SDU to identify energy savings across ship systems

A pump that uses less electricity may seem an obvious route to a more energy-efficient ship. Yet changing how the pump operates can also affect cooling-water temperatures, engine efficiency and the waste heat available for use elsewhere on board.

Energy savings therefore need to be assessed across the entire vessel. This is the starting point for STERN, a research project in which SDU and maritime partners will develop a modelling framework to map ship energy flows and investigate opportunities for improvement.

“The best solution for an individual component is not necessarily the best solution for the whole ship. The systems interact, and we need to account for those interactions when assessing opportunities to save energy,” say Baris Burak Kanbur and Marie Lützen from SDU Mechanical Engineering at the Department of Mechanical and Electrical Engineering.

A pump can affect the entire energy balance

An example considered during the preparation of the project illustrates the difference. In this case, reducing the capacity of a cooling-water pump corresponded to a fuel-equivalent saving of around 0.25 per cent. A system-level change in cooling-water operation delivered roughly twice that benefit.

The example is not a finding from the forthcoming project, but it illustrates why the researchers will examine interactions between components. Changes in cooling-water temperature can influence both engine fuel consumption and opportunities to recover heat. The pump’s electricity consumption is therefore only one part of the overall calculation.

“Energy-efficiency measures are often assessed separately for a pump, a cooling system or a heat-recovery unit. With STERN, we want to establish a more realistic basis for assessing what those changes mean for the ship’s overall energy consumption,” says Baris Burak Kanbur.

Helping shipping companies assess upgrades

The researchers will develop a detailed modelling framework based on thermodynamics, the study of energy and its conversion. It will map where energy is produced, used, lost and potentially recovered under different operating conditions.

This matters because energy requirements change depending on whether a vessel is sailing, manoeuvring or in port. An upgrade therefore needs to be assessed against how the ship is actually operated.

The aim is to give shipping companies a stronger basis for selecting retrofits and upgrades for existing vessels. The framework will allow different options to be compared and help identify those that warrant further technical and economic investigation.

Equipment suppliers will likewise be able to assess how their pumps, cooling systems and heat-recovery technologies influence the performance of the complete vessel.

“We want to make it more transparent where energy is lost, which energy streams can be recovered and which improvements deserve further investigation. In the longer term, the framework could form the basis for more advanced decision-support tools and fleet-level analysis,” says Baris Burak Kanbur.

Savings depend on the individual vessel

The scale of the potential savings will emerge from analyses of the selected vessels and their operating profiles. According to Baris Burak Kanbur, existing maritime studies indicate that individual efficiency measures often deliver savings of a few per cent, while well-selected combinations can potentially achieve double-digit improvements.

He also points to industry assessments suggesting that, in suitable cases, energy-efficiency measures can reduce fuel consumption and emissions by up to around 15–20 per cent.

These figures are not a prediction of what STERN will achieve. The project will investigate how much of that potential is realistically achievable for the selected vessels when interactions between their systems are taken into account.

STERN will run from 2027 to 2028 with support from the Danish Maritime Fund. The collaboration brings together SDU, Fredericia Maskinmesterskole, Hafnia, DESMI and ShippingLab. The project team also welcomes contributions from other stakeholders in the Danish maritime sector throughout the project.

“We want to develop the framework in close collaboration with industry, so that it is both scientifically robust and practically relevant,” says Baris Burak Kanbur.