The shelf life on these orbs is nonexistent. If you are not in close quarters to what you kill they disappear before you can get to them. THIS IS SO F'N STUPID!
EDIT: Points taken in regards to too many objects and crashing the game... thats fair. That said, maybe the requirements should be orbs generated instead? Then you picking them up just impacts getting the empowerment or not. They could then reduce the number of orbs needed to compensate for only counting your orbs. Just a thought.