Just wanted to make sure you were clear to this requirement, and attempt to add a bit to the other posts (which are very much to the point!).

Any "Remote" structure (A structure which is independent, or physically separate from another structure) is required to have it's own local Grounding Electrode System (AKA "GES" at ECN... how about those TLAs??? 'Three Letter Acronyms'...).

For a simple GES, driven rods work fine. Other types of Electrode Systems include encased electrodes, plates, combinations of encased electrodes and driven rods, underground metallic water pipes (yuck!), deep earth rods, water wells with metallic tubing extending deep into the water table (great deep earth electrode!) and such.
I like the idea of combining UFER electrodes with a water well for a nice GES!, but that's another story,,,ahhhm,,, thread!

If the building is made of exposed metal, or if there's a considerable amount of exposed metal which may become energized, bond this to the local GES.
Local GES refers to the GES for that building.

Bond the GES for the remote building to the GES / GEC for the service which feeds it.

For a "Subfeeder" which includes an Equipment Grounding Conductor, bond the EGC to the remote building's GES, to the Subpanel / Subfeeder conduit (if metallic), and land it to the location where the Grounded Conductor and all the EGCs + GEC bond together at the main service.

As to a Subfeeder run without an EGC, this is kind of a "No-Brainer" [Linked Image]

Scott s.e.t.

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!