“The wireless charging industry is being driven by the automotive and consumer electronics industries,” says Ingve Sørfonn, Chief Expert Electrical & Automation, Wärtsilä Marine Solutions.
“How many power cords for different appliances have you had in your lifetime?” he asks. “They are often unique, incompatible, and fast become obsolete while gathering dust in a drawer. There is a strong demand across many industries to implement some kind of standard, and even do away with power cords altogether.”
Cutting the cord
Wireless charging eliminates the cable connection between the vessel and shore, thereby creating a safe and convenient means of charging the ship’s batteries. It also reduces maintenance, as wear and tear to physical connection lines is eliminated. The integrated Wärtsilä system is based on inductive power transfer and is capable of transferring more than a MW of electrical energy.
“Inductive charging uses an electro-magnetic field to transfer energy between two coils,” explains Sørfonn. “A sending induction coil is used to create an alternating electro-magnetic field, while a second induction coil takes the power from the electro-magnetic field and converts it back into electrical energy.”
The recent tests were carried out in Norwegian waters on the 85-metre-long ‘MF Folgefonn’, owned by Norled, one of Norway’s largest ferry operators. The project was partly funded by Innovation Norway, a Norwegian funding institution.
In practice, the system allows a hybrid-powered ferry to dock for a few minutes at a time while it is charged without the need for cables, the fitting of which is a challenging task in the harsh Norwegian seas. On the Folgefonn, the charging plates are approximately two square-metres in size and can send an electrical charge without physical contact over a distance of 40-50 centimetres. The physical stability of the ferry is accomplished by an innovative vacuum-mooring system developed by Cavotec.