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General layout of electricity networks. Voltages and depictions of electrical lines are typical for Germany and other European systems.


An electrical grid is an interconnected network for delivering electricity from suppliers to consumers.


When referring to the power industry, "grid" is a term used for an electricity network which may support all or some of the following three distinct operations:

  1. Electricity generation
  2. Electric power transmission
  3. Electricity distribution

The sense of grid is as a network, and should not be taken to imply a particular physical layout, or breadth. "Grid" may be used to refer to an entire continent's electrical network, a regional transmission network or may be used to describe a subnetwork such as a local utility's transmission grid or distribution grid.

Electricity in a remote location might be provided by a simple distribution grid linking a central generator to homes. The traditional paradigm for moving electricity around in developed countries is more complex. Generating plants are usually located near a source of water, and away from heavily populated areas. They are usually quite large in order to take advantage of the Economies of scale. The electric power which is generated is stepped up to a higher voltage—at which it connects to the transmission network. The transmission network will move (wheel) the power long distances—often across state lines, and sometimes across international boundaries—until it reaches its wholesale customer (usually the company that owns the local distribution network). Upon arrival at the substation, the power will be stepped down in voltage—from a transmission level voltage to a distribution level voltage. As it exits the substation, it enters the distribution wiring. Finally, upon arrival at the service location, the power is stepped down again from the distribution voltage to the required service voltage(s).

This traditional centralized model along with its distinctions are breaking down with the introduction of new technologies. For example, the characteristics of power generation can in some new grids be entirely opposite of those listed above. Generation can occur at low levels in dispersed locations, in highly populated areas, and not outside the distribution grids. Such characteristics could be attractive for some locales, and can be implemented if the grid uses a combination of new design options such as net metering, electric cars as a temporary energy source, or distributed generation.


Structure of distribution grids

The structure, or "topology" of a grid can vary considerably. The physical layout is often forced by what land is available and its geology. The logical topology can vary depending on the constraints of budget, requirements for system reliability, and the load and generation characteristics.

Classic North American electricity distribution grids were simple "radial" trees, sending power from a source (red dot representing power generation or a substation) to delivery points (blue dots representing homes, businesses, or other subnetworks).

The cheapest and simplest topology for a distribution or transmission grid is a radial structure. This is a tree shape where power from a large supply radiates out into progressively lower voltage lines until the destination homes and businesses are reached.

Most transmission grids require the reliability that more complex mesh networks provide. If one were to imagine running redundant lines between each limb and branch of a tree that could be turned in case any particular limb of the tree were severed, then this image approximates how a mesh system operates. The expense of mesh topologies restrict their application to transmission and medium voltage distribution grids. Redundancy allows line failures to occur and power is simply rerouted while workmen repair the damaged and deactivated line.

Other topologies used are looped systems found in Europe and tied ring networks.

In cities and towns of North America, the grid tends to follow the classic "radially fed" design. A substation receives its power from the transmission network, the power is stepped down with a transformer and sent to a bus from which feeders fan out in all directions across the countryside. These feeders carry three-phase power, and tend to follow the major streets near the substation. As the distance from the substation grows, the fanout continues as smaller laterals spread out to cover areas missed by the feeders. This tree-like structure grows outward from the substation, but for reliability reasons, usually contains at least one unused backup connection to a nearby substation. This connection can be enabled in case of an emergency, so that a portion of a substation's service territory can be alternatively fed by another substation.

Geography of transmission networks

The Continental U.S. power transmission grid consists of about 300,000 km of lines operated by approximately 500 companies.

Transmission networks are more complex with redundant pathways. For example, see the map of the United States' (right) high-voltage transmission network.

A wide area synchronous grid or "interconnection" is a group of distribution areas all operating with alternating current (AC) frequencies synchronized (so that peaks occur at the same time). This allows transmission of AC power throughout the area, connecting a large number of electricity generators and consumers and potentially enabling more efficient electricity markets and redundant generation. Interconnection maps are shown of North America (right) and Europe (below left).

Electricity generation and consumption must be balanced across the entire grid, because energy is consumed almost immediately after it is produced. A large failure in one part of the grid - unless quickly compensated for - can cause current to re-route itself to flow from the remaining generators to consumers over transmission lines of insufficient capacity, causing further failures. One downside to a widely connected grid is thus the possibility of cascading failure and widespread power outage. A central authority is usually designated to facilitate communication and develop protocols to maintain a stable grid. For example, the North American Electric Reliability Corporation gained binding powers in the United States in 2006, and has advisory powers in the applicable parts of Canada and Mexico. The U.S. government has also designated National Interest Electric Transmission Corridors, where it believes transmission bottlenecks have developed.

Some areas, for example rural communities in Alaska, do not operate on a large grid, relying instead on local diesel generators.[1]

High-voltage direct current lines or variable frequency transformers can be used to connect two alternating current interconnection networks which are not synchronized with each other. This provides the benefit of interconnection without the need to synchronize an even wider area. For example, compare the wide area synchronous grid map of Europe (below left) with the map of HVDC lines (below right).

The wide area synchronous grids of Europe. Most are members of the European Transmission System Operators association.
High-voltage direct current interconnections in western Europe - red are existing links, green are under construction, and blue are proposed. Many of these transfer power from renewable sources such as hydro and wind. For names, see also the annotated version.

Redundancy and defining "grid"

A town is only said to have achieved grid connection when it is connected to several redundant sources, generally involving long-distance transmission.

This redundancy is limited. Existing national or regional grids simply provide the interconnection of facilities to utilize whatever redundancy is available. The exact stage of development at which the supply structure becomes a grid is arbitrary. Similarly, the term national grid is something of an anachronism in many parts of the world, as transmission cables now frequently cross national boundaries. The terms distribution grid for local connections and transmission grid for long-distance transmissions are therefore preferred, but national grid is often still used for the overall structure...

Distributed generation

Utilities are under pressure to evolve their classic topologies to accommodate distributed generation. As generation becomes more common from rooftop solar and wind generators, the differences between distribution and transmission grids will continue to blur.

Modern trends


The three components of a complete grid: generation, transmission, and distribution of electrical power, can all be found in most large utilities. A utility can be completely self-sufficient, but finds it advantageous to have the opportunity to buy and sell power to and from neighboring utilities. This improves their reliability, and that of their neighbors. Utilities are often awarded a "monopoly" status (at least at the distribution level) simply because it doesn't make sense to have competing utilities installing their hardware in the same location as another utility. The idea of a monopoly becomes less compelling as one considers the generation of electrical power. Wildly varying costs for the production of electricity, and the opportunity to encourage free market competition spurs many legislatures to move towards deregulation of the electric utilities (also known as "liberalization" in some parts of the world.) The idea of de-regulation usually involves the separation of the generation, transmission, and distribution operations into separate financial entities. Generation assets in particular can often be sold-off in piecemeal fashion to the highest bidders. With the aging infrastructure present at many utilities, and the pressure to de-regulate, there are numerous opportunities to re-engineer the system[2].

Transitioning utilities from regulated monopolies to a deregulated market has run into a number of challenges such as those surfaced by the California electricity crisis.

Demand response

Demand response is a grid management technique where retail or wholesale customers are requested either electronically or manually to reduce their load. Currently, transmission grid operators use demand response to request load reduction from major energy users such as industrial plants.[3]

Distributed generation

With everything interconnected, and open competition occurring in a free market economy, it starts to make sense to allow and even encourage distributed generation (DG). Smaller generators, usually not owned by the utility, can be brought on-line to help supply the need for power. The smaller generation facility might be a home-owner with excess power from his solar panel or wind turbine. It might be a small office with a diesel generator. These resources can be brought on-line either at the utility's behest, or by owner of the generation in an effort to sell electricity. Many small generators are allowed to sell electricity back to the grid for the same price they would pay to buy it.

Smart grid

Numerous efforts are underway to develop a "smart grid". In the U.S., the Energy Policy Act of 2005 and Title XIII of the Energy Independence and Security Act of 2007.[4] are providing funding to encourage smart grid development. The hope is to enable utilities to better predict their needs, and in some cases involve consumers in some form of time-of-use based tariff. Funds have also been allocated to develop more robust energy control technologies.[5]

Micro grid

Decentralization of the power transmission distribution system is vital to the success and reliability of this system. Currently the system is reliant upon relatively few generation stations. This makes current systems susceptible to impact from failures not within said area. Micro grids would have local power generation, and allow smaller grid areas to be separated from the rest of the grid if a failure were to occur. Furthermore, micro grid systems could help power each other if needed. Generation within a micro grid could be a downsized industrial generator or several smaller systems such as photo-voltaic systems, or wind generation. When combined with Smart Grid technology, electricity could be better controlled and distributed, and more efficient.

Super grid

Various planned and proposed systems to dramatically increase transmission capacity are known as super, or mega grids. The promised benefits include enabling the renewable energy industry to sell electricity to distant markets, the ability to increase usage of intermittent energy sources by balancing them across vast geological regions, and the removal of congestion that prevents electricity markets from flourishing. Local opposition to siting new lines and the significant cost of these projects are major obstacles to super grids.

See also

External links


  1. ^,_United_States
  2. ^ American Scientist Online - Reengineering the Electric Grid
  3. ^ "Industry Cross-Section Develops Action Plans at PJM Demand Response Symposium". Reuters. 2008-08-13. Retrieved 2008-11-22. "Demand response can be achieved at the wholesale level with major energy users such as industrial plants curtailing power use and receiving payment for participating."  
  4. ^ "U.S. Energy Independence and Security Act of 2007". Retrieved 2007-12-23.  
  5. ^

Template:About Template:Infobox Game Power Grid is a multiplayer German-style board game designed by Friedemann Friese and published by Rio Grande Games. It is also well-known in its earlier version, Funkenschlag, published in Germany by 2F-Spiele.

In the game, each player represents a company that owns power plants and tries to supply electricity to cities. Over the course of the game, the players will bid on power plants and buy resources to produce electricity to provide power to the growing number of cities in their expanding network.



  • 1 board (map, scoring track, resource market) on both sides (Germany and U.S.A.)
  • 132 wooden houses (22 each in green, yellow, red, blue, lilac, and natural)
  • 84 wooden tokens (24 coal (brown), 24 oil (black), 24 garbage (yellow), 12 uranium (red))
  • money (in Elektro)
  • 5 summary cards: order of play/payments
  • 43 power plant cards (42 power plant cards and 1 "Step 3" card)


The game comes with a double-sided board with a map of the United States of America and Germany on either side. After a map is chosen and placed in the middle of the table, each player selects one area. There are six areas, each of a different color: red, green, brown, yellow, purple, and blue. The players collectively choose the areas, the only restriction being that the areas must be adjacent. (The players may begin building their networks on the first turn in any of the colored areas.)

The players each choose a color and take the wooden houses in that color. Each player places one on the Scoring Track (which relates to how many cities this player has connected) and one on the Playing Order track. The Resource Market is then prepared based on a grid found on the back of the booklet, adding the wooden tokens representative of four fuel sources: coal, oil, garbage, and uranium. The number of tokens placed on the Market depend on the number of players in the game. Players also receive $50 in Elektro (the game's currency) to start with.

The Power Plant Market is then laid out. Power Plants are depicted on 3"×3" cards and are numbered 03 to 50. Each Power Plant card indicates the initial cost, the type of fuel it needs to run, the amount of fuel it can store, and how many cities it can power. Eight cards (03 through 10) are laid out for the Power Plant Market in a two-by-four grid to start the game.

The game is then played over a number of rounds. In each round, five phases are followed:

  1. Determine the Player Order
  2. Auction Power Plants
  3. Buying Resources
  4. Building
  5. Bureaucracy

Phase 1: Determine the Player Order

The colored player tokens on the Playing Order track are rearranged based on the number of cities that player has connected. The player with the most connected cities is placed on the first spot, and the remaining player token are placed in descending order of connected cities. Ties are resolved by the player with the higher-numbered power plant going first. (On the first turn, the player order is random.)

Phase 2: Auction Power Plants

During the first turn, every player is required to buy a power plant. During other turns, purchasing a power plant is optional. However, each player is limited to owning a maximum of three power plants at any one time. If a player already owns three power plants and purchases another, one of the power plants must then be discarded. During the first round after power plants are purchased, the player order is redetermined according to the normal rules.

The leading player starts the auction phase, selecting a power plant for the auction and making the opening bid. The opening bid must be at least the number listed on the Power Plant card. In clockwise order, each player who hasn't bought a power plant this turn has an opportunity to bid or pass. If he elects to pass, he is out of the bidding for that Plant. Once the Plant is purchased (everyone else has passed), then the cost of the highest bid is paid to the bank, and the player places the Plant in front of him. The highest remaining player who hasn't bought a power plant this turn opens the bidding for the next plant, and so on, until everyone has purchased one plant or passed on buying this turn. If, when it is a player's turn to choose a power plant to bid on, he may pass but he is then not allowed to purchase a power plant during that turn.

As power plants are purchased, they are replaced from the draw pile. During Steps 1 and 2 of the game, only the lowest-numbered four power plants (of the eight displayed) are available for purchase. During Step 3 of the game, only six power plants are displayed but they are all available for purchase.

Phase 3: Buying Resources

Starting with the player in LAST place on the Playing Order track, and working backwards, players purchase the resources that their Power Plants can use or store. Players pay the cheapest going rate on the Resource Market. Because of the reverse player order in this round, players that are behind (have the fewest connected cities) pay less for resources. As the resources are purchased, players place them on their Power Plants. They can buy as many as the icons on the Power Plant card indicate, times two. That is, a Power Plant can store an extra set of resources.

Phase 4: Building

During this phase, a player seeks to expand his power network. This phase is also played in reverse player order, thus, players that are behind have better choices for purchasing connections to cities. Each city is divided into three sections and labeled "10", "15", or "20". At the beginning of the game, players will place their wooden buildings on the "10" section of a given city. This costs 10 Elektros. The player can branch out into another city, paying the connection cost (the number on the pipe connecting the two cities) plus the 10 Elektros for setting up in that city. Later in the game, the sections marked "15" and "20" can be used as part of a player's network (Steps 2 & 3 respectively), but in the initial Step 1, only one player may occupy any given city.

If at any time, a player has equal or more cities than the lowest-numbered power plant displayed (available for purchase), then the lowest-numbered power plant is removed from those available for purchase and is placed in the discard pile. The power plant is replaced with the card from the top of the draw pile, then the available power plants are sorted from lowest to highest.

Phase 5: Bureaucracy

Every player "fires" their power plants, consuming the resources that were purchased and earning the player money. The player's plants produce the electricity for the number of cities that it can support, assuming the player has that many connected cities in his network. For example, the #10 Power Plant card can power two cities with two coal. The resources used are removed, and the player is paid in Elektros based on a provided scale. The more connected cities that are powered, the more money the player earns.

During Steps 1 and 2, the highest-numbered power plant is removed from those displayed and placed at the bottom of the draw pile. During Step 3, the lower-numbered power plant is removed from those displayed and is put in the discard pile. The removed power plant is replaced from the top of the draw pile and the power plants available are resorted, lowest to highest.

Game steps

These phases are repeated until certain "steps" are reached. These are as follows:

  • Step 1: Play as detailed above, only one player can occupy a given city.
  • Step 2: After a player has connected his 7th city during the Building Phase, Step 2 begins. The lowest Power Plant in the market is removed from the game and replaced by a new one from the draw pile. Players can build in to the "15" spaces in cities.
  • Step 3: When the "Step 3" card appears in the Power Plant draw pile, Step 3 begins and the game enters the final stretch. Players can build in the "20" spaces in cities, and new rules governing the selection and availability of Power Plants are enacted.

End game

The game ends after the bureaucracy phase once one player connects a minimum of:

  • 21 cities for a 2-player game
  • 17 cities for a 3 or 4-player game
  • 15 cities for a 5-player game
  • 14 cities for a 6-player game

The winner is the player who can supply electricity to the most cities with his network. Tie breakers first look at who has the most money, then the most cities.

Differences in editions

The "29" plant in the 1st edition was printed with a capacity to power 3 cities. Friedemann Friese has made it clear that he intended this plant to have a capacity to power 4 cities. 2nd edition copies of Power Grid have this correction incorporated. If you play with a 1st edition copy, you should agree before play whether you will play the "29" plant as printed, or with the corrected capacity.


The France & Italy Expansion for Power Grid was published in 2005. The expansion requires the original game to play. As with the original, the board has a different map on each side: France and Italy. Along with the maps are small rule changes to reflect the power culture in these two countries. France, a land that has embraced nuclear power, has an earlier start with atomic plants and more uranium available. Italy has fewer coal and oil resources, but more garbage (called "waste" in the expansion rules), making Plant 06 a viable first plant.

Benelux/Central Europe

The Benelux & Central Europe Expansion for Power Grid was published in 2006. The expansion requires the original game to play. As with the original, the board has a different map on each side: Benelux and Central Europe. Along with the maps are small rule changes to reflect the power culture in these two regions. Benelux (Economic union of Belgium, the Netherlands and Luxembourg) has more ecological power plants and more availability of oil. Central Europe has rules changes in Steps 2 and 3, and limits on what type of power plant may be used to power cities in different regions (countries) of the map.

Power Plant Deck 2

The Power Plant Deck 2 Expansion for Power Grid was published in 2007. It was released at Spiel (the annual game fair in Essen) in 2007 and will be available for purchase in the United States around October 2007.


The China & Korea Expansion for Power Grid was published in 2008. The expansion requires the original game to play. As with the original, the board has a different map on each side: China and Korea. Along with the maps are small rule changes to reflect the power culture in these two regions. On the Korean side, players are confronted first with richly varying geographical challenges, making building expensive. In addition, because of the political division between North and South, there are two resource markets; in each turn a player must choose only one market to buy resources from, with fewer resources and no uranium available in the North. On the Chinese side the market is structured as a planned economy. In this version of the game, there are no surprises -- the power plants on the power plant market are offered in ascending order during the two first steps of the game. (If the game reaches its final stage, then the power plant market becomes more like that in the original game, to reflect the beginnings of economic reform in modern China.) Additionally, the resource table is designed such that resources are likely to be in short supply as the game proceeds. Players must plan their resource needs very carefully or find their grid dark and their incomes reduced.




External links

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