Hybrid Systems

The idea behind hybrid systems

Conventionally propulsion diesel engines on all types of vessel are specified to deliver sufficient power to realise the required top speed. However, in most cases the vessel operates at top speed for only short periods and for the rest of the time runs at a much slower cruising speed for reasons of comfort and fuel economy. This means that during these periods the diesel engine is only partially loaded and is therefore not operating at its optimal efficiency. This results in higher emissions, increased engine wear and maintenance, and reduced fuel efficiency. A hybrid system, however, maintains full load on the engine and utilises the unused capacity to generate electric energy and store this in batteries for later use. By adding additional load to the diesel it runs at an optimal setting, and is cleaner and more efficient.

The stored electrical energy can then be used later as power for auxiliary systems or electric propulsion at low speed, or to boost the diesel engine when top speed is required. The combination of diesel and electric power usually means that the diesel engine can be smaller than otherwise, which further improves efficiency and reduces volume, weight and investment costs. The potential advantages of hybrid systems are particularly apparent for boats that operate at a wide variety of speeds, such as yachts, patrol vessels and ferries.

Hybrid propulsion system
The term hybrid propulsion system refers to a system that has two independent drive systems for the propulsion. In most cases these are a diesel engine together with an electric motor.

Hybrid power system
The main characteristic of a hybrid power system is that it uses more than one energy source to generate power, e.g. diesel fuel, electric shore power, wind power, solar power, hydrogen or power generated by the yacht’s propeller while sailing. The electric power can be stored in batteries or in a supercapacitor or be utilized instantly by electrical equipment.