Assessing zero-emissions energy transitions : a systemic view / lead author: Dr. Germán Bersalli, RIFS Helmholtz Centre Potsdam ; contributors: Prof. Dr. Johan Lilliestam, Friedrich-Alexander-Universität Erlangen-Nürnberg, Lennart Brien, RIFS Helmholtz Centre Potsdam, David Gottheit, RIFS Helmholtz Centre Potsdam