Hybrid Electric Boat with large Wind Generator

Discussion in 'Boat Design' started by rainmaking, Jan 4, 2014.

  1. kerosene
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    kerosene Senior Member

    why do you want to do the whole hybrid thing?

    I mean getting 20kw or something like (in practice) from the wind turbine is not going to cover much more than the extra energy needed to move the weight of the batteries etc. Cost wise its a non-brainer = makes no sense.

    What size battery back are you envisioning? You said its more for intermittent use/cache?
     
  2. Jeremy Harris
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    Jeremy Harris Senior Member

    I like the idea, but the engineering and physical problems to overcome are massive.

    VAWT efficiency is generally poorer than HAWT efficiency, and like a HAWT, a VAWT needs to run in clean air so needs to be well above the turbulence at the sea surface and over the deck of the boat.

    The other issue that doesn't seem to have been mentioned is overcoming the precessional forces resulting from the gyroscopic action of the VAWT combined with pitch and roll movement of the boat. These forces may be substantial and vary in magnitude and direction rapidly, so would be difficult to counteract, I think. The best bet would seem to be to start with a very stable hull form, as already suggested.

    Finally, we're not yet at the point where any form of wind turbine driving a propulsion system by any means can come close to the efficiency of sails, in terms of extracting useful wind power for propulsion. One or two people have built and sailed wind turbine powered boats, some quite large, with varying degrees of success. None have become a commercial reality and some have been converted back to sail.

    Right now, to make this concept feasible needs a usage pattern where the boat only makes short journeys under battery power and deploys the wind turbine to recharge the battery pack when moored. Such a scheme may well suit the pattern of use of some leisure users and has been discussed here several times in the past. In terms of neighbour-friendliness at moorings I'm inclined to the view that photovoltaic charging is perhaps better, although it needs a far greater deck area.
     
  3. Skyak
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    Skyak Senior Member

    Rain,
    sorry I am late. I wasn't paying attention.

    My point was that roll is a concern for all seagoing monohulls -realy all boats.

    You description of a 3000 lb gyroscope 42ft up rings alarm bells in my mind. I am just an engineer who studies boat design for recreation but there is a good chance alarm bells should be rung.

    A boat on the ocean is a mass spring damper system and the damper value is almost always too small. Your 1.5 ton mass 42 ft up is a huge inverted pendulum -it will tend to lower the natural frequency of the ship and greatly INCREASE the amplitude response. As for damping all I can say with certainty is its is nowhere near that of a sailboat. So my concern is that you are creating a boat with a high susceptibility to severe roll from common low frequency ocean waves.

    I don't know much about vertical turbines and I might have been thinking about horizontal ones when I commented, but I still think it is unlikely your terrestrial control is up to the task of swinging around on a stick above a ship. The 9.5M radius is less than a horizontal but your 'updates hundreds of times a second' means nothing. The control circuit has a frequency response - likely 10 hz or less. How would it perform in a LARGE slow roll?

    I don't know anything about your active ballast control but I am pretty sure it would take enough power to cause a rethink of the whole project.

    I can certainly be wrong about the problems above. But again I strongly recommend you consult with a NA. In short order they can give you the following important answers
    -what is the frequency response of your proposed boat?
    -what roll amplitude would result in various sea states?
    -what are typical wind velocities at different heights above the water?

    and I don't know how you can proceed without this information.
     
  4. Tcubed
    Joined: Sep 2008
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    Tcubed Boat Designer

    I think it would be appropriate at this stage for you to post a clearly defined SoR (including priority hierarchy or weighting) , as well as your estimate on time spent in each "mode" ; cruising, at anchor, dockside. For cruising you could substitute typical length of trips and frequency. Also your target cruising speed and max speed.
    As you have evidently been thinking about this a fair bit already , as well as going to the trouble of creating a preliminary visualization model, i think it should be straightforward for you to do this.

    Only then can an idea be formed as to whether or not this design concept is worth pursuing.

    Be sure to include in the SoR what is the real motivation behind the wind energy input here; You say «however; shore power is a fine substitute.» which makes me sense the wind energy generation is neither for reasons of economy, nor of ecology.. so what is it?
    The areas around Florida and the Bahamas do not, in general, have enough current for hydropower (at anchor) to make economic sense. Worth doing a brief bit of number crunching just to make sure, but am confident that the numbers would corroborate on this. Wind is generally very good there in the winter months, less so in the summer months.

    Agree with keeping all energy storage options at this stage.

    I cannot/will not comment on your model without that.. ;)
     
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  5. rainmaking
    Joined: Jan 2014
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    rainmaking Junior Member

    Kerosene-
    It's a good question. It does seem like a lot to go through for the amount of energy benefit. The key drivers for me are:
    -sustainability--being able to sit at anchor in comfort without depleting resources (both onboard and earthly), polluting, or consuming foreign oil
    -unlike a traditional sailboat, having the ability to store wind energy for future use
    -solving the engineering problems associated with a project like this is fulfilling
    -a displacement power boat needs weight deep in the hull anyway, so why not use batteries
    -my company developed and builds the EcoVert turbine and has expertise in energy systems, machine controls, etc.

    As I said in my opening post, the initial idea for battery capacity is 2,500kWh
     
  6. rainmaking
    Joined: Jan 2014
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    rainmaking Junior Member

    Jeremy-
    You make good points about the challenges. I think with some working of the concept they might become more surmountable though. For instance, as you can see I have lowered the main rotor and adjusted the blades accordingly. This scenario could be about 2400 lbs approximately 26' off the water. That is only about 1-1/2% of the boat's mass and likely a more realistic scenario. I would think a large tuna tower on a smaller boat could have a higher moment of inertia.

    Yes, VAWT's are normally less efficient than HAWT's, but not in the case of EcoVert. Our machine has a validated power curve Cp >0.5 for much of its operating range, which is higher than even the best HAWT's.

    I am not sure how much effect the gyroscopic forces would have on pitch and roll during operation but I can tell you that at some point we would simulate it--probably in matlab--before building the boat.

    As for neighbor friendliness on the hook, I can assure you that the turbine presents no irritant other than the potential shadow flicker that one could have nearby for a short while at the wrong time. Besides part of the point of being on a boat is to get some distance between you and your neighbors. Solar PV is great and I would incorporate as much of that as practical also.
     
  7. pdwiley
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    pdwiley Senior Member

    Can't *wait* until the first time you try to bring that alongside a fuel dock or similar.

    PDW
     
  8. philSweet
    Joined: May 2008
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    philSweet Senior Member

    Rainmaker, I'm trying to imagine the experience of being in the near field of one of these things when it's working. Would any part of the boat's deck be habitable? I imagine the wind buffeting must be like sitting beside the interstate with trucks going by every second. There are conventional micro helicopters that only have 40 kw of shaft power. If this thing is generating more than twenty, even at slower speeds, it still must be making one heck of a near field disturbance. I'm thinking little hurricane-force eddies swirling across the deck every second. You've got a few kW of wake energy going somewhere.

    Okay, I found a wake analysis of a straight bladed VAWT. See ch 7 for conclusions. Best guess is trashcan sized eddies with 150mph core speeds wafting over the deck every second. Does this sound right?

    http://www.lr.tudelft.nl/fileadmin/...shed_Master_projects/doc/Kristian_Dixon_r.pdf
     
  9. rainmaking
    Joined: Jan 2014
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    rainmaking Junior Member

    True, but spread out over >100m^2 it doesn't amount to anything noticeable. It's a good paper you found, I do not remember it being in our library. Note that our turbine operates at a tip speed ratio of 3, which is below the range of operation of what Mr. Dixon studied--he used different airfoils at different reynolds numbers and did not consider pitch control. This low tip speed ratio we use contributes to both high efficiency and low noise. The extremely large tip treatments also dramatically lower the energy lost at the blade ends as well the corresponding magnitude of disturbance. We did spend a lot of time optimizing them with CFD.

    As far overhead as the blade tips would be on deck I don't think you will notice anything if you aren't looking at them. But of course you are welcome to climb our tower at our facility with the turbine running and see for yourself.
     
  10. rainmaking
    Joined: Jan 2014
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    rainmaking Junior Member

    Skyak-
    You make insightful points. Stability is a key challenge and you describe it well.

    As for the turbine control, understanding its normal environment at the top of the tower, I do think it will handle the job. Remember, like the boat, the tower is also a spring. It is perhaps stiffer, but still has a natural frequency lower than the 'pulse' frequency the turbine produces while running. If anything the lower natural frequency of the boat will be easier on it. This might seem counterintuitive, but the amplitude will also be lower on the boat in terms of g-forces. There is nothing about a reasonable heeling angle that will impact the turbine. Of course it could not be allowed to strike the water but we could not run it in those conditions anyway.
     
  11. philSweet
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    philSweet Senior Member

    Well it's reassuring to know that you can walk out and check on it. I've had a little waterspout come aboard midship and throw the parrot's cage across the boat exactly like I'd hit it with a baseball bat. I was 8 feet away at the helm and only felt a gentle breeze on my face. The slack genoa sheet took off through the car like a canon shot messenger line. As long as you know you can keep the eddies at a safe distance.

    I think I would insist on an expansive hardtop, at any rate. If only to prevent you from being carronaded by the odd seagull that flys through your wake. I've also seen what happens when a motorcyclist catches a seagull in the face at 80 mph, and it isn't a pretty site.
     
  12. rainmaking
    Joined: Jan 2014
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    rainmaking Junior Member

    T^3-
    I need to do more thinking around a total SoR. Some of this I approach from the side of what is possible....and then try to back into how it could be used and see if there is enough overlap that makes any sense to pursue. The boat would be used for family cruising in the Eastern US and Caribbean. Other important factors:
    -nice, modern yet timeless aesthetics
    -easy to operate and maintain
    -probably would like 10kt cruise/15kt top end
    -other things as stated already like the garage

    I don't know how it is that your math differs from mine on the hydropower....we have >3kts just a few miles from my house pretty much all the time. The islands are also full of cuts with tidal currents....have you been to Staniel?
     
  13. rainmaking
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    rainmaking Junior Member

    Phil-
    Ouch and ouch! I don't want to be anywhere near a waterspout or a seagull at 80!
    You can see in my model I put in pretty big overhangs, except on the foredeck. The foredeck clearance as modeled (to the blades) is about 15 feet and the aft upper deck is 12'.
     
  14. rainmaking
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    rainmaking Junior Member

    Two arms will need to collapse relative to each other to allow the rotor to be contained within the beam of the boat. But thanks for your ill wishes!
     

  15. pdwiley
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    pdwiley Senior Member

    Not ill wishes. I frankly don't care if you succeed or fail and I'm certainly not hoping that you fail, or wishing you to do so.

    I just think you've got yourself a hammer (wind generator) and are in search of a nail to hit with it. I simply can't see any practical use on a boat, and I've spent over half my working life around or on ships, not toy sailboats. The power output is pathetically small and the bulk, materials engineering and frankly aesthetics are awful for the theoretical gain.

    As has been pointed out to you already, it's less efficient than a good set of sails.

    PDW
     
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