Energy intensitites, EROI (energy returned on invested), for electric energy sources D. Weissbach, F. Herrmann, G. Ruprecht, A. Huke, K. Czerski, S. Gottlieb and A. Hussein EPJ Web Conf., 189 (2018) 00016 Published online: 02 October 2018 DOI: 10.1051/epjconf/201818900016