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  • AnneDT

    It amazes me that tidal power does not get more press - thank you for posting this. Despite the huge cost to set something like this up, I hope this is an energy source we will hear a lot more about in the future.

    I was not even aware that we can harness energy this way until a friend of mine shared this article with me:

  • Jack Baldwin

    why do we have to produce large amounts and send it all over if we can what we need where we are?

  • Jack Baldwin

    I feel like we are going about the producing, and consumption of power backward. We tend to centralize the creation, then distribute to where it's going to be used. I kinda think of it like the leave only footprints concept. ideas like this used like a heat sink, or anywhere our tech creates waste heat.

  • FarmerGiles

    It's all very well harnessing the tide where it gives a big surge. Such a phenomenon is also called a bore. There's one in the Solway Firth in Scotland, and one at least in Alaska. But if the tidal rise is not large, you don't get much out of it. I doubt that human interference with the tides will make much difference to the Moon, otr the Earth. The actual energy that causes the tides is not external, it's the angular momentum of the planet. The tides transfer some of that momentum to the Moon, pushing it outwards, and slowing down the Earth's rotation. You could measure it, if you have the patience and math ability of Lord Kelvin, by computing today's angular momentum from the radius and distribution of mass of the Earth, and noting the loss of momentum that puts a "leap second" into the calendars maintained by observatories, so that stars distant enough to have no parallax from one side of the Earth's orbit to the other, will always be in the same place relative to the telescopes at a given time on a given date. But this article is hugely flawed. It uses units of power, terawatts, when it should be using units of energy, such as kilowatt-hours, or better, gigawatt-years. There are 24x365.24 hours in an average year, which is 8765.76 hours A gigawatt-year is 8765.76 million kWh, or 8.76576 TWh (terawatt-hours).
    The actual DOE report cited does correctly give the energy estimates in TWh , citing the nation's electric energy consumption at 4000 TWh annually, and the maximum theoretical electric generation from waves and tidal currents at approximately 1,420 TWh per year. Later, it mentions "the path to supplying 15% of the nation's electricity through water power technologies". Note that this is mere estimation, of hypothetical technologies. Nevertheless, Even that probably optimistic figure is less than the 20% of the electric energy reliably supplied by nuclear right now, at a cost of about 3000 tons of spent fuel rods per year, compared with the abominable quantities of far less controllable waste spewed into the atmosphere by coal, or even the 130 million tons of toxic ash. This is vexatious to me, since I also know that a promising technology, the Integral Fast Reactor, could have been running at Fukushima, meltdown proof, and generating less than a ton of waste per gigawatt-year, a thousand times less long lasting than what present reactors produce. It was renewable and sustainable, but canceled 1994, in response to the ignorance of my allies like the anti-nuclear weapons people and the Sierra Club.

  • ajithapg

    i can share my concept with one who are interested to work together.

  • ajithapg

    I have a great idea to produce power from tide than this idea. but really i don't know how to make it possible. please some one help me.

  • Jack Baldwin

    The problem I have with tidal is exactly that, we can't stop the moon from tumbling around us. That isn't a problem, The problem comes in converting some of the energy from the tide itself into energy we find usable. when that force is redirected, transformed into something we can use, it is taken out of the ocean itself, In effect lowering the visible effect of the moon on the oceans. What this change would do to other cycles dependent on this motion I haven't a clue. Though I think saying it would be nothing might be premature.

    • FarmerGiles

      Don't worry about the tides and the moon. If we could really get significant energy from the ocean movements, we'd be slowing the Earth's rotation perhaps by doubling the number of leap seconds the observatories have to put in their clocks and calendars. Please note that 250 kilowatts is a mere quarter of a megawatt. A serious hydro turbine spinning in air - to be ready at grid frequency to take up many megawatts of sudden demand - requires a couple of megawatts to drive it, and that's one of the least expensive ways to meet variations of demand. They don't tell us if the folk of Eastport Maine will schedule their peak loads to match the tides, but it does not look as if those turbines are attached to any stored water, the way river hydro is. If not, then when the tide is turning it's not moving much. And what happens to the fishes?

    • Jesse McDougall

      Hi Jack. That's a fair point. All turbine-generated power—wind, tidal, air pressure, etc.—remove momentum from a mass in order to turn it into electricity. Motion energy is converted into electrical energy and therefore the energy is removed from the ocean. And, no conversion of energy is perfect, so some energy is lost in the process through heat or mechanical inefficiencies.

      However, what we must do—and I'll leave this to better scientists and mathematicians—is compare the effect on the environment of removing motion energy from the ocean and the effect of all the different ways we produce the energy that we're not capturing through tidal turbines—petroleum, coal, natural gas, hydro, wind, solar, etc.

      I believe, based on what I understand about the pressing problems of the day, that harnessing the "motion of the ocean" will be less destructive for the planet—and will help mitigate the current disasters of irresponsible energy production—than any production based on fossil fuels.

      Nothing is free, unfortunately. All we can do is choose how to pay, and then spend wisely.

      • FarmerGiles

        Dear Jesse, the sad thing about the classification "renewable energy" is that most of it was the stuff that was abandoned in the Industrial Revolution, displaced by the "alternative" of fossil carbon, fossilised solar power. In particular, if wind were a reliable, plentiful, inexpensive resource, why are we not building fleets of sailing ships? We do in fact have two fleets of ships not dependent upon coal or oil. They run on highly enriched uranium. We also have a clean technology already developed that does not require the burial of long lived uranium and plutonium, and is both renewable and sustainable. It is even the way to get rid of post-Cold-War weapons plutonium. It was a breeder reactor project, designed and proven immune to what destroyed the Chernobyl reactors, a week before that happened.
        In particular, among the renewable resources -- forests are renewable, but in very few instances do we renew them. I'm pretty sure that the E85 ethanol that Brazil gets from sugar involves the clearing of tropical forest to grow the sugar cane. It's actually 200 proof rum, adulterated with gasoline enough to make it unfit to drink.

  • Jonathan Teller-Elsberg

    I like your quick history overview. It's pretty surprising that this tidal turbine project is the first ocean-based generator to go online in the U.S.

    The DoE's estimate of potential tidal power is substantial, but I'd be cautious about projecting out improvements on that from technological improvements. Wind turbines, for example, have a maximum theoretical efficiency in converting the energy of wind into electrical energy of 59.3%. (I only know that because your link above regarding world wind power led me on a little Google chase to one of the original source papers by Jacobson et al at That paper mentions this "Betz's limit" in the first paragraph.) I don't know for sure, but I think it's safe to assume that something similar is the case for tidal power given that it works on the basis of turbines same as wind. As I understand it, what has been great for wind is not so much technical improvements that make individual turbines more efficient, rather lower costs and the shift toward larger turbines--which are more cost effective than smaller turbines.

    I can't tell from the DoE site if they are talking about theoretical power from tides or if they put some practical limits on power extraction, such as avoiding tidal turbines in shipping channels or atop biologically sensitive sea beds. Their wording makes it sound like theoretical maximums, and there's no reason to think we can -- or perhaps even should -- plan to tap that much tidal power.

    Even if it's a smaller resource than some others, the nice thing about tidal power is that it's totally predictable, unlike solar or wind, so can fit into the grid more reliably. That moon just keeps going round and round the Earth, and, as yet, there's nothing we can do to mess that up.

    • FarmerGiles

      Let's not forget that even at maximum theoretical efficiency, a 5 MW wind turbine (presumably in a 10 MW wind) only delivers that power level when the wind is strong enough -- I think it's when it's intense enough that meteorological offices put out small craft warnings. At lower speeds, the power of the wind itself drops off as the cube of the wind speed. At higher speeds, the force trying to topple the turbine tower goes up as the square of the speed.

    • Jesse McDougall

      Ah yes. You've found my logic leap of faith!

      Very good point. I'll go back and see if I can determine if the DoE's number is based on current tech or total theoretical potential.

  • bruce miller

    Could the Tides power our world?
    ""One of the most significant events in this recasting was the realization in the early 1980s that the average American consumed as many natural resources as 1000 average inhabitants of India. It was also realized that the average American produced as much waste (including the all important carbon footprint) as 2500 Indians! even today, the ratios are still approximately 1:300 (US compared to India) and 1:500 compared to China.""
    If we all intend an "American Dream" lifestyle and with unlimited breeding, eating, possibilities, no equation will work.
    China will alter the Global Energy Map soon enough with their superior Thorium fissioning technologies?
    “Had the $4 Trillions+ spent on Iraq, been spent even only on conventional Solar/Thermal development of South Western U.S.A. – Today, Americans would receive a huge ROI ( “Return On Investment”) in cheap electricity, in place of horrendous tax rates to service unpayable war debt to China. Americans would be gainfully working, using this renewable, perpetual, eternal, clean, radiation free, radioactive waste free, domestic, electricity source – to compete in world markets with well priced products, to irrigate dry lands, to heat and cool homes, and much less foreign oil would have be imported, fewer “Parasite Nations” supported. This is the lost “opportunity cost” for having Saddam’s scrotum on the Bushes mantlepiece? Shiite eh!”
    P.S., (Oil, gas, wells do go dry, not really sourced from an eternal pipe up &Allah’s-ass, as some believe – But, the Sun never stops shining, Wind blows forever)
    (See: tells where U.S. ‘went wrong’?
    Never mistake the American idiom 'noocleer" or 'nuclear', to mean anything more than enriched uranium fissioning including plutonium production by the American Nuclear Establishments processes. The American meaning of "nuclear" excludes CANDU reactors, Thorium fueled devices, Slow Poke reactors, and many more, valid fissioning schemes in this world, from space gadgets for electric power, to Russian lighthouses, Even China's Tsinghua University has for a long time had Pebble Bed Gas reactors - and had they been installed at Fuckoshima, today there would be no radioactive wastes there to wash to sea.
    America was told clearly by T. Boone Pickens of the Prairie Wind Corridor and how it was the "Saudi Arabia of Electric Energy" for this nation. He was right. He will prove prophetic in years to come. Meanwhile greed and Oil barons, with "sunk money" to protect, hold back the greatest people on earth and even starve some of them to save their own small-minded investments. Cars will go Electric the electricity will come from all: Solar, Wave, Wind, Hydro, Tidal, Geothermal, and safer Thorium fission heat sources All domestic, All American, with no "Parasite OPEC oil nations" to support for the privilege, and no one to kill for their oil.
    Tidal, unlike Solar and Wind, never ceases. This advantage alone makes it the most valuable of all. Tidal is renewable, perpetual eternal in nature and with the proper mined tunnels from shore , the least expensive and most durable. Scotland has natural rock formations like this, converted, modified as "air compressors' driving turbines, and even schemes exist for underwater flows to drive huge propellers to trap the energy available. Tidal power, the effect of gravitational variations caused by the Moon's passing around earth have hardly been considered by the Oil rich and now foreign oil dependent U.S. The Sands of Time have shifted, the fate of the U.S. ever altered now, as even the Chinese Thorium reality comes crashing down on Oil, and America out-priced in the world's marketplaces by their inability to make cheaper goods, tied to their inability to move from coal and Oil to Solar, Wind, Wave, Hydro, Tidal, Geothermal, Bio-gas, Thorium fission, all used extensively by competing nations? Sad.

    • FarmerGiles

      We have in this country a design for a renewable, sustainable, factory-built small breeder reactor, from a proven but abandoned design. It was designed at Argonne National Labs, on whose website I found it. It's no longer there. There was a copy at Berkeley U. in California (-- have you heard of berkelium and californium?) and it disappeared too. But claims that their design, based upon the successful prototype EBR-2, can produce 100 MW continuously for 20 years, on a fuel load of 20.7 tons of enriched uranium, converting 8% by mass of that load to fission products and energy, and requiring at the end of the period only the removal of short-lived fission products (1.7 tons) and replacing it with un-enriched, even depleted uranium.
      It is inexcusable in my fellow liberals and environmentalists, that they do not recognise this as by far the best way to eliminate coal burning and its filthy acquisition and disposal practices.

  • Jack Baldwin

    sorry for the 2nd post, wanted to explain a little of the concept I have behind that idea.
    As the air naturally heats, and cools with the daily warming/cooling cycles, that very "air" around us becomes more and less dense, it's gases expanding and contracting. putting these artificial constraints on the natural process should direct it causing the work already taking place to harnessed. side note, if you put the whole thing in a cradle that tilts you should be able to flip the whole thing 180 degrees on the vertical, or horizontal axis and switch from taking advantage of expanding, then contracting of the very air around you to power anything.

    this is all should be a mute point, most people are already aware of the electromagnetic grid that surrounds the planet, we already have the tech to tap this, it's just not being made available,
    think of what USB means, or what we've made data into. Usb is already bidirectional, and data itself a charge. the radio waves are power, it's only harnessing them.
    I hope someone with more in depth knowledge then mine can shed some light on what to me seems simple

    • FarmerGiles

      There is a natural heat engine that makes use of the warm sea as an energy source, and its sink is the stratosphere and outer space. The pppplanet receives more radiant energy from the sun in an hour than the entirety of human technological processes for a year. The snag is, that the planet has to GET RID of that energy just as quickly.
      The kind of heat engine to which I refer is called a tropical storm, hurricane, or typhoon. Its area is the size of two or three Eastern States of the USA and its height is about that of the stratosphere. These are big machines, and our best meteorologists can just about tell us a day or two in advance where to expect the maximum destructiveness. Employing that energy for human purposes is very unlikely. So the usefulness of that vast influx of radiant energy to replace its stored version - fossil carbon -is wildly exaggerated. We need to find something else, and it is stored supernova energy, a.k.a. thorium and uranium.

  • Jack Baldwin

    that was my thoughts to Megan, or the disruption to the overall ocean currents, which play a big part in shaping global weather.

    side note to harnessing whats around. I had a much simpler idea for self power generation, I'm poor and have little access to or the practice to apply my ideas.

    think nest metal bottles, kinda like the water cooler type from offices. Only bigger on the "base" and going to a narrower "top". now in the base cut a hole, and then with the nested interior bottle forms cut slightly smaller holes, make sure not to make the cut holes parallel. like put 2 holes on the next nested bottle on the sides, then the next nested bottle back on the bottom. eventually letting the air escape out the bottle neck at the top, with the desired effect of multiplying the force of the air current.
    when the air shoots out the top have it spin a turbine, or even a fan motor this should generate enough juice for small applications.

    Let me be clear, I'm a high school, and college drop out, that likes pot, and has a peter pan complex. so listen to me at your own caution


  • megan.manni.5

    Question though - what are the dangers to ocean wildlife and the ecosystem? As far as I read I didn't see anything mentioned about that. This is a must-know before I endorse anything of the kind.

    • Jesse McDougall

      Great question. The answer is: it largely depends on where the turbines are sited. Obviously, if done irresponsibly, a turbine field on the ocean floor could have disastrous results for an existing ecosystem—and therefore proper siting must be a priority for all tidal power companies. However, often in areas of strong tide, the power of the current is such that ecosystems are unable to develop—leaving only the water rushing over bare rock. In these places, a turbine field would have minimal impact.

      Here's a good answer I came across:


      "Tidal energy is a renewable source of electricity which does not result in the emission of gases responsible for global warming or acid rain associated with fossil fuel generated electricity. Use of tidal energy could also decrease the need for nuclear power, with its associated radiation risks. Changing tidal flows by damming a bay or estuary could, however, result in negative impacts on aquatic and shoreline ecosystems, as well as navigation and recreation.

      The few studies that have been undertaken to date to identify the environmental impacts of a tidal power scheme have determined that each specific site is different and the impacts depend greatly upon local geography. Local tides changed only slightly due to the La Rance barrage, and the environmental impact has been negligible, but this may not be the case for all other sites. It has been estimated that in the Bay of Fundy, tidal power plants could decrease local tides by 15 cm. This does not seem like much when one considers that natural variations such as winds can change the level of the tides by several metres."

      • FarmerGiles

        Two Scotsmen had different views on the usefulness of the tides. J.B.S. Haldane reckoned that ultimately that would have to be what humans used. Lord Kelvin actually performed a calculation for a hypothetical tidal impoundment, and concluded that it was impractical for the expense.
        Neither of these gentlemen, brilliant as their work is, were aware of radioactivity and nuclear energy.

  • agnus

    What happens if you take the energy out of the tides? Is it 100% replaced, or do the tides slow, eventually? I'd like to see some projections of the effects.

    • FarmerGiles

      I'm pretty sure that each tidal surge is simply reduced, and probably not by a noticeable amount. But compared with the most successful use made of the winds, it's trifling as an energy source.
      The use to which I refer, is that airlines route their flights to take advantage of the jet stream. I'd love to know how many kilowatt-hours of energy is the equivalent of flying a jumbojet in a 50 mph jet stream, going its way.

    • Jesse McDougall

      I agree. I'd like to see those projections too. I assume, and I could wrong, that because the tides are created by the gravitational pull of the moon, the speed and momentum of the tides would be only minutely decreased. Every tide cycle would be "restarted" by the circling of the moon. I wonder if those projections exist....

    • Jonathan Teller-Elsberg

      Agnus, David MacKay's excellent book, Sustainable Energy--Without the Hot Air, addresses this. Here's what he writes:

      Mythconceptions: Tidal power, while clean and green, should not be called renewable. Extracting power from the tides slows down the earth’s rotation. We definitely can’t use tidal power long-term.
      False. The natural tides already slow down the earth’s rotation. The natural rotational energy loss is roughly 3 TW (Shepherd, 2003). Thanks to natural tidal friction, each century, the day gets longer by 2.3 milliseconds. Many tidal energy extraction systems are just extracting energy that would have been lost anyway in friction. But even if we doubled the power extracted from the earth–moon system, tidal energy would still last more than a billion years.

      The entire book is available online at . Skip to the chapter on tidal power is at .

  • Jack Baldwin

    could tides power everything? don't they already? without our tidal forces life here wouldn't exist as we know know it. It is that lunar cycle tugging on the planet, along with a bunch of other factors that make our world the hospitable place we find it.
    That doesn't answer the question, yes it can, should we do it, I'm not so sure.
    people are going to figure out any movement or state change can be tapped for power. it's a matter of how efficient the particular method is.
    I'm pretty sure they can make little pressure switches using the pizo-electric effect of crystal to power many things we haven't even dreamed they could.
    Imagine your home, During the course of a day it heats and cools, if you put the right materials in the building of the home. Just using the expansion, and contraction that is constantly occurring could be harnessed to power the home.
    As always these are only my perspectives

    • Jesse McDougall

      Hi Jack,

      Great points. I love the idea for micro-generation of power based on the expansion and contraction of your own house. In my case, I hate to say, it would take a LOT of caulk to seal up my house to anywhere near tight enough to make it feasible.

      One thing I like about the tidal power is, as you mention, the tugging of the moon that makes it happen. Other than solar power, it may be the only external source of energy, available to our world. IMHO, the only feasible power source is an external power source. Otherwise, we'll just run out of whatever it is we're using. But, as you say, there are MANY ways to capture the power of the sun, for example. PV isn't the only way. Leveraging expansion and contraction is possible, etc.


  • GAP Marilyn

    You could also take a look at - just received an award from WWF. Wave power is well established in several countries; it seems that what is happening now is mostly improvements to the efficiency. And, of course, dissemination to places like Maine!

    • Jesse McDougall

      Hi Marilyn! I will absolutely take a look. I'd heard through the grapevine of some wave power generators a few years ago. At the time they looked like long tubular snakey things. I'll see if I can find a link... (cue Jeopardy music) ...

      Here we go! Of course, as your link makes clear, wave-power tech (and web site design) has come along way since this link was current.


  • Andy Middleton

    There's a neat connection here. The original Bangor, in north Wales, UK, is the nearest large town to a tidal development by Marine Current Turbines that, subject to planning, will produce 10MW of electricity. It's based on proven technology that's already passed commercial testing.