KOTUG puts the first European ‘Hybrid’ into service

Known as the E-KOTUG, the vessel is a carefully planned conversion of a recent new addition to the company’s fleet, completed in 2010 to one of the latest Rotor Tug designs. A vessel of 32m in length, the tug is powered by the unique Rotor Tug triple unit propulsion system, comprising three main engines producing a total of 6,884,bhp to give a maximum bollard pull of 85 tonnes towing ahead, astern or sideways.

The conversion of RT Adriaan into a fully functioning hybrid tug in a little over three months is a success story in its own right. On 14 November 2011 the tug was withdrawn from service in the Port of Rotterdam and entered the dry dock at the Padmos Stellendam shipyard, to be retrofitted with a XeroPoint Hybrid Propulsion System designed by Aspin Kemp & Associates (AKA) of Canada. During the conversion of its patented and certified hybrid system, KOTUG was encouraged and inspired by the hybrid tugs of Foss Maritime, California, which also have the AKA power management systems.

The conversion process included installing electric motor/generators in the driveline of each of the unique triple propulsion systems. A Lithium Polymer battery pack was installed in the tug along with the hybrid power management switchboard and the necessary connections were made with the existing auxiliary generators. The batteries, supplied by the Canadian specialist Corvus Energy, have ten times the capacity and lifespan of conventional lead acid batteries.

RT Adriaan returned to service in Rotterdam early in March resplendent in its new E-KOTUG livery. The process of optimising the power management system continues, to ensure that the vessel operates efficiently in each of its hybrid modes.

Commenting on the tug’s initial performance, Daan Merkelbach, KOTUG International’s Manager of Nautical & QHSE said, “We are happy with the first results of the E-KOTUG after its conversion into a hybrid Rotor Tug. In partnership with AKA Canada, supplier of the Xeropoint Hybrid Propulsion System, an extremely environmentally friendly and fuel-saving tugboat was developed.”

Retrofitting an almost new Rotor Tug with this system ensures that the electric motors and diesel engines, generators and environmentally friendly batteries will be controlled efficiently.

KOTUG believes that the hybrid option is the best solution for harbour tugs, due to its highly variable duty cycle.

In a conventional diesel powered tug, the main engines and the diesel driven auxiliary generators are rarely operating in their most efficient mode, which is when they are heavily loaded. Studies have shown that during harbour towage, 100% of full load (maximum bollard pull) on the main engines is used for only 2% of their operating life, leading to very poor fuel consumption and excessive exhaust emissions. Much the same can be said for the auxiliary engines that spend much of their time idling or lightly loaded.

Aboard the E-KOTUG RT Adriaan the situation is quite different:

• At low speeds travelling between jobs (about 4.5 knots), while maintaining station or on standby duties, the batteries permit the vessel to be operated in noiseless zero emissions mode, with no generating machinery running.

• As the speed or load is increased one or both auxiliary generators will come on line running at their most efficient loading. Any surplus current is used for battery charging. The main engines will start only when demands are made for high bollard pull situations.

• There is a 50% reduction in harmful emissions of CO2, NOxm PM2.5 and soot. With Xeropoint Hybrid technology, engines run at or near best efficiency and only when needed. Lower fuel usage and cleaner combustion contribute to reducing harmful emissions.

• Improved fuel economy: The RotorTug’s main engines are designed for a high output. Because Hybrid technology shares the propulsion load between diesel and electrical sources, it means no unnecessary idling.

• Maintenance savings: Hybrid technology means minimized engine use and more time between engine overhauls and oil and filter changes.

• Healthy Workplace: Hybrid technology allows engines to be shut down at sea. Fast switching from hybrid modes with electrical engines to conventional modes with diesel engines is possible. For low power operations, E-KOTUG is fully operable on battery power alone.

• The Xeropoint power management system is the key to the success of this type of hybrid propulsion system. It automatically provides the power necessary to perform all of the tug’s normal functions, utilising the batteries, auxiliary generators and main engines as required in a ‘step-less’ manner requiring little or no additional effort from the tugmaster.

• The vessel can always be operated as a conventional Rotor Tug if required.

The system design increases redundancy and reliability.

KOTUG and its employees have an active ‘Go Green’ policy, seeing sustainability and innovation as a challenge, The E-KOTUG is a demonstration of the company’s ongoing commitment to the environment and lowering emissions. “Our company is committed to hybrid technology. To be a leader for our community and to be good for the environment means for us a challenge”, said Ard-Jan Kooren, CEO van KOTUG International.

KOTUG collaborates with other parties who are seeking sustainability in the maritime sector. With the business network Deltalinqs Energy Forum, KOTUG is an ambassador for promoting the sustainable inland shipping. A Letter of Cooperation has been signed with the Municipality of Rotterdam and the Rotterdam Climate Initiative.

The E-KOTUG RT Adriaan will be formally launched sometime in April/May 2012.