From a fellow workaholic: Talk with him and see what really excites him. Suggest that you work together with him on an open source side project (possibly relat

From a fellow workaholic: Talk with him and see what really excites him. Suggest that you work together with him on an open source side project (possibly related to a something your team is building). A piece of the project he can get excited about and occupy his excess energy. Help him promote it so he can get him some recognition / feedback outside of just the internal company employees. And your team might still get some additional benefits from the open source project he's working on.