The ability to design technological solutions that address sustainability is considered pivotal to the future of the planet and its people. As technology professionals engineers are expected to play an important role in sustaining society. The present article aims at exploring sustainability concepts of newly enrolled engineering students in Denmark. Their understandings of sustainability and the role they ascribe to sustainability in their future professional practice is investigated by means of a critical discourse analysis including metaphor analysis and semiotic analysis. (...) The sustainability construal is considered to delimit possible ways of dealing with the concept in practice along the engineering education pathway and in professional problem solving. Five different metaphors used by the engineering students to illustrate sustainability are identified, and their different connotative and interpretive implications are discussed. It is found that sustainability represents a dilemma to the engineering students that situates them in a tension between their technology fascination and the blame they find that technological progress bears. Their sustainability descriptions are collected as part of a survey containing among other questions one open-ended, qualitative question on sustainability. The survey covers an entire year group of Danish engineering students in the first month of their degree study. (shrink)