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Diesel Electric Propulsion

Discussion in 'Technical Discussion' started by Crewagency, Nov 26, 2004.

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  1. Navatech

    Navatech New Member

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    Solid state stuff (e.g. TV, hot water boiler, galley range & oven) could't care less if they're on a 60 or 50 Hz system... It's only stuff with motors (e.g. pumps, hair dryers, fridge, AC compressor etc) which care about the Hz.

    If they're designed for 50 Hz they'll turn a bit faster if they're powered by 60 Hz and visa versa for 60 Hz stuff running on 50 Hz.

    Not a big deal either way IMHO.
  2. Navatech

    Navatech New Member

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    As for the thread's subject, on big ocean going ships (e.g. Panamax box carriers) it has long been practice to use a shaft generator for "house" uses. The reason being that the main engine is the most efficient one on board.

    The auxiliary plant is used only in port, when the shaft generator is inoperable etc.

    The advantage of a DE setup is that when you don't need all the power you have you can run of a fraction of your setup. With a regular (e.g. port and starboard main engine) setup you'll be running BOTH even if you're running each at only 20% load. Eating up engine hours. Never mind the fact that they won't even be running efficiently. Plus you'd be running a generator for electricity.

    With a 5 generator setup under the same circumstances you'd be running 2-3 of the units at almost 100% efficiency. The other two would be doing nothing (no cost). Even with a 3 or 4 generator setup you'd still have only 2 - 3 of the units working.

    When you need more power then can be had of the running generators you start up one of the standby's. Also, propulsion redundancy is built into the system. Especially if you run the units of separate fuel sources.
  3. K1W1

    K1W1 Senior Member

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    Hi,

    Anything that uses the frequency to drive a clock/timer will have issues with the freq change sometimes to the point of failure.

    I was on a yacht that was setup to run on 208 3 Phase 60 Hz.

    This was determined to be the equivalent of a particular 50 Hz voltage and a transformer was constructed.

    Fluorescent Lights, The Coffee Machine, The Oven, The Microwave all clapped out.
  4. HTMO9

    HTMO9 Senior Member

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    The gearbox equipped Genset is not so far out of reality as you might think (albeit this one was thrown in for discussion purposes). A lot of shaft generators work with a hydraulic constant speed device in the main gearbox, in order to compensate for RPM changes of the main engine.

    By using a constant speed gearbox (with a high enough COP), you would be able to have a variable speed diesel engine with a constant speed alternator. But as said before, IMO the variable speed DC diesel generator with a consequent DC distribution and usage throughout the ship and a dedicated AC bus via inverter (i.e. for the hotel load) will be the future. ABB is showing the way to the future.

    You would be surprised, what kind of electric power is used in airplanes. 12, 24 or 28 Volt DC, 96 Volt DC, 110 Volt/60 Hertz AC or even 115 Volt/400 Hertz AC. Anything is possible. I remember one aircraft, were the alternator shifted gear at a specific engine RPM, because of his limited capabilty in stabilizing the AC frequency. High DC voltage is used to save weight on the cables and equipment.

    The European car industry conducted a study about the change of DC-voltage on cars. They came up with the result, that if going from 12 Volt DC to 42 Volt DC, they would save mare than 120 kg of weight on a Mercedes E-class type car. The change is pending, because of international standardization problems.

    By the way, most container vessels operate on 60 Hertz (even European), because the reefer boxes worldwide are powered with 60 Hertz. They only have 50 Hertz for the hotel load sometimes, in order to make the hairdryer of the female master work properly.:D

    Cheers
  5. karo1776

    karo1776 Senior Member

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    Now a very long time ago now screaming up on 50 years... In university my graduate project was what is now called a serial hybrid car. It was theoretical and a study. The power plant was a small turbine that could be fueled from most any hydrocarbon liquid fuel directly driving a wild voltage and PM frequency brushless alternator. The wheel hubs were electric PM motors. There was electronic conversion of the wild voltage and frequency to DC to feed a small peak load bank battery pack and the wheel motors... and a control system allowing the power to be directed and controlled as the system demands were meet. I still think this is viable... and likely the ideal situation for a diesel fueled electric drive. However, as has been pointed out herein the turbine end of things has narrow range and is expensive in cost and fuel.

    Quite similar systems were in use in space applications and some missile applications... from the early 1960s on. Interesting a friend and mentor who had invented pulse width modified fuel control for space attitude control, i.e. pulse attitude control rockets, which made the first spy satellites and the Apollo possible... in fact he proposed the first spy satellite to NRO and the winning idea/scheme for the moon mission based on what the new NASA defined as "radiation cooled thrusters".

    What is interesting for this thread, is the fact the first demonstrations of pulse attitude control systems were the installation of the tiny rockets as basically injectors on a small diesel engine of about 31 kw output driving an PM alternator for load absorption in early 1958. The fuel UDMH, unsymmetrical dimethyl hydrazine and red fuming nitric acid was used for the oxidizer. This was I believe was the first proposed hypergolic powered diesel (note all diesels work on hypergolic ignition, i.e. fuel ignites on contract with the oxidizer... usually diesel and compression heated air) with electronic control based on pulse width modified signals (all modern injection systems) and with electronic control of the power generated even though in this case it simply was dumped in a load bank for dissipation.

    The PMs were samarium cobalt based.

    My years later and even more year ago from now I originated program on a portable power unit program... using a small turbine directly coupling a PM wild frequency machine for military application as a man portable power supply for behind the lines aircraft ground and refueling applications.... 110,000 rpm turbine... originally directly coupled to a samarium cobalt PM toothless generator designed by Joe Denk at Allied Signal... putting out around 50kW continuous. Later and its down fall was the addition of a intermediary gear box by the staff assigned to its engineering development... which I was against but it was out of my hands by then.

    So I think it is not a huge technical hurtle to accomplish a small ship power system based on similar or identical technology... using high speed diesels.
    But the issue is cost. In the early 1960s a small turbine development program was around $1 million US.... In the 1980s the dwg package on the 50KW system turbine cost $5 million US to produce. Now-a-days one could spend a $100 Million US and have nothing to show.

    In thinking on it the last few days... I think a very small team could take an existing high speed marine diesel and couple to a custom designed toothless PM machine and have the basis of the power system less controls and load devices such as the pod drives.

    So I think the key for most yachts in the 80-150 foot category would be a power supply module, perhaps:
    Something like using the Steyr SO 6 cylinder 3.2 Liter diesels running at around 3600 rpm (makes no difference) directly couple to around 140-160kW output generators custom designed for the application.... make it a package with insulated for heat and sound and it would be less than 1 meter wide- 1 meter tall and about 1.5 meters long with a mass of about 600-750 kg. A replacement life of around 10,000-12,000 hrs.

    A 42 meter yacht would need about 6 or 7 of these along with a control and battery storage system for peaks and idle situations at anchor were the boat would operate off the batteries for a few hours and then a gen set would start and recharge it fairly quickly while suppling the load direct.
    Underway the system would automatically start and stop the gen sets as needed while balancing hrs on them. If the gen sets were plug and play easily removable from the boat for replacement you would have a good to go package. And, as technology improved on the gen sets you could easily update.

    Of course you could select several other engines but that one is marine based and high speed... and light weight.

    The thing that holds me up is money... and time. More importantly time... if I ran the thing I am sure of success... but I have bigger fish to fry. The guys I would trust to run it would still need my supervision... and all all past retirement by some years... .
    Therefore, it is a money issue... why... I have seen $25 million US (cost of the boat) evaporate in such similar efforts with nothing to show...
    or $50 million US even evaporate now-a-days .... so for success its a $100 million project US which I find almost disgusting to contemplate and just go out for a day sail by myself leaving everyone else home and forget it.

    And, don't anyone try to sell me an investment opportunity in this either.
  6. HTMO9

    HTMO9 Senior Member

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    There is a company on the market, building PM Gensets like you mentoined. Its Fischer Panda (Generatoren, Energie und Systemlösungen | Fischer Panda). They produce high speed diesel Gensets, either as 1-phase. 3-phase, combined 1-/3-phase or variable speed gensets with build in inverter or variable speed DC Gensets up 200+ KW of shell or more if you want. The diesel engines in their inventory range from Faryman, Kubota, Yanmar, Deutz, Mercedes up to MTU depending on size.

    Without placing them by any means above Onan, Northern Light or any other of the big players, they have one advantage. The alternators are watercooled in a combined circuit with the diesel engines. By this feature, the cocon can be closed completely and they are remarkably quiet. I am using them in my sail boats for pretty long time now without problems.

    But they do not build anything for the very big boats jet, but they will, if you ask them.

    For the commercial ships use we only take MANs or MTUs with Leroy-Somer alternators, it always works, no trouble, no hassle.

    The Gas Turbine driven Generator is under R&D for an LNG Membrane Carrier project. The task is to have dual fuel (MGO and NG) gas turbines driving large high voltage alternators in order to drive a watercooled PM E-Motor gearless with VP Prop. When the LNG membrane tanks are full, the gas turbines are driven by the bleed off NG of the cargo tanks. On the way back, when the LNG tanks are empty, the ship runs on MGO. A very simple concept. But here we are talking about ships with propulsion power of 35.000 KW and higher.

    NG driven ships are a great possibility as far as enviromental aspects are concerned. Norway is operating serveral short range commercial ships like ferrys with NG propulsion already. Very economical and clean type of fuel for your ship, if a filling station is always in your reach.
  7. brian eiland

    brian eiland Senior Member

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    Small Turbines, Turbine Generators, and LeMans Electric Car

    I've got a lot of reading to do to catch up with this discussion :eek: ....and that's if I can understand it all. But you fellows have contributed some very interesting discussion.

    I saw mention of turbine generators and this came to mind. This company here has been working on small turbines for a long time.

    http://www.microturbine.com/news/story.asp?id=536

    The concept for the high performance hybrid electric micro-turbine vehicle was developed by Electronic Arts Chief Creative Director Richard Hilleman, creator of popular video games, with support from Capstone Turbine, the world's leading clean technology manufacturer of micro-turbine energy systems.

    Capstone and Hilleman's micro-turbine enabled hybrid super-car features a Capstone C30 (30-kilowatt) micro-turbine that runs on diesel or biodiesel, which is housed inside a sleek Factory Five Racing GTM body. The Capstone C30 microturbine is so clean it does not require any exhaust after treatment to meet stringent clean air requirements of the California Air Resources Board or EPA 2010.


    I first became acquainted with their name when they were going to supply the small turbine generator for Chrysler's LeMans Electric Race Car
  8. HTMO9

    HTMO9 Senior Member

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    The biggest issue with gas turbine driven generators or turbine propulsion, is the origin of the gas turbine.

    Normal diesel engine driven gensets have a TBO of 10.000 hours ore more. Turbines which are mostly based on aviation sources like propeller turbines or helicopter engines have a TBO of 3500 hours or less. Smaller turbines which are based on RPVs or APUs have much lower TBO and / or not cleared for continuous operation.

    Some of the small turbine Gensets available on the market are rebuild military GPU (ground power units). The mil spec never had fuel economy or the enviroment on their primary focus.

    The very small turbines like the Microturbine TRS 18 (remember the James Bond BD-5 Jet) are not build to last very long (40.000 RPM). There are new micro turbines on the market which derive from modell plane turbines. They are for example used to power manned gliders, but with a TBO down to 50 hours (110.000 RPM).

    The real Gas Turbine powered Genset has a turbine which is build for that purpose, which is cleared for continuous operation, with highest possible TBO and the optimum power output is really used during its operation. A gas turbine Genset needs a perfect cocon to eliminate the noise and the proper installation within the ship. GT do not like long and winding exhaust stacks which cause exhaust backpressure. That wiil cause hot starts exceeding the engine operating limits. And that will happen to modern GT too.

    The examples I would call out by this parameters are the Vericor TF40 / TF50 version or the big GE LT 2500 or those professional types build by Rolls Royce.

    Cheers
  9. K1W1

    K1W1 Senior Member

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  10. brian eiland

    brian eiland Senior Member

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    Small Turbine Powered Generators

    I do realize that the smaller the turbine size is, the faster it must rotate to make its at least somewhat efficience. But higher speeds don't always mean shorter life span...at least not in all cases.

    I found this discussion interesting:
    Gas turbine - Wikipedia, the free encyclopedia

    BTW I was not suggecting that turbine generators where a 'cure' for exploration vessels. Its just they were brought up in the previous discussions to my initial posting about Capstone. I had been interested in where the 'smaller/micro' such units might be developing for possible use on lighter weight vessels such as multihulls, where space and light weight are limitations to be considered with more emphasis....and total power requirements are not so large as a BIG ship.

    I found this other subject thread where smaller sets (and the Capstone units) were discussed at greater length.
    Capstone Turbine and Electric Ship Facilities Team Up on Hybrid Electric Boat
  11. brian eiland

    brian eiland Senior Member

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    Newer DC Diesel-Electric Technology

    I am 'in the same boat',...maybe more so :D.....electrically challenged.

    I have been trying to follow this newer DC diesel-electric technology since it really emerged in 2002. This was one of the early subject threads I followed:
    Solomon Technologies - "Electric Wheel" electric motor propulsion systems

    ...and this one:
    Diesel/Electric Propulsion for Sailboats

    I became a real believer in this company's approach as it appeared to be the most 'comprehensive' ,.....Glacier Bay and the OSSA PowerLite System.
    I wrote in several postings:
    I keep laboring under this idea that the DC gen sets did NOT have to operate at 'full speed' as the AC sets needed to, in order to put out the correct AC cycles. So the DC sets could operate at a lower output to more fully match the power needed by the electric prop driving motors at any different speed..

    Maybe the DC set's lower operating speed was not the most efficient, BUT it was more versatile over a range of power requirements, thus necessitating fewer gen sets and power sources....fewer engines onboard.
  12. brian eiland

    brian eiland Senior Member

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    Two PDF's for Glacier Bay

    Regrettably I think this company has gone out of business, but here are a couple of PDF's they produced to describe their system.

    Opps, I could upload one of them, but the other file was a little to large for this forum,...so you can access it here:
    High voltage DC generator - Boat Design Forums

    Attached Files:

  13. HTMO9

    HTMO9 Senior Member

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    turbine powered generators

    As said before, installation issues are a big part of gas turbine powered ships. A GT wants free breething. They loose a lot of power with long and winding intakes and exhausts. If you look at their specs, the nominal power is mostly shown as uninstalled performance. Thats why the mighty liner QM2 has her GT generator installed in her funnel.

    The next importent point is engine effiency. The average GT will show an overall efficiency of 20+ to 35 %. Other than in military applications or pleasure boats (booster engine) were many does not count, in merchant ships, these percentages are not accepted.

    LNG carrier are a special case, because the GT uses the bleed off gas of the LNG reservoir, which maybe lost otherwise. But it is still not very profitable, if the GTs has used most of the cargo, when reaching the destination.

    Cogeneration will be the only answer to get the engine efficiency of an GT into acceptable regions. A modern large 2-stroke, low RPM Diesel with consequent wast heat recovery, can reach an overall efficiency of up to 57 %. A GT with their much higher EGT can do much better.

    Modern natural gas, turbine powered powerstations with large gas turbines and waste heat recovery via steam turbine reach efficiency levels of up to 70 %. This is up now the highest efficiency level of any thermo dynamic power generation in industry.

    The name of the game is, to adapt this principle for ships and you will see more GT propulsion in merchant ships.

    Cheers
  14. karo1776

    karo1776 Senior Member

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    Gas turbines are wonderful but in most yacht use not practical I suppose for under 80m... which mean most yachts. If you want to spend the up front and operating money on your hobby OK.

    I think fuel cells are in the same boat as for a submarine it is government funded endeavor and for its limited use the fuel cell is perfect... even better than nuclear. That use is very quiet very slow operation non air breathing operation.

    Very rich and enthusiastic men are in yachting but I have not seen anyone willing to step up to those challenges. Why is because fundamentally yachts are places of escape and relaxation. Technical risk and challenges are not fun when things do not work out and can be bottomless pits.

    Currently the US Department of Defense is having to face that fact. Designing and developing such become what is termed spiral development as per various spy satellite programs, Global Hawk and even the F35 aircraft. The exact same issues apply to yachts. Certainly, hulls and masts and other structural pieces are much less costly and risky than power plants. The old rule of thumb was a new airframe could be accomplished in 1 year but an new power plant was 10 year program. That applies to yachts too... so that is why propulsion technology drags behind advanced technology structures in yachts.

    Ship and boat construction is very conservative in structures with huge safety margins... making risks taken relatively safe in comparison with military aircraft structures. Typically many of the cutting edge aircraft like F35 have zero margin safety factors... this only used to apply to drone aircraft... and is the reason behind large cost increases. Following Apollo 13 the structural margins in space as in life safety have increased to .8 margin meaning a 20% safety margin at failure to normal expected use loading.
    Yachts are not so highly engineered... but submarines approach the margins of life safety in space. NO BOAT IS DESIGNED ANYTHING CLOSE. That is why technical advances proceed quicker in the structural realm.

    The issue with diesel electric and costs has to do with mass or weight issues. Yes a large 60m displacement yacht can suck up the extra mass but a 40m boat its becomes overwhelming. That is where the risk is to get both mass and size small enough to reasonably compete with convention diesel direct drive propulsion. A day sailer like the J Boat Rainbow can do it but its use is limited and it has nothing like the power loads of a motor boat to serve. That is why when I start doing estimates I get scared off. To shrink the things down to practical in a reasonably sized yacht is just too risky for the benefit.
  15. Ju52

    Ju52 Senior Member

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  16. karo1776

    karo1776 Senior Member

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    Yes, the 209 / 214 submarine is state of the Art in Diesel electric boats. The sub is powered by 4 MTU diesel electric alternators which power a single shaft concentric motor. The can run submerged on the Diesel electric at up to 22 knots and go about 7000 miles at reduced speed... noting this means using the snorkel. For AIP (air independent propulsion) they have batteries and Fuel cells. With the batteries combined with the hydrogen/oxygen fueled fuel cell they can make flank submerged for a short period. On the fuel cells alone they can do 4 knots for as I remember about 96 hours... and doing that the fuel costs make initial fueling for Lurssen's new Azzam look cheap.

    The latest are the 209PN/214 type with the latest Siemens BZM120 fuel cell modules, PEM type modules with 120KW per module at a max continuous draw of 560 amps at 208v, efficiency of 58% at 80 degrees C. The efficiency increases to around 68% at low draws. These have the twice the power to area of the cells output compared with the older modules are 34 KW each with slightly higher efficiencies. The problem is NO YACHT can afford such and having the pure hydrogen and oxygen fuel supply is not so easy or cheap to run a PEM fuel cell.

    Here is a nice article on conceptual design of such subs:
    https://www.navalengineers.org/SiteCollectionDocuments/hamilton_award_papers/122_1/paper9.pdf

    And here is one on AIP... AIR-INDEPENDENT PROPULSION – AIP Technology Creates a New Undersea Threat

    These boats are for very stealthy operations of short duration... and are extremely dangerous as close to shore cruise missile and torpedo threats.

    But as yachts you have to remember the benefit to cost picture is way way upside down... and the resistance on the surface is hugely increased from submerged operations. So unless you like lurking in the deep and going very slow and quiet... and having to creep around the boat so not to make the slightest sound so you don't have a torpedo up your butt these are not for you... as they are not fun or low stress for relaxation time away.
  17. walkinginshadow

    walkinginshadow Member

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  18. Marmot

    Marmot Senior Member

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  19. karo1776

    karo1776 Senior Member

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    The problem with the pneumatic engines are they are hugely energy inefficient as the power losses in compression of the working fluid (air) are the problem... if you had a windmill to pump them up maybe...

    But then you might as well just have sails and join us snail boaters... and be solar powered (wind is created by solar energy absorption by the atmosphere, sea and earth.

    The article I posted on submarine technology design choices is very excellent. However, it is misleading that AIP operation has duration of 2 weeks submerged... I believe that is at a creeping speed of less than 2 knots... and just floating there submerged hiding... on life support.

    The problem for the Sterling and this pneumatic system is bubbles!

    One of the interesting things is you can do a system of rocket fuel propulsion. High speed torpedos have used such for a long time. But now-a-days they are pretty much electrically powered...
  20. Marmot

    Marmot Senior Member

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    I guess I should have added a few smileys ...