Are Power Crystals a finite resource in Clank in Space?
Yes.


There's a Major Secret that gives victory points for each Power Crystal one possesses. An unlimited supply of Power Crystals would provide a unlimited supply of points for the owner of that Secret. Anything that encourages a player to spend the entire game walking back and forth between two squares is a problem.
There's a cards whose effect is multiplied by the number of Power Crystal one possesses. An unlimited supply of Power Crystals would provide a unlimited benefits from those cards. Anything that encourages a player to spend most of the game walking back and forth between two squares is a problem.
There is precedent for limited quantities of resources, namely the items in the market.