Capstone Microturbine . . .

Discussion in 'Hybrid' started by auriel, Aug 13, 2011.

  1. auriel
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    auriel Junior Member

  2. Stumble
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    Stumble Senior Member

    Hybrid propulsion has been covered ad nausium in this forum. Basically it is an inefficient way to power a recreational boat. Though it does have commercial advantages in some applications.
     
  3. auriel
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    auriel Junior Member

    Contempt prior to investigation?
    You obviously didn't bother to review the information or you wouldn't have made the acerbic comment.
    I was hoping to see some critical thinking skills engaged at this forum

    Auriel
     
  4. FMS
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    FMS Senior Member

    People react against hybrid because of all the grossly impractical "hybrid" concepts floated. 99% have their primary design requirement being the use of the word hybrid!

    For a houseboat with the emphasis on house loads you might be on to something.
     
  5. auriel
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    auriel Junior Member

  6. Stumble
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    Stumble Senior Member

    Auriel,

    It isn't without thought. Spend a few minutes with the search function, and you will find thread after thread on the idea. Or just read the ten threads following this one.

    Here is a quick set of numbers though. The largest load a boat will experience by far is propulsion loads. So to have a hybrid system requires sizing the generator for these loads. Think something in the 100kw range for a 50 foot displacement hull. You will also need to size for house loads. This will be something less than 15kw. To be even moderator efficient you will need two generators a 100kw for propulsion and a 15 for house loads. In this case it is more efficient to just use the 100kw for propulsion instead of making electricity.

    Where hybrid propulsion is reasonable is where the house loads are larger, or of similar size to propulsion. Or where there are major differences in propulsion requirements like on tugs where the hybrid allows the operator to turn off the large engine.
     
  7. auriel
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    auriel Junior Member

    Stumble,

    Before I spoke I did my homework. I searched the whole site, I even discovered a few threads about Narrowboats which is the basic houseboat design I was inspired by even though I plan on traveling American waterways. There has been plenty of discussion of hybrids but no mention what-so-ever of the new generation of high efficiency microturbines that have just come on the market. The article I cited was about the first ship to be converted to hybrid using this new design of power plant. Turbine auxiliary powerplants have been around for a lot of years, every commercial jetliner has one, but never have they been available in a package this compact, efficient and with this low of an emissions signature.

    There is no comparison between standard marine diesel generators and Capstone diesel fueled microturbine generators. If you had actually done your research before commenting you would of seen that for yourself.

    All I expected was for people to READ the literature and contribute some lively discussion.

    I can see that I expected too much.

    Auriel
     
  8. daiquiri
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    daiquiri Engineering and Design

    I have read the literature in the links, but can't see where was that big efficiency gain over a standard (reciprocating engine) diesel solution claimed. Could you please point us to a document which shows these numbers?
     
  9. Yellowjacket
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    Yellowjacket Senior Member

    The efficiency of the Capstone unit is about the same as a similar size diesel when it comes to producing electricty. It has the potential to be a lighter and smaller electrical generation system since the engine is obviously lighter and it has a high speed alternator, which is a lot lighter and smaller than a low rpm unit on a diesel.

    At this point you are making electrical power and you want to power a boat. So you have to convert that back into thrust and to do that you need a electric motor. Unfortunately, low speed electric motors are expensive and very heavy. The weight of the Capstone unit, added to the weight of the drive motor, results in a system that is as heavy, and since there is a little thing called electric motor efficiency, not as efficient as directly driving a prop with a diesel engine.

    The cost of the Capstone unit, by itself is about $1,000/kw, or the last time I looked it was over $30,000 for the 30kw unit. A marine diesel of 30kw, combined with a gearbox and set up in your boat is going to cost less than a third of that.

    While the Capstone unit is quiet, smooth running and clean, (and that's not a bad thing) you have to want the turbine pretty badly to spend that much more for a propulsion system that doesn't have have any measurable advantages in terms of fuel efficiency.

    If you have a pressing desire to have an electric drive system, and are going to go that way with a diesel anyway, then such a system deserves a look. It depends on how many hours a year you are actually driving the boat, the Capstone unit will probably outlast the diesel, but since you can buy three diesels for the cost of the Capstone unit, it starts to lose its rationale. Any good financial advisor would tell you to buy the diesel and pocket the difference.

    Finally, be careful of all the "puff pieces" that you see in the press on these kinds of things. The real world is a tough place. In a power gen system that is backed up by the grid, if your generation system goes down nothing bad happens. If you are out in a storm and lose power it's a whole nother story.
     
  10. Submarine Tom

    Submarine Tom Previous Member

    Good points YellowJ.

    -Tom
     
  11. Stumble
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    Stumble Senior Member

    And even assuming the turbine was significantly more efficient than a standad diesel, it would still be more efficient to hook it up to a transmission instead of a generator for almost all boats.
     
  12. auriel
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    auriel Junior Member

    Thank you Yellowjacket.

    Wow, for a minute I thought I was actually about to have a serious argument about a comparison between turbines and IC engines and efficiency? There is a reason why no power generation on the grid is being done with anything but turbines these days. You cannot beat a turbine for efficiency or low maintenance. Decades of use have proven this.

    There is only one moving part in the Capstone microturbine generator. One.
    http://en.wikipedia.org/wiki/Capstone_Turbine

    It's light, quiet and as close to zero maintenance as you can get.
    It has air bearings so it doesn't even need oil.

    $30k is pretty steep for a generator but as the foundation for a high-tech "house on the water" it becomes a more reasonable capital investment. Besides that if $30k is too much money for you then you also wouldn't be able to afford the kind of houseboat and fittings I'm talking about either. Lease-to-purchase and rental options are also available.

    The cost is high because Capstone right now has no competition in the market. As soon as we see competitive designs make their way into production and infiltrate the market we will certainly see the price drop.

    I have had a similar discussion before about a Capstone HEV bus design and ordered a comparative analysis between turbines and IC diesels from Capstone. I've searched my emails but couldn't find it so I've ordered another copy from them. As soon as I get it I promise to post it.

    I was thinking about using the Voith Propulsor for a directional main drive and a bow thruster. From what I've learned it would be powerful enough to navigate rivers like the Ohio and the Mississippi.
    http://www.voithturbo.com/vt_en_pua_marine_vct_inline-thruster.htm

    That's only one of several electric traction motors that I've found that don't weigh a ton, are powerful and efficient.

    Of course they could all be exaggerating about the performance and efficiency of their products.

    I generally trust the free market to take care of such things, which by the way is why I trust Capstone's claims. The company and their stock have been doing well. The market clearly approves of the Capstone product.
     
  13. brian eiland
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    brian eiland Senior Member

    Capstone Turbine & Canal Boats

    Don't get discouraged with your pursuit of discussions on the forum, at this time of the year it is slow and doesn't bring as a great of a variety of replies.

    I have some interest in both of your subjects, but limited time to respond at this time.

    I've know of Capstone for a long time, back when they were going to supply a small turbine powered alternator unit for a hybrid electric car to race at La Mans.
    http://www.boatdesign.net/forums/propulsion/new-propulsion-sytems-ships-9630-11.html#post85848

    And here is my favorite river/canal vessel, Roi Soleil
    http://www.boatdesign.net/forums/boat-design/dutch-barge-long-distance-cruisers-11316-20.html#post455644
     
  14. Stumble
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    Stumble Senior Member

    Auriel,

    You opened this thread asking about a turbines use in a hybrid boat, and most of us were answering that question. Our answers weren't directed at the turbine, but at the concept of a hybrid recreational vessel.

    I think most of us would admit and perhaps champion the fact that turbines are more efficient and typically require less maintenance than an ICE. In fact there are a few turbine driven boats that work fine, but the initial purchase price is a pretty big problem when compared to a traditional engine. Assuming a difference in price of 30,000 per engine, that will add let's say 70,000 to the purchase price of the boat. With the extra money in non-standard system costs.

    For a boat that is operated regularly this would take a long time to make back in fuel economy. I for instance burn about 2000 gallons a year on my big boat. Even at 5 dollars a gallon, factoring in opportunity cost on the extra cost at 10% it would take something like 30 years to make it up. Now I use my boat something like 5 hours a week on average.

    So to make this worth doing it would be limited to boats that are actually used very heavily. And the reality is very few buyers will use a boat often enough to pay back the initial purchase price. And most manufacturers are unlikely to go through the expense and complexity of adding this to their product line for just a handful of buyers.
     

  15. auriel
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    auriel Junior Member

    Stumble,

    I made it clear from the being of the thread that I WASN'T talking about a recreational vessel that somebody is only using a few hours a week.

    I am talking about a luxury home that is lived on and used 365 days out of the year including a home office space, workshop, laundry, dishwasher and everything else one would expect in a land based home. Maybe even a nice hot tub?

    I want the main and bow thrusters because I would plan to do quite a bit of traveling on the Allegheny, Ohio, Cumberland and Mississippi Rivers.

    Otherwise a powerful genset and drive-train wouldn't make any sense for a boat that mostly stays at its mooring and has access to land based facilities.
     
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