How debri is generated?

there are 3 possibilities:

- when a fleet is destroyed
- when a fleet is disbanded
- asteroid belts release 10 to 25 debri per hour until it debri belt deplete (beta server only)
-- also, if the asteroid belt have a Starbase, the debri release is increased in 25 debri per SB level.

Note the difference between Debris and Debris belt. The first one is available to be recycled, the other one need a SB.