Both Fredrik Ahlgren at the Kalmar Maritime Academy at the Linnaeus University and Francesco Baldi at the Department of Shipping and Marine Technology at the Chalmers University of Technology are interested in the efficiency of the ship as a whole and how to optimize it. They see the ship as one big energy system instead of focusing on the details.
This is a proven concept when looking at energy in power stations, but a relatively new thing in maritime research. Baldi has earlier developed a model for analyzing the energy loss in one of Laurin Maritime’s bunker ships. His research contributed to the improvement of the energy efficiency of the company’s fleet.
Ahlgren has been gathering data at the MS Birka Stockholm, a passenger ship that resides in Stockholm. They met at Francesco’s licentiate seminar in Gothenburg and they found their similarities.
The data that Ahlgren had, together with Baldi’s model, started the collaboration between the two.
- It is very rewarding to use the model on a passenger ship, Baldi says. The research becomes much more interesting since the energy system is much more complex.
They look at all the parts of the vessel that are using energy. The main engines, electric usage, thrusters, bow thrusters, boilers etcetera. The data is taken during one full year to see how much energy the ship uses. Since they already know how much fuel they put into the ship, now they check how much of the fuel the different parts of the ship use.
In the diagrams they use it is easy to see how much of the energy put in that goes to the different parts of the vessel. Much goes to propulsion and electricity, but a great deal goes to heat.
One aspect of the study that the researchers are particularly fond of is the concept of exergy.- Imagine having a large tank of water at 100 degree Celsius and a smaller tank with water at 1000 degree Celsius, both of different volumes but the same amount of energy. If you measure the energy you will get the same figure in Joule in both tanks. But still you can’t do much with the water in the large tank, whilst the water in the smaller tank can run an engine. The exergy concept considers how much mechanical work you get from the energy, says Ahlgren.