Drives & Controls September 2022

28 n ENERGY EFFICIENCY September 2022 www.drivesncontrols.com High-efficiency electric ferry sets world distance record E arlier this year, an battery-powered ferry called Ellen set a newworld record of 92km for the distance travelled by an all-electric vehicle and passenger ferry on a single battery charge. Normally, the vessel travels 40km between the Danish islands of Ærø and Als – the longest purely electric ferry route in the world. Ellen, which has been plying this route since 2019, has operating costs that are at 24% lower than those of a new diesel ferry. The payback time for the extra capital cost is reckoned to be 5-8 years, with a cost saving over the ferry’s expected lifetime of €2m – and these figures were calculated before this year’s massive energy price hikes. The 60m-long ferry travels at speeds of 13- 15.5 knots – faster than its diesel predecessor – and can carry up to 198 passengers and 31 cars (or five trucks). It can complete seven round- trips between the islands each day. Ellen is cutting CO 2 emissions by 2,520 tonnes of per year compared to the best technological alternatives, and by almost 4,000 tonnes compared to existing diesel ferries. The ferry’s battery is charged on the island of Ærø, which gets all of its electricity fromwind power. Even if Ellen was supplied with an average Danish energy mix, it would still cut carbon emissions by around 2,010 tonnes per year, as well as eliminating 2.5 tonnes of particulates and 1.4 tonnes of sulphur dioxide emissions. The purpose-designed vessel is long and narrow, and shaped more like a traditional sailing ship than a conventional ferry. To reduce weight and to avoid the need for elevators, the car deck is open and the passenger deck is close to the waterline. Extensive use was made of lightweight materials, with the bridge being constructed of aluminium, and the use of steel restricted to the specially designed hull. The ferry’s electrical system has an efficiency of 87.4% – more than twice as much as the propulsion system of a traditional diesel ferry The drivetrain, supplied by Danfoss Editron, consists of two 750kW propulsion motors and two 250kW thruster motors – all synchronous reluctance assisted permanent magnet machines controlled by DC/AC inverters. The drivetrain system also manages automated power and load control on the vessel. Ellen has one of the largest battery packs in maritime use, with a capacity of 4.3MWh. This pack, supplied by Leclanché, consists of high- energy lithium-ion cells with built-in safety functions including, including a fire suppression system that protects it against external hazards. Unlike hybrid-electric ferries, there is no emergency back-up generator on board. The ferry was part-funded by an EU- backed project called E-Ferry that addresses the urgent need for Europe to cut emissions and air pollution from waterborne transport. Shipping accounts for about 13% of the EU transport sector’s greenhouse gas (GHG) emissions and the Commission is hoping to have 100 or more electric ferries in service by 2030, thus saving roughly 100,000-300,000 tonnes of CO 2 emissions annually. There are almost 700 ferries operating in Europe that could be replaced by electric vessels similar to Ellen. The EU has reviewed the performance of the electric ferry during its first two years of service and found that Ellen delivered“exceptional” results, with significant immediate and potential long-term impacts. These include applying an extremely energy-efficient design and demonstrating that a fully-electric, emission-free, medium-sized ferries can operate successfully over longer distances than previously achieved. Globally, more than a quarter (27%) of all energy-related CO 2 emissions come from transport. According to the International Maritime Organisation (IMO), the shipping industry is responsible for about 2.5% of the world’s GHG emissions. The IMO wants to cut shipping GHG emissions by at least 40% from their 2008 levels by the end of 2030. Each year, the world’s ferries transport 4.27 billion passengers and 373 million vehicles, and are significant carbon emitters. They often operate close to cities where they add to already critical air pollution levels The carbon footprint of these ferries depends on their age and efficiency. According to a report by the Intergovernmental Panel on Climate Change (IPCC), the average carbon footprint for a passenger travelling by ferry is 15–150 grams of CO 2 per km, compared to 90– 250g for passengers travelling by aircraft. Electrifying maritime transport is an obvious way to cut greenhouse gas emissions. The solutions are there both to build new electric ferries and to electrify existing ferries with the potential to cut carbon emissions in lakes, cities and straits around the world. n An all-electric ferry operating in Denmark is achieving operating costs that are at 24% lower than those of a new diesel ferry. Its electrical system has an efficiency of 87.4% – more than twice as much as a diesel ferry’s propulsion system.