Primary energy type
From The Dim Future Wiki
An ability's or action's primary energy type is the energy type of which the most is required to play the action. If two types are equally high, the controlling player may choose between the highest types.
For instance, if an action costs 2 3 its primary energy type is protein (3 is greater than 2). If an action costs 3 3 its primary energy type is either protein or electricity at the controllers choice.