Marine networks are experiencing an expanding role in the global transportation of goods and are demanding an increasing energy resource while being a contributor to climate change-related emissions. This paper investigates the potential of hybrid energy source systems (HESS) that employ energy storage devices and peak power devices in a combination that is capable of providing average energy while recovering and managing the electrical power system transients. Moreover, the contribution of the energy storage device, or power buffer, may result in reduced rating for the main energy source, reducing system mass and volume while improving energy conversion efficiency. Crane system power flow is analyzed and energy saving calculated for a representative load cycle. Experimentally validated power-train models are presented, control strategies developed, and alternative energy/power storage devices in single and HESS configurations analyzed. While many papers discuss similar concepts for road vehicles, the application to port cranes has not been reported previously. Similarly, detailed design encompassing system losses, thermal management, component mass, volume, and system dynamic operation have not been reported previously. This paper develops procedures for the design of battery alone and battery-supercapacitor HESS that are shown to be different and independent of the optimization method chosen.