High tech visions play an important part in public technology policy and are often promoted through technology foresights. The article presents and analyses results from a green technology foresight of nano-, bio- and information- and communication technologies initiated by the Danish Environmental Protection Agency with the purpose of acquiring knowledge about the environmental potentials and risks related to the three areas of technology. The foresight was organised with a social shaping of technology (SST) approach to the field in order to cater for the complex relationship between societal demands, technology options, innovation dynamics and environmental impacts. The approach involved studying actor-networks, laboratory programmes and technology trajectories as well as deconstructing different stakeholders’high tech visions. The identified environmental potentials and risks related to the three areas of technology and recommendations for future governance of research, innovation and application areas are discussed.