Quantum technologies drive high expectations as they promise safer and faster ways to extract, transfer, and process information. Will it require a nuclear reactor to run a useful quantum computer or will there be a “quantum advantage” of energetic nature, owing to which it will execute the tasks of classical ones with less energy? Or even inaccessible tasks to these, at a reasonable energy cost? Despite its impact on industry and society, these new technologies’ energetic footprint remains largely unexplored by quantum strategies and research agendas worldwide. Not only answers, but methodologies are needed to address these questions. Optimizing quantum technologies’ energy cost is highly nontrivial as it requires coordinated inputs ranging from fundamental research to enabling technologies. Indeed, metrics of performance are set at the fundamental level, basically capturing the ability to control quantum systems and mitigate noise. Such control mandates physical resources at the macroscopic level, supported by enabling technologies. But these macroscopic resources usually add noise, degrading the performance instead of increasing it. Minimizing the energetic footprint of a quantum technology, under the constraint of a target performance can only be realized within an interdisciplinary research line. This is the goal of the quantum energy initiative called in the present Perspective. It will allow us to optimize the energy efficiency of quantum machines as they are being architected, ensuring as such their scalability. It is also the only way to bring out an energetic quantum advantage, and develop sustainable quantum technologies in a responsible manner.