damage pulley bearing

I own a 1982 xjs HE V12. My technical knowledge of car engines is very low, so my question might seem a little strange, but here it is:

After replacing a broken alternator, I found that a pulley located right above my alternator is rotating unevenly and makes quit a bit of noise. I tighten the pulley, and now it has gotten worse, its bearing seems to be destroyed (I've included a jpg image with a red arrow pointing to the pulley in concern).

Since English is not my first language, I have problems searching for a new one, or new bearing for it (I'm writing to this forum from Denmark).

Among all the English names the Danish mechanics have given me, which I have used to locate the part, gives no result, so I was wondering if you could help me identify the part, and if it is possible to acquire a new one, with bearing or just its bearings. Perhaps none exist on the market, and it needs to be rebuilt?

Thank you for your help.