Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Diesel to electric conversion

  1. Aug 28, 2007 #1
    Diesel to electric conversion

    1. What is the "lightest" and most practical (affordable) set-up TODAY that one may convert Bio-Diesel fuel to electricity for use in electric motors?

    2. What disruptive technology is just around the corner (near future, 5 years away) which one may convert Bio-Diesel fuel to electricity for use in electric motors?

    The context: Automotive, Naval, Aircraft and landbased systems.

    The "lightest" comes into being a technology which is transferable to all types listed.

    Macro, micro and everything in between may be included, but my mindset is in transportation.

    What's out there?

    Are fuel cells only for hydrogen?
     
  2. jcsd
  3. Aug 28, 2007 #2

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    The engine in your Volkswagon + a dynamo.
    A diesel engine will burn pretty much anything liquid that can burn. It doesn't really matter if it waste oil from french fries, biofuel or dead dinosaurs.

    Huge goverment grants to farmers to grow bio fuels, to replace the huge goverment grants to grow corn syrup.

    Most fuel cells combine hydrogen and oxygen. This is reasonably energy efficient and has the advantage that the waste product is water.
     
  4. Aug 28, 2007 #3

    Danger

    User Avatar
    Gold Member

    I suspect that it depends upon the scale. A gas turbine is probably the overall best, but a 2-stroke Diesel would be more practical for a small application. Just my best guess, though.

    edit: Hi, Mgb... you sneaked in while I wasn't looking. Isn't a 2-stroke lighter for the power produced?
     
    Last edited: Aug 28, 2007
  5. Aug 28, 2007 #4

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    I've only seen 2stroke diesels on realy massive (marine or railway) engines.
    I suppose this is because you need a turbo to get the compression and it wouldn't be worth making a two-stroke diesel chainsaw with a turbo (might be fun!)

    In a big 2-stroke diesel is as close to thermodynamically perfect as you are going to get. That (and maintenance simplicity) is why most ships use direct diesel engines instead of turbines.
    I imagine cars aren't two-stroke diesel because of noise or vibration.
     
  6. Aug 28, 2007 #5
    I've read that 2/3rds of all new naval (non-rec) designs are Diesel to electric. It started with tug boats so that they have instant start up and torque (no problems matching drivetrain and engine output to load). Now used in cruise ships (turbine) to help lower vibrations and to help move it's large mass around using stearing pods.

    There is a large 100 long hovercraft being built which will be using Diesel to electric converter. I'm thinking on a scale at least half of that for widest application in real world.
     
  7. Aug 28, 2007 #6

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    Cruise ships, tugs and specialist rig support boats are diesel-electric with steerable thruster pods. This makes the ships highly manouvarable and in the case of cruise ships has the advantage of reducing noise and vibration and saving a large amount of space that the propeller shafts wasted. My company makes the laser rader system that controls the docking!
    Cruise ships also use a huge amount of electrical power for the passengers so they sometimes have separate gas turbines as auxillary generators. These are often the same engines as used on airliners.

    Big cargo ships use direct drive 2 stroke diesel as it is the most fuel/cost efficent. These engines get close to the theoretical thermodynamic efficency.
    Fast warships use gas turbines as they give the most power to weight if fuel and maintenance costs aren't an issue.
     
    Last edited: Aug 28, 2007
  8. Aug 28, 2007 #7
    Let me add that the US military is moving toward Diesel to electric conversion systems as they already must generate a lot of electric power to run their computers, communications, weapons and logistic hardware.

    If you can build a better mouse trap, maybe uncle Sam will fund it.

    The DoD SBIR & STTR Programs
    http://www.acq.osd.mil/osbp/sbir/
     
  9. Aug 28, 2007 #8

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    They also like steam turbines because they use a lot of high pressure steam to launch aircraft.
    For very big ships (aircraft carriers) you use steam turbines.
    For big/slow you use direct diesel
    For big and fast you use direct drive gas turbines.
    For manouverable or quiet you use electric thrusters, generated from diesel or gas turbine. Since marine dielsels and gas turbine will run on pretty much anything flammmable they could probably have both on the same fuel.

    One other possible advantage of thrusters for warships is that each thruster is independantly powered and steered and the connection to the engine is just an electrical cable so it would be much easier to have multiple redundant systems.
    A single prop shaft and rudder is very vunerable to a single lucky hit - as the Bismark discovered!
     
  10. Aug 28, 2007 #9
    Article is from 2001, I've read that they have already installed a few of the electric (electromagnetic) catapuls.

    Navy to Phase Out Steam Catapults on Carriers
    http://www.nationaldefensemagazine.org/issues/2001/Jul/Navy_to_Phase.htm
    Steam and hydraulics generally are considered a “maintenance nightmare” on board Navy ships, particularly aircraft carriers.
     
    Last edited: Aug 28, 2007
  11. Aug 28, 2007 #10

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    We had a grad student who was a navigator on carriers, I asked him why they still used steam catapults instead of something more modern.
    Basically they like simple heavy reliable systems. The carriers were designed to still operate when the entire battle fleet had been hit with multiple H-bombs, so anything that you couldn't repair in the middle of the atlantic with a sledgehammer and a file was out of the question.
    I guess now that is less of a threat - they, like everyone else, want new expensive complicated toys to play with.
    It would be interesting to know what the interference from a 100m long electromagnet capable of throwing a 30ton aircraft at 150mph does to all the other electronics around it!
     
  12. Aug 28, 2007 #11

    russ_watters

    User Avatar

    Staff: Mentor

    Most of the "normal" warships in the navy (frigates, destroyers, cruisers) use direct-drive GTEs with variable pitch props. The frigates use diesel generators for power and the destroyers and cruisers use GTEs.

    GTEs seem to be on the verge of replacing diesels when it comes to small-scale power generation, cogen, etc. for buildings and industry.
     
  13. Aug 28, 2007 #12

    russ_watters

    User Avatar

    Staff: Mentor

    Degaussing already kills computer monitors and tvs on navy ships pretty quickly.
     
  14. Aug 28, 2007 #13

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    Hard to beat for low maintenance long service life - especially the large installations that just use slightly modified aircraft engines. As I said in the other thread https://www.physicsforums.com/showthread.php?t=182038 the main modification for a RR Trent is to make sure it is VERY securely bolted down.
    I think some of the cruise ships actually use this engine for aux power and diesels for the electrical propulsion generation.

    ps They still degauss the hulls for protection from magnetic mines? I would have thought that with sensitive solid state magnetometers you could detect a ship how ever well it was degaused. The devices we use have to be tested/calibrated in the middle of a field in a wooden shed with copper nails.
     
  15. Aug 28, 2007 #14
    1. What is a GTE?

    2. Does it use steam?
     
  16. Aug 28, 2007 #15

    russ_watters

    User Avatar

    Staff: Mentor

    Gas Turbine Engine. AKA a jet engine. The engine the Navy uses (GE LM2500) is from the same family as what powers the DC-10.
     
    Last edited: Aug 28, 2007
  17. Aug 28, 2007 #16

    Astronuc

    User Avatar

    Staff: Mentor

    Back in the old days -

    ALCO and EMD (subsidiary of GM) were the major suppliers of diesel locomotives. GE became the third major supplier, and supplied ALCO with motors and generators, until ALCO went out of business.

    Anyway EMD favored 2-stroke, while ALCO and GE favored 4-stroke. ALCO and GE units 'smoked' a lot.

    http://www.sdrm.org/roster/diesel/alco/index.html - 244 and 251's were standard
    http://alcoworld.railfan.net/alco_eng.htm - IIRC, the 244 came out in 1944 and the 251 in 1951.

    http://www.sdrm.org/roster/diesel/emd/index.html - 567 was standard until replaced by 645, then the 710.

    Fairbanks Morse was another supplier of railroad diesels, but gave up early. They concentrated on marine diesels.
    http://www.fairbanksmorse.com/marine_power.php

    Detroit Diesel favored 2-stroke and Cummins 4-stroke.

    Cat got into the RR diesel engine late - as replacement power. IIRC, they used 4-stroke for large diesels.
     
  18. Aug 28, 2007 #17

    AlephZero

    User Avatar
    Science Advisor
    Homework Helper

    And various R-R marine gas turbines as well.

    "AG9140 generator sets power all US Navy DDG51 destroyers ... The MT30 has been selected to power the engineering development model for the US Navy's DD(X) future surface combatant, [and] the Lockheed Martin Littoral Combat Ship ..."

    http://www.rolls-royce.com/marine/downloads/market/naval_range.pdf

    The MT30 is a marine version of the Trent.

    It's a bit ironic that the USN are happy with non-US, engines but they won't let UK engineers on the ships to install them because we are "aliens". Did somebody just say "special relationship"?
     
  19. Aug 29, 2007 #18
    I'm having a hard time thinking of thirsty gas turbines engines as efficient for anything. Light weight and powerful, yes. However you have to lug all the fuel around and fuel costs money.

    These 40,000 hp applications are out of scale with my nomal frame of reference (automobile engines). What hybrid system would be best for something 1/10 as powerful and which may not be operating 24 hours a day seven days a week?
     
  20. Aug 29, 2007 #19

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    4000Hp is still pretty large (railway locomotive or small ship) for that you would use a two stroke turbo diesel. For auto applications 40-200Hp a small automotive turbo diesel.
     
  21. Aug 30, 2007 #20
    Thank you, this is more or less what I first thought, just wanted some new ideas to kick around and consider.
     
    Last edited: Aug 30, 2007
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Diesel to electric conversion
Loading...