question: How exactly is current stored in power plants?
comment: It's not being stored at all in the powerplants. The power grid is a carefully balanced dance of supply and demand. Supply exceeding demand: A waste. Demand exceeding supply: Blackouts. When discussing "reserve", it means what additional generation capacity that can be quickly brought online to handle additional demand. When you're talking about the power grid, there's systems like nuclear or coal that provide the "base load". A coal or nuclear plant can't easily be throttled up or down to handle fast peaks, but something like a combined cycle gas turbine can. & #x200B;
passages: From the generating station it goes to the generating station's switchyard where a step-up transformer increases the voltage to a level suitable for transmission, from 44 kV to 765 kV. Once in the transmission system, electricity from each generating station is combined with electricity produced elsewhere. Electricity is consumed as soon as it is produced. It is transmitted at a very high speed, close to the speed of light.
  
  Section::::Primary distribution.
   BULLET::::- Transient (fluctuations due to individual's actions, differences in power transmission efficiency and other small factors that need to be accounted for)
  
  There are currently three main methods for dealing with changing demand:
  
  BULLET::::- Electrical devices generally having a working voltage range that they require, commonly 110–120 V or 220–240 V. Minor variations in load are automatically smoothed by slight variations in the voltage available across the system.
  
  BULLET::::- Power plants can be run below their normal output, with the facility to increase the amount they generate almost instantaneously. This is termed 'spinning reserve'.
   BULLET::::- Chemical
  
  BULLET::::- Biofuels
  
  BULLET::::- Hydrated salts
  
  BULLET::::- Hydrogen storage
  
  BULLET::::- Hydrogen peroxide
  
  BULLET::::- Power to gas
  
  BULLET::::- Vanadium pentoxide
  
  Section::::Methods.:Mechanical storage.
  
  Energy can be stored in water pumped to a higher elevation using pumped storage methods or by moving solid matter to higher locations (gravity batteries). 
  
  Other commercial mechanical methods include compressing air and flywheels that convert electric energy into kinetic energy and then back again when electrical demand peaks.
  
  Section::::Methods.:Mechanical storage.:Hydroelectricity.
  
  Hydroelectric dams with reservoirs can be operated to provide electricity at times of peak demand. 
   The capacity factor is often computed over a timescale of a year, averaging out most temporal fluctuations. However, it can be also computed for a month to gain insight into seasonal fluctuations. Alternatively, it be computed over the lifetime of the power source, both while operational and after decommissioning.
  
  Section::::Sample calculations.
  
  Section::::Sample calculations.:Nuclear power plant.
   Another electricity storage method is to compress and cool air, turning it into liquid air, which can be stored, and expanded when needed, turning a turbine, generating electricity, with a storage efficiency of up to 70%.
  
  Section::::Forms.:Batteries.
   BULLET::::- Storage batteries
  
  BULLET::::- DC distribution system.
  
  For safety and reliability reasons, it is desirable that all telecommunications loads be DC powered with minimal AC-powered devices used. Telcordia GR-513, Power Requirements in Telecommunications Plant (LSSGR Section 13), contains detailed industry requirements for using power in an inside plant.
   , the largest form of grid energy storage is dammed hydroelectricity, with both conventional hydroelectric generation as well as pumped storage hydroelectricity. Alternatives include rail energy storage, where rail cars carrying large weights are moved up or down a section of inclined rail track, storing or releasing energy as a result; or disused oil-well potential energy storage, where weights are raised or lowered in a deep, decommissioned oil well.
  
  Developments in battery storage have enabled commercially viable projects to store energy during peak production and release during peak demand.
   Section::::Installation examples.:Nickel-Cadmium.:Golden Valley Electric – Fairbanks.
   To protect pipelines, an ingot of buried or exposed magnesium (or zinc) is buried beside the pipeline and is connected electrically to the pipe above ground. The pipeline is forced to be a cathode and is protected from being oxidized and rusting. The magnesium anode is sacrificed. At intervals new ingots are buried to replace those lost.
  
  Section::::Electrolysis.
   Section::::Installation examples.:Lithium iron phosphate.
   Section::::Operating characteristics.
   Section::::Load following power plants.:Hydroelectric power plants.
  
  Hydroelectric power plants can operate as base load, load following or peaking power plants. They have the ability to start within minutes, and in some cases seconds. How the plant operates depends heavily on its water supply, as many plants do not have enough water to operate near their full capacity on a continuous basis.
   Grid energy storage
  
  Grid energy storage (also called large-scale energy storage) is a collection of methods used to store electrical energy on a large scale within an electrical power grid. Electrical energy is stored during times when production (especially from intermittent power plants such as renewable electricity sources such as wind power, tidal power, solar power) exceeds consumption, and returned to the grid when production falls below consumption.
   Normally, the electric power used within the plant is provided from the station's own generators. If all of the plant's main generators are shut down, station service power is provided by drawing power from the grid through the plant's transmission line. However, during a wide-area outage, off-site power from the grid is not available. In the absence of grid power, a so-called black start needs to be performed to bootstrap the power grid into operation.
   Section::::Auxiliary systems.:Fuel preparation system.
  
  In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers. The coal is next pulverized into a very fine powder. The pulverizers may be ball mills, rotating drum grinders, or other types of grinders.
   Section::::Forms.
  
  Section::::Forms.:Air.
  
  Section::::Forms.:Air.:Compressed air.
  
  One grid energy storage method is to use off-peak or renewably generated electricity to compress air, which is usually stored in an old mine or some other kind of geological feature. When electricity demand is high, the compressed air is heated with a small amount of natural gas and then goes through turboexpanders to generate electricity.
  
  Compressed air storage is typically around 60–90% efficient.
  
  Section::::Forms.:Air.:Liquid air.
   Section::::Installation examples.
  
  Some of the largest battery storage power plants are described below, arranged by type, date and size.
  
  Section::::Installation examples.:Lithium-ion.
  
  , the largest battery storage power station is the Hornsdale Power Reserve adjacent to the Hornsdale wind farm, built by Tesla. 
  
  Its 100 MW output capacity is contractually divided into two sections: 70 MW running for 10 minutes, and 30 MW with a 3 hour capacity. Samsung 21-70-size cells are used.
   where "I" is current, and "V" is the voltage drop across the thermistor. This power is converted to heat, and this heat energy is transferred to the surrounding environment. The rate of transfer is well described by Newton's law of cooling:
  
  where "T"("R") is the temperature of the thermistor as a function of its resistance "R", formula_37 is the temperature of the surroundings, and "K" is the "dissipation constant", usually expressed in units of milliwatts per degree Celsius. At equilibrium, the two rates must be equal:
   There are 195,000 megawatts of grid storage installed world-wide; 94% is pumped-storage hydroelectricity; 2% is in batteries. Pumped storage uses cheap power at times of low demand, usually night, to pump water from a lower reservoir to an upper reservoir, then lets it drop back through turbines during peak demand times, usually in the day. Availability of solar power in peak hours of the day can reduce the need for storage. The biggest storage facility in the world is on the Virginia-West Virginia border, with 50% more capacity than the Hoover Dam.
  
  Section::::Economics.
   The most aggressive contributor to corrosion of underground plant is dc stray current from electrified rail transportation systems, cathodic protection rectifiers, or welding and mining operations. Although such dc currents are mostly dealt with “after the fact” using protective systems (e.g., low resistance bonds, reverse current switches, cathodic protection), some of the protection has to be included at the manufacturing stage. This protection may include insulating covers on cable shields, or nonmetallic components or coatings for apparatus.
  
  Section::::Protecting equipment in the outside plant.:Corrosion resistance.:Buried plant.
   Battery storage power station
  
  A battery storage power plant is a form of energy storage power plant which uses a group of batteries to store electrical energy. 
  
  Battery storage power plants are used for short-term peak power and ancillary services, such as frequency control.
  
  Section::::Construction.
   Calculation of the required breaking capacity involves determining the supply impedance and voltage. Supply impedance is calculated from the impedance of the elements making up the supply system. Customers of an electrical supply utility can request the maximum value of prospective short-circuit current available at their point of supply. Networks involving multiple sources of current, such as multiple generators, electric motors, and with variable interconnections may be analyzed with a computer. A system study will generally consider the maximum case of additions of generation and interconnection out to some projected horizon year, to allow for system growth during the useful life of the studied installation. Since practical calculations involve a number of approximations and estimates, some judgment is required in applying the results of a short-circuit calculation to the selection of apparatus.
   While historically large power grids used unvarying power plants to meet the base load, there is no specific technical requirement for this to be so. The base load can equally well be met by the appropriate quantity of intermittent power sources and dispatchable generation.
  
  Unvarying power plants can be coal, nuclear, combined cycle plants, which may take several days to start up and shut down, hydroelectric, geothermal, biogas, biomass, solar thermal with storage and ocean thermal energy conversion. 
   thyristors, developed by AEG under GE’s license, In recent times, many important developments have come from extending innovations in the information and communications technology (ICT) field to the power engineering field. For example, the development of computers meant load flow studies could be run more efficiently allowing for much better planning of power systems. Advances in information technology and telecommunication also allowed for remote control of a power system's switchgear and generators.
  
  Section::::Basics of electric power.
   Some forms of storage that produce electricity include pumped-storage hydroelectric dams, rechargeable batteries, thermal storage including molten salts which can efficiently store and release very large quantities of heat energy, and compressed air energy storage, flywheels, cryogenic systems and superconducting magnetic coils.
  
  Surplus power can also be converted into methane (sabatier process) with stockage in the natural gas network.
  
presuppositions: Current is stored in power plants. Current is stored in power plants.
corrections: Current is not stored in power plants at all. Current is not stored at all in power plants.
raw_presuppositions: Current is stored in power plants. Current is stored in power plants.
raw_corrections: Current is not stored in power plants at all. Current is not stored at all in power plants.