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Reducing the fuel consumption of ships

We could greatly reduce the fuel consumption and emissions of ships if we used the energy of waves. This could done by adding a pipe all the way around the ship above sea level. Water enters the pipe at the bow and exits at the stern to push the ship forward. The pipe is higher and wider at the bow than the stern. Waves force water into one way openings at the bow to give pressurised water with potential energy. This pressurised water forces jets of water out at the stern.

All the pipework is above sea level so ships could be retroftted without the need to go into dry docks. There is no change to the laminar flow of water below sea level.

The motion of the ship adds to the kinetic energy of waves. By diverting this energy around the ship we can reduce drag and fuel consumption. This would be a low cost way to reduce greenhouse gas emissions without the need for people to reduce their standards of living.

  • Canvas? Dear me! How about Flettner rotors? Said to save 25%. 

    2ecea85ea2a50ab9899df437b2066cec-original-enercon_e-ship_1_atsea.jpg
    Enercon's E-Ship-1
  • Sorry, forgot the photographer. Lpele CC BY-SA 4.0, from the German WWW page on E-Ship 1.

  • Flettner rotors are being seriously considered on a number of projects, though the 25% saving is going to be under ideal conditions (ship with a lowish speed, so low power, with the wind directly from the side). The benefits are only when the wind is from the side, so say 50% of the time, and for 25% of the time with the wind from ahead the rotors will add to the fuel consumption due to the extra wind resistance. They also need power to operate and can cause issues with stability in high winds and provide little (or no) benefit when the wind is low. They also are impractical for some ship types.

    Please note I am in favour of them, but we must be realistic about how much benefit they provide.

  • Peter Bernard Ladkin: 
     

    Sorry, forgot the photographer. Lpele CC BY-SA 4.0, from the German WWW page on E-Ship 1.

    That's a fantastic machine. 25m high cylinders 4m diameter doing up to 300 RPM.

    That is a surface speed on the cylinders of ~ 60 metres per second at full chat !! Finger nipping good.  I assume the bottom bit is fenced off.

    I wonder how noisy it is and if the gyroscopic effects make it hard to turn the ship..

    Mike

  • I am proposing we recover some of the energy lost to the production of bow waves and moving the ship up and down and from side to side, by diverting the energy to kinetic energy at the rear. There is no change to the smooth flows below sea level. There is no extra drag at the bow  as water applies pressure against the one way openings  rather than the side of the ship. The pipes on the side of the ship are raised to minimise drag losses.

  • There is of course the option to increase the speed of the ship in rough seas for the same amount of fuel consumption by utilising wave energy. As there would be less movement of the ship up and down the journey would be smoother.

  • Have you actually done any modelling of this idea yet. Either computational fluid dynamics, or a model boat in a wave tank?

    Until you know how much propulsion you're going to get out of it, you aren't going to attract much interest.