Dam

Dam-Atoll's

name tells how it

extracts energy from ocean waves.

Let's take the 'dam' part first. Just as a dam captures river water and converts its energy to electricity, Dam-Atoll's underwater artificial atoll captures the wave and converts its energy to electricity. Both the dam and the artificial atoll convert water energy to electricity when the water passes through a hole in the dam/atoll to power a generator. Picture Source.

Atoll

Second, consider the 'atoll' part of the name. When it has the proper shape, the submerged dome of an atoll will cause approaching waves to spiral in towards its center. This spiral bending is called wave refraction. Now let's say that the diameter of the atoll is one mile. Approaching the atoll is a wave whose crest is, say, 1,000 miles in length. Some part of that length will be affected by the atoll, and will keep bending towards the atoll until it hits the center. The center of the atoll will receive the total energy of one mile's worth of wave. That is to say, the energy received by the atoll is equal to the energy present in the length of wave equal to the diameter of the atoll. Now the wave itself is nothing but energy—a pulse traveling across the ocean—so in receiving the energy contained in a one mile segment of the thousand mile wave, the atoll has captured one mile's worth of that wave.

This is the basic principle of Dam-Atoll as an ocean wave energy concentration device.

Picture Source.

Wave

An ocean wave is always half potential energy and half kinetic energy so long as it is propagating in deep water. As the wave enters shallower water, this proportion changes. The kinetic portion of the wave's energy becomes greater as the water becomes shallower. Conversely, the potential energy decreases. Finally, the wave's shape changes, its front side becoming steeper until it becomes completely vertical—a moving wall of water. At this point, its energy is nearly all kinetic. This wave configuration is unstable, and the wave breaks into a churning turbulence. This turbulance converts the kinetic energy into heat, so the wave water is a little warmer as it returns to the ocean. Picture Source.

Vortex

A vortex is a natural swirling motion in any fluid such as water or air. If there is a hole in the center of an atoll with the proper shape, a vortex will form in that hole because the approaching waves are spiralling in towards the atoll's center. In this way, an atoll (if the reader can stomach yet one more pun) adds a special twist to the atoll's natural transformation of the wave's potential energy to kinetic energy. The really nice feature of vortexes is that very little energy is lost in them: they are, in a very real sense, fluid flywheels. Dam-Atoll, a

sea wave power station,

uses the kinetic energy of this vortex to power a turbine generating electricity. Picture Source.

Dam-Atoll Video

Dam-Atoll functions as an artificial atoll, bending incoming waves and focussing their energy as they spiral into the center. Vanes at the center guide the incoming spiralling waves and directs the resulting vortex into a shaft. The whirling water in the vortex transfers its energy to a mechanical component, a shaft-mounted turbine, which then runs a generator to create electrical energy. The shaft-mounted turbine is the only moving part in this beautifully and elegantly simple design. Click here to see a video of working model of Dam-Atoll. In a full-scale prototype of this

ocean wave power station,

real boats will replace the toy boats, which L.S. Wirt stole from his grandsons. Picture Source.

Patents, Articles, Technical Descriptions

Click here to see an html version of the patent. Click here to see commentary on Dam-Atoll by John Isaacs at the First Symposium on Wave Energy Utilization, held at Gothenburgh, Sweden. Click here to see an excerpt from the Advanced Techniques chapter of Michael E. McCormick's book, Ocean Wave Energy Conversion. Click here to see various other articles, books, and links to resources on the web discussing Dam-Atoll. Click here to see the Abstract, Table of Contents, and List of Figures of an article working out the mathematics describing the optimal shape of the artificial atoll that will result in the greatest efficiency in conversion from wave energy to electrical energy.

Future Prospects

The world's energy requirements. Alternative energy clearly a necessity. Picture Source.

Humor

Humor may not be the first thing you associate with an

ocean wave power station.

Nonetheless, humor and brilliant technical inventions sometimes spring from the same source in the inventive mind. Click here to see some Dam-Atoll related humor, starting with the name itself, Dam-Atoll (pun definitely intended). Picture Source.

History

The mathematical principles explaining how atolls cause waves to refract were first worked out by the brilliant oceanographer Robert S. Arthur while he was still a graduate student at Scripps and under contract with the navy during the second World War. These mathematical principles form the basis of Dam-Atoll. Click here to see Arthur's classic paper, "The Effect Of Islands On Surface Waves." As noted by Arthur, the ancient Polynesians were aware of many of the same principles for which Arthur provided a mathematical description. Click here to see a discussion of their navigational charts composed of sticks representing islands, currents, and waves. Picture Source.

Concise Description Of Dam-Atoll:

In their book RENEWABLE ENERGY SOURCES AND THEIR ENVIRONMENTAL IMPACT (New Delhi, Prentice-Hall Of India, 2006, pp. 60-61), S.A. Abbhasi and Naseema Abbasi provide the best and most concise description of Dam-Atoll that we have seen:

This device [Dam-Atoll] does not respond to the up-and-down wave motion but utilizes wave refraction to alter the wave direction and concentrates the wave energy into a vortex that drives a turbine. The vortex in the central core of the device serves as a fluid flywheel. The flywheel turns a turbine generator. A key element in the dam-atoll device is the large dome. The dome must be about 100 m in diameter, comparable in size to the roof covering a football stadium. As a wave travels over the dome, the velocity of the wave slows as the water depth decreases. This causes the wave to bend, or refract, so that it is focused into the centre of the dome. Vanes then help to guide the flowing water into the vertical cylinder and turbine. The Polynesian people apparently understood this principle well because they knew there was no safe lee side on a volcanic atoll. An ocean wave breaking over an atoll is always refracted around to the lee side, where it breaks on the shore, as well as breaking on the windward side. The Lockheed Missiles and Space company has built and tested a 1/100-scale model to demonstrate the proof of this concept. [See the video of the working model.] A full-scale unit, 80 m in diameter, is expected to generate about 1MWe of power output. Ecological impact should be minimal for the dam-atoll type machine....

Dam-Atoll And Acoustic Labs:

As a minor correction, we would like to note that the 1/100-scale working model wasn't built and tested at Lockheed Missiles and Space (located in Sunnyvale, California), but at the Lockheed California's Rye Canyon Acoustical Testing Laboratory in Santa Clarita, California, where it was conceived and designed by its inventor, L.S. Wirt. This is the circumstance that prompted one Lockheed executive to label Dam-Atoll "The damndest thing ever to come out of an acoustic lab." But that the invention came out of an acoustic lab does make sense, since, in a brilliant leap of the imagination, it applies acoustical principles such as Fermat's to the problem of extracting energy from ocean waves.

Waves And Roses:

With apologies to Gertrude Stein (whose famous/infamous poem reads: "Rose is a rose is a rose is a rose"), a wave is a wave is a wave, whether it be a pond ripple, a massive ocean breaker, or a sound wave.

The Patent Is Now In The Public Domain:

One more minor correction: although Lockheed California was the original assignee of the patent, Lockheed for various reasons failed to follow through on the invention and develop it beyond a working scale model. The patent is now in the public domain, where it may be used by any individual or organization with the requisite insight, imagination, alertness to possibility, and sense of environmental urgency.

Continuing With The Explication Of What Dam-Atoll Is And How It Works:

In the pages that follow, we present more detailed explanations of the principles behind Dam-Atoll, starting with an explication of its name.>>>next

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Click on any of the following topics that may catch your eye

Worst Pun Of The Year Every Year

Best And Most Concise Description Of Dam-Atoll

The damndest thing that ever came out of an acoustics lab

Fermat's Principle

The Patent for Dam-Atoll is now in the public domain

The Name Dam-Atoll Tells How It Extracts Ocean Wave Energy

Dam-Atoll An Amalgam Of the Concepts Dam And Atoll

Dams And Kinetic, Potential, and Mechanical Energy

River As Kinetic Energy

Kinetic Energy Transformed To Potential Energy

Potential Energy Transformed Back To Kinetic Energy

Kinetic Energy Turned Into Mechanical Energy

An Atoll Bends And Refracts The Approaching Wave

Wave Velocity

Wave Refraction

When the submerged atoll is dome-shaped, it refracts the wave path to its center

The exact shape of the atoll's dome is critical

the atoll acts as a kind of lense concentrating the wave energy

A Wave's Potential Energy Gets Changed To Kinetic Energy By An Atoll

A wave is nothing but energy

Waves And Potential And Kinetic Energy

A deep-water ocean wave is always half potential and half kinetic energy

Wave is all kinetic energy when it breaks on the center of the atoll

Changing A Wave's Kinetic Energy To Mechanical Energy By Means Of A Vortex

Vortex

Vortex is a fluid flywheel

Dam-Atoll, Vortex, Guide Vanes

This in sum is how Dam-Atoll works

Smoothing out the succession of wave pulses

Advantages Over The Other Ocean Wave Energy Extraction Devices

Dam-Atoll has only one moving part

Thus Dam-Atoll loses no energy in monkey motion

Monkey motion

Competing Ocean Wave Energy Extraction Devices are monkey motion machines

Energy Efficiency

Diffuser Important To Energy Efficiency

Mathematically Optimal Shape Of Dome Crucial To Energy Efficiency

A Future So Bright For Ocean Systems You Will Need Sunglasses

The Patent for Dam-Atoll is now in the public domain

The Opportunity

Leslie Wirt is available for lectures

Leslie Wirt offers consulting services

Video of working scale model of Dam-Atoll

Dam-Atoll Patent

Michael McCormick's Comments On Dam-Atoll

John Isaac's Comments On Dam-Atoll

Links To Books, Articles, And Web Sites Mentioning Dam-Atoll

Excerpts From Scattering And Absorption Of Surface Waves By Arthur's Island

Future Prospects For Dam-Atoll

Dam-Atoll Humor

Dam-Atoll_History

About the inventor of Dam-Atoll, Leslie S. Wirt

Contact Leslie Wirt

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Next: The Name Tells How Dam-Atoll Works

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Tags: Dam-Atoll, India, Waves, Acoustics, Gertrude Stein, Renewable Energy, Polynesians, Environmental Impact

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Author:

Cliff Wirt

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Copyright:

©Dam-Atoll, Inc.

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