We argue that the high energy use by present-day semiconductor computing technology will prevent the emergence of an artificial intelligence system that could reasonably be described as a “superintelligence”. This hard limit on artificial superintelligence (ASI) emerges from the energy requirements of a system that would be more intelligent but orders of magnitude less efficient in energy use than human brains. An ASI would have to supersede not only a single brain, but a large population of humans, further multiplying the energy requirement. A hypothetical ASI would likely consume orders of magnitude more energy than what is available in industrialized society. We estimate the energy use by ASI with an equation we term the ”Erasi equation”, for the Energy Requirement for Artificial SuperIntelligence. Additional efficiency consequences will emerge from the current unfocussed and scattered developmental trajectory of AI research. Taken together, these arguments suggest that the emergence of an ASI is highly unlikely in the foreseeable future based on current computer architectures, primarily due to energy constraints, with biomimicry being a possible solution.