Navy Set to Install Hybrid Electric Drives in Destroyer Fleet Staring Next Year – USNI News

Next year the Navy will begin installing a hybrid electric drive (HED) system on 34 Flight IIA Arleigh Burke guided missile destroyers in a bid to lower the fuel costs of the ships, Naval Sea Systems Command (NAVSEA) told USNI News in a statement.The system, which will marry an electric motor to the ships’ main reduction gear to drive the ship at low speeds, promises to save the service thousands of barrels of fuel in over a ship’s deployment.Earlier this year L-3 — the company was awarded contract in 2012 to develop the technology — delivered two pre-production HED systems for testing ahead of the first installation in the Burkes in the fourth quarter of Fiscal Year 2016 after research and development testing is done, NAVSEA said.

Source:  Navy Set to Install Hybrid Electric Drives in Destroyer Fleet Staring Next Year – USNI News

Interesting. I didn’t know this when I wrote about hybrid drives this morning.

The normal DDG-51 plant is four LM2500 gas turbines, two per shaft. Turbines spin at ridiculous speeds, whereas ships propellers work best at low speeds. To fix this mismatch, the LM2500s drive through a main reduction gearbox for each shaft. You can also operate with one engine on each shaft offline. I suppose you could just idle one shaft, and run the other on one engine only.

Here, you can use power from the ships service turbine generators to power a small motor that’s linked to the main reduction gearbox. Given a light enough load on the rest of electrical bus, you could simply run the ship off the generators and save quite a bit of fuel.

12 thoughts on “ Navy Set to Install Hybrid Electric Drives in Destroyer Fleet Staring Next Year – USNI News”

  1. That is interesting, and I’ll be very intrigued to hear more details about it when they get started.

    Incidentally, yes, you can feather one screw and run the ship on a single engine on the other shaft. That’s called “trail shaft.”

    1. I’m not sure. What’s the difference in radiated noise levels between the SSTGs and the main powerplant? And given that we haven’t seen Big Navy emphasize ASW much in well over a decade, I have to guess it really is all about fuel costs. That it works well for that mission is just a bonus.

    2. A bit of speculation on my part: I’m guessing a turbine electric may not require quite so large a turbine. If that’s the case, just the smaller engine would be a help. Also not having the turboshaft tied directly to a reduction gear would allow more sound isolation. This would be intuitive, but such things have been wrong in the past.

    1. They have; and they retain a very large battery as well as a diesel generator to supply power in the event that the reactor scrams. You probably wouldn’t need a battery for skimmers, since they are only good for one dive.

      1. Just to clarify, the NORMAL operational mode for US subs is that the steam from the nuclear plan turns the turbine directly (as well as operating the ships service steam turbogenerators for electricity). It’s a purely mechanical powertrain. Using the battery bank (and charging the batteries via diesel) is an emergency mode.

    2. There was a sub years ago that tried for direct electric drive, but there were a lot of problems with the system. Subs have an Electric Propulsion Motor, as well as electrically-driven outriggers, but they aren’t good for much speed, basically just enough to let you steer the ship while on the surface. Submariners put a lot of emphasis on continuity of power. Surface sailors just cross-connect the plants.

  2. This falls into the, “We should have done this long ago,” category.
    -Efficiency at slow speeds (i.e. stay in the box ops). We did a whole lotta that.
    -Controllability at low speeds. Now you’re not stuck with a shaft spinning continuously. Perhaps could make pier side handling better?
    -Most importantly: Casualty ops. There’s a whole lotta ways to keep the mains from starting, but if you’ve electrical power, you can move. Lock the pitch, go to motor. Movement is life.

    Now, for heaven’s sake: Make a generator that doesn’t need $%^&*!! high-pressure air to start! Nothing like being cold and dark with no way to start a generator because you just used the last gasp of HP air. BTDT. Look at the UK Type 23 frigates for a good example of what to do.

    1. … you know that half (or maybe more) of our GT-powered warships don’t even HAVE an HP air system, right?

Comments are closed.