Fuel Savings with Danfoss Drives at the Heart of Electric Hybrid Ferries

Case story | VACON® NXP Liquid Cooled Drive

Fuel savings with Danfoss Drives at the heart of electric hybrid ferries

38% reduction in fuel consumption

drives.danfoss.com As part of its commitment to supporting Scotland’s target of achieving a reduction in environmentally damaging emissions by 2020, Caledonian Maritime Assets Limited (CMAL) has developed a groundbreaking diesel-electric hybrid propulsion system for its newest roll-on/roll-off (RORO) ferries. Equipped with variable speed drives from Danfoss, this system is achieving fuel savings of up to 38% with a commensurate reduction in emissions.

CMAL is the asset owner for the ferries greatest benefits would be an electric means that advantage can be taken of operated by CalMac Ferries Limited, the hybrid propulsion system. Essentially low-cost off-peak electricity. company that provides almost all of this comprises diesel engines driving the ferry services to Scotland’s offshore generator sets to produce power To turn this concept into reality in islands. Following confirmation of for electric motors that drive the the form of an innovative ferry with funding from the Scottish Government vessel’s propulsion units, just like a high-efficiency hybrid diesel-electric- and the European Regional conventional diesel-electric propulsion battery propulsion, CMAL worked with Development Fund in 2011, CMAL system. Ferguson Shipbuilders of Port Glasgow, embarked on a project to develop ship design specialists Seatec, and electric hybrid ferries that would create A key feature of the hybrid electrical specialists Tec-Source. The new benchmarks for fuel economy and arrangement, however, which sets it initial contract covered the design, low environmental impact. apart from traditional diesel-electric construction and fitting out of two systems, is that the propulsion motors ferries – the MV Hallaig, destined for After carrying out detailed evaluations can be powered not only from the use on the Sconser-Raasay route, and of several alternative approaches to the generator sets, but also from high- the MV Lochinvar, for the Tarbert to project, which included high-efficiency capacity energy storage batteries. In Portavadie route. diesel-mechanical and diesel-electric the CMAL vessels, these batteries are systems, the CMAL team concluded charged overnight from shore supplies that the solution that offered the while the vessels are in dock, which

2 Danfoss Drives · DKDD.PC.938.A1.02 The propulsion system devised for lithium-ion battery bank connected Because of the novelty of this the ferries has three diesel-driven to its DC link. This arrangement is application, extensive on-shore 368 kVA three-phase generator sets particularly convenient and cost- factory tests and trials were carried operating at 400 V, 50 Hz. These feed effective as, with NXP-series drives, out on the new drive system before the vessel’s main switchboard, which no additional electronics or control it was installed in the first vessel. This also has provision for connection of a circuitry is needed for the batteries. proved the concept and also enabled shore supply when the vessel is in port. potential problems to be identified The switchboard provides power for “We had many reasons for choosing and addressed at an early stage. In fact, two VACON® NXP-series liquid-cooled Danfoss drives for this flagship project,” system implementation proved to be variable speed drives from Danfoss. said John Salton, Fleet Manager and largely trouble-free, apart from some Each of the drives controls one of the Project Director at CMAL. “They’re minor teething problems encountered vessels’ two propulsion motors, which compact, which is very important on with the integration of the battery are rated 375 kW and have an operating board ship, and they combine excellent management systems. speed range of 0 to 615 rpm. The performance with an efficiency of motors drive Voith Schneider Propellers better than 98% and a power factor MV Hallaig, which was the first ferry to that combine propulsion and steering of 0.99. And, thanks to the previous incorporate the new environmentally in one unit. experience of our Director of Vessels, friendly hybrid drive system, Jim Anderson, we knew that VACON® accommodates 150 passengers and To make provision for pollution-free drives from Danfoss offer long, reliable 23 cars or two HGVs, and has a service operation of the propulsion motors operating lives in the toughest of speed of nine knots. It entered regular from batteries, each of the VACON® NXP shipboard environments. The drives are service in November 2013, and is variable speed drives has a 350 kWh also well priced.” delivering impressive results.

“We will certainly look at hybrid technology in any further new small vessels or upgrading existing vessels. And, of course, it depends for its success on the use of reliable, efficient and well-engineered components, which, as it happens, is a very good description of VACON® NXP drives from Danfoss.”

John Salton, Fleet Manager and Project Director, CMAL

Danfoss Drives · DKDD.PC.938.A1.02 3 “We now appreciate the benefits of hybrid technology protecting the environment and reducing operating costs.” John Salton Fleet Manager and Project Director CMAL

Against a target of 20% reduction in Just a year after the MV Hallaig fuel usage and emissions, the vessel is entered service, its sister ship, MV actually achieving a reduction in fuel Lochinvar, followed. This uses Danfoss consumption of 38%. It is anticipated equipment in the same configuration that this will lead to a decrease in CO₂ as that adopted for the MV Hallaig, emissions in excess of 5,500 tonnes and is consistently delivering over the lifetime of the vessel, with equally impressive fuel savings and a proportionately similar decrease in performance. sulfur and nitrogen oxide emissions. The success of these two vessels, Other benefits are that the new drive which have achieved or surpassed all system incorporates a high level of the ambitious targets that were set of redundancy, allowing the vessel for them, encouraged CMAL to order to continue to operate even if one a third new vessel, the MV Catriona, of its two drive systems fails. It can once again incorporating Danfoss also operate even if no diesel fuel technology. The third vessel was built is available and, indeed, it regularly in Port Glasgow by Ferguson Marine provides the Sunday service between Engineering. It was delivered to Raasay and Sconser running on battery CMAL in September 2016 and, after power alone, which means that the completing sea trials, it will sail on the level of emissions is zero. Claonaig to Lochranza crossing.