Who’s betting on electric ships
Hybrid and electric propulsion on board of yachts
If after an uncertain beginning hybrid and/or electric propulsion in the automotive world has now become a consolidated reality, which is conquering for ever larger market segments of the industry as years go by. When it comes to the yachting world we’re still ‘pioneering’. It is a known fact however that several shipyards began to tread that path several years ago; sometimes with great determination and some conviction and at times only to follow the trendy “green” course to which they’re undeniably fond of. Up until now we can safely admit, it has all boiled down to interesting attempts, which have been limited by a technology that needs to progress further and a market which is still unprepared. What’s more the high costs involved in adopting this kind of propulsion or power house as it were, which still offers little capability to effectively run electrical power efficiently more than the mechanical one, together with the high costs of battery banks and the considerable volume of space and weight they absorb have no doubt been a further limiting factor to the development of on board hybrid / electric systems. All things considered; there has been scarce information technology which seen from users’ view points, all too often was translated in extra complications and not as a real advantage. Today, probably time is ripe and may well give way to greater understanding and diffusion of hybrid and /or electric power houses in yachting, if not else where, but certainly yes in large superyachts. Infact if from a purely technical perspective there are no limits at either end of the yacht size scale, but the added costs involved in going for hybrid and/or electric propulsion are such, which are not commeasurable to engine power installed, they become too heavy to bear in proprtion and limit their use in smaller yachts specially when taking into account their effective seasonal use. Consequently the number of shipyards producing very large yachts are betting on the undoubted advantages that hybrid and/or electric propulsion offer potentially speaking as a way of renewing their offer (see table 1). Some of the major shipyards in favour of electric ships and their point of view can be seen in the following pages:
SANLORENZO YACHT (sourcetilli Antonelli, Sanlorenzo SPA)
“E Motion”, for such is the name of Sanlorenzo’s new yachts which applies to the shipyard’s entire range comprising both the displacing steel built yachts which will adopt a diesel / electric solution while the fast planing GRP built ones will be powered by hybrid power houses.the ELECTRIC AND HYBRID systems can produce propulsive energy, as well as whatever else is needed on board.
In detail: ❑ ELECTRIC Means the system by which the propeller is made to rotate via an electric engine ‘fueled’ by gen. sets passing energy through to lithium batteries or by a mix of the two accordingly. In the specifics the diesel /electric system installed on board of Sanlorenzo yachts is made up of four gen. sets or more working at variable speed or VSG (Variable Speed Generator) according to the yacht size and the performance requested. In this way traditional gen.sets disappear.
De facto on board generators represent an electricity board/ power house from which diverse sized cables supply energy to electrically operated i PODS which house the electric engines inside their casing directly connecting to the propellers. This translates into a series of advantages in terms of decibels and limited vibration when conventional drive shafts have been eliminated. In this way the new compact power house by comparison with a conventional engine room can also be installed in a variety of adequate places. For example, on the Sanlorenzo 500EXP E Motion which will be built in the imminent future it will be possible to view the engine room by walking along an internal passageway with tempered glass walls (“Art Gallery Engine Room”) on the way from the main living area to the beach club aft in the stern.
Finally lithium ion batteries of different sizes will stock the energy needed accordingly so as to ensure ZEM zero emission mode when lying to an anchor, or when cruising at night or in marine parks.
HYBRID ❑ Is the propulsive system which depends mainly on diesel engines, while the electric ones deliver additional power when requested. This system leaves you free to choose the best solution, or a mix: diesel engines and/ or electric ones to reach the objective which can be several or one of several objectives: top speed, maximum comfort, or reduced consumption. The hybrid system installed on Sanlorenzo’s smaller units in GRP in fact deploys smaller less powerful diesels than larger classic ones, which translates into less fuel consumption when the yacht is travelling at cruising speed. To reach best performance the ‘auxiliaries’ are called to perform as well (gen. sets and batteries) with the diesels. While just cruising slow the electric engines can be also exploited as gen. sets and/or to recharge batteries.
TANKOA YACHTS (source Andrea Parodi, Head of Technical Department Tankoa Yachts S.P.A.)
Tankoa Yachts is currently handling the second hybrid vessel of the S500 series, it is the S502 Elettra. This yacht’s hull is perfect to host a hybrid system as she possesses much reduced drag to speeds up to 12 knots. Among a variety of solutions in terms of drive units and hybrids. Tankoa’s choice for Elettra fell on a so called parallel E-motion system fine tuned with valuable input from Diesel Center. We’re looking at a plant comprising a main diesel engine(mtu 8V400M54 895kw@1800 rpm ) and a ZF reducer permanent magnet synchronous electric motor of 300 KW. This technology means you can reduce the length of the electric motor, increasing the width and thereby optimising needed space in the engine room. An electric/mechanical clutch disconnects the main engine accordingly from the drive unit. The electric motor can, according to the choices made remain inert, but producing electric energy when dragged by the main engine, rotates the the propeller with the main engine disconnected or supplies added power as need be to further increase speed. Two variable speed MASE gen. sets with a maximum output of 250 KW each provide the necessary energy. To stock energy, lithium /AKASOL) batteries each one equal to 24.4 KWH with a peak of 150 KW and a nominal tension of 661V are used where the number of batteries determines the range in terms of propulsion in ZEM mode as well as the duration expressed in hours and minutes of the time spent lying to an anchor with gen. sets switched off. The main unit defined as DC BUS receives and supplies electric current to peripheral units and to the services’ mother board. Simplyfying the concept: all the available energy from the gen.sets, from the batteries, and from the electric motors enter the DCBUS and from here the energy is distributed accordingly. The power management System, via PLC controls and monitors the set parameters of the flow. The flow between electric motors, batteries and gen.sets is DC exiting at 780V. At the services control panel it is transformed in triple phase 380 V in AC. The integrated monitoring and control system allows you to select different modes of propulsion directly from the helm controls station thanks to a touch screen.tankoa’s Diesel Center parallel hybrid propulsion main feature is made up of the power house comprising the electric motor – reducer, the configuration of which is mechanical and highly simplified. The mechanic electric clutch engages onto the main engine and disconnects only in modes 1 and 2 or when in batteries only mode.this means that in any anomalous situation, which is nevertheless improbable, the S502H becomes a traditional yacht propelled by the main diesels installed. As mentioned, propulsion modes can be selected accordingly as follows:
1 - Diesel – electric mode 2 - Hybrid mode 3 - Traditional mode 4 - Booster mode 5 - ZEM mode “zero emission” (only electric). Current and available propulsion modes have been detailed in the figures, with the exception of the ZEM which foresees
the exploitation of battery power alone. This one is in absolute terms the most silent in terms of decibels and the most ecological. Maximum speed and range are dependant on the number of batteries. In this case the owner has to decide how many and where to place them according to the technical spaces available. Eight batteries would allow a given yacht to cruise at 5 knots for about two and a half hours or the same number of batteries would allow the yacht to lie to an anchor in a bay with gen. sets switched off for about eight hours.
ROSSINAVI (source Gabriele Zucconi, Technical department- Rossinavi)
Rossinavi has taken on the electric ship challenge in more ways than one. We’re also building two diesel-electric units. In fact in both of these cases our clients have opted (due to weight/ cost/ space reasons) not to install batteries just to enjoy and guarantee few hours in ZEM, (zero emission mode)
The two units are the following:
Construction FR.032 “ENDEAVOUR 2”,already delivered ❑ and equipped with ‘fixed’ frequency gen.sets and PODS.
Construction FR.037 “POLARIS 2”, in construction ❑ equipped with variable frequency gen. sets and PODS with tractor propellers and feathering blades.
As is clearly visible notwithstanding the fact that both units have been installed with a diesel –electric system, the systems differ from one another. In fact one of the great advantages diesel electric solutions possess, is in the multiple possibilities they can offer. More especially today thanks to notable improvements and to the development of the technology now available, In other words the capacity to use inverters and permanent magnet synchronous generators which are also currrently largely exploited for trains on rails. As a mere example let’s assume a given ship requires 1000KW to work, the energy required can be entrusted to a single gen. set capable of the same output or to ten gen. sets with an output of 100 KW each. However it is worth noting that any intermediate solution is equally possible. The factors determining the choice are then in proportion to the power needed (for example when cruising as opposed to full speed ahead), and also the power required by the services or “hotel” ( mostly when lying to an anchor as the main engines are “off”). At this point the choice to be made has to be according to the requirements to be fulfilled which will determine the system’s characteristics. For example the requests for construction FR.032 “ENDEAVOUR 2, were the following:
❑ A ship capable of cruising the world (no limits – unrestricted)
❑ Top speed not less than 16 knots;
❑ A recommended cruising speed of 12 knots attainable with one main engine linked to two propellers.
❑ Maximum comfort in terms of noise levels and vibration.
❑ Excellent integrated manoeuvrability given by dynamic positioning.
❑ Electric plants (gen. sets, inverters, motors, ECM filters etc) renowned for quality and availability.
❑ Flexibility and user friendly inutitive PMS (Power Management Sysytem).
On the basis of these requirements, the choice went to a diesel-electric system equipped with five gen. sets ( two main ones of 952 KWE each and three auxiliary ones with an output of 82 KWE each) and two Rolls Royce PODS with counter-rotating propellers to deliver the requested manoeuvrability and dynamic positioning wanted. The yacht can reach a top speed exceeding 16 knots with both main gen. sets at full capacity and one or two of the auxiliaries to fulfil “hotel” requirements. A cruising speed (in ECO mode requests 600 KWE) of 11 – 12 knots requires only a single gen. set. Furthermore, when the yacht is lying to an anchor or berthed in a marina with no shore line one of the three gen, sets may suffice (possibly two depending on loads) to fulfil “hotel” requirements. Marine Automation from Viareggio contributed in setting up this AC system (60 Hz frequency) which transits from a
PMS (Power Management System) panel. Another feature is in the exploitation of two Tema produced permanent magnetic electric motors directly coupled to Rolls Royce Pods. For construction FR.037 “POLARIS 2”, a diesel-electric system was chosen. This one is made up of 3 CAT C32 gen. sets with an output of 1080 KW each with variable rpm and frequency and a further two CAT C9.3 gen. sets of 355 KW with variable rpm and frequency. These deliver energy to DC panels via inverters which in turn supply hotel requirements as well as two variable frequency Marelli electric motors of 1600 KW connected to 360° rotating Pods. The use of variable frequency means that when cruising at about 15 knots or in Eco mode at about 12 knots, gen. sets function responding to effective loads thus engendering lower fuel consumption.
AZIMUT BENETTI (source Gilberto Francesini, R&D team AZIMUT BENETTI Group)
Azimut Benetti Group was among the first to invest in R&D with a view to build yachts equipped with hybrid diesel-electric power houses. Three different innovative solutions have been developed in recent years. Each one serves a specific typology of yacht with its own features. Let’s take a closer look.
Azimut Magellano 50 and “EASY HYBRID” system (completion in summer of 2012)
Magellano 50, was equipped with traditional diesel engines side by side with a full hybrid system which envisages the same performance delivered by the conventionally propelled model but also to cruise up to about 6 knots in electric mode. “EASY HYBRID” – the system’s name was developed at Az-
imut Benetti Group’s R&D section with input from RTN equipped with an electric Auxilia 19 Kw motor installed onto each one of the two shafts in line. The yacht can cruise on main diesels only, on a diesel-electric combination or solely on 28 KWH batteries via the two electric motors which allow you to cruise along when the main engines are switched off. In alternative to the batteries or ZEM mode a 37 KW diesel gen. set can be used instead. EASY HYBRID system means you can switch from traditional to electric any time also while cruising. This was the most complex and futuristic project developed by the group at the time. Benetti Trideck My Paradise: Completion in the Spring of 2014 The first of the Benetti 108’ models was built to carry auxiliary diesel- electric drives coupled to the main diesel engines. Azimut Benetti Group’s R&D team drew up the project work in collaboration with RTN. Thanks to the hydrodynamic characteristics of displacing yachts of this size which sport a speed which is 40% higher than the top speed with only 8% of the main diesel engines’ power and with the auxiliary diesel-electric system made up of two Auxilia 35 KW electric motors supplied by an 85 KW gen.set. With this set up a maximum of 6 knots can be attained, in total comfort in comparison to the 14 knots that can be reached by deploying the diesel engines alone.
Benetti FB262 Lionheart: Completion in the Summer of 2016 La FB262 is a 90 metre Giga yacht sporting a diesel-electric drive system with 8 gen. sets: fixed rpm. 830 KW 690V and 50 HZ for each of the Caterpillar C32 engines supplying to electric drive motors: Indar/abb of 2.8 MW each. In practical terms the ship has a single electric power house which supplies what is needed to serve on board requirements as well as the electric drives. T he following advantages have been obtained by deploying this system:thanks to a more compact engine room and to the flexibility in positioning the gen. sets, space available can be optimised to offer more of it to guests. Enhanced distribution of energy and less fuel consumption thanks to the fractioning of the power house (made up of the 8 gen. sets) which allows you to deploy only the ones needed. Enhanced manoeuvrability delivered by electric engines. Added comfort thanks to noise dampened diesel gen. sets equipped with efficient low vibration silent blocks. With this set up the ship can reach more than 18 knots while guaranteeing sufficient energy to all on board requirements. While four gen. sets are enough to guarantee 14 knots while cruising by day including cruising by night on batteries alone.
(source Gianpaolo La Penna, production manager Columbus Yacht) Columbus Yacht, with considerable experience gained in the building of naval vessels from brand owner Gruppo Palumbo installed diesel electric drives for the first time in 2013 on Columbus 40S Hybrid. It was later proposed for the all new series of “Sport Hybrid” yachts made up of semi-displacing aluminium yachts between 25 and 65 metres. We’re talking about weight saving yachts featuring wind piercing lines to minimize fuel consumption and specially while cruising slow and cruising in electric mode becomes possible. Accordingly the Columbus 40S Hybrid designed and engineered by Hydro Tec studio owned by Sergio Cutolo (engineer) we’re talking about a yacht displacing 190 tons which can cruise at 8 knots with only 30 litres /hour of diesel fuel thanks to two Siemens 60 KW electric motors supplied by gen. sets. When deploying the main engines (two MTU 12V 2000 M94 of 1.920 HP) the yacht can reach 22 knots. The installed and fine tuned hybrid system on the Columbus 40S Hybrid is made up of a mix of different elements and devices put together to generate satisfactory mechanical and electric energy which is then run intelligently via user friendly touch screens. It combines conventional drives (engines, gear transmission box, shaft and props) which have been modified by inserting a Power Take In/power Take Off device or PTI/PTO which when pressed on the touch screen you switch mode accordingly (electric mode, diesel mode, shaft generator mode).
On the left page, Columbus 40S Hybrid “DIVINE”DRIVE systems. A) ELECTRIC MODE In this mode two 100 Kw gen. sets produce enough energy for the ship’s requirements including the electric motors ( diesel-electric propulsion) each of which can absorb up to 75 KW to cruise up to 8 knots.this means there are still another 50 KW available with which to handle the other on board requirements. In this mode the electric engine is made to spin the propeller shaft. B) DIESEL MODE In this mode the ship cruises only with the main diesel engines. C) SHAFT GENERATOR MODE In this mode the main diesels spin the propellers and the electric ones are engaged and perform as gen, sets as needed.
(source Jennifer Humphrey, Communication Manager Volvo Penta) Swedish giant Volvo Penta introduced PODS thanks to its IPS drives dedicated to mid and small yacht sizes. The company is betting on what’s in store in the near future in terms of hybrid propulsion by presenting a ZEM project of its IPS or Inboard Performance System. And with the addition of the hy- brid variable, further advantages will enhance IPS installations when cruising zero emission zones and added comfort (less noise and vibration), lower running costs, as well as enhanced manoeuvring. In fact the maximum torque electric engines develop at very low rpm bring about directional, immediate response and control of the Inboard Performance System and offer the possibility to cruise up to 10 - 12 knots. Thanks to a very intuitive control system which acts on a clutch, the captain will be able to decide between the following options:
Electric mode only, this is where the electric motor is pow❑ ered by lithium ion batteries which can be charged with a shore line, or by the yacht’s main diesel engine.
Hybrid mode, the diesel engine powers the yacht’s drives ❑ with an auxiliary electric engine.
Traditional mode, is where the (Inboard Performance Sys❑ tem) IPS works off the main diesel engine only. The batteries’ versatility means that performance and design can be customized according to use type: recreational or commercial. More powerful batteries translate into opting to cruise on an electric basis with smaller less powerful diesels and lower running costs ( less fuel). The parallel hybrid Inboard Performance System is currently being developed at Volvo Penta’s premises in Gothenberg Sweden . A test unit will hit the water to carry out sea tials in early 2020. The hybrid IPS is scheduled to be on the market as of 2021 for commercial shipping and immediately after that for recreational purposes on yachts with an engine capacity ranging from 8,000 c.c. to 13,000 c.c. or from 8 to 13 litres.the evolution of this system into multiple hybrid technologies with all electric options is also envisaged in the course of time.
Efficiency - The possibility to ‘optimize’ diesel and electric engines according to effective necessity and more so at the higher end. All of this significantly reduces fuel consumption.Comfort - Cruising on electric power alone reduces noise and vibration significantly. Reduced exhaust emissions - With greater propulsive efficiency, which brings about lower consumption and less unwanted exhaust gases and when cruising in Zero Emission Mode (ZEM) by deploying battery powered electric engines alone.Space available - Gen. sets are generally more compact and lighter than classic diesel engines. They supply electric energy easily and can be installed and split in diverse places accordingly which results in added often crucial space.Flexibility - Propulsion and required energy can be paid out in diverse ways according to courses undertaken and to guests’ wishes.Safety - Multiple numbers of the same units (gen. sets) ensure added safety in case of failure of some of the apparatus and otherwise consequent lack of energy. Above, potential advantages offered by diesel/electric hybrid propulsion.
Diagram showing Sanlorenzo yachts’ Electric system – the core of the system being the PMS or Power Management System which runs the diffusion of the diverse forms of energy and the distribution of the energy required accordingly: through variable speed generators ( VSG) which must be switched on to respond to varying loads and consequent needs required by the yachts’ plants, or when in harbour by using energy from shore lines as well. This way best exploits the resources which supply energy where needed only. The system is split in two sections which can also function independently of one another.
Sanlorenzo 500 Exp E Motion
Some of the functions devised for Sanlorenzo’s hybrid system: 3a - boost mode: in addition to diesel engines, electric ones supply extra power ( boost) to reach top speed. The energy necessary to the electric engines is supplied by gen. sets or by batteries. 3b – Eco speed mode: specially devised and suitable over long distances at displacing speeds (10-12 knots) with a single diesel engine working with an electric one coupled to it which acts as gen.set to power up the electric one of the other drive shaft and to deliver energy to on board
On the Sanlorenzo 500Exp E Motion which is about to be built, and thanks to the compactness of the generators when compared to a conventional plant, extra space has been made available(18.5 m2) and an internal passageway with see through walls has been installed to view the “Art Gallery Engine Room”.
services by recharging the service batteries.3c – ZEM mode: In Zero Emission Mode drive is solely ensured by the electric engines powered by batteries which also deliver energy to on board services. Obviously this mode is limited accordingly to the energy stored in the batteries. By switching to (variable speed generators) VSG or by turning on diesel/electric mode the range and or duration period in ZEM is resolved.
Sanlorenzo’s thoroughly tested yacht: the SL86 has recently been renewed with the Hybrid version. The first two of these yachts were already in the water in early 2018.
Tankoa – la S502 Elettra in construction
Tankoa Mode 2 - “Hybrid” mode instead exploits a single, main diesel engine to propel the yacht and involves the electric one as a dynamo which covers the needs of the services and of the other electric motor. The Elettra S502 can reach 12 knots this way. The “hybrid” mode is best exploited when covering long hauls and when it is possible to make full use of the options therefore reducing the main engines’ running times as in this way the gen.sets can also remain periodically off which lengthens the intervals of programmed maintenance work. In the given mode fuel consumption is still limited to about 145 litres per hour just a shade more than the previous mode. The batteries come into action if/when loads reach peak levels and recharge automatically when not in use. Tankoa Mode 3 - “traditional” mode simply means using both main diesels and a gen.set with the electric motors switched off. This mode exploits the full potential of the propelling diesel engines thereby pushing the yacht to 17 knots. Tankoa Mode 4 - In “booster” mode both main diesels are working as well as the two gen. sets since the electric motors are also switched on to increase power output further. In this mode the yacht can reach 18 knots.
Tankoa Mode 1 - “Diesel Elettric” mode envisages sole use of gen. sets delivering a maximum of 90 KW to cover the needs of the electric motors as well as all else. This cruising mode is both ‘economical’ and comfortable. In this mode, the Elettra S502 can reach 10.5 knots and the noise level is minimal given the noise dampened gen. sets and furthermore the hourly consumption of the generators is of about 116 litres per hour. It is ideal when cruising at night given the lack of unwanted noise and when entering or exiting ports and bays.
Rossinavi – Diesel-electric plant diagram for construction FR.032 “ENDEAVOUR 2” which can be run and monitored via touch screen controlling the PMS (Power Management System) made by Marine Automation.
Rossinavi - construction FR.032 “ENDEAVOUR 2”.
Rossinavi - construction FR.037 “POLARIS 2”, new 70 metre ICE Class superyacht.
Magellano 50 A
Magellano 50 B
Magellano 50 C
C Azimut Magellano 50 – EASY CRUISING device allows users to change drive mode in an intuitive and safe way by choosing between the following three modes: HYBRID, DIESEL, ELECTRIC. In HYBRID MODE the system automatically switches from Electric to Diesel and viceversa according to the position of the control lever and of the state of charge in the batteries.B Azimut Magellano 50 – Cruising on standard diesel engines: drive is provided by main diesel engines while gen. sets deliver energy supply to all else and recharge batteries. Azimut Magellano 50 – Cruising in diesel-electric mode: diesel gen. sets supply the electric drive motor and also maintain 10 KW available for on board appliances while the batteries always kept in ‘float’ come into action to cover peaks. On the left page,A Azimut Magellano 50 – crusing in ZEM (zero emission mode) on batteries alone (28.2 KWH) can guarantee a range of 6 nautical miles at a top speed of 6 knots.
Benetti 108 Trideck My Paradise – electric auxiliary propulsion was realized by installing a pair of modified Reintjes WAS 344 inverters so as to obtain two gates for incoming power, one for the diesel engines and a secondary PTI (Power Take In) one by which to connect an electric auxiliary to.
Benetti 108 Trideck My Paradise
Azimut Magellano 53
Columbus 40S Hybrid “DIVINE”
Typical Dieselelettric architecture adopted for the Benetti FB262 Lionheart Benetti FB262 Lionheart’s drive system: Pure diesel- elettric drives where the electric engine connected to the the propeller shaft is considerably smaller than a traditional diesel engine and the gen, sets can be installed elsewhere.
B Diesel mode
A Electric mode
C Shaft Gen. mode
Benetti FB262 Lionheart
Make up of Volvo Penta’s parallel hybrid IPS.