8 OCTOBER 2017 • FOGHORN FOGHORNFOCUS: MARINE PROPULSION energy density and the capability to recharge large amounts of power over a short period during unloading and loading of passengers. It is however important to distinguish between different Lithium-ion batteries. A mobile phone battery, an electric car battery, and a marine propulsion battery are all Lithium-ion, but they are manufactured in different ways. In a con- ventional Lithium-ion battery, a fire/meltdown can occur when one internal cell fails, starting a chain reaction to all the other cells around it. The marine batteries have a passive safety function that prevents this chain reaction from happening. Class societies have been heavily involved with battery suppliers in both developing and testing today’s marine propul- sion batteries. The solutions we now have are safer than 3-4 years ago with stricter requirements for type approved batteries, machinery space and moni- toring. The guidelines provided by class societies ensures a safe and reliable battery installation. Infrastructure: Electricity is an easily available power source in almost all areas where ferries operate. Even a weak electrical grid can be utilized as a power source with a shoreside battery pack, which is explained in detail in the charging section. LNG is one of the other options to create lower-emission propulsion systems with a reduced fuel cost compared to conventional diesel. Some of the biggest challenges for LNG are the infrastructure with supply, and the safety regulations from port authorities and Coast Guard. LNG must be purchased, liquefied, stored and supplied to the ferry, therefore demanding a large infrastructure in- vestment. This fuel complexity, LNG- safety aspects and uncertainties are all eliminated by choosing an all-electric system as the infrastructure of electric- ity are already there. Economic analysis shows that the long term operational benefit in only fuel savings for a LNG- HSC CODE ANNEX 10 ISO 9001:2008 Proud supplier of the New York Citywide Ferry Project solution are about the same 20-30% reduction as an all-electric system. This is based on the current and future an- ticipated development in the oil, gas and electricity price. The maintenance benefits are however significantly larger for an electric solution as there are no engines and LNG fuel-arrange- ment to maintain. The electric batteries and converters are static components which require less maintenance, giving an estimated 50% reduction in operational cost compared to a con- ventional diesel. Charging: Lithium- ion batteries can be charged quickly, but on many routes the desti- nation at each end are served by a rather weak electrical grid. Therefore, recharging the ferry’s battery, direct from the main supply during the short turnaround time, would be an unac- ceptable load on the grid. To overcome this challenge additional battery packs can be installed at the terminals ashore. When the ferry docks, its battery will be rapidly topped up by drawing power from the shore batteries. Those batteries can in turn be recharged from the grid at a slower rate before the ferry returns, thereby reducing the power spikes on the grid.Ahigh peak power demand to the grid means a higher cost of energy as the grid owner must charge more per kWh to be able to operate a reliable power grid. A shore-side battery bank will then reduce the operational cost as the maximum power demand is reduced, and it also supports in strengthening the local grid by giving it a constant load. Connecting the charging equipment when docking is an automated system that does not require any breakers or switches to be operated by the crew. The newest concept in charging are even performed wireless through induction technology combined with vacuum mooring. Comfort: The first large all-electric car ferry “Ampere” has already been operating in Norway for over two Figure 2 - The SAVeCHARGE system illustrated on a double-ended ferry.