This synthesis report provides an overview of primary electricity supply sources, including power generation potentials and costs as well as the as- sociated environmental burdens of electricity pro- duction in Switzerland. It gives a synthesis of the main findings and selected deep-dives into key tech- nologies supporting the transition of the Swiss en- ergy system, namely solar photovoltaics (PV), hy- dropower, biomass and deep geothermal energy generation.