The system measures the maximum usable energy from each component, also known as “available energy” or “exergy”, and calculates energy losses from the hull, propulsion power train, machinery and electrical systems. “We have revisited the basic and universal laws of thermodynamics to develop a methodology based on exergy,” explained Rune Torhaug, DNV GL strategic research and innovation director.
Although optimisation of individual components, or component packages such as complete propulsion systems, is nothing new in the shipping industry. However, the Cossmos system takes into account all the components on board the vessel, and optimises each, in what DNV GL senior research engineer George Dimopolous called “a holistic system” at a London conference.
Dimopolous cited the example of the highly-advanced hybrid platform supply vessel Viking Lady, asserting that an analysis of the vessel's fuel cell fuel pre-processing sub-system with the Cossmos system demonstrated the vessel could cut its energy losses by 50%. “The system that went aboard the Viking Lady was the first marine prototype,” Dimopolous explains.
Another case study was found in the fuel savings achieved on an existing waste heat recovery system - “a highly complex system with many components” - using the exergy-based method: “the true sources of useful energy losses were identified, revealing a picture far from self-evident. Subsequent optimisation in DNV GL Cossmos yielded an increase in fuel savings that halved the payback time of the system.”