One possibilty is the anemia. That can cause fatigue like this. I would ask his doctors about EPO and IV iron. Oral iron is poorly absorbed in renal patients and many require IV iron. Epo would boost the red cells and increase hemoblobin. I dont know anything about his anemia but these are worth looking into at least.
I will ask his doctor at his next appointment. In the meantime, I have done some research and found that L-Cartinine is good for energy and has been studied in hemodialysis patients. He has started it 2x per day and says he feels a lot better