This paper presents results that are part of a larger effort driven by the International Resource Panel of the United Nations Environment Program. The reports aims to identify and, when possible, quantify the trade-offs, benefits, and risks of low carbon energy technologies. In order to provide a meaningful comparison a common assessment approach is developed by selecting common environmental indicators, common background data, and common assumptions for inventory construction. The assessment is based on a systematic review of the literature and an extended analysis of life-cycle inventory data in which the global environmental pressure of introducing technologies following widely used scenarios are investigated.