Some plugs cost Energy, which is a stat on the item that can be increased by other plugs (that, at least in Armor 2.0, have a "masterworks-like" mechanic for upgrading). If a plug has costs, the details of that cost are defined here.
Type: object
Object Properties
The Energy cost for inserting this plug.
Type: int32
Mapped to Definition
The type of energy that this plug costs, as a reference to the DestinyEnergyTypeDefinition of the energy type.
Type: uint32
Mapped to Manifest Database Definition: Destiny.Definitions.EnergyTypes.DestinyEnergyTypeDefinition
The type of energy that this plug costs, in enum form.
Type: int32