mixedpropulsion

Mixed propulsion refers to propulsion systems that use two or more energy sources or propulsion methods to generate thrust, aiming to combine the efficiency or flexibility of each. It spans land, sea, and air transport and includes hybrid propulsion, dual-fuel engines, and multi-mode control.

In hybrid propulsion, power comes from internal combustion engines, electric motors, and energy storage such as batteries. Configurations include parallel hybrids (an engine and motor both drive the propeller), series hybrids (an engine charges storage or a generator while a motor provides propulsion), and more complex power-split arrangements that share power between sources.

Dual-fuel propulsion uses two fuels in a single powertrain, enabling fuel-switching to optimize cost, emissions, or availability. Multi-mode systems can switch between regimes, such as electric-only, combustion-only, or hybrid operation, depending on operating conditions.

Advantages include improved fuel efficiency, lower emissions, greater operational flexibility, and resilience to fuel disruptions. Challenges include higher upfront cost, added weight and system complexity, safety considerations for electrical systems, and the need for sophisticated control software and certification.

Applications include maritime diesel-electric and gas-turbine-electric propulsion for ships and ferries; road and rail vehicles with hybrid powertrains; and experimental or early-stage hybrid-electric aircraft. In practice, mixed propulsion is often marketed as hybrid propulsion, but the term also covers dual-fuel and multi-mode schemes.

See also: Hybrid propulsion; Diesel-electric propulsion; Gas turbine–electric propulsion.