At the Port of Barcelona, a quiet transfer of 2,800 tons of bioethanol onto a large container vessel marked something the maritime world has long been reaching toward: evidence that alcohol-based fuels can move beyond experiment and into the rhythms of commercial life. Repsol, Maersk, and the port itself arrived at this moment not by accident but through years of parallel preparation — each building the piece the others would need. The significance is less about the fuel than about the system: when infrastructure, logistics, and institutional will converge, transitions that once seemed distant