Electric Boats

Discussion in 'Class Societies' started by a24, Oct 4, 2010.

  1. a24
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    a24 Junior Member

    Hello,

    I am looking for some info regarding ships engine room, ventilation (battery room), arrangement and so for fully electric ship.
    I do not know if these type of boats/ships can be treated as common ships or not. or solas and class rules are applied as normal???

    any have experience in electric boats?

    thanks
     
  2. jehardiman
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    jehardiman Senior Member

    If using wet cell batteries you must ventilate, and/or catalyze, to keep the hydrogen and oxygen gas levels in the compartment low. The rate at which the cells off gas is dependent upon charge voltage and amperage. High rates of charge produce more gas and can be a concern depending on the operational cycle.

    Note that ship/submarine propulsion wet cells are not constructed like automotive wet cell or VRLAs (valve-regulated lead-acid) or modern absorbed glass mat (AGM) batteries found in boats. They are of a much different form and generally fitted with agitation systems to extend life and power so ventilation is more important
     
  3. darr
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    darr Open Minded

  4. jehardiman
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    jehardiman Senior Member

  5. daiquiri
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    daiquiri Engineering and Design

  6. daiquiri
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    daiquiri Engineering and Design

    I have to correct myself. Ships are exempted from application of ATEX directive (page 33 of the previously linked guidelines). Sorry.
    However, that's a pitty imho, since ATEX is more stringent than SOLAS, when it comes to highly-explosive atmospheres, like hydrogen.
     
  7. jehardiman
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    jehardiman Senior Member

    I think the problem here is that you are not going to find anything that is going to say "Battery compartment ventlation shall be....". If you look at it one way, you could say that it is a "fuel bunker", seal it, and never ventilate except when entering it like any fuel tank. It is not a hazardous "cargo", so those rules don't apply. So we are back to general engineering space requirements which means keeping the concentration at some value less than the flash point and/or MSDS MEL.
     
  8. daiquiri
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    daiquiri Engineering and Design

    Let me just add that a hydrogen-air mixture (when present) is flammable in the 4%-75% range (volumetric), and is explosive in the 18% and 59% range. That's a very large range of concentrations. The electrostatic-charge buildup and discharge must be considered at much more detailed levels than ordinary fuels require, taking into consideration even the electrostatic charge of HVAC ducts or pipings, electrical switches, or clothing, for example.
     
  9. a24
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    a24 Junior Member

    sorry for the delay,

    thanks a lot.

    I have been looking in DNV rules, I found some comments on vent requirements for battery rooms.
    this is new to me, so the main issue is to know if they cannot be in engine room (something more or less obvious, but if the ship is quite small?which is the case) and the requirement I found is 10 times the battery capacity and stowed in separated watertight room.
    but I did not think in any other requirement so far.
     
  10. gonzo
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    gonzo Senior Member

    In Spain all boats have to be designed or approved by a Spanish Naval Architect. If you are planning on designing or building, your best first step is to find a Spanish NA that is willing to work with you.
     
  11. Guillermo
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    Guillermo Ingeniero Naval

    Well, not all boats in Spain have to be designed or approved by a chartered NA. This only applies to commercial vessels but not to recreational ones under the RCD.

    Regarding an electric propulsion system based in a batteries bank and a conventional charging system (diesel generator or shore mains) it is necessary to install the batteries bank within a sealed box or compartment with direct ventilation to the outside, to eliminate the H2 gasses from the batteries when charging. If the box is in the engine compartment, a tube vent to deck with a gooseneck is the simplest accepted solution.

    By the way, I'm studying a project to convert an small commercial FV to hydrogen fuel cell - batteries- electric motor propulsion. It is going to mount 6 hydrogen cylinders 1 m long x 50 cm diameter, and, as far as I have been said, those are not allowed to be located under deck, but in the open air. As this is my first time with this kind of system, I'd appreciate a hint to what rules (marine) should be applicable.

    Thanks in advance.
     
  12. jehardiman
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    jehardiman Senior Member

  13. daiquiri
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    daiquiri Engineering and Design

    Then (In addition to guidelines from JM's previous link) I would again point you to the ATEX Directive, although it is not mandatory for ships. It means that all the electrical systems should be done in accordance with the following technical norms:
    IEC 60070-0 Electrical apparatus for esplosive atmospheres - Part 0: "General requirements"
    IEC 60079-10 Electrical apparatus for explosive atmospheres - Part 10: "Classification of hazardous areas"
    IEC 60079-17 Electrical apparatus for explosive atmospheres - Part 17: "Inspection and maintenance of electrical installation in hazardous areas"

    It would be wise, imho, to use only electrical apparatus with flameproof enclosure (Ex-d protection), which is regulated by:
    EN 50018 - "Electrical apparatus for potentially explosive atmospheres. Flameproof enclosure 'd' ".
     
  14. Guillermo
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    Guillermo Ingeniero Naval

    Thanks a lot.

    Not having marine rules to referr to is calling for problems with authorising maritime authorities here...I'm thinking about installing over deck both the hydrogen bottles and the fuell cell, coming down to the engine room only the electrical cables to the battery bank and electric motor. This way there are no H2 gasses under deck other than the battery bank produced ones.

    But there is a "regulamentary" problem with the battery bank in the engine room, as the Spanish rules only allow banks over 1400 Ah to be installed in an "independent compartment" (boxes only allowed for powers under 400 Ah). 30 air changes for hour are mandatory only for banks over the mentioned 1400 Ah. Under that power natural ventilation can be used. Ventilating fan has to be connected to the battery bank charger, so it remains working during all charging time and at least another 30 minutes after charging has stopped. A security device shall be provided to not allow battery charging if fan is not working.

    Possibilities? Creating one or two independent & ventilation forced battery compartments at the engine room, or then a set of boxes dividing the bank in 400 Ah groups. Not very practical this last, I'm afraid.

    I'll have to find out with authorities.....
     

  15. a24
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    a24 Junior Member

    Dear guillermo,

    I am a spanish naval architect too.
    Under which rules are you working for your project?



    regards

    aitor
     
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