Integrated electric propulsion (IEP) or full electric propulsion (FEP) or integrated full electric propulsion (IFEP) is an arrangement of marine propulsion systems such that gas turbines or diesel generators or both generate three-phase electricity which is then used to power electric motors turning either propellers or waterjet impellors. It is a modification of the combined diesel-electric and gas propulsion system for ships which eliminates the need for clutches and reduces or eliminates the need for gearboxes by using electrical transmission rather than mechanical transmission of energy, so it is a series hybrid electric propulsion, instead of parallel.
Eliminating the mechanical connection between the engines and the propulsion has several advantages including increased freedom of placement of the engines, acoustical decoupling of the engines from the hull which makes the ship less noisy, and a reduction of weight and volume. Reducing acoustic signature is particularly important to naval vessels seeking to avoid detection and to cruise ships seeking to provide passengers with a pleasant voyage, but is of less benefit to cargo ships. Because ships require electricity even when not underway, having all of the engines produce electricity reduces the number of engines needed compared to more traditional arrangements in which one pool of engines provides electricity and another pool of engines provides propulsion, reducing capital costs and maintenance costs.