<b>Hybrid Drives</b> The reverse process of electrolysis takes place in the fuel cell. The fuel cell reverses this process and generates electrical energy from the reaction of oxygen and hydrogen to form water. The actual cell consists of two electrodes in an electrolyte (e.g. potassium hydroxide). In the two electrodes (anode and cathode) the so-called reactants hydrogen (on the anode side) and oxygen (on the cathode side) are continuously fed from storage tanks in the boat as long as the process is running. Depending on the type of fuel cell, methane, methanol or glucose solutions can also be used as fuel. On the cathode side, hydrogen peroxide or potassium thiocyanate can also be used as the oxidizing agent. The two electrodes of a cell consist of a substance with catalytic properties, e.g. Platinum. This means that this substance favors the reactions to take place. In the electrolyte, the positively charged hydrogen ions migrate to the cathode and combine with the oxygen to form water. A positive potential is created at the cathode. The electron balance takes place via the circuit via a connected consumer under workload Long-term shipbuilding research already deals intensively with the topic of fuel cells. Companies in the shipbuilding industry and universities work in the “National Innovation Program for Hydrogen and Fuel Cell Technology” (NIP) on the fuel and drive technology of tomorrow. With the joint project “e4ships - fuel cells in maritime use”, the emission-free ship operation of the future is being prepared on the one hand, but practical, modular solutions for on-board power supply and port operation of the present are also being developed. Building on the success of the demo projects “PA-X-ell” (passenger ships) and “SchiBZ” (cargo ships), hybrid drives, consisting of a gas combustion engine, fuel cell, solar cells and energy storage system, are now being developed for river cruise ships in the new “Rivercell” project.