MV Catriona shares certain similarities with other diesel-electric vessels, in so much as it is powered by three small diesel generator sets (in this case Volvo Marine D13 MGs) that feed into a 400V switchboard that supplies power to two 375kW permanent magnet motors that turn two Voith 16 R5 EC/90-1 propellers. However, the key difference here is that the Catriona’s bank of lithium-ion batteries works in tandem with the generators, making the propulsion system cleaner and quieter, and cheaper to operate and maintain.
“The hybrid aspect – the batteries – is an energy reserve to reduce fuel consumption,” explains Alexander Breijs, from RH Marine (formerly Imtech Marine), which designed MV Catriona. “The way they’re used is very important. We try to keep the battery on as long as possible so that the energy is never used all at once.”
Breijs says that the power output form the batteries is controlled by an automated system that feeds the right amount of energy into the system to minimize fuel consumption. “Power output from the batteries is based on all sorts of data, such as the weather conditions and so forth. The idea is to make the batteries last from the first to the last voyage every day.”