Boosting thermodynamic performance by bending space-time

Black holes are arguably the most extreme regions of the universe. Yet, they are also utterly inaccessible to experimentation, and even just indirect observation poses significant technical challenges. The phenomenological approach of thermodynamics is uniquely suited to explore at least some of the physical properties of such scenarios, and this has motivated the study of so-called holographic engines. We show that the efficiency of an endoreversible Brayton cycle is given by the Curzon-Ahlborn efficiency if the engine is fueled by a 2-dimensional ideal gas; and that the efficiency is higher, if the working medium is a (2+1)-dimensional BTZ black hole. These findings may be relevant not only in the quest to unlock the mysteries of black holes, but also for potential technological applications of graphene.