Figure 3. The three main electricity producing methods have their specific qualities.
3. ENGINE QUALITIES
In this context machinery would maybe be a better denomination than engine. Anyhow a tremendous development has taken place when it comes to the nature of the ships' propulsion machinery - from nearly always mechanically coupled Heavy Fuel Diesel Engines in the beginning of the 80:ies (for merchant ships) to today's multifuel Combined Cycle electricity producing configurations. Figure 4 below tries to illustrate the development going on.
The most exciting prospect is indeed the possibility of hydrogen coming on board. There are a lot of things going on when it comes to hydrogen as fuel. As well known all major automakers have hydrogen operated fuel cell cars under development. A commercial success requires that the fuel infrastructure is ensured. If - or rather when - this is the case the propulsion market is open for one of its greatest opportunities. As shown before in Figure 3 the natural energy converter for hydrogen is the fuel cell. The main obstacles for use of fuel cells for ships' propulsion are size and reliability. However, we do not necessary have to wait for fuel cells until we can utilise hydrogen on board.
Figure 4. The development of the ships' machinery as experienced and anticipated.