Battery cooling for a revolutionary hybrid vessel

Adwatec was part of a completely new kind of project within the marine industry when the company won a contract and was to deliver the solution that will cool down the batteries of the world’s largest plug-in hybrid vessel.

Key Benefits of Adwatec’s cooling solution:

  • High-power cooling in compact size
  • Fast delivery
  • Easy commissioning

Ulstein is a modern shipyard that builds vessels for offshore wind, exploration cruise, RoPax, and offshore oil and gas. It recently delivered the world’s largest plug-in hybrid vessel, the Color Hybrid, for Color Line. The 160-meter long ferry, servicing between Sandefjord in Norway and Strömstad in Sweden, can accommodate 2,000 passengers and 500 cars.

The challenges and objectives

The ground-breaking vessel was to be equipped with four battery stacks consisting of several battery cells that will offer approximately 5 MWh and can operate for up to 60 minutes at speeds up to 12k. For a battery-powered vessel of this size, highly effective liquid cooling is a prerequisite.

As a Passenger/RoRo Ship, the Color Hybrid is subject to strict safety and quality regulations. It is important that the battery cells remain at as steady temperature as possible. To make sure the cooling is efficient enough for such a large battery pack, the cooling stations needed to have a rather high coolant flow rate. At the same time, the cooling system pressure was not allowed to rise too much even in case of a leak and an automatic closing of the coolant lines in the battery system. Also, the dimensions and footprint of the cooling system were to be kept as small as possible, while also maintaining the easy start-up and serviceability. These demands created some special challenges in the system design.  

Picture of Ulstein Color Hybrid vessel

The solution

Adwatec is experienced in providing cooling solutions for power electronics in marine application like drives and propulsion, with dozens of deliveries in vessels sailing all over the world.

For the Color Hybrid, Adwatec provided two C series water cooling stations, one on both sides of the ship. The stations are designed specifically according to the tough conditions at high seas and limited space available in ships.

The cooling stations were equipped with two pumps. One is in operation, and in case of a pump failure, the redundant pump steps in. Furthermore, the standby pump is automatically switched as the duty pump every two weeks to ensure both pumps remain functional. To gain a high enough flow rate to supply the right temperature cooling water for the large number of battery cells, rather large pumps were selected. To control the flow rate and to keep the pressure from rising in case a leak is detected in the batteries, the stations were equipped with frequency converters and a state-of-the-art control system.

On-site commissioning support and user training were also included in the delivery.


During the project, some rather significant modifications were made to the project scope as well as to the battery system initial data. Thanks to Adwatec’s agile engineering team and experience in the marine industry, the new requirements were applied without a substantial delivery delay. The cooling system was commissioned on time.

The need for electrification of marine vessels is growing. The pioneering Color Line project introduces new technology in shipbuilding. The model created in this project will be easy to duplicate in building new hybrid ships.

Need help with your project?

Please contact our Marine industry experts for your water cooling needs

Ismo Lehtonen
Sales and Marketing Director

+358 40 669 2220