A system for providing rechargeable energy onboard a marine vessel, the system including an energy storage device aboard a marine vessel, an interface device connected to the energy storage device configured to provide power to charge the energy storage device and/or provide power from the energy storage device to the marine vessel, a converter device connected to the interface device configured to convert power to alternating current and/or direct current, depending on an intended purpose of the system, and a conditioning device connected to the converter device, interface device, and/or energy storage device, and configured to establish an acceptable power level and/or an acceptable power waveform. The energy storage device is configured to provide power to the marine vessel to reduce fuel used, emission output, and/or mechanical noise output. A method for providing rechargeable energy onboard a marine vessel is further disclosed.