Facing a growing demand for higher power plant efficiency, reduced fuel consumption and lower emission levels, the marine industry is increasingly applying concepts based on the use of hybrid power plants with energy storage systems.
With the availability of high-power and energy-dense batteries, such systems are now being applied as additional and/or alternative power source to diesel generator sets for on board electrical power plants. Load sharing has to be controlled, especially when the battery system is operating in parallel with other power sources.
Hybrid systems will reduce the energy consumption. When an offshore vessel is operating on dynamic positioning, using batteries for spinning reserve and peak shaving the fuel saving potential is significant. Ships may also use batteries for zero emission port call and port stay and thereby reduce the local emissions. Additional benefits are related to the reduction in the machinery maintenance cost and in lower noise and vibrations.
Ferries operating on short-distance routes, such as river and fjord crossing ferries, can operate fully battery driven with fast charging at both ends or only at one end, depending on the distance of the crossing. A hybrid version, where the vast majority of the energy is delivered by the batteries supported with onboard diesel or gas generators can also be considered.
The objective with using batteries may be:
- An energy backup source which is instantaneously available for the equipment essential to safety and operations, in case of main power supply interruption.
- Overall efficiency improvement by temporary storage of braking energy and smoothening of power consumption from power network in case of process dependent fast load fluctuation (peakshaving).
- Reducing frequency variation in network by avoiding fast load gradients of diesel generators.
- Low emission power plant by use of hybrid system; a combination of combustion engine and electrical energy storage system, or pure electrical power plant with electrical energy storage systems.