Technology roadmap is emerging as an indispensable management tool in the modern society, because it can be used to direct future paths of advancing technologies and to foster understandings among stakeholders including scientists, engineers, R&D managers, and policy makers. Current technology roadmaps are limited in its functions, because uncertainties embedded in the presented pathways and major consequences in the future realized by following the roadmap are often not well presented. In this paper, a new approach in technology roadmapping is proposed. The new approach includes identification of technological, economic, environmental and social risks and constraints and apply scenario planning concept. A case study in Japanese energy sector was conducted. Inputs from more than 40 experts in energy sector were collected and assessed to synthesize an integrated perspective on energy technologies, consistently describe inherent risks, and quantify expected outcomes. Findings obtained in the execution of this case study are organized as useful guidelines to construct a useful, reliable, and informative technology roadmap.