Could you also clarify the difference between electric propulsion and hybrid propulsion, that is if a difference exists. Well a little light is called for to clarify some of the chaotic terminology currently being used in the maritime world. I’ll try to de mystify with my own personal contribution. There are two types of electric propulsion: the first is the principal or main electric propulsion system and the second one is an auxiliary one. Taking the main one first, 100% of the power thrust on the propeller is produced by an electric engine, while in the second case the electric engine generally delivers a little less than 20% of the power to the propeller and is an alternative to using the diesel engine. However both diesel and electric engines can work at the same time (booster mode). When the auxiliary electric engine alone is being deployed the boat speed will be less than than the top speed normally obtainable with the diesel engine (normally with 11% of available power the boat will reach 50% of its top speed). All of the certifying naval bodies (Lloyd Register, DNV,GL, RINA, ABS) have been using APS data records (Alternative Propulsion System)for decades which standardizes auxiliary electric propulsion. Having now defined what is meant by electric propulsion we’re going to look at “HYBRID propulsion” which is the term by which we refer to those propulsive systems in which energy is stored in two entirely diverse ways: fuel and batteries. In this way therefore the ship’s captain will decide which source of energy to use accordingly. And what is the diesel electric exactly and how does it work? Is it the same system as the one used in trains or in cruise ships? Exactly.there’s a diesel engine connected to an alternator (which transforms mechanical energy into electric energy); which generates electric current which is then passed through drivers deployed by an electric engine connected to a drive shaft which
delivers power to the propeller. In a train for example the electric engine makes the wheels spin so the system is conceptually the same. For cruise ships the system is also conceptually the same. I must point out the following fact; a cruise ship is basically a floating city with thousands of people living on board.these “inhabitants” need loads of electric energy to live well and have fun.therefore there’s need for imposing power plants similar to the ones on land in a city. Consequently part of the electric energy requirement can be easily deployed to work the propellers. And what about the hybrid system how does that work? And is it the same as the one used in the automotive industry? Both systems are conceptually very similar because the electric auxiliary engine works as drive engine and as a gen. set. Well then why have hybrid systems in motor cars become ecological? Well that’s because in a hybrid car there are two kinds of benefits/ savings: the first is represented by the recovery of energy obtained when braking (the energy thus generated is not dissipated in the brakes but on the contrary it is stored in the batteries using the electric auxiliary engine as a gen. set), the second one optimizes the degree to which the diesel engine is to work thanks to an intelligent control of the electric engine/ gen. set which increases the effectiveness of the diesel engine. The final result is a vehicle which uses less fuel and is therefore less polluting. On a ship though there’s only the second possibility: an electric auxiliary engine doubling as gen. set through an “intelligent” control which accordingly generates low cost electric energy with reduced toxic emission. This energy can be stored in the batteries and can be deployed when required as it is emission free and is deadly quiet. A good result can be obtained only when there’s an overall and intelligent management of the power split between the electric engine and the diesel one. Still on the hybrid topic we talk about degree of hybridisation : what does that mean? Does it have something to do with several of the various hybrid systems we hear about? I don’t believe we can talk about degree of hybridisation as such if not intending that it is only possible thanks to an intelligent management of the electric power available and the mechanical one together with an optimised use of the batteries themselves, then it is possible to exploit on board energy at its best at lower cost and with less harmful emissions. Therefore an appropriate use of PMS (Power Management System) is necessary as it controls the forms of power and available energy accordingly. And this is exactly one of the strong points of our Auxilia system thanks to our technical team’s dedicated work. Are batteries indispensable in a hybrid system? Without the capacity to store the energy produced in an efficient way, while considering also environmental problems, we cannot really talk about a real hybrid system applicable to ships and yachts. The next hurdle is to have the kind of efficient and low cost technology which allows us to store energy more efficiently.
When is it better to use hybrid and when is it best to use diesel electric? We should remember that on board energy has basically three different types of use: propulsion, technical plants and hotel services. We can have a hybrid ship of course (one with batteries in which to store energy) which uses batteries’ energy to run technical plants and hotel requirements alone and not for propulsion. An important example of this is provided by the six hybrid ships commissioned by Grimaldi. They will carry a huge battery bank to serve the ships’ hotel requirements when in port. This is to avoid noxious emissions generated by gen. sets which would be supplying the ‘hotel’ requirements night after night with much environmental pollution. But in more general terms when the ship cruises extensively diesel deployment is a necessity or when moving slowly near coasts perhaps patrolling a given area then the advantages offered by hybrid propulsion are notable. Can you quote a few concrete examples of diesel electric and hybrid uses? Well WIDER shipyard has built two mega yachts (one is 150 feet long and the other is 165’) both are powered up with diesel electric propulsion (main propulsion is electric) and hybrids. RTN the company I founded using the “AUXILIA ELECTRIC PROPULSION” brand handled the project design work in terms of propulsion, as well as the installation of the electronic and electric machinery. In this case we’re looking at an all electric propulsion system (100% of the power to the propellers is supplied by electric engines) via diesel generator sets and an enormous set of lithium batteries. The gen. sets charge the batteries and when they are fully loaded the gen. sets switch themselves off.the ship works on battery power alone for a few hours (the duration is proportional to the intensity of the exploitation of the same). When the energy stored in the batteries drops below 20% the gen. sets kick off automatically and begin to recharge. The same concept has been applied to hybrid ships with electrical auxiliary engines (where the electric engine supplies only 10 to 15 per cent of the power needed for the propellers) guaranteeing the advantages of electric hybrid propulsion from zero to 10/12 knots (Benetti, Azimut, San Lorenzo etc). Which are the smallest and largest sizes where hybrid systems are better suited? Electrical systems and batteries are costly items. Far from the costs of those for the automotive industry. In marine naval terms the numbers are a lot smaller and it is therefore more difficult to compare. Furthermore electric propulsion’s complexities even in a small yacht are very similar to those of a large one. For these reasons prices don’t vary in a consistent linear way at least according to size range and proportionally speaking hybrid propulsion costs more on smaller yachts than on larger ones. There are de facto no limits in terms of length but surely costs are more quickly recoverable on larger units. The full hybrid version installed on the Magel-
lan 50 a smallish 15 metre yacht has been equipped by Auxilia for the Azimut Benetti group in 2012:but while the diesel propulsion version proved successfull the hybrid one was not. Was this due to the fact it was too innovative a project given the nautical market’s conservative tendency? The hybrid version in the Magellan 50 was for us a real challenge which we overcame successfully thanks also to Azimut’s R&D department. The end result was an intelligent hybrid system which is intuitive, and user friendly. The downside was that the price for this choice offered on request was 20 % of the yacht’s value! The market simply did not go for it at the time given the relative few hours of use a yacht of the type undergoes seasonally it cannot even think about recovering costs by saving on fuel not even in a lifetime, so it was not cost effective. Today though parts and battery prices have gone down somewhat and will tend to do so in the foreseeable future which could mean 5% of the unit’s value against the previous 20%. This would certainly allow for a much wider all round use of the hybrid solution. Have these installations been made to other small yachts other than on the Magellan 50’? We need to understand what is meant by “small”. Acting now on behalf of AUXILIA ELECTRIC PROPULSION, we have to date installed about twenty of our hybrid or full electric plants to yachts of every major brand ( Azimut-benetti, San Lorenzo, Wider, Wally, and so on). These yachts go from about 15 metres to nearly 60. Without delivering a complete listing I can remember the first and the latest easily: in 2008 Benetti Legend was the first to have been installed with electric propulsion which started the trend. The latest one was the Dynamiq D3, designed with “Porsche Design”.this yacht possesses an auxiliary electric propulsion system equipped with latest generation POD with counter rotating propellers driven by variable rpm diesel gen. sets. Do you think that sooner or later it will be possible to deploy only electric power houses to propel ships and yachts with no time limits? The capacity to store limitless energy is the theme regarding future mobility.for decades and decades we have deployed fos-
sil forms of it as energy containers to transport people and things. We’re on the threshold of a new era which will bring about the gradual elimination of fossil fuels be they in liquid or gaseous form used in shipping and other forms of transportation. This will occur in each sector gradually: land transportation, air planes and ships. Battery technology is still in its prime but over the past few decades giant leaps have been made in this field. Certainly we’ll be witnessing very interesting things in the foreseeable future. However any way you tackle the situation the production of electric energy needed to charge batteries with is the problem. But that is another topic. From a purely financial view point as is for the automotive industry, is electric propul- sion more expensive? Can you outline this in broad terms for us? And some idea of amortisation over time. We put pen to paper and with an important ship yard we attempted to estimate some of the costs involved for pertinent plants in the naval and recreational boating sector. And with no intent of being exhaustive I’d like to highlight a few points. Assuming that 100 is the cost of a conventional propulsion system (engine, gearbox, stuffing box, drive shaft, propellers and so on), an electrical one with diesel ( electric engine to deliver 100% energy to the propeller) costs 300 which is three times more. An auxiliary propulsion (with electric engine delivering only 20% of the power needed) costs 130-140, so 30/40% more than a traditional system. In this case more than 50% of the maximum yacht speed can be obtained with a set of ‘fringe benefits’ in terms of fuel reduction and greater on board comfort thanks to less noise and last but not least less noxious emission from the exhaust pipes. Obviously the “old“diesel engine can be used to deliver cruising and top speeds when required. I am certain that auxiliary propulsion is the best choice available and the easiest one to amortise in some cases in just a few years. Which is Auxilia’s role in an electric ship? Let’s first consider the needs of live aboard people or those spending long periods on board their yachts. With input from owners and shipyards we can draw up the most suitable solution by analysing all the variables. We then proceed to finalize the project and order the material needed to integrate all the machinery involved. The final phase is made up of tests and fine tuning prior to delivery of the yacht to the owner. We care for project design work just as much as we do for details and the “intelligence” behind the management of each
system we install taking into account the distribution of power via PMS or “Power Management System” because the degree of success of a hybrid propulsion is all in that. Which are the main components developed by Auxilia for an electrically propelled ship? One of the major factors for a hybrid ship is the way in which the engine/generator is set up in the engine room. Traditional PTO/PTI systems are heavily limited and do not take into account any form of optimisation of the system where PTI means “Power Take In” and PTO means Power Take Out”.in most cases they are mechanical components inside the gear box / inverter casing which extract power from the main engine (PTO) or introduce power which goes to the propeller (PTI). Electric machinery is installed on PTO/PTI to generate energy as a gen. set or electric engine for auxiliary propulsion. This is why we devised and patented a primary engine/generator system which is installed directly onto the diesel engine’s flywheel (AUXILIA HYBRID MOTOR/GENERATOR). With this innovative AUXILIA engine/generator we are certain of delivering the most reliable, easy to use and efficient solution to our clients. I wish to underscore our system possesses a patented “centrifugal clutch” which is reliable and does not require any special control. Years of study and many tests were invested in this project which led us to do away with other less efficient technical solutions (among which electrically activated or hydraulic clutches that were not entirely reliable),while this type of clutch system guarantees simplicity reliability and safety. What’s new chez Auxilia and what’s in store for the near future? Often enough shipyards and owners have had bad experiences with hybrid systems which put them off understandably. The cause as often happens was due to improvised installers who knew very little. Unfortunately despite my efforts there are still a number of suppliers claiming they are experts when they are not and clients get hurt. Themes as the integration with other on board plants, problems of electromagnetic compatibility of some of the engineering, cooling systems just to name a few when taken lightly without the required competence and know how are sure to land short of the mark and cause any hybrid project to fail. At RTN/ AUXILIA, we’re currently working on simplifying the system, to make it more user friendly also from installers’ view point. The new system will be intuitive with plug & play technology. The European Community awarded AUXILIA the “SEAL OF EXCELLENCE” motivated by the fact that our hybrid plant is “The sole hybrid drive to provide small-to-medium ships with an ecological economical and comfortable propulsion”. We want to offer the simplest system possible so that our clients can fully enjoy the benefits and advantages of our hybrid avoiding unwanted technologic complications and headaches. There are plenty of new things on the way! One last question: can hybrid propulsion pave the way to make new yachts compliant to international requisites and norms which year after year become increasingly rigorous and demanding in terms of pollution caused by motor yachts and ships? The norms concerning marine diesel emissions by Tier lll of the IMO (International Maritime Organisation) request that new motor yachts over 500 Gross Tons with keels installed after January 1st 2016 are to reduce harmful NOX gas emissions from the engines’ exhaust pipes by 70% ( a very restrictive and challenging value). In spite of the difficulties and complexities in finding valid technical solutions there are plenty of new yachts being built in compliance with Tier III norms. What began just a handful of years ago as a challenge for our sector is becoming standard practice for the benefit of the environment. Currently to date North American and Caribbean waters are covered by Tier lll NOX norms while the sea contouring the Scandinavian peninsula comply to SOX. Certainly there will be others, and probably also for Mediterranean waters. In any case ocean crossing yachts are plenty and consequently everyone will have to comply to TIER lll unless they wish to be excluded from cruising TIER lll zones. Every owner can decide for himself and whether or not he wishes to help reduce pollution. We believe that hybrid systems on superyachts are the best possible solution and in our own small we way are more than happy in contributing.
Make up of an electric auxiliary engine via PTI. “Power Take In” comprise components (generally rods) of the gear box which extract power from the main engine ( PTO or “Power Take Out” or direct it to the propeller. An electric device is installed onto PTO/PTI which acts as a gen. set supplying energy or as an electric engine exploited as an auxiliary. The main advantages are: the electric engine can be disconnected when there’s a problem, its lightness, and reduced size. The disadvantages are: space enough for drive shafts, the installation and purpose built base in which to lodge the electric engine, to build a PTI with additional required gearing mechanism, change of engine rotation to electric mode and capacity to generate energy only while cruising.
An electric hybrid auxiliary engine system (fig 02a) offers two yields one is relative to the functioning of the four stroke engine( blue graph) and the other when the electric one is deployed (yellow graph).clearly the degree of efficiency is considerably higher in the electric system which is however dependant on a scarcely realistic energy stocking capacity in batteries. We can supply loads of energy to batteries with a gen. set, but at that point further transformation of energy causes loss of overall efficiency which make the system less efficient than a conventional mechanical four stroke engine (fig 02 b).
Make up of hybrid AUXILIA engine(on SAE flywheel). SAE are the initials which show the standardisation of diesel engine flywheels. Thanks to this the electric /generator Auxilia engine is installed onto flywheels with standard universal brackets for (CATERPILLAR, MAN, CUMMINS, MTU engines etc.. And therefore there is no need for PTO/PTI. Main features are little space needed, compact size, only 60 – 70 cm needed. Adaptable to any SAE standard, can link to every engine and gear box, no need for additional mechanisms to gear box, capacity to generate energy any time even when in neutral with ship not moving, capacity to switch propeller rotation in electric mode in few seconds. The disadvantages are: heavier than PTI solution in terms of weight, longer size of the overall system.
View of AUXILIA electric engine/generator installed onto a flywheel
Conceptual breakdown of hybrid AUXILIA plant
AUXILIA electric engine/generator ready for bench testing (fig. 6a), coupled to the main diesel engine (fig. 6b), on board of a San Lorenzo 106 (fig. 6c).
Functional mapping of hybrid auxiliary system carried out by Auxilia for Admiral’s E MOTION 55m: this is a hybrid system made up of two main 1000 KW diesel engines and two Auxilia 150 KW electric engines which act on two conventional drive shafts. The top speed declared is of 16.5 knots with the diesels and 9 knots with the electric ones.
Functional mapping of the hybrid system designed for Wider 165 and 150 carried out by AUXILIA and supplied by RTN: this is a real diesel-electric hybrid sporting two electric engines developing 531 KW each with POD with a top speed of 15 knots.
Functional mapping of the hybrid system carried out by Auxilia for the Canados OCEANIC 140’ SUV: this is a more articulated system with three 1940 KW diesel engines and two Auxilia 120 KW electric engines with POD. The top speed declared is 28 knots with the diesels and 9 knots with the electric ones.
Conceptual breakdown of Auxilia hybrid engine for Magellano 50: offered by Azimut Benetti in 2012 show casing that hybrid is possible on any boat, even on relatively small ones: it’s only a question of the ‘extra’ cost in proportion to the value of the boat… at least for the time being.