hybride diesel electric

Discussion in 'Hybrid' started by bertho, Sep 3, 2006.

  1. bertho
    Joined: Aug 2006
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    bertho bertho

    I just start to have some interest for electric complicated system..for my new 46'/50' sailing boat (schooner long keel, 25/28 tonnes),
    as i can include on the initial drawing and calculation a sufficient amount of batterie as "internal ballast", after all is heavy lead !
    I want install twin engines, for maneuvrability, redondance, and avoid a prop in the midlle of my rudder (long keel), it's a sailing boat!.
    I need also power from genset for AC, freezer and so..
    now it's 3 diesel.. to much for me,
    come the possibility to use 2 small diesel each some 30hp, connected to a electric motor ( with sprag clutch) i imagine some 12hp each ?, this electric motor connected the shaft with a small gearbox.( to disconnect shaft when use as genset only) ??
    i will get 2 genset, even if the efficiency is not as a good alternator,
    i will get 2 diesel for propulsion with the electric motor running free (hope i will not lost to much power ),
    and perhaps both if we use the diesel at proper speed (1500 rpm..)??
    as i'm not interested to re-generate power from the prop, i want use foldable prop to reduce the drag.
    it will be probably a problem for the pich of the prop, but as the torque from electric motor is much important, it's perhaps possible..
    it's some specialist to comment such system? if feasible ! :confused:
    bertho
     
  2. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    Search "diesel-electric" in the forums, there's a lot on here on this.
    There are a few key factors that are usually forgotten in homebrew (and some commercial) DE installations, among them:
    - The total efficiency of all components (motor, motor controller, and generator) must be considered, and these efficiencies must be high, for it to beat a plain diesel system
    - DE gets its efficiency not from holding the motors at constant RPM, but from decoupling engine RPM and prop RPM. Thus a DE's engine can slow to a lower point on its power curve as the boat comes down a wave, and speed up to a higher power point as the boat goes up a wave, while boat speed remains constant. The engine output is continually being matched to the ACTUAL load on the prop. In a pure DE system you also have the option of having either or both motors powering both props.
    It sounds like what you're considering resembles the hybrid driveline of the Honda Civic. While OK for cars, this architecture won't gain you much in the boat; pure DE likely would.
     
  3. Frosty

    Frosty Previous Member

    A friend of mine spent a whole year on the hard fitting Vetus electric motors, shafts etc. He has a 7 KW Onan generator but he needs such a huge battery charger. To make a long story short the electric motors were usless not much power for the 54 foot cat and consuming more power than was anticipated. Basically a very dissapointing project. The guy is so down hearted the boat is up for sale.

    54 foot cat 160.000 us ?? anybody
     
  4. Ben Hawkins
    Joined: Aug 2006
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    Ben Hawkins New Member

    I think you will see more and more boats going in this direction. In 10 years, we will be seeing boats down in the 30 foot size using diesel/electric propulsion.

    Below is a site for Solomon that will help you pick what you need. Also, dig through their site and you will find some South African sail cat builders offering hybrid/electric optins. Good luck. I would appreciate hearing how you make out.

    http://www.solomontechnologies.com/m_recreational.htm
     
  5. bertho
    Joined: Aug 2006
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    bertho bertho

    ben,
    i already look after few supplier, but none have what i'm looking for, it's more a ''genset with a prop at the end " , with clutch system..( sprag clutch and small gearbox) i want to have the choice to use or diesel or electric, as one electric motor can also generate power, total weight = +- one genset...
     
  6. StianM
    Joined: May 2006
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    StianM Senior Member

    Buy a old gearbox with pto for shaft generator.

    When you clutch out the diesel engine you can use the shaft generator as propulsion instead;)
     
  7. Pericles
    Joined: Sep 2006
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    Pericles Senior Member

    Hello Bertho,

    Have you heard of the Bavaria 49 Diesel Electric? http://www.fischerpanda.de/doc/eng/products/12DBC81946370A5BC1256FE70029D8AC

    You say you want twin props for redundancy and manoeuvrability, which could mean one prop directly driven by a diesel engine with a generator driven by a power take off (PTO) supplying electricity to the second prop driven by an electric motor. However, take a look at http://www.ossapowerlite.com/faq.htm and go to the eLeopard installation. http://www.ossapowerlite.com/customers/moorings/leopard_43/moorings_leopard_43.htm

    I have investigated all the DE options listed here http://boatdesign.net/Directory/Propulsion/Electric/ and Ossa are the only people to offer a fully integrated system that is controlled by NMEA 2000 as far as I know.

    Good luck with your project.

    Pericles
     
  8. bertho
    Joined: Aug 2006
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    bertho bertho

    pericles,
    in fact i like simple and minimaliste system, and basicaly all electric component are not "marine '' stuf on my point of view.., but just for fun and exercise...
    is not exactly what i have on my mind.., will be more easy with a small sketch..
    i want to have on line, one diesel, one motor/genset/ and the shaft,
    few problemes, coupling, ratio and need to find a electric motor who can turn freely when we use only diesel as propulsion.
    the coupling between diesel and motor can be a sprag clutch, as running both with same rotation. the electric motor can run alone.
    (we can't use permanent magnet motor)
    for use as ''genset only, we need disconnect the shaft, a small gearbox need to be installed, what can also solve speed engine proble, elctric motor ca be find with same range speed as diesel, 1500 to 2450rpm..
    i thing yanmar already make a diesel/genset + gearbox, but can't use the genset as electric motor..
    total wheight compare with on diesel and one genset save on diesel...( puriste will said is not the same injection gouvernor..bouuu! ) anyway, to try to have all system available, DE, classic, genset on one pack. using standard indusriel component..( less $$$ !!)
    somebody follow me??
     
  9. Pericles
    Joined: Sep 2006
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    Pericles Senior Member

    Hello Bertho,

    If the diesel is turning the genset to make electricity, then the genset cannot function as an electric motor. If you use the genset as an electric motor to drive the prop you will need a large number of batteries to power it, because the diesel cannot generate electricity. The genset has been disconnected to become an electric motor. When the batteries are discharged, the diesel has to work to recharge the batteries with the genset, so there is no drive to the prop.

    The rationale for diesel electric is to remove the genset to a better position within the boat and use cables to carry electricity to an electric motor mounted directly to the prop shaft to turn a larger prop with a greater pitch, more slowly and therefore more efficiently.

    "The potential to improve efficiency is based in the fact that by "decoupling" the engine from the propeller, it is possible to reduce the substantial energy losses of the propeller while operating the engine within a more optimum power range regardless of load conditions. It is worth noting that simply "generating electricity and putting it through a motor" does not automatically accomplish this. A diesel-electric system simply creates the potential for fuel savings. A poorly designed electric drive system could be less efficient than a conventional drive. Improving fuel economy is a primary design goal of the OSSA Powerlite system." http://www.ossapowerlite.com/faq.htm

    Doing diesel-electric the wrong way - http://www.ossapowerlite.com/tech_library/fuel_efficiency/fuel_efficiency.htm

    "In closing, it may be helpful for the reader to have a clear example of how not to set up a diesel-electric system. This is a real system - an effort by a major boat manufacturer to create their own low-cost hybrid-electric propulsion system. Because the system will be outfitted as standard (rather than an option to conventional diesel) it is a primary goal of the manufacturer to provide what it views as the maximum number of benefits at the minimum cost. The system uses standard industrial grade components and a conventional constant-speed 15kW marine AC generator (efficiency is 87%). Power from the generator is sent to an 8.5 kW battery charger (efficiency approximately 78%) and from there to a large 48v battery bank. Power from the batteries flows to a commercial motor control (typical efficiency 93%) and on to a commercial grade 12kw BLDC motor (typical efficiency 89%).

    The purpose in describing this system in this paper is not to argue the merit or lack of merit of such a configuration except as it relates to fuel efficiency. While this is a diesel-electric system (hybrid electric to be exact), it should not be expected to provide much in the way of improved fuel efficiency. For every horsepower produced by the engine, only 0.56 hp will be available at the propeller shaft. Combined with the single-speed generator and the limited power available through the battery charger/power supply, it is safe to assume that the boat will be a disappointment for anyone watching the fuel gauge too closely."

    In truth Bertho, the diesel electric boat will become more and more popular, but only if it is correctly designed. Look at the names on http://boatdesign.net/Directory/Propulsion/Electric/ and study the proposals. The wheel has already been invented, so there is no reason to re-invent it. Use the research and experience and knowledge of Siemens or OSSA and enjoy the benefits.

    Happy reading.


    Pericles
     
  10. Bill Burpee
    Joined: Oct 2006
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    Bill Burpee New Member

    I don't know where you are in this design process, but here is one solution.
    If you have need to for an AC generator, then you can have an AC electric motor as your main propulsion. You can also have a bank of batteries as a back up. Both power sources would supply power to a VFD (variable frequency drive), which is the only way you can control the AC motor. In this design, your supply would be either the generator or the batteries (not a trua hybrid). This works and is very reliable (I have built 8 commercial ferry boats with approaching 200,000 hours of use).

    An alternative (and more technically complicated) method is to have a true diesel/electric hybrid. One way to do this is to have an electric motor pancaked on the back of your diesel propulsion engine and a bank of batteries to supply power to the motor. The other is to have a control that "parallels" the battery bank with your generator, which, in turn, supplies the required power to an AC propulsion motor. I have built 4 of the latter systems and have found them to be reasonably reliable (over 20,000 hours to date).

    Frankly, I am not overly impressed with either system, but am willing discuss your needs, if you wish
     
  11. Jimbo1490
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    Jimbo1490 Senior Member

    This is by no means the only reason electric drive is used. A major reason, though I suspect it won't matter as much in this particular instance, is that an electric transmission is ultimately more efficient than a mechanical one. Gears running in oil waste power, sometimes a lot of power. The more gear ratios you add, the more gears spinning in oil. This can easily waste 15% or more of total power into the transmission. Electric drives are typically in the >90% efficient range, besting all but the most efficient gear drives. The largest transmissions typically have thick oil running in them, reducing efficieny. So the smaller size transmissions will see less increase in efficiency switching to electric drive since they typically run thinner oil.

    Diesel electric drive has a long history in rail locomotives, going back almost 90 years by now. Rail locos need several different drive ratios which means lots of gears running in thick oil wasting power. You presumably only need one drive ratio, so that particular advantage is of less value in your application.

    Rail locos used DC generators and motors for the longest time. But in th last 20 years or so they have made a switch to AC power using induction motors. Induction motors run at a synchronous speed, ie a speed that is tied to the frequency of the AC power used. In applications where the motor is connected to the land power grid, this has meant that induction motors could run at only one speed, since domestic AC power is of a constant frequency.

    But recent advances in high-current semiconductors have made it economical to make large variable frequency AC drives which can be used as AC induction motor controllers. This coupled with a three-phase AC alternator can make a very efficient electric transmission with true infinitely variable speed, with full motor torque avaiable at all motor speeds down to zero RPM. This has become the preferred drive system for industrial machinery such as lathes and milling machines.

    Induction motors also offer the advantage of bieng brushless, thus virtually frictionless. They are easily reversible for use as a generator. A large variety of continuous duty induction motors is available off the shelf, and even used, in many duty ranges such as for severe overloads or off-spec power input.

    As Bill Burpee posted earlier, this is a very reliable system and proven now by many years experience in both land and marine applications.


    Jimbo
     
  12. StianM
    Joined: May 2006
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    StianM Senior Member


    Ellectric waste energy too. A generator has 97% efficensy and so dos a electric engine so then you allready got 6% loss and then you have loss in cables, frequensy converters, couplings and so on.

    I think for a ship traveling long ranges the efficensy would be the same. For manuvering at diferent loads I have no doubt electrical is superior.

    There is some semi diesel electric systems running where you runn the engine on the proppeler and one you nead manuvering in port and sutch the engine is clutched out and a electric engine is clutched in witch is powered by a generator in fron off the main engines.

    I sen it used on a boat with fixed pitch proppeler and engines that can not be reversed.
     
  13. SpikeMillikin
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    SpikeMillikin New Member

    You can email me 'northwestmarine@shaw.ca. I have done quit a bit of research within my design resposibilty on hybrid boats and sailing vessels.

    spike
     
  14. SpikeMillikin
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    SpikeMillikin New Member

    email me 'northwestmarine@shaw.ca. I have done quite a bit of engineering research into hybrid vessels and looking at the most efficient way size and power to achieve this.

    regards

    Spike Millikin
     

  15. apex1

    apex1 Guest

    And what have you discovered?

    If we paint the problem brown we can call it a cashcow?


    And donĀ“t be so impatient! This thread died 4 years ago, most likely the OP does not watch it every other minute.
     
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