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Wave device raises hope of renewable power for ships

British engineers have begun testing a device that could allow ships to harvest energy from the sea by capturing wave movement in any direction.

The Whatever Input to Torsion Transfer device, developed by Martin Wickett at small firm WITT Energy, uses two pendulums connected to a flywheel to generate electricity from movement.

The company, working with Exeter and Plymouth universities and engineering firms A&P Falmouth and Supacat, have built a version of the device for use in water that they hope could be installed in sea craft to generate renewable auxiliary power from the waves.


The WITT Energy device

Supacat’s engineering director, Sean Limbrick, said although the WITT device would be less efficient than a marine turbine that captured movement for a single direction, it would enable energy generation in more difficult environments.

‘The vessel could be travelling in any direction relative to the waves, which have a lot of mess [in their movement], so we’re in a fairly chaotic input environment,’ he told The Engineer.

‘The multiple degrees of freedom allow us, in principle, to harvest those energy inputs even though they are chaotic and coming from all directions.’

The device’s two pendulums are arranged perpendicularly and attached to a shaft that rectifies their two dimensional movements into a single dimension. And because the device can also freely rotate it can also capture movement along a third dimension.

As part of the Technology Strategy Board-funded project, Supacat turned WITT Energy’s prototype into a test model around 450mm x 450mm x 200m in size using commercially available parts, but if it were to be scaled up for commercial use it would require custom-made components, said Limbrick.

The new model has now begun a five-month test programme at Exeter University’s Dynamic Marine Component (DMAC) facility that will assess how the pendulums and flywheel can be tuned and enable the team to improve their mathematical models of how the device works.

They hope to use this information to determine how the device could be adapted for and installed in ocean-going vessels. Limbrick said one possibility might for it to replace ballast in a ship’s keel.

WITT Energy last year won a $100,000 prize for the device from US environmental organisation The Ocean Exchange.

The prototype WITT Energy device underwent its initial testing at the University of Exeter.

Readers' comments (15)

  • What a brilliant idea. I hope they can patent and protect the IP and most of all manufacture the device in the UK. I wonder if a smaller version for yachts is practical. Power on longer voyages is always an issue.

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  • Surely if this device was deployed in proximity to a ships hull in motion, the governing wave forces would be from the ships wake. This would mean that any energy generated would be from the driving force of the vessel. In other words the vessel's engine/s would have to produce more power to replace that absorbed by the device.

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  • In response to the above comment, Sean Limbrick, engineering director at Supacat, says: 'Whilst the ship’s wake might be dominant in calm conditions, the motion of the ship in terms of roll, pitch and heave results from the sea surface conditions (that is the waves) and it is this energy which the device will harvest. As a side effect, as some of the energy is absorbed by the devices, the motion of the ship may well be reduced, particularly for smaller vessels.'

  • What proportion of the energy used to drive a ship around will this device capture? 1%? 0.001%? Like wind turbines, I expect, a complete waste of time and effort.

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  • Hydraulic Ram Turbine Dissociators would work better.. a sea saw float would pressurise water inlet through a valve into a tank below the water line.. the uplift of the float would force the water through a turbine with a momentum flywheel generating enough electricity to dissociate the water into hydrogen and oxygen to explosively motivate a ringdrive like a chambered waterwheel with ignition devices.. to further accelerate and incrementally maintain the momentum of the flywheel on the spindle.. to generate more electricity to dissociate more water into stored explosive gases.. the approach could work on a lifecraft.. and provide heating and drinkable hot water.. with light and power for equipment.. all the way across the oceans back to land in heavy seas..

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  • Most large passenger vessels are dynamically stabilised and VLCC type vessels are too big for any rapid pitching or yawing in response to wave movement, making this device useless in such situations, so it must be aimed at the Leisure market. It could be an ideal battery charger in moored boats if it is cheap enough to buy and install. This means keeping it small. Scaling it up is just not economic. There are probably not enough 'all electric' boats to make a slightly larger version viable. The cynic in me could believe this is just another' grant catcher' ploy.

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  • I thought boat stabilisers required energy input to react the motion of the ship to stabilise it. By having a passive device and withdraw energy from it would actually increase the roll of the ship and discomfort of the journey I'd have thought, and possibly increased the risk of capsize to due to greater angles of lean.
    Feels amost as silly as Pavegen but not quite. No-one has suggested a daft idea to trump that one.

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  • What is the point if the engines are driving the ship they are generally driving the generator. Sea based devices all end up on the shore. Just look at the stormes we get. A huge wave can contain thousons of ton of liquid energy and can go in any direction. nothing last very long against it.

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  • Imagine a dynamic soaring device submerged; imagine a somewhat conventional wave machine moving along with the ship. With such ideas in mind, I suppose one could extract wave energy whilst moving; its been done before with the wind...

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  • In my opinion, this is a brilliant yet simple idea, will work in any dynamic conditions and will act as a small stabiliser. Size WILL be scalable. It should get all the encouragement available provided it is made in UK!

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  • This sounds promising. I can't help thinking that there must be a place for good old wind power ( the ultimate renewable ) in the marine mix. With cargo ships slowing down now to save money there must be potential

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  • Other bloggers might enjoy an e-mail sent to Prof Ken Evans at Exeter, where I had the privilege of working for several years about ten years ago!

    Dear Ken, etc,
    first my best wishes to the School, University for 2014
    Delighted to read about the above in The Engineer: the idea of using energy sources that are free has always appealed! Indeed there is another free energy source available to all vessels which travel the deep oceans -wind power. My nephew (who works for a very major Engineering firm) recently advised that (with the advent/advances of drone technology/control, GPS location, and enhanced weather forecasting in real time and locally-measured on the vessel itself)...his firm are studying the possibility of sail-driven sea-going vessels without any crew whatsoever: ie completely served from shore, thus reducing the danger envelope for sailors to zero! Such would have a small powered section for in-shore/ port/ harbour location /manoeuvrings and the balance of the journey would be wind powered. This concept has substantial possibilities. I hope Exeter might be amongst those involved?

    Mike B

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  • MikeB. Wind powered or assisted cargo ships have been mooted for decades. I recall seeing both a fixed vertical aerofoil and a rotating vertical cylinder being used to propel ships. I presume the research you mention is a development of these earlier initiatives.

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  • Dear JohnK
    I agree: I too recall these: I think the difference now is that advances/re-designs of the military drone control technology and weather analysis is sufficiently advanced that it can be used on board ship! linking its output directly to the sail setting.

    I do recall many years ago not unrelated comments about the contour canal in the UK: ie no locks: with vessels (which in effect were the warehouses) being loaded and set off moving to their 'markets/customers' at the rate their cargo's were needed. Presumably this is much more efficient than having trucks and trains dashing around the country at 70+mph -having been loaded up from one stationary! warehouse and depositing their loads into another. Where the cargos had and will sit stationary for many days!

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  • In the American Southwest are gusty winds that typical wind turbines are ill-adapted for. Connect the WITT to something what sways (chaotically) in the wind, and you have power.

    Also this would be highly useful in lakes, harbors, etc where maker bouys need a good source of power, with very infrequent maintenance. I like this WITT idea a great deal, and wish them the best of fortune in exploiting the market with it.

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  • Hi Mike. I know we are off subject here, but contour canals seem just about the perfect use for solar powered electrical transport. As you say, the latest computer software would allow planning and scheduling of huge volumes of such traffic. Question does one fit a new, or modified canal system into our crowded little island.
    Back on subject. James Stewart (Is that really your name James? :o) seems also to have found a niche use for the pendulum generator. Buoys already have wave powered generators although I think these only use vertical movement so perhaps a plug-in replacement may offer scope.
    It is good to see a mechanical device being shown as I was starting to think this periodical was morphing into Computer weekly.

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