Fresh Idea – Dockside Tidal Power

Tidal dock power

start of a sketch

Fresh ideas come along that might be worth a lot or a little; and some should be launched into the world because they may be needed now and shouldn’t wait for me to develop them fully. Sometimes, ideas have to flow and go. Maybe I can catch up later.

Of all the renewable energy sources, tidal power is one of the most predictable and ubiquitous – at least along shorelines. From my research, it would appear that I’ve come up with a variation that generates power without interfering with wildlife and also without having to be submerged in the corrosive environment that is salt water. Tides are inexorable. As long as something is buoyant, the rising tide will lift it, regardless of its weight. In its simplest form, my fresh idea (invention?) uses the tide to lift heavy objects; then, as the tide goes out, the potential energy of the lifted object can be converted into electrical energy. No need to guess about the weather and the winds. No need to check the latitude. No need to wait for the Sun to shine.

Some tidal power concepts rely on tidal currents turning submerged rotary machinery. They are successful but many people worry about wildlife hazards (though the rotation rates are so slow that it would be hard to get hit), and operators worry about maintenance and repair which is necessarily deep enough to necessitate divers and some danger.

Some tidal power concepts trade potential energy for electrical energy by trapping the high tide in a reservoir and using the outgoing current to power rotary machinery, as above. The machinery is easier to access, but the tidal reservoir takes up acreage and can also interrupt sea life.

Even with those caveats, I am fans of those systems.

Imagine instead, a floating dock like those we have in my neighborhood’s marina. As the tide goes in and out, the docks go up and down. If we tried to lift and lower the decks with electric motors it would require a ridiculous amount of energy. Yet, they go up and down about twelve feet every day.DSC_6079 My idea for Dockside Tidal Power leaves the docks as nothing but inspiration and as a physical foundation for the power generator. For discussion, imagine a weight that is allowed to slide up and down along a piling. The pilings are there to keep the dock in place. They are overbuilt for the purpose because all they do is make sure the dock doesn’t move back and forth too much. As the tide lifts the dock, it also lifts the weight. As the tide goes out, the dock drops. The weight drops, too; but the weight’s motion is retarded by any of a series of mechanisms that brake its motion and turn that braking action into power. In the simplest form, it only generates power as the weight descends. In the more advanced form, it generates power as the dock lifts. In a more sophisticated form, the dock is the weight with the proviso that the dock always remains in contact with the water. This latter form is more elegant, but also has some failure modes that could affect the use of the dock.

I came up with this fresh idea years ago. It wasn’t until a conversation during a land trust work party that happened to overlook the bay that the idea became defined well-enough to pursue. To me, the idea was simple enough that I thought that someone must have already developed it, and found some fatal flaw. After hours of research into tidal energy I became more of a fan of that version of renewable energy, and was surprised that I couldn’t find an example. One reason for posting this fresh idea is to find out if someone knows of such an application.

I did find a proof of concept that had nothing to do with tides. There are many gravity powered lamps. Raise a weight, let it slowly fall, transfer the motion to electricity through gearing and braking, and provide pollution-free light anywhere. One such device is a floor lamp that uses a 50 pound weight and a 58 inch drop to generate 40 watts for four hours. A 55 gallon barrel weighs about 450 pounds, suggesting 360 watts. A typical American house needs 1.24 kilowatts. So, this could work for partial supply or backup; or gang four and power the house.

Given my Aerospace and Ocean Engineering background I’d thoroughly enjoy designing, testing, developing, and maybe even producing and selling such a device. If I had the money and the time, I’d turn off most of my other projects, build a team, and get to work building the device and the business. Unfortunately, I don’t have enough money which is I am working so many hours that I also don’t have the time. I considered crowdfunding the idea, but my recent crowdfunding campaign already delayed development and its lack of success makes me hesitant to embark on another campaign so soon. I could take the long and slow approach, something I am known for. Someone I’ve known for decades is also an inventor, and also has an extensive blog about the process and the probabilities. I think, however, that the world needs low-impact renewable energy now. Any delay simply so I can claim ownership is putting my needs over those of the coastal communities of the world. I think I should let the idea out there so it can grow, or be proven to have a fundamental flaw.

So, I pass along the fresh idea along with a sketch or two. If anyone wants to develop it, do so. Do it right and quick and pass it along, and no one will own it but many can benefit from it (if it works.) If you want me to help, definitely contact me. Of course, I’d like to help. Compensation would be appreciated, though. I ask for that from need, not choice.

There are too many variants to adequately describe here. I enjoy brainstorming and have had to pull myself back from generating yet another way to convert the power, arrange the system, and develop new applications. If you want more details, contact me.

My neighborhood has a marina, but I don’t use it. I don’t have a boat (and least not one that floats for very long.) When I bought my house I expected to buy a boat, too; but my Triple Whammy hit. I still hope to buy a boat, but that’s another story.

My neighborhood also has a beach, a twelve foot tide, a view of dozens of miles of Puget Sound to a hidden horizon. It is awesome to stand at the shore, look down to the horizon, and realize that quietly, every day, enough water flows in and out of that basin to cover square miles with feet of water – for free, predictably, without polluting anything, in a way that the sea life has evolved to live with. If we harness a small portion of that energy, we could probably power a city, or a marina could power a neighborhood, or at least someone with a dock might be able to power their house.

November Sunset

About Tom Trimbath

real estate broker / consultant / entrepreneur / writer / photographer / speaker / aerospace engineer / semi-semi-retired More info at: and at my amazon author page:
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17 Responses to Fresh Idea – Dockside Tidal Power

  1. Steve K says:

    Great idea. Better than the wave action testing being done off the OR coast.
    Just like regenerative braking on an electric car; rack and pinion to a transmission to convert slow rise and fall to fast rotational speed. Guts of a Prius. A way to switch from rise to fall, power each way. Batteries. Inverter. AC power.

    The problem will be regulatory, especially beside the water, but do-able. Imagine an entire marina, self powered including power to the boat slips… Or just one dock, units on each post.

  2. James Roberts says:

    I live in Eureka ca. We have up to 8 foot tides. I want to know what there is available to attach to my piling and dock to generate electricity. For one home.

  3. Tom Trimbath says:

    At this point, I don’t know of anything commercially available. That’s a surprise to me, and also why I decided to publish my idea in case someone wanted to make it happen.

  4. Sadie Reed says:

    Hi ,my name is Sadie and I have been thinking about this for several years .My home is in the Discovery Islands a few hundred kms north of Vancouver . I have been thinking a lot about desalination lately as freshwater tables drop globally and is becoming increasingly scarce . Its not that relevant now but will be in my sons future . I am no engineer so the numbers are shaky but with a dock designed to hold so much weight , what about using the tidal power to harness the hydraulic power needed for reverse osmosis ? It seems like there could be huge potential for off grid grid systems . I just read a report stating the energy required for 1cbic meter of desalinized water was approx 2 Kwh (though this may require an energy recovery pump ).Thats enough water to irrigate 40′ x 25′ garden on a drip line system for at least an hour . I also would like to know if there would be fewer parts to wear out on a hydraulic power generating system ?

  5. Tom Trimbath says:

    You’re right. The power could be used in many ways. As for the numbers, that’s the next level that I’d like to investigate; but that takes money or someone talented and resourceful. Every system, including the one you mentioned, has tradeoffs: complexity, life cycle costs, reliability, etc. Each can probably find a niche and a use that it fits best. Also, the system I’ve described in the post fortunately don’t have to put the weight on the dock. It can put the weight on the piling/support.
    Do you know anyone who can build you a prototype rig?

  6. E Vine says:

    Hi Such tidal lift systems have occurred to me many years ago and research shows many others and various variants.
    I too advocate the principle it’s especially effective because it’s possible to extract energy on both rising and falling tides twice a day. Thus a 10m tidal level change will lift weights or water ( my preferred choice) 40 metres, done on a vast scale millions of tons of water can be lifted and used as and when needed.
    Such systems can be used where least damage to ecosystems can occur. (Tidal lagoons can be very damaging) QED but backers are needed, suggest you look to Scotland Neil Kermode might be the person or the Scottish government, they seem more open minded thank the English government who only today wrote to me to say nuclear power remains part of their strategy, this is wrong thinking.

  7. Forerut Hfsihr says:

    Hi, i have also been going around for years with this exact idea, and not knowing what to do with it. It have evolved a bit conceptually over time , so now i am starting to think big really big, like coastal city blocks, industries, kind of floating islands, can also be built in man-made basins, that connect the ocean, all going up and down each tide, imagine the power that could generate. Hope there is not some fundamental flaw with the idea.

  8. Graham Mahoney says:

    Hi there, i been thinking of this concept of harnessing power for many yrs now and think if some sponsor out there could take a barge say the size of a football field just as a trial filled with water or sand cement what have you with a huge piling worm gear coming through the center and with the use of huge springs to control the time to raise and lower barge and control the capture rate of this huge power energy when captured properly, remember when barges are stacked on one another the ocean is pretty deep imagine the weight and energy that would provide when held and slowly released via huge springs and ok i will leave the rest up to electrical and the mechanical engineers but hey i can’t see such a divice emitting to many toxic gases other than h2o, should be pretty clean and green as no fuel required, depending how heavy it is you could add multi worm gears up to capture its full potential, so glad there are others brain storming this same idea, now please somebody take it on

  9. Tom Trimbath says:

    Agreed. This is one of my more popular posts, so someone’s been seeing it. Now to find the resources to make it happen. Good luck to all who are trying to find such clean energies.

  10. yep. On an island here off the coast of Maine. Same thoughts for decades. Up and down, relentlessly, two (average) 10′ tides a day. Searched “tidal lift” and arrived here. Had been reading about bladeless wind turbines and reignited the thought process.

  11. Russell P says:

    I had also thought of this. You could even have a ratchet system so each incoming tide raised the mass higher storing the energy for use at peak times. Would be useful in areas that only have a small tidal range – 10 tides of 1m would add up to 10m height gain of the mass. Have 10 masses and each day one would be ready to release and generate power.

  12. John Boullie says:

    Reach out to Uncharted – start up company in NYC that specializes in kinetic energy to electricity. You can reach out to Jessica O. Matthews who is the President/Founder/CEO. You can find her on LinkedIn or via her website.

  13. Tom Jefferis says:

    Lock it down at low tide and let it up in gear to spin up flywheel generators. At high tide let it down when the tide’s dropped.

  14. Tom Trimbath says:

    Excellent! Does away with the need for a dock, or is another application. Cool and thanks.

  15. Tom Jefferis says:

    Most of what’s on the internet seems to be turbines etc, but all I can think about is the mothballed fleet and the tons of torque rising and falling every day. With new vacuum enclosed flywheel generators and superconducting materials for nearly frictionless spin, a fleet of ships could easily convert mechanical energy to tons of electricity. There must be a grant or funding out there somewhere that would love to recycle old ships to make this work.

  16. Marc says:

    Just seen a company looking to suspend weights at the top of mine shafts. These are winched up when there is an abundance of energy from renewables. By storing energy as potential energy for when it’s required. But with Tides that would lift a weight for free. Tides in the Thames estuary London are about 15ft. By lifting a weight on a ratchet or pumping fluid via the tide?

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