First Inline Shaft Generator Retrofit Done by Wärtsilä and Berge Bulk

first inline generator retrofit
Delivered in 2017 Berge Toubkal became the first vessel retrofitted with the generator systems to improve performance (Berge Bulk file photo)

Published Feb 7, 2023 7:08 PM by The Maritime Executive

Ship operators are increasingly looking for new means of improving the operating efficiency for in-service vessels as new regulations such as the IMO’s EEXI and CII going into effect and the EU’s carbon emission fees loom over the industry. In a first for the maritime industry, Wartsila reports it has been able to successfully retrofit an energy-saving inline generator system to a six-year-old bulk carrier in an effort that is expected to will improve the vessel’s Energy Efficiency Existing Ship Index (EEXI) while reducing overall carbon footprint.

Shaft generator systems have grown in popularity with Wartsila for example reporting has delivered over 650 of the systems. They however are less common for bulk carriers which Wartsila reporting only 17 of its deliveries go to this category while 40 percent go for containerships. Until now, shipowners also have not retrofitted the system to an in-service vessel.

Shaft generator systems onboard ships are driven by the main engine to supply power to the mains, thus saving fuel and emissions. They are sized to eliminate the need to operate auxiliary engines while at sea. While such systems, also referred to as Power Take-Off (PTO) systems, are today’s standard installations on newbuild vessels, large inline versions with the generator sitting directly on the propeller shaft and turning at 50 to 100 rpm have never before been retrofitted.

“Berge Bulk made an industry commitment to go carbon neutral well before the IMO’s plan, and we are installing now the latest fuel-saving technologies, like shaft generators, air lubrication, or wind propulsion on our vessels,” says Paolo Tonon, Berge Bulk’s Technical Director. “Wärtsilä has a proven track record and is one of the market leaders in shaft generator systems and electrical integration.”


Berge ordered the retrofit adding both the inline generator and air lubrication to improve the vessel's performance (Wärtsilä)


The vessel selected for the first retrofit was Berge Bulk’s Berge Toubkal, a cape-size bulk carrier owned by the Singapore-based shipping company. The vessel is 984 feet in length and 211,000 dwt. Delivered to Berge Bulk in 2017, the company highlighted that she was one of the largest bulk carriers in the world. She was equipped with an efficient super-long stroke main engine, optimized for low-fuel consumption. Other special features included the installation of exhaust gas boilers for the generators and an upgraded anti-fouling system.

“Berge Bulk is one of the front runners in shipping’s transition to decarbonized operations, and we are proud to support them in this,” said Torsten Büssow, Director for Ship Electrification at Wärtsilä. “Wärtsilä is actively working on the development of new technologies that can be integrated into existing vessel systems to make their operations cleaner and more economical.” 

The Berge Toubkal retrofit was completed in late 2022, following ten months of preparation time according to Wärtsilä. The retrofitted shaft generator will also provide power to an air lubrication system installed at the same time. The system includes a Wärtsilä control system, as well as a converter to allow the generator to operate over a broad span of rpm. The existing intermediate shaft and bearings were replaced to accommodate the increased weight.

The bulker is back in service currently sailing between China and Australia.