It is mentioned somewhere in the Megatraveller books that at high TLs
teleportation became intersystem capable and was used by ancients. In
the Traveller Adventure "Secret of the Ancients" it is noted that the
Ancients used entire suns as source of energy by "pinching" them out of normal
space and then carrying along this pinched sun as a poerplant for their
ships!!!
At these TLs you wouldn't need to put a mesh around the sun/gas giant just
pinch it off and put a tap on the emitted energy. Wouldn't need to refuel for
atleast 5 billion years!!!
Ameer Z. Sulaiman.