True power train optimization is holistic

Optimizing how something as powerful as vessels use of energy is a huge endeavor. Luckily, there are ways that support your work to achieve maximum efficiency, starting with the propeller.

What exactly leads to hydrodynamic propulsion efficiency? Instead of trying to optimize the individual components within a power train, our approach at Steerprop is to consider all critical components in a holistic manner. This includes frequency converters, generators and other power consumers. We also look at the cooling and auxiliary equipment, that add to the total cost, but are often forgotten.

We start with the propeller. This is where mechanical energy is converted to thrust to propel the vessel. If the propeller is inefficient – or the best propulsion efficiency is not achieved for every type of vessel operation – the rest of the power train needs to be overdimensioned to transmit the power required for different propulsion needs.

When the power train is overdimensioned, it is constantly operating in partial load mode. This means the best possible efficiency cannot be achieved through the power train.

Figure 1 shows how power train losses are born. By increasing efficiency on the right side, the losses on the left become automatically smaller as you move from right to left.

Figure 1. The basis of Steerprop’s efficiency doctrine: fuel to thrust chart.

To help shipowners and design offices analyze the efficiency of their entire drive train and reach the best possible performance at sea, we have created an approach that considers the holistic power train.

Together with partners in our ecosystem, we can deliver a complete power train that encompasses the propulsor drive solution, our propulsor and permanent magnet generators for efficient power distribution. With this solution, the vessel’s electrical power is created with permanent magnet variable-speed generators connected via inverters to a common DC link. The generators and power battery bank continuously operate in parallel. Energy storage systems, such as a battery, can be used for peak-shaving functionality. Other power sources can also be included.

When combining these with a careful design and thoughtful decision on the choice of propulsor, the efficiency of the whole propulsion line can improve significantly.

This energy optimization balancing act, when done right provides both short- and long-term benefits that include more profitability though greater hydrodynamic efficiency, less chance of disruptions such as surges and blackouts, lower and more predictable maintenance costs.

What’s more, an optimized solution offers the flexibility to use power input from different sources. This enables vessels to be designed using alternative power sources to reduce their carbon footprint and meet the increasingly more stringent CO2 regulations. 

About the author:

Juho Rekola works as Chief Design Engineer at Steerprop. He has been involved in marine technology from the beginning of his career, focusing on high-efficiency solutions for the industry.

Today, he works closely with electrical and hybrid power to bring the marine industry the best solutions for tackling climate change and rising operational costs. He feels that optimizing the entire power train holistically is the best way to achieve maximum efficiency.

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