material generated while the battery is operating in a discharge mode. The expended electrode material may be removed and reprocessed into recharged electrode material for use in the battery according to various embodiments. Various embodiments may provide a refuelable battery including a battery chamber configured to trap anode material, such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc., generated from anode material of the battery while the battery is operating in a discharge mode. The oxidized anode material may be removed and reprocessed into recharged anode material for use in the battery according to various embodiments. Various embodiments may provide a refuelable battery including a battery chamber configured to trap cathode material, such as reduced cathode particulate, reduced cathode powder, reduced cathode shards, etc., generated from cathode material of the battery while the battery is operating in a discharge mode. The reduced cathode material may be removed and reprocessed into recharged cathode material for use in the battery according to various embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate example embodiments of the claims, and together with the general description given above and the detailed description given below, serve to explain the features of the claims. 
         FIG. 1  is a schematic representation of an embodiment system; 
         FIG. 2  is a graph of an exemplary impact of embodiment systems and methods on energy production by a solar farm; 
         FIG. 3  is a graph of an exemplary impact of embodiment systems and methods on energy production by a wind farm; 
         FIG. 4  is a process flow diagram illustrating an embodiment method for refueling and reprocessing primary battery units; 
         FIG. 5  is a process flow diagram illustrating another embodiment method for refueling primary battery units; 
         FIG. 6  is a block diagram illustrating the operation of components of an embodiment refuelable battery power grid system according to the embodiment method illustrated in  FIG. 5 ; 
         FIG. 7  is a block diagram of an embodiment refuelable battery; and 
         FIG. 8  is a block diagram of another embodiment refuelable battery. 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes and are not intended to limit the scope of the claims. The following description of the embodiments of the invention is not intended to limit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention. 
     Systems and methods of the various embodiments may provide a refuelable battery to provide a sustainable, cost-effective, and/or operationally efficient solution to matching energy supply and demand variability. In particular, the systems and methods of the various embodiments may provide a refuelable primary battery solution that addresses various challenges, including bulk seasonal energy storage needs, demand increase response needs, etc. 
     Systems and methods of the various embodiments may be employed in combination with a primary energy source connected to a power grid. The systems and methods of the various embodiments may utilize primary battery units within a battery power supply site. A primary battery unit or primary battery may be a battery unit or battery that is not recharged through an electrochemical reaction. A battery power supply site may be a site, such as a battery power plant or system, including at least one battery configured to output energy, such as to a power grid or other system. In various embodiments, the primary battery units may cycle through usage with a supply system supporting a “refueling process” which may be located on-site and/or offsite. In various embodiments, at the end of discharge, a primary battery unit may be decommissioned and the spent fuel (i.e., battery chemical materials, such as anode materials, cathode materials, etc.) removed and new fuel added. In various embodiments, the refueling process may include the delivery, removal, and/or exchange of primary battery units and/or material components of the primary battery units. In various embodiments, the refueling process may include physical replacement of electrode materials (e.g., anode materials, cathode materials, etc.) within the primary battery units. For example, a primary battery unit may be refueled by inserting a new anode and/or a new cathode into the primary battery unit. 
       FIG. 1  illustrates a refuelable battery power grid system  100  according to various embodiments. In the refuelable battery power grid system  100 , a refuelable battery power plant (or system)  101  may be set up on-site at a renewable energy source  103  (e.g., a wind farm, hydroelectric dam, solar farm, etc.). The refuelable battery power grid system  100  may include a battery power plant  101  that includes a plurality of connected battery units  110 , such as primary battery units. The battery power plant  101  may additionally include various systems configured to manage the operation and refueling of the battery power plant  101 , such as an electrical system  120 , thermal management system  121 , and control system  122 . The thermal management system  121  may include temperature sensing and regulating components. The electrical system  120  may include various components such as an inverter. In one variation, the inverter may be a unilateral power inverter. The control system  122  may manage operation of the set of primary battery units  110 . The control system  122  may additionally include a data interface to a primary power system or an associated data source. The control system  122  may facilitate selection of primary battery units  110 , activation of primary battery units  110 , and/or other operations. In one mode of operation, the control system  122  may utilize the primary battery units  110  in a manner at least partially coordinated with refueling capacity. 
     The refuelable battery power grid system  100  may function as an on-site installation that interfaces with a consumer of the energy. The consumer of the energy may preferably be a connected power grid  102 , but may alternatively be any suitable system such as building, factory, or other suitable energy powered system. The battery power plant  101  may be installed onsite with a renewable energy source  103 , such as a wind farm, a hydroelectric plant, a solar farm, or any suitable energy production site. The renewable energy source  103  may connect to the grid  102  directly via a primary power connection  105 . The battery power plant  101  may connect to the grid  102  via a supplementary power connection  112  that connects to the grid  102  through the renewable energy source  103 . In this manner, power supplied to the grid  102  from the battery power plant  101  via the supplementary power connection  112  may appear to the grid  102  as if received from the renewable energy source  103 . 
     The battery power plant  101  may be setup with stationary equipment to support the operation of the refuelable battery power grid system  100 . Transportation access may be positioned near the battery power plant  101  to facilitate convenient refueling. Refueling of primary battery units  110  may be handled using typically available machinery and tools. A full-scale solution may then reprocess the battery materials of the primary battery units  110  at a second site, such as reprocessing site  104 . In some cases, this reprocessing site  104  may be located in a location with an alternative power source (such as an alternative power source using renewable energy generated by renewable energy source  103  (or another renewable energy source) during periods when renewable energy is abundant). In other cases, the reprocessing site  104  may be in connection with the power grid  102 . In various embodiments, reprocessing of the primary battery units  110  may occur during seasonal periods that result in excess renewable energy generated by renewable energy source  103  (or another renewable energy source). 
     In one variation, the battery power plant  101  may include docking stations for the primary battery units  110 . There will preferably be a large number of primary battery units  110  that will be installed to supplement power production over long seasonal periods. The number of docking stations may include enough docking stations to house active primary battery units  110 , depleted primary battery units  110  awaiting refueling/removal, and reserve primary battery units  110 . When a primary battery unit  110  is depleted it will need to be refueled, and as such, there are preferably sufficient docking stations so that the power supply target may be satisfied while primary battery units  110  are being refueled before the active primary battery units  110  are depleted. 
     The battery power plant  101  may include an array of docking stations. In one variation, the docking stations may allow stacking of primary battery units  110 . In some variations, the battery power plant  101  may include lifts and/or conveyors to facilitate installing/instantiating and/or removal of primary battery power units. 
     The primary battery unit  110  functions as the source of power. The primary battery unit  110  includes primary battery elements that may use any suitable chemistry such as Al, AlCl 3 , Fe, FeO x (OH) y , Na x S y , SiO x (OH) y , AlO x (OH) y , and/or any suitable type of primary battery chemistry. Similarly, the primary battery unit  110  may use a solid material, such as a sheet, foil, rod, or disc for the primary battery active material. In certain other embodiments, the primary battery unit  110  may use a powdery form, such as a particulate, for the primary battery active material. In certain other embodiments, the primary battery unit  110  may use a slurry such as a colloid, suspension, or dispersion suitable material state for the primary battery active material. 
     The primary battery units  110  may additionally include an activator mechanism wherein, the materials of the primary battery unit  110  can be kept separated or otherwise inactive until it nears the time for use of the primary battery unit  110 . This may function to better hold energy during storage by mitigating self-discharge reactions which occur when the primary battery active material is in contact with the electrolyte. 
     The primary battery unit  110  may be composed of multiple cells. Individual battery cells maybe any suitable form factor. Additionally, a primary battery unit  110  itself may be composed of sub-units. For example, a primary battery unit  110  may be a container that can contain a number of sub-units, which may be exchangeable by human workers or machines. In part because of the amount of energy the refuelable battery power grid system  100  is expected to deliver, the primary battery units  110  may have a large form factor (e.g., several hundred or thousand pounds). 
     The primary battery units  110  may use materials that are earth abundant, non-toxic, recyclable/reusable, and cost effective. In various embodiments, the primary battery units  110  may be processed and/or reprocessed at scale at dedicated sites, such as reprocessing site  104 . Primary battery units  110  and/or the refueling material used in the primary battery units  110  may be transported onsite for use with refuelable battery power grid system  100 . 
     In some refueling options, the primary battery units  110  may be exchanged as a form of refueling the energy supply. In some implementations, the primary battery unit  110  may include a housing that conforms to a form factor compatible with shipping containers, which may make the primary battery unit  110  easily transported using standard industrial equipment such as forklifts, cranes, conveyors, and also loaded onto trucks or onto trains. 
     In an alternative refueling option, the primary battery units  110  may have depleted material removed and processed material added. Depleted (i.e., expended) electrode materials may be removed and processed (i.e., new or recharged) electrode material may be added. For example, an anode material of the primary battery unit  110  may oxidize during discharge into oxidized anode material, such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc., that may be removed, reprocessed at the reprocessing site  104  into a new anode material, and the new reprocessed anode material may be inserted into the primary battery unit  110  to thereby refuel the primary battery unit  110 . As another example, a cathode material of the primary battery unit  110  may reduce during discharge into reduced cathode material, such as reduced cathode particulate, reduced cathode powder, reduced cathode shards, etc., that may be removed, reprocessed at the reprocessing site  104  into a new cathode material, and the new reprocessed cathode material may be inserted into the primary battery unit  110  to thereby refuel the primary battery unit  110 . The primary battery unit  110  may include a material refueling supply system that may manage or facilitate removal and deposit of materials to renew the stored energy of the primary battery units. For example, the primary battery unit  110  may include pumps and/or circulation systems to facilitate removal and deposit of materials. Additionally, the primary battery unit  110  may include access ports to enable material to be placed into the primary battery unit  110 , such as refueled electrode material (e.g., refueled anode and/or cathode material) to be placed on one or more electrode supports (e.g., one or more anode and/or cathode supports) in the primary battery unit  110 . The primary battery unit  110  may include access ports to enable material to be removed from the primary battery unit  110 , such as expended electrode material (e.g., oxidized anode material such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc. and/or reduced cathode material such as reduced cathode particulate, reduced cathode powder, reduced cathode shards etc.) generated while the primary battery unit  110  is operating in a discharge mode. Further, the primary battery unit  110  may include valves and other partitions operable to fluidically isolate portions of the primary battery unit  110  from one another to support insertion or removal of material from the primary battery unit  110 . For example, a filter area trapping oxidized anode material may be fluidically isolated from the rest of the primary battery unit  110  to enable the electrolyte to be drained from the filter area and the oxidized anode material to be removed to be reprocessed into new anode material at the reprocessing site  104 . Similarly, a filter area may trap reduced cathode material and may be fluidically isolated from the rest of the primary battery unit  110  to enable the electrolyte to be drained from the filter area and the reduced cathode material to be removed to be reprocessed into new cathode material at the reprocessing site  104 . As another example, valves and pumps may enable the electrolyte level of the primary battery unit  110  to be raised and/or lowered. 
     The primary battery unit  110  may include integrated unit control systems, power management, thermal systems, data connections, and/or other features. The primary battery unit  110  may additionally include a power and control interface such that it can be installed and removed from a docking station. The power and control interface may be configured to automatically connect when inserted into the docking station. Alternatively, the primary battery unit  110  may be manually connected to the battery power plant  101 . 
     In some variations, the refuelable battery power grid system  100  may include a mixture of battery power sources, which can include batteries with different chemistries. In some variations, secondary batteries may be integrated into the refuelable battery power grid system  100  to provide temporary storage of excess storage alongside bulk energy storage of the primary battery units  110 . For example, the refuelable battery power grid system  100  may include electrochemically rechargeable lithium-ion batteries along with the primary battery units  110 . 
     The reprocessing site  104  may be a refueling system that functions to facilitate the restocking of energized primary battery units  110  after they are depleted. For example, the reprocessing site  104  may restock/reenergize the electrode materials after they are expended/depleted. As a specific example, when the primary battery units utilize iron based anodes that need restocking/reenergizing, oxidized anode material from the primary battery units  110  may be reprocessed into new anode material by reduction (e.g., direct reduction iron (DRI) processing, hot briquetted iron (HBI) processing, etc.), smelting, electrolysis, or any other reprocessing operation (e.g., any metallurgical process that generates new anode material) at the reprocessing site  104 . 
     In a first variation, the primary battery units  110  may be reprocessed. Such reprocessing may include the removal of the primary battery unit  110  from the battery power plant  101 , transport to the reprocessing site  104 , where reusable components and materials may be extracted and reprocessed into an energized primary battery unit  110 . In some cases, non-reusable materials and components may be recycled, disposed of, and/or replaced. In an implementation, reprocessing may be performed at a site with a source of renewable energy. Reprocessing may alternatively happen at the same site as the battery power plant  101  and in some cases may be performed during the season when there is excess renewable energy generated by renewable energy source  103 . 
     In another variation, the primary battery units  110  have a chemical makeup where material may be extracted and replaced to energize the primary battery unit  110 . For example, expended electrode material may be collected and removed for reprocessing. As a specific example, as anode material of a primary battery unit  110  is oxidized it may be collected and removed for reprocessing. The reprocessing at the reprocessing site  104  may generate new anode material that may then be inserted into the primary battery unit  110  to refuel the primary battery unit  110 . Thus, the entire primary battery unit  110  may not be removed for reprocessing, and only a portion of the materials within the primary battery unit  110  may be removed for reprocessing. The refuelable battery power grid system  100  and battery power plant  101  may incorporate mechanisms to support the efficient material removal and material depositing in depleted primary battery units  110 . For example, the primary battery unit  110  may include pumps and/or circulation systems to facilitate removal and deposit of materials. Additionally, the primary battery unit  110  may include access ports to enable material to be placed into the primary battery unit  110 , such as refueled anode and/or cathode material to be placed on one or more anode and/or cathode supports in the primary battery unit  110 . The primary battery unit  110  may include access ports to enable material to be removed from the primary battery unit  110 , such as expended electrode material (e.g., oxidized anode material such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc. and/or reduced cathode material such as reduced cathode particulate, reduced cathode powder, reduced cathode shards etc.) generated while the primary battery unit  110  is operating in a discharge mode. Further, the primary battery unit  110  may include valves and other partitions operable to fluidically isolate portions of the primary battery unit  110  from one another to support insertion or removal of material from the primary battery unit  110 . For example, a filter area trapping oxidized anode material may be fluidically isolated from the rest of the primary battery unit  110  to enable the electrolyte to be drained from the filter area and the oxidized anode material to be removed to be reprocessed into new anode material at the reprocessing site  104 . Similarly, a filter area may trap reduced cathode material and may be fluidically isolated from the rest of the primary battery unit  110  to enable the electrolyte to be drained from the filter area and the reduced cathode material to be removed to be reprocessed into new cathode material at the reprocessing site  104 . As another example, valves and pumps may enable the electrolyte level of the primary battery unit  110  to be raised and/or lowered. 
     As one potential benefit, the refuelable battery power grid system  100  may offer energy at scale during periods of seasonally low renewable power availability. The battery power plant  101  may be customized to account for long seasonal patterns in use. Related to the use as a seasonal power supply, the battery power plant  101  may offer long-term battery energy storage that enables power management responsive to seasonal usage patterns. The battery power plant  101  may additionally or alternatively be used with non-seasonal variables. 
     As another potential benefit, the battery power plant  101  may mitigate reliance on conventional sources of electricity generation. Seasonal declines in renewable energy supplies generated by the renewable energy source  103  may be offset by the battery power plant  101 . The battery power plant  101  may be used for a sustained period during low or no renewable energy supply. For example, solar power from the renewable energy source  103  may be used primarily during the summer to provide power to the grid  102 , and the battery power plant  101  may be primarily used during winter months to provide power to the grid  102 . 
     As a related potential benefit, the battery power plant  101  may effectively increase the renewable energy production ratings of the renewable power source  103 . Without a bulk energy storage solution, a renewable power source  103  may be granted a power rating based on expected power and coverage capabilities. Seasonal declines and/or unpredictability of the renewable power source  103  conventionally result in lower ratings meaning renewable energy sources are relied upon less. However, the battery power plant  101  may normalize the power ratings of the renewable energy source  103  such that the renewable energy source  103  may operate with power ratings closer to peak power capabilities. 
     As another potential benefit, the battery power plant  101  may use a modular design, which may function to enable the battery power plant  101  to scale for different use-cases. 
     As yet another potential benefit, the battery power plant  101  may function to transform renewable energy into a material good in the form of primary battery units  110  that may be shipped and transported. 
     Herein, the various embodiments are primarily discussed as they may be applied in combination with renewable energy. In solar energy production, the battery power plants of the various embodiments, such as battery power plant  101 , may be used in supplementing solar energy production during the winter months.  FIG. 2  is a graph of power output over time of an embodiment system including a battery power plant, such as battery power plant  101 , connected to a renewable energy source, such as renewable energy source  103 , wherein the renewable energy source is a solar farm. As shown in  FIG. 2 , the actual solar farm power production indicated by the dashed line may vary seasonally over the course of a year, but the supplemental power provided by the battery power plant during the lower solar power production times may enable the total power output of the embodiment system to remain constant over the course of the year as indicated by the solid line. Hydroelectric power systems that rely on the melting of snowcaps may have similar seasonal patterns to solar systems, and the battery power plants may similarly supplement hydroelectric power systems to offset season patterns. 
     In wind energy production, the various embodiment battery power plants, such as battery power plant  101 , may be used on demand to account for seasonal and short-term variability in wind energy production.  FIG. 3  is a graph of power output over time of an embodiment system including a battery power plant, such as battery power plant  101 , connected to a renewable energy source, such as renewable energy source  103 , wherein the renewable energy source is a wind farm. As shown in  FIG. 3 , the actual wind farm power production indicated by the dashed line may vary seasonally and due to short-term wind changes over the course of a year, but the supplemental power provided by the battery power plant during the lower wind power production times may enable the total power output of the embodiment system to remain constant over the course of the year as indicated by the solid line. 
     The various embodiments may also be applied to other type renewable and/or conventional power sources. For example, the battery power plants of the various embodiments, such as battery power plant  101 , may facilitate transitions between energy sources as a region decommissions a power plant and/or onboards a new power plant. The battery power plants of the various embodiments, such as battery power plant  101 , may similarly be used off-grid as a secondary power option for a site or even as the primary power option. 
       FIG. 4  is a process flow diagram illustrating an embodiment method  400  for operating a refuelable battery power system and specifically for refueling and reprocessing primary batteries. The operations of method  400  may be performed using one or more components of the embodiment refuelable battery power systems described herein, such as refuelable battery power grid system  100 . The method  400  may include instantiating a set of refuelable battery units at a site in step  402 , monitoring a state of at least one power system, such as at least one grid system, and cycling use of primary battery units in step  404 , refueling the primary battery units in step  406 , and reprocessing the primary battery units in step  407 . 
     Step  402 , which may include instantiating a set of refuelable battery units at a site, functions to setup a number of primary battery power sources for long-term storage to supply energy at a site. Instantiating the refuelable battery units may include delivering the set of refuelable battery units and installing them in a battery power plant that interfaces with a grid or other power consuming/delivery system. 
     Step  404 , which includes monitoring a state of at least one power system, such as at least one grid system, and cycling use of primary battery units, functions to manage the set of primary battery units so as to supplement another power supply. The primary battery units may be reserved to supplement a renewable power source over a long duration such as over one or more weeks, one or more months, a year, or multiple years. The primary battery units may be activated and used until depleted. When they are depleted or nearing end of their useful life, the primary battery units may be identified as needing “refueling”. During the next refueling process the primary battery units in need of refueling may be removed or otherwise refueled. 
     Step  406 , which includes refueling the primary batteries, functions to reprocess and/or replace the primary batteries used in the primary battery units. In a first variation, the battery components of primary battery units can be reprocessed in step  407 . Material reprocessing can involve transport to a reprocessing site, reprocessing, transporting back to the site of the battery power plant, and reinstalling into the battery power plant in step  402 . In some variations, the offsite location is in a region that has more access to renewable energy during the refueling periods. In this way renewable energy can be applied in the manufacturing processing of the battery fuel. 
     In another variation, the battery components of the primary battery units can be exchanged with new materials. Thus, the primary battery units themselves may only be installed once, but the materials within the primary battery units may be removed, reprocessed, and replaced to refuel the primary battery units. The primary battery units can be kept in place with battery materials exchanged. Such reprocessing operations may be particularly feasible with the seasonal patterns of renewable energy. For example, a battery power plant, such as battery power plant  101 , may be used primarily in winter months and then refueled during over the summer months in time for winter. 
       FIG. 5  is a process flow diagram illustrating an embodiment method  500  for refueling materials within primary battery units, such as primary units  110  of refuelable battery power grid system  100 . The operations of method  500  may be performed using one or more components of the embodiment refuelable battery power grid systems described herein, such as refuelable battery power grid system  100 . In various embodiments, the operations of method  500  may be performed in conjunction with one or more of the operations of method  400  ( FIG. 4 ). 
     In step  502 , the battery power plant, such as battery power plant  101 , may be operated to discharge power. To discharge power one or more primary battery units, such as one or more primary battery units  110 , of the battery power plant, such as battery power plant  101 , may be operated in a discharge mode. For example, the primary battery units  110  may be operated in a discharge mode to generate and provide supplemental power to the grid  102  to offset drops in power generation by renewable energy source  103 . The primary battery units  110  may be operated in the discharge mode to generate and provide supplemental power to the grid  102  and renewable energy source  103  over a long duration such as over one or more weeks, one or more months, a year, and/or multiple years. The discharge of power from the battery power plant, such as battery power plant  101  may occur for a timeframe that is seasonal, such as for a timeframe of one or more weeks, months, seasons, and/or years. Such seasonal timeframe discharges from the battery power plant, such as battery power plant  101 , may be longer in duration than hourly or daily discharges and may offset seasonal reductions in the ability of renewable energy sources, such as renewable energy source  103 , to generate power. 
     In step  504 , the spent fuel from the primary battery units, such as primary battery units  110 , may be collected and removed. In various embodiments, as the primary battery units  110  are operated in a discharge mode to generate power, anode material (i.e., charged fuel) of the primary battery unit  110  may oxidize and the oxidized anode material (i.e., the spent fuel) may be collected and removed for reprocessing. In a similar manner, in various embodiments, as the primary battery units  110  are operated in a discharge mode to generate power, cathode material (i.e., charged fuel) of the primary battery unit  110  may be reduced and the reduced cathode material (i.e., the spent fuel) may be collected and removed for reprocessing. In some embodiments, the charged fuel may oxidize in place and the fuel material may be removed directly from its support within the primary battery unit  110 . For example, in an electrolyte solution with a pH greater than 6, an iron anode may oxidize in place to form an oxidized anode material, such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc., of Fe(OH) 2 , Fe(OH) 3 , Fe 2 O 3 , Fe 3 O 4 , FeOOH, or combinations thereof. In some embodiments, the charged fuel may oxidize and circulate into the electrolyte where it may be filtered out for removal. For example, in a high pH electrolyte solution (e.g., with a pH greater than 6) an iron anode may form an oxidized anode material, such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc., of Fe(OH) 2 , Fe(OH) 3 ,Fe 2 O 3 , Fe 3 O 4 , FeOOH, or combinations thereof in the electrolyte and the electrolyte may be filtered (such as in a filter area) to trap and remove the oxidized anode material. In some embodiments, the filter area may include a foam, such as a seeded foam, to trap the oxidized anode material as the electrolyte circulates through the filter area. The foam may be seeded with a metal hydroxide (OH), such as calcium hydroxide (CaOH). In some embodiments, the filter area may be a bag or other type container, removable from the primary battery unit  110  in which oxidized anode material, such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc., may be collected. In various embodiments in which cathode material is to be removed, a filter area may trap and remove reduced cathode material in similar manners as discussed above. In various embodiments, electrolyte levels in the primary battery units  110  may be raised and/or lowered to facilitate collection and removal of spent fuel. As examples, pumps, valves, and other partitions of the primary battery units  110  may be used to fluidically isolate portions of the primary battery units  110  to enable the electrolyte levels in the primary battery units  110  to be raised and/or lowered to facilitate collection and removal of spent fuel. 
     In step  506 , the spent fuel may be reprocessed into charged fuel. For example, the spent fuel may be reprocessed into charged fuel at the reprocessing site  104 . In embodiments in which the primary battery units  110  may utilize iron based anodes that need restocking/reenergizing, oxidized anode material (i.e., spent fuel) from the primary battery units  110  may be reprocessed into new anode material (i.e., charged fuel) by reduction (e.g., DRI processing, HBI processing, etc.), smelting, electrolysis, or any other reprocessing operation (e.g., any metallurgical process that restocks/reenergizes anode material). In some embodiments, additives may be added to the spent fuel during reprocessing. For example, carbon (e.g., graphite) may be added to the spent fuel during reprocessing. This additional carbon may help with reduction of the spent fuel into charged fuel. Alternatively, carbon (e.g., graphite) may be added to the anode during the anode manufacturing. This additional carbon may increase conductivity of the anode during the battery operation and help with reduction of the spent fuel (i.e., oxidized anode material) into charged fuel during the reduction process via a carbothermal reduction process at the reprocessing site  104 . In some embodiments, the reprocessing may include carbon based thermal reduction using natural gas or coal burning furnaces which may add carbon to the charged fuel. In some embodiments, the spent fuel reprocessing of step  506  may include reprocessing spent cathode material into recharged cathode material. 
     In some embodiments, the energy used for reprocessing the spent fuel into charged fuel may come from renewable energy sources, such as renewable energy source  103  or another renewable energy source. For example, when reprocessing site  104  and renewable energy source  103  are co-located, the renewable energy source  103  may provide the power for the reprocessing operations of reprocessing site  104 , such as when the renewable energy source  103  has excess power available (e.g., during summer months for solar farms, high wind periods for wind farms, spring thaws for hydroelectric dams, etc.). In this manner, during seasonal periods of high renewable energy output, a portion of the excess renewable energy may be used for fuel reprocessing. 
     In step  508 , the charged fuel may be inserted into the battery power plant. For example, new anode material formed from reprocessing the spent fuel into charged fuel in step  506  may be placed onto anode supports of the primary battery units  110  in step  508  to thereby refuel the primary battery units  110 . As another example, new cathode material formed from reprocessing the spent fuel into charged fuel in step  506  may be placed onto cathode supports of the primary battery units  110  in step  508  to thereby refuel the primary battery units  110 . The charged fuel (e.g., a Fe anode, etc.) may be placed into a battery chamber of the primary battery unit through an opening in the battery chamber (e.g., an access port) and onto a support, such as an anode support, cathode support, etc. With the new charged anode and/or cathode the primary battery unit  110  may be refueled and the method may proceed to step  502  to operate the primary battery unit  110  in discharge mode as needed. 
     In various embodiments, the primary battery units, such as primary battery units  110 , may be air-breathing batteries and the refueling of the primary battery units in step  504  may include collection and removal of anode material and the charged fuel inserted in step  508  may be new anode material. In various embodiments, the refueling of the primary battery units in step  504  may include collection and removal of cathode material and the charged fuel inserted in step  508  may be new cathode material. In some embodiments, the primary battery units, such as primary battery units  110 , may be non-air-breathing batteries having two different materials used as electrodes, such as one metal oxide, such as an ore or mineral, for the cathode and one metal for the anode. One of the electrodes may be recharge/renewed after discharge and the other electrode may be removed and sold or otherwise consumed as an electrorefined metal. That removed and sold or otherwise consumed electrode may be partially or entirely replaced with a new electrode. For example, one metal may be in the oxidized state and the other metal in the reduced state (e.g., Fe 2 O 3  and Al). The primary battery unit may be operated in a discharge mode and one of the two metals of the cathode and/or anode may be processed into an electrorefined metal during discharge that may have value. For example, the couple including Fe 2 O 3  and Al would produce iron (Fe) metal and aluminum oxide (Al 2 O 3 ). The electrorefined metal may be removed from the primary battery unit and sold or otherwise consumed. That electrode that resulted in the electrorefined metal (e.g., the original cathode or original anode) may be replaced with an entirely new electrode. The other metal may reduce or oxidize into an expended electrode material (e.g., reduced cathode material or oxidized anode material). The expended electrode material (e.g., reduced cathode material or oxidized anode material) may be processed into a recharge electrode material (e.g., recharge cathode material or recharge anode material) and replaced back into the battery to refuel the primary battery unit. In this manner, while both electrodes may be replaced, only one of the two electrodes may be processed into new fuel for the primary battery unit. 
       FIG. 6  is a block diagram illustrating the operation of components of an embodiment refuelable battery power grid system, such as refuelable battery power grid system  100 , operated according to the embodiment method  500  illustrated in  FIG. 5 .  FIG. 6  illustrates a single battery unit  110 , such as primary or secondary battery unit. For example, the primary battery unit  110  may be an iron-air (Fe-air) battery that is mechanically refuelable. Alternatively, the primary battery unit  110  may be a battery with an anode including iron (Fe), zinc (Zn), magnesium (Mg), aluminum (Al), or an alloy formed substantially of one or more of iron, zinc, magnesium and/or aluminum. The primary battery unit  110  may be a battery with an anode including iron (Fe) or an iron alloy. The primary battery unit  110  may be a battery with an anode including zinc (Zn) or a zinc alloy. The primary battery unit  110  may be a battery with an anode including magnesium (Mg) or a magnesium alloy. The primary battery unit  110  may be a battery with an anode including aluminum (Al) or an aluminum alloy. The primary battery unit  110  may be a non-air-breathing battery. The primary battery unit  110  may include a battery chamber  600  supporting the anode  602  and at least one cathode  603  in an electrolyte  601 . The anode  602  may be an anode material disposed on an anode support, such as a bed, mesh, foil, or other scaffold, within the battery chamber  600 . The anode  602  may include iron(Fe), zinc (Zn), magnesium (Mg), aluminum (Al), and/or an alloy formed substantially of one or more of iron, zinc, magnesium and/or aluminum. In certain embodiments, the anode  602  may be a monolithic anode, including only a single phase of matter. For example, the anode  602  may be a block, plate, sheet, or foil of metal and the anode  602  may be dense or porous. In certain embodiments it may be advantageous for the anode  602  to be porous to allow liquid electrolyte to infiltrate the anode  602  to increase the surface area of contact between the metal anode  602  and liquid electrolyte  601  and to promote rapid ion transport through the anode  602 . In certain other embodiments, it may be advantageous to have a dense metal electrode to minimize the volume of the anode  602 . In certain other embodiments, the anode  602  may be comprised of multiple phases of matter, such as a metal powder and an inert (i.e. non-reactive) material such as carbon or a polymeric binder. The addition of an inert material may improve the electrochemical and/or mechanical properties of the anode  602 . For example, the anode material in the anode  602  may be powdered Fe and a binder material, wherein the binder is added to improve the mechanical integrity of the electrode. In certain other embodiments, the anode material in the anode  602  may be powdered Fe and a carbon material, wherein the carbon is added to improve the electrical conductivity of the electrode. In certain other embodiments, the anode material in the anode  602  may be powdered Fe, a binder material, and carbon, where the anode  602  enjoys the benefits of both improved mechanical integrity from the binder and improved electrical conductivity from the carbon. 
     The cathode  603  may be a gas diffusion electrode to enable reactions which have a combination of liquid and gaseous reactants and products. The cathode  603  may be formed from a porous support material (alternatively called a scaffold or substrate) which may be optionally decorated with a catalyst to improve the interfacial reaction kinetics. The cathode  603  may be formed from various materials, such as carbon (C), nickel (Ni), or titanium (Ti), or nickel-iron alloys (NiFe). The cathode  603  may be optionally decorated with a catalyst known to promote the desired discharge reaction. 
     The primary battery unit  110  may receive air into the battery chamber  600  via one or more air inlets in the battery chamber  600 . The air inlets may act as oxygen inlets providing air including oxygen (O 2 ) into the battery chamber  600 . In some embodiments, the primary battery unit  110  may receive oxygen (O 2 ) into the battery chamber  600  via one or more oxygen inlets in the battery chamber  600 . 
     The electrolyte  601  may be an alkaline solution comprised of water as a solvent and one or more dissolved hydroxides, such as lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), or ammonium hydroxide (NH 4 OH). The electrolyte  601  may optionally contain additives to promote or inhibit certain desired or undesirable reactions. For example, the electrolyte  601  may contain hydrogen evolution reaction inhibitor (e.g., Sn(OH) 6   2- ) and/or a Fe activator (such as a sulfide salt such as bismuth sulfide (Bi 2 S 3 ) or sodium sulfide (Na 2 S)). In a discharging mode, the primary battery unit  110  may generate power and an oxygen reduction reaction (ORR) may occur on the cathode  603 . In various embodiments, the primary battery unit  110  is not configured to operate in a charging mode (or recharging mode). 
     As discussed above, in step  502  of method  500  the battery unit  110  may be operated in a discharge mode to generate power output to the grid  102  or any other system or device receiving power. In the discharge mode, the anode  602  may oxidize and oxidized anode material  604 , such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc., may be generated in the battery chamber  600 . While illustrated as having the oxidized anode material  604  falling through the electrolyte  601 , the anode  602  may oxidize in place. The oxidized anode material  604  may include Fe(OH) 2 , Fe(OH) 3 ,Fe 2 O 3 , Fe 3 O 4 , FeOOH, or combinations thereof when the electrolyte has a pH of greater than 6. 
     As discussed above, in step  504 , the oxidized anode material  604  may be collected and removed from the battery chamber  600 . Filters, pumps, valves, and access ports may be used in various embodiments to collect and remove the oxidized anode material  604 . As discussed above, in step  506 , the oxidized anode material  604  may be reprocessed into charged fuel (i.e., anode material  602 ). The metallurgical processing applied to the oxidized anode material  604  may reconstitute the anode  602  which may be replaced in the battery unit  110  in step  508  as discussed above. 
     While  FIG. 6  is illustrated and discussed in relation to oxidized anode material  604 , such as oxidized anode particulate, oxidized anode powder, oxidized anode shards, etc., being collected and removed, being reprocessed into charged fuel, and being replaced in the battery unit  110 , the discussion of oxidized anode material  604  is merely for illustration purposes. Reduced cathode material may be substituted in the various examples for the oxidized anode material  604  and reduced cathode material may be collected and removed, reprocessed into charged fuel, and replaced in the battery unit  110  in a similar manner as discussed above. 
       FIG. 7  illustrates an embodiment configuration of refuelable battery that may be used as a primary battery unit  110  in various embodiments. The refuelable battery illustrated in  FIG. 7  may operate in a similar manner to the refuelable battery discussed above with reference to  FIG. 6 . The refuelable battery illustrated in  FIG. 7  may be a Fe-air type battery including a battery chamber  700  supporting an anode  701  of powdered Fe and a binder. Additionally, the anode  701  may include a concentration of carbon (C), such as at a volume per volume percent (v/v%) concentration of 2 v/v%, which may be added before, during, or after reduction of the anode  701  and which may aid in reduction and increase conductivity of the anode  701 . The anode  701  may be a packed bed of Fe powder and the binder. As an example, the anode  701  may have previously been reprocessed under hydrogen (H 2 ) at  800  degrees Celsius using DRI processing. A porous separator  702  may support the electrolyte, such as potassium and/or sodium hydroxide (e.g., (K/Na(OH)). The outer wall of the battery chamber  700  may be formed of a porous gas diffusion electrode  703  that may operate as a cathode. The gas diffusion electrode  703  may operate as an air inlet, such as an oxygen inlet, to provide air, such as air including oxygen, oxygen, etc., into the battery chamber  700 . A carbon dioxide (CO 2 ) scrubber  704  may be coupled to the air inlet, such as the oxygen inlet, to remove CO 2  from air provided to the battery chamber  700 . The CO 2  scrubber  704  may be any type CO 2  scrubber, such as a selective membrane or other CO 2  removing device. In certain other embodiments, the CO 2  scrubber  704  may be a reactive pebble bed loaded with powdered NaOH which reacts with CO 2  to form Na 2 CO 3 . The CO 2  scrubber  702  may be either regenerable or not. The anode  701  may be removable and replaceable to refuel the primary battery unit  110 . The refuelable battery illustrated in  FIG. 7  may be expected to achieve a 1.1 kWHr/kg Fe based on a geometry of 10 mA/cm 2  and expected polarization behaviors. Additionally, the porous gas diffusion electrode  703  may be removable and replaceable to refuel the primary battery unit  110 . 
       FIG. 8  is a block diagram of another embodiment refuelable battery that may be used as a primary battery unit  110  in various embodiments. The refuelable battery illustrated in  FIG. 8  may operate in a similar manner to the refuelable batteries discussed above with reference to  FIGS. 6 and 7 . Refuelable battery illustrated in  FIG. 8  may include a recirculation system  801  and a filter area  802  as part of the battery chamber  600 . The recirculation system  801  may be configured to circulate electrolyte  601  past the anode  602  and cathode  603  and through the filter area  802 . For example, the recirculation system  801  may include a circulation pump  806  configured to circulate electrolyte through the filter area  802  and the rest of the battery chamber  600 . As discussed above, the anode  602  may be an iron or iron alloy anode. The anode  602  may include iron, zinc, aluminum, and/or magnesium. The anode  602  may be a zinc (Zn), magnesium (Mg), or aluminum (Al), anode. 
     The anode  602  may include iron (Fe), zinc (Zn), magnesium (Mg), aluminum (Al), and/or an alloy formed substantially of one or more of iron, zinc, magnesium and/or aluminum. The anode  602  may include iron (Fe) or an iron alloy. The anode  602  may include zinc (Zn) or a zinc alloy. The anode  602  may include magnesium (Mg) or a magnesium alloy. The anode  602  may include aluminum (Al) or an aluminum alloy. As discussed above, the anode  602  may oxidize to form solid phase reaction products which may be dispersed or suspended in the electrolyte  601 . The electrolyte  601  passes through the recirculation system  801  to the filter area  802  and the oxidized anode material  604  is filtered out of the electrolyte  601  and trapped in the filter area  802 . The filter area  802  may include a filter element, such as a foam, to act as a trap for the oxidized anode material  604 . The foam may be seeded, such as with a metal hydroxide (e.g., calcium hydroxide (CaOH), etc.) to facilitate trapping of the oxidized anode material  604 . The electrolyte  601  may have a high pH value, such as greater than 6. The filter area  802  may be a compartment, such as a bag, box, trap, or other type compartment that may be fluidically separated from the battery chamber  600  by closing a valve  805 . The filter area  802  may then be drained of electrolyte  601 . The oxidized anode material  604  may be removed for reprocessing by opening access port  803  providing access to the filter area  802 . Once the oxidized anode material  604  is removed, the access port  803  may be closed, the valve  805  may be opened, and electrolyte  601  may once again be filtered through the filter area  802  to trap oxidized anode material  604 . Another access port  807  may facilitate the insertion of a recharged anode  602  into the battery chamber  600 . The access port  807  may be configured to allow charged anode material (e.g., solid Fe) to be placed on an anode support  808  of the battery chamber  600  that suspends the anode  602  in the battery chamber  600 . The refuelable battery illustrated in  FIG. 8  may achieve a 1.3 kWhr/kg Fe for 3e −  discharge at 1.0V. The refuelable battery illustrated in  FIG. 8  may have a high impurity tolerance. 
     While  FIG. 8  is illustrated and discussed in relation to oxidized anode material  604  being trapped in the filter area  802 , being reprocessed into charged fuel, and being replaced in the battery chamber  600 , the discussion of oxidized anode material  604  is merely for illustration purposes. Reduced cathode material may be substituted in the various examples for the oxidized anode material  604  and reduced cathode material may be trapped in the filter area  802 , reprocessed into charged fuel, and replaced in the battery chamber  600  in a similar manner as discussed above. For example, the access port  807  may be configured to allow charged cathode material to be placed on a cathode support  810  of the battery chamber  600  that suspends the cathode  603  in the battery chamber  600 . 
     The foregoing method descriptions are provided merely as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the order of steps in the foregoing embodiments may be performed in any order. Words such as “thereafter,” “then,” “next,” etc. are not necessarily intended to limit the order of the steps; these words may be used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an” or “the” is not to be construed as limiting the element to the singular. 
     Further, any step of any embodiment described herein can be used in any other embodiment. The preceding description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.