Power is needed by buildings in a city in order to function at their best performance. It is especially important in the Industrial Era and later. Cities without sufficient Power cannot produce yields as well. A well-functioning city will have enough Power to supply its needs.

If a city has enough Power to meet all its needs, then it is considered Powered. A city that does not have enough Power is Unpowered. A city is either one or the other, it cannot provide Power to some buildings and not to others. Buildings which require Power provide less than half of their normal yield when the city is Unpowered.

One source of Power is resources such as Coal, Oil, and Uranium. Once a player has an improvement that provides this resource, and they build the appropriate kind of Power Plant in the Industrial Zone, the city automatically converts the resource from the stockpile into Power. The Power Plant can provide Power to any city that needs it, within a 6 tile range. However, using Coal, Oil, or Uranium to produce Power can also lead to Global Warming, so there will be long-term costs to the environment for doing so.

A Power Plant generates Power for each unit of resource that it consumes. Coal and Oil Power Plants provide 4 Power per resource, while Nuclear provides 16 Power per resource. For example, a Coal Power Plant will convert Coal from the player’s stockpile into Power each turn. Power Plants automatically try to provide enough Power to meet the demands of the cities in range and will draw from the most power-efficient resource first, before moving onto other resources. If there is a tie, a player’s largest resource stockpile is used first. If there is still a tie, they start with the resource that the player is earning more of each turn. If there is still a tie, they start with the more technologically advanced resource. For example, if a player has both a Coal Power Plant and an Oil Power Plant in their Civilization, but a larger supply of Coal than Oil, the Power Plants will draw from the Coal stockpile before making up the difference with Oil. If that player also had a Nuclear Power Plant, they would draw from the Uranium stockpile before anything else, since 1 Uranium provides 16 Power.

Alternatively, a player may attempt to build green sources of Energy, such as hydroelectric dams and wind farms. These are unlocked with later technologies and can provide power without adding to global warming.