The term has the same basic meaning in the energy industry as it has when applied to traffic conditions or cold symptoms. It refers to clogging and stress at a point where something must pass. In this case, that something is electricity.

Congestion in energy transmission systems occurs when local demand for energy approaches the limits of the transmission system's ability to supply it. One of the reasons why the the US' national energy grids were constructed was to help alleviate congestion in urban areas by allowing energy to be fed from several locations as needed, but this doesn't necessarily help when energy demand is high across a large area. Major urban centers with congestion problems may need to construct their own generating facilities to insure that sufficient power is available to meet peak demand and to prevent stresses on the system caused by limitations in the distribution system.

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