Generate link to user's album from user list

I have found out how to display a link to the current user's album, but now I am struggling with generating a link to some other user's album.
What I want to do:
Somewhere in my joomla application, I display a list of all my users. For each user, I would like to display a link to "his" album in gallery2.
The underlying problem is how to get the G2-User-ID from the joomla-user-id. I found a method called utility::getG2Id($my->id);, but i was not sure how to call it (where do I get the class utility:: from?).
Any ideas? Any examples?