Fully Electric Cargo Ship for Amazon River (Boat Design: 1st Post)

Discussion in 'Boat Design' started by FullyElectricAM, Feb 27, 2016.

  1. WestVanHan
    Joined: Aug 2009
    Posts: 1,374
    Likes: 56, Points: 0, Legacy Rep: 746
    Location: Vancouver

    WestVanHan Not a Senior Member

    Rastapop:
    Thank you for making my point for me:that ferry travels only 5.5 kms/ 3.4 mile in 20 minutes,yet still needs a 20 minute top up recharge after every 5.5 km run.
    Uses ten tons of lithiums which "The batteries have a combined capacity of 1,000 kilowatt-hours (kWh), which is enough to make a few trips between the two fjord communities"
    Each trip takes 20 minutes. Ergo,it can go what-15 or maybe 20 kms(?) and run for maybe an hour or a bit more,with ten tons of lithiums.

    And BTW you ought to learn more about the differences between freighters and catamarans vs overall dimensions vs displacement vs cargo capacity.

    As for DE,as Gonzo mentioned, it's been beaten to death here many times.
    http://www.boatdesign.net/forums/powerboats/another-hybrid-success-43764.html

    http://www.boatdesign.net/forums/hybrid/hybrid-system-sunreef-82-needed-34142-3.html


    The ONLY reason this ferry should be in any way considered a viable option is that it uses hydro electricity for power.
    Yet I'm wondering if they could just have 6 kms of power cable-hanging down 20 feet under water- on a powered spool in one of the villages trip....

    ---------------------------------------------------------------------------------------

    Chris,thanks for finishing that. I couldn't deal with the absurdity any longer. And had assumed anyone with a bit of knowledge knows about the "hours"

    At any rate,another way to work it out (for anyone interested) is from the discharge rates on the specs of the batteries.The longer the discharge time,the more amps that one can ultimately pull.

    We can work out that for 7200 minutes he can pull roughly about 10 amps per hour,which is about .65 hp:
    -those cells are 2 volts,so he'd need 24 of them in series,which is 2900 pounds for 48V to give .65 hp for 7200 minutes.

    That freighter needs 700 hp, but lets say 650 hp to make the math easy,so he needs 1000 of these 2800 pound series packs,which is about 1400 tons of the heavier duty batteries I chose.

    As Chris says,scaling works but also with the time,to an extent. If he wants it to run for 24 hours,he'd only need 280 tons. If it was 350hp for 24 hours he'd only need 140 tons. 100 hp for 24 hours 40 tons but with the quicker discharges he's get less amps out so he'd need to start adding 5-10-20% more capacity to make up for the decreased discharge capacity.

    Anyways, I'm off to go fiddle around on the boat.
     
  2. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    What point would that be?

    Is it that this project in its current form isn't feasible? Perhaps you managed to read the whole of my post and see that that was my personal assessment of it...

    Or was it something about electric boats in general? Their range perhaps? (I'm just guessing in the dark here)
    You might be interested in this 31m vessel: http://gcaptain.com/worlds-largest-solar-powered/
    It circumnavigated the globe on nothing but solar power, using 93kW of panels, and 1130 kWh of batteries (12 tons - which they said allowed them to cruise for "several days" without input from the solar panels).

    There's nothing scary or magical about electrical propulsion, and it's going to become even more popular in the future than it is now. Crewed, electric planes have flown from Japan to Hawaii, for example, and you can go down the street today and buy an electric car.

    Don't make electrical propulsion an emotional issue. It's just an engineering problem like any other.

    A nonsensical sentence that I'll comfortably ignore.

    I don't recall him saying that or anything like it. If you have something you want to say about diesel-electric, just say it (although this thread isn't the ideal place). I can't read your mind.
     
  3. gonzo
    Joined: Aug 2002
    Posts: 13,950
    Likes: 486, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Diesel/electric ships run an AC. Converting DC to AC introduces a huge loss, particularly when the power is stored in a battery. A diesel/gearbox has a loss of 3%. A diesel electric, running 440V AC, has a loss of about 9% when fed directly from a generator. Only at fix speeds, where the system has been optimized for, it can offer the possibility of economy. A river boat that need a large range of speed is not an economical application. This website has a lot of information on diesel/electric systems. https://marine.man.eu/docs/librarie...diesel-electric-drives-guideline.pdf?sfvrsn=0
     
  4. cmckesson
    Joined: Jun 2008
    Posts: 161
    Likes: 7, Points: 18, Legacy Rep: 55
    Location: Vancouver BC

    cmckesson Naval Architect

    Off topic: Diesel electric

    Gonzo, I fear that your post is overly general. The reasons for choosing diesel electric are myriad, and not only relevant to a single optimized speed. The ferries of the Washington State Ferries (I believe all of them) are diesel electric, and yes they operate mostly at a single fixed speed. But other cases exist. We have a design under way right now for an LNG bunkering vessel which is diesel electric. (In her case it was because a conventional shaft would have driven the design up in length.) Many modern cruise ships are diesel electric or GT electric, because of the widely varying loads in their various modes of operation. And an increasing number of tugs are going diesel electric, again because they spend a substantial amount of time in a low-power loiter mode.

    My point is: Yes, one must account for the losses, whatever drive one chooses. But No, Diesel-Electric drive is not only appropriate for vessels with a single fixed speed.

    All the best,

    Chris McKesson
     
    1 person likes this.
  5. Heimfried
    Joined: Apr 2015
    Posts: 337
    Likes: 37, Points: 28, Legacy Rep: 37
    Location: Berlin, Germany

    Heimfried Senior Member

    Gonzo, the MAN paper, you linked, tells to me just the opposite:
    The first of referred advantages is:
    "The gensets in operation can run on high loads with high engine efficiency.
    This applies especially to vessels which have a large variation in power demand, for example for an offshore supply vessel, which divides its time between transit and station-keeping (DP) operation."
     
  6. gonzo
    Joined: Aug 2002
    Posts: 13,950
    Likes: 486, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Read "gensets", it is plural. Running gensets at full capacity all the time means that there have to be several to be able to adjust output to loads. Also, read the cost and complication of phase synchronization.
     
  7. rainmaking
    Joined: Jan 2014
    Posts: 34
    Likes: 1, Points: 0, Legacy Rep: 13
    Location: Florida

    rainmaking Junior Member

    Gonzo, you are right with many of your points; like round trip efficiency of Li being much more efficient than Pb.

    In the case of DE, on the scale of this project there are variable speed gensets available with electronic converters that will synchronize. An even more efficient option would be to skip the AC bus altogether, except for hotel loads.

    This project has a fair amount to be planned out, but at some cost/performance level it is doable.
     
  8. WestVanHan
    Joined: Aug 2009
    Posts: 1,374
    Likes: 56, Points: 0, Legacy Rep: 746
    Location: Vancouver

    WestVanHan Not a Senior Member


    As for DE with tugs,cruise vessels etc: aziprops.
     
  9. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    You've made many assumptions there that you haven't given details of.

    No, the opposite is true.

    When a conventionally propelled vessel will travel at a fixed speed it can be geared so that its engines are running at peak efficiency at that speed.
    (This is why deisel-electric cargo ships are relatively rare - they travel at one speed)

    If it travels at a variety of speeds, it must change the rpm of its engines and so introduce significant losses (a large deisel enge is wonderfully efficient at its peak efficiency rpm, but efficiency drops off pretty fast as you move away from that rpm).

    It's vessels that travel at different speeds that benefit most from diesel-electric: they charge the batteries only at peak rpm for the generators, and so don't suffer the losses of using their engines at less efficient rpms.

    EDIT: even your own link says exactly the same:
    Lower fuel consumption and emissions due to the possibility to optimize the loading of diesel engines / gensets. The gensets in operation can run on high loads with high engine efficiency. This applies especially to vessels which have a large variation in power demand, for example for an offshore supply vessel, which divides its time between transit and station-keeping (DP)
    operation.
     
  10. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    The output load from genset(s) to batteries doesn't need to be adjusted, and they don't need to run all the time - they can just top up the batteries at one, best, rate.

    Between batteries and motors things are changing, and that doesn't involve running diesels at less than peak efficiency.
     
  11. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    If you have a point to make I'd be more than happy to respond to it. This post of yours is barely comprehensible from anywhere outside your head.

    Again, no clue what your point is unless you actually write it down.
     
  12. gonzo
    Joined: Aug 2002
    Posts: 13,950
    Likes: 486, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Charging and discharging batteries with a generator is inefficient. Further, converting DC to AC has large losses too. The OP seems to have a very limited budget. He said it would be $150,000, then that we should assume he had one million dollars. That may seem like a lot of money to him, but is unrealistic for the system he is describing and the whole ship included. He got offended when the budget was pointed out. However, a design has to be limited by cost. Otherwise, it is never going to be built.
     
  13. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    Neither batteries nor AC are necessary for diesel-electric propulsion..

    Vessels are using diesel-electric for just one reason at the end of the day: their bottom line. It isn't going to save fuel for every vessel, but for many it does. Of course there are losses, but there are losses in a traditional diesel propulsion system too, and for many vessels these would be higher than the losses they'd have with diesel-electric.

    To say that diesel is more efficient than diesel-electric is just sticking your head in the sand. For some vessels it is, for some vessels it isn't.
     
    1 person likes this.
  14. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,164
    Likes: 395, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    A good jolt from an electric eel should cure this compulsion.
     

  15. gonzo
    Joined: Aug 2002
    Posts: 13,950
    Likes: 486, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The OP's plan is to charge batteries and then run the ship on the stored energy. The diesel/electric system he proposes is based on a single generator.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.