We explore a new way to design a quantum version of the classical Otto engine, a basic model of how heat engines work. In our setup, a single quantum system (a qubit) moves in a special circular path at near-light speeds, where strange quantum effects of empty space itself act like a heat source. We find that this motion plays a key role in how much useful work the engine can produce, which grows with acceleration and eventually levels off. Interestingly, while the work output changes, the efficiency of the engine remains the same as in earlier models.