7 ms·

28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

282 points by bornelsewhere 3y ago

bruce511 3y ago
The sea is a harsh environment, but the energy it contains, in the form of waves (basically concentrated wind) and tides is enormous (partly thanks to the density of water.) Of course, like with all renewable, location matters. But there are lots of places with strong tides, and lots of places with reliable waves. Harvesting this abundant energy at scale, with reasonable maintenence costs will be the next breakthrough in green energy.
- mywacaday 3y ago
  I've often thought why not dam a whole estuary or bay and use hydro to collect the energy on the the fall and rise of the tide. I know the environmental impact wouldake it unpalatable but are there any reasons it wouldn't work?
  - flipbrad 3y ago
    https://www.gov.uk/government/publications/1-severn-tidal-power-feasibility-study-conclusions-and-summary-report https://www.gov.uk/government/publications/1-severn-tidal-po...
    - hardlianotion 3y ago
      That Severn project has on-again, off-again cycles that are typical of so many UK infrastructure projects. It's a little depressing.
  - lelag 3y ago
    It's been done. Biggest one is Sihwa Lake Tidal Power Station[1] and France had a 240MW tidal plant since the 60s [2]. This type of project has been few and far between and I would guess they might be very costly to build and maintain compared to the harvested energy. [1] https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station [2] https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station
    - macNchz 3y ago
      This is interesting–it made me wonder if this had ever been considered on NYC's East River, which is a tidal estuary with strong currents. Turns out there's been a company working on it for a while, with free-moving turbines rather than something that spans the whole thing: https://www.energy.gov/eere/water/articles/tidal-testing-underway-new-yorks-east-river https://www.energy.gov/eere/water/articles/tidal-testing-und...
  - KeplerBoy 3y ago
    Meet project Atlantropa, a proposed plan to dam the Mediterranean (or more accurately the atlantic ocean) at the strait of Gibraltar. A project so absurd and gigantic it would deserve its own thread really. https://wikipedia.org/wiki/Atlantropa https://wikipedia.org/wiki/Atlantropa
    - bagels 3y ago
      Meanwhile, Egypt wants to expand the mediterranian: https://en.wikipedia.org/wiki/Qattara_Depression_Project https://en.wikipedia.org/wiki/Qattara_Depression_Project
      - KeplerBoy 3y ago
        That's interesting,I have never heard of it before. It seems outright feasible and sensible in comparison.
  - himinlomax 3y ago
    https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station 240 MW, built in 1966.
  - theropost 3y ago
    Where I'm from they have some of the highest tides in the entire world and there's an area not far from here that has always been sort of a local talking candidate for such a huge project. https://earthsciencesociety.com/2014/05/01/a-tidal-power-lagoon-in-nova-scotias-scotts-bay/ https://earthsciencesociety.com/2014/05/01/a-tidal-power-lag...
IshKebab 3y ago
Definitely seems more feasible than a lot of crazy energy ideas! E.g. I think this makes more sense than the air versions because you don't have problems launching/landing or when the wind stops. Probably the biggest issues I could imagine are maintenance and wildlife. They might be minor issues though. Also in most of the world (maybe not the Faroe Islands) this has to compete with solar & batteries which are getting cheaper and cheaper. If this is more than £5-10m then I think solar and batteries would be a much better option in most of the world.
- Someone 3y ago
  > Probably the biggest issues I could imagine are maintenance and wildlife. They might be minor issues though. Might, yes, but I think it’s unlikely all problems will be minor. Salt water isn’t kind to metal, no matter how well painted. Also, I expect barnacles will start growing on it. If you’re a filter feeder, this may be even better than sitting on the sea bed or on a whale. Question will be how much that effects their $/MWh calculation. The only real way to find out is to try, I guess.
  - usrusr 3y ago
    The good news is that we do have a bit of experience with metal machines that operate in sea water for decades. We (as in humanity, I don't) know exactly what to expect. You'd want to have a permanent service operation scaled exactly to how much overhauling capacity you need to put the tide kites in a round robin maintenance loop.
    - hoseja 3y ago
      And yet, every other tidal powerplant has been rendered hopelessly useless by barnacles.
      - usrusr 3y ago
        Have they? And how many of them can be ordered to surface under tide power, for easy maintenance access and towing into a maintenance dock without involving expensive divers? I presume the tether on this would be built long enough for controlled surfacing, a longer tether means larger deadzone between inbound and outbound tide, but there won't be much energy in the flow close to the turning point anyways.
throwbadubadu 3y ago
More renewable is good.. but there is always one fear in my crazy mind about these: This isn't actually renewable but taking energy out of a huge reservoir (Same for solar if pea counting, but solar is really endless until the end of the solar system).. and if we'd scale it massively the result could be another catastrophe. (Same btw. with geothermal?). (Btw.. I maybe got tidal wrong, so if it is just taking energy from waves via wind this counts as endless solar. Still, consider systems which would really break the tides and take energy out of the earth<=>moon system). The answer to this fear is that this reservoirs are so massive they are quasi endless in regard to what we ever could take out? It is hard to find numbers for these crazy thoughts :)
- HPsquared 3y ago
  There's also ocean thermal energy conversion, which exploits the temperature gradient in the ocean. https://en.m.wikipedia.org/wiki/Ocean_thermal_energy_conversion https://en.m.wikipedia.org/wiki/Ocean_thermal_energy_convers...
- lm28469 3y ago
  > (Same btw. with geothermal?). Not a chance, we're barely scratching the surface > More renewable is good.. but there is always one fear in my crazy mind about these It depends a lot on the rate of maintenance, materials used, &c. For example small windmills are next to useless: https://solar.lowtechmagazine.com/2009/04/small-windmills-put-to-the-test/ https://solar.lowtechmagazine.com/2009/04/small-windmills-pu...
- zakary 3y ago
  You’re right that nothing is unlimited. Luckily in this case, the energy of waves and tides is given to the oceans mostly by the gravity of the moon pulling the water as it passes overhead. Also a little bit by the wind which is fed by solar heat energy. The moon is slowly moving away from earth and eventually, in hundred of millions of years, it will impart significantly less energy into the tides. The energy that the moon gives the tides is essentially the same as how the sun gives energy to the ground with light. That is to say: If we don’t collect it, it just gets turned into another kind of energy that is absorbed by the environment. For tides and waves that would be mostly heat, and a little sound. And most of that heat would eventually be radiated back out into space. So suffice it to say, while there is a finite pool of energy stored in the tides, it is so massive we could never make a difference, and it gets recharged everyday by the moon.
tetha 3y ago
Since the number 1.2MW didn't mean much to me, modern on-shore wind turbines seem to supply 3-4MW and offshore ones 8 - 12MW. But this seems a lot easier to transport and install compared to cranes and the nightmare of navigating turbine blades on trucks through places. And if these hold up to water and don't cause too many problems for wildlife, there would be a lot less discussions about these "messing up my skyline", while tapping a new source of energy. Quite interesting and cool.
- out_of_protocol 3y ago
  > too many problems for wildlife There were a meta-analysis regarding population of birds in areas with/without wind turbines, found no statistically significant difference (unlike coal, where difference was huge)
  - tetha 3y ago
    Yep. I mostly meant for or rather caused by this kite. I wouldn't expect it intuitively, as it's just a big object in the water, not moving erratically or obstructing anything.
    - thfuran 3y ago
      I guess erratic is in the eye of the beholder, but it's certainly moving.
    - imzadi 3y ago
      It has a 39-foot wingspan and moves in a figure 8 pattern on a seabed tether. There's going to be at least some implication for local wildlife, but is it worse than the impacts of fossil fuels? I have no idea. It's definitely an interesting concept. I'm sure it will get more efficient and require a smaller footprint over time, assuming we invest in it.
      - duskwuff 3y ago
        > There's going to be at least some implication for local wildlife, but is it worse than the impacts of fossil fuels? For that matter, how does it compare to the local impact of other watercraft?
Benbobby 3y ago
[dead]
mukundmr 3y ago
While 28 tonnes appears to be a lot of material for generating 1.2MW of energy, it compares favourably when you look at wind turbines. How often does this need maintenance though?
- pbmonster 3y ago
  > How often does this need maintenance though? Moving parts in salt water? Frequently. The positive thing about this design is that maintenance is potentially much easier than on an seafloor mounted turbine: if the tether is long enough, you can just make the craft surface next to a maintenance vessel with a small crane. No divers necessary, and no giant crane platforms like for offshore wind turbines, either.
  - Sammi 3y ago
    > No divers necessary, and no giant crane platforms like for offshore wind turbines, either. This is critical to the economic viability of the project.
    - pbmonster 3y ago
      It's certainly one advantage. I still worry about some of the technical aspects. The craft is going to pull it's own tether through the water behind/"under" it while it "flies" loops in the current at a speed faster than the current itself. That must induce quite a bit of drag, right? Especially because that tether is delivering several megawatts of electric power do the anchor, while holding all the mechanical load of that power being generated. That has to be a beefy cable. And the joints where that cable meets the craft and the anchor are moving parts, for all intents and purposes. I also wonder how much the craft actually resembles a full submarine. Are there ballast tanks and ballast pumps for altitude control? Full set of diving and directional rudders? What happens when any of those fail? Potential complexity is certainly higher than for an offshore wind turbine.
- Mistletoe 3y ago
  Yes I’m envisioning this thing covered in barnacles. Surely they’ve thought of that?
LysPJ 3y ago
For those wondering how they transfer the generated energy from the tidal kite to the shore: > The turbine shaft turns the [onboard] generator which outputs electricity to the grid via a power cable in the tether and a seabed umbilical to the shore.
bjourne 3y ago
How on earth can such a small device generate so much energy? Wouldn't 1.2 MW of power make it very brittle just like a real kite? Or else why not scale it up and make one 100 times larger that generates 120 MW of power? Since tidal currents are much more reliable (I think) than offshore wind it almost seem to good to be true. There has to be a catch.
- KaiserPro 3y ago
  The speed of the tide between those islands is something like 5-6mph, and in some places much much higher (think tens of miles an hour). Water is 800 times more dense, so moving water contains much much much more kinetic energy when its moving. But that also means it has a lot more drag. That drag can be quadratic, meaning that you'd need to a monster fucking cable to stop it being dragged away by the tide.
  - arethuza 3y ago
    The Grey Dogs channel between the Scottish islands of Lunga and Scarba has a peak flow of about 15km/h with large standing waves - quite incredible to watch this up close and watch the sea shooting past!
    - Super_Jambo 3y ago
      And of course some lunatics will go and find a way to have fun in them! Here's a sea kayaker at Penrhyn Mawr off Anglesey in Wales. https://www.youtube.com/watch?v=l5o7qV1Gy04 https://www.youtube.com/watch?v=l5o7qV1Gy04
      - btbuildem 3y ago
        Looks like fun! FPV [1] and drone footage [2] 1: https://www.youtube.com/watch?v=Qo28x0CYBaA https://www.youtube.com/watch?v=Qo28x0CYBaA 2: https://www.youtube.com/watch?v=ehN9c7WfLMI https://www.youtube.com/watch?v=ehN9c7WfLMI
        3y ago
tamimio 3y ago
It’s just a matter of time before the orcas start playing spikeball with it, hopefully the team considered that.
- Sammi 3y ago
  Fortunately they are smart. They will learn fast. This isn't a new problem. Ships do get whales caught in the propellers from time to time. I was in a ship that had exactly this experience in 2001. Whole ship stopped and wouldn't start again until the third attempt to start it. A crew member reported he saw blood and guts at the stern.
ksec 3y ago
Too good to be true? I assume this does no harm to fish. And electricity can be easily transported back to land ( there was no mention of how this was done in the video ). Since it is portable, small, fits into a 40ft Container. And you could mass manufacture these, ship it with container. There isn't another manufacturing problem and transportation problem like wind turbine. If Yes. You could have tens of thousands of these in north of Scotland of or seas around England. Surely there has to be a catch somewhere. Right?
- PaulRobinson 3y ago
  I will 100% guarantee that the unique brand by Brit NIMBY-ism will rise, and some of my fellow citizens will complain about them affecting the nesting habits of the migrating lesser-spotted blue crested greeb warbler or something, and that'll be that. It's happened to many wind projects, this won't be any different (despite there being no evidence). Never mind that if CO2 in the atmosphere continues to climb, all those birds will die anyway, the global food ecosystem will go crazy, hundreds of millions of people will die and so on: that picturesque estuary has to remain unencumbered with man-made engineering, or else!
  - Sammi 3y ago
    Production of the kites is partly in the UK and there are projects in the works to put them to use there: https://minesto.com/holyhead-deep/ https://minesto.com/holyhead-deep/
- jokoon 3y ago
  > Surely there has to be a catch somewhere. Right? Underwater things are expensive to maintain, nothing is 100% waterproof, so rust rust rust. Underwater cables are no joke either, especially if you're building a network of sea cables. Making watertight is not cheap. And there is the question of doing high power electricity under seawater. I'm not an engineer in that field, that I think it is going to being a whole lot of new headaches.
  - ksec 3y ago
Eddy_Viscosity2 3y ago
I was hoping for some sort of diagram or animation about what this thing is set up and does underwater and how this movement gets converted to electricity. Does anybody know?
- ljf 3y ago
  Check out the embedded video in the story (link: https://www.youtube.com/watch?v=dkXinDn67Kw https://www.youtube.com/watch?v=dkXinDn67Kw ) The turbine (propeller) at the back of the kite rotates and generates electricity. Since this can 'fly' at an angle to the current, the speed of the 'kite' moving through the water, will be faster than the movement of the water - therefore the turbine can be spun faster than if it were just anchored in one spot.
  - Eddy_Viscosity2 3y ago
    thank you!
DrNosferatu 3y ago
The long-term projected levelized cost of the generated electricity really has to hit that $54/MWh target, otherwise the economics won't work - unless you absolutely must use some form of offshore energy production, then I guess it's an interesting niche application. It will be interesting to see.
- Sammi 3y ago
  The tides are always moving so this energy is much more useful as baseload energy. They will lessen the need for energy storage for wind and solar, making wind and solar even cheaper. So tidal doesn't actually have to be as cheap as wind and solar by itself, as it will lower the total cost of wind and solar and be economically viable as a part of the mix. If you're a company operating wind or solar, then you will be able to have a much smaller battery installation, by using tidal kites for most of the baseload instead. And the kites actually generate energy instead of just storing it.
  - DrNosferatu 3y ago
    This system, as presented, will be really prone to *mechanical wear*. Maybe it can be done, but I need to see long-term (price & reliability) performance to believe it.
    - Sammi 3y ago
      What type of mechanical wear are you thinking of? I can think of a propeller and generator, but those are solved problems. This is just a boat with a propeller. Only instead of using the generator as an engine to spin the propeller, the tides spin the propeller which generates power in the generator. Steering is also a solved boat problem. Then there's the tether and anchor. This is the reason it swims in a figure 8, instead of it just being a propellar anchored straight to the seabed. So the "pulling" force is actually mostly to the sides instead of directly on the tether and anchor.
      - DrNosferatu 3y ago
ederamen 3y ago
We should probably just do nuclear.
- mikro2nd 3y ago
  Per Wikipedia, nuclear LCOE runs to $81-82/MWh, so is not cost competitive.
h1fra 3y ago
Neat, I just didn't get why they designed it this way vs a regular turbine at the floor of the ocean? if anybody knows
- Sammi 3y ago
  That has been attempted in the same location in Vestmanna in the Faroe Islands. From what I've been told it pulled itself loose immediately, and the anchoring was pretty significant. This kite swims in a figure 8, so I guess that doesn't pull as much on the anchor.
titzer 3y ago
Interesting! Given the small amount of power relative to the total amount in the tides (I've seen an estimate of 3.7TW), this doesn't make a big difference to the Earth/Moon gravitational system, but I'm curious how this will affect the Moon's orbit (yes, I know it's millimeters or meters). For example, the Moon's orbit is increasing by stealing rotational energy from the Earth--i.e. Earth rotation slows down, Moon speeds up and orbital distance increases. Does this friction in the tidal system reduce the energy transfer to the Moon and therefore preserve Earth's rotational energy, or just redirect that rotational energy into our power grid? I would guess it would have to be the latter...
- vikingerik 3y ago
  I believe it would reduce the transfer to the Moon. The Moon's orbit increases by stealing rotational energy from the Earth -- this happens because Earth's rotation carries its tidal bulge ahead of the Moon angularly, so the bulge pulls the Moon forward. The tidal harness uses some of the motion of the water to do work, so it gets carried less farther ahead by Earth's rotation, so it pulls the Moon forward less.
dylan604 3y ago
When the wind isn't blowing, no wind generation. When the sun isn't shining, no solar. So these guys come in with a "gap" filling idea of using tidal, yet their own marketing says this "kite" parks itself when there is no tidal flow. So how is this continuous power generation?
- 7952 3y ago
  It's not continuous, but would presumably be very predictable. And times of less movement would be different across the world which makes it possible to have some geographic resilience.
Donaldbendo 3y ago
[dead]
beefman 3y ago
For comparison, electricity was sold to the U.S. grid at about $48/MWh in 2023. This is less than any of the cost projections mentioned in the article. Howabout materials? It says this weighs 28 tons and makes 1.2 MW. That's 21g/W assuming a 100% capacity factor, no balance of plant, and assuming those are short tons. Compare to an iPhone 15, which consumes about 1W per 150g in use. That's a materials intensity multiple (EROI estimate) of ~ 7. An average automobile on an average commute dissipates about 67kW, or 27g/W for a multiple of ~ 1.
- rsynnott 3y ago
  That would benefit from various subsidies; from the article it _looks_ like the $54/MWh projected figure is before subsidy.
  - beefman 3y ago
    Subsidies would be useful in getting it from $108/MWh to $54/MWh faster, but they don't change the underlying physics of the technology.
    - rsynnott 3y ago
      Sorry, what I mean is that the $48/MWh figure benefits from significant subsidy; it's not a realistic cost of provision.
      - beefman 3y ago
        Perhaps surprisingly, it is a realistic cost and could be much lower if the electricity market were efficient (as opposed to being an amalgam of regional monopolies with essentially no price incentives).
bagels 3y ago
Does it present a navigation hazard?
- vitiral 3y ago
  maybe for submarines. Pretty sure the video said the depth is 50m
User23 3y ago
The Earth’s angular momentum is the exact opposite of renewable. It’s even less renewable than so-called fossil fuels.
- ars 3y ago
  True, but it's being wasted anyway. The amount of power dissipated in the daily tides is around 3.75 terawatt, around 3 million times as much. And don't assume this 1.2 MW adds to that total, a good portion of it is simply substituted.
- vitiral 3y ago
  ??? by that metric literally nothing in the universe is renewable. RENEWABLE ENERGY IS IN VIOLATION OF THERMODYNAMICS. WE ARE ALL HEADING TOWARDS THE HEAT DEATH OF THE UNIVERSE.
hnthrowaway0328 3y ago
I'm thinking loudly about three questions: 1. How does the maintenance fee and replacement fee look like, per year? 2. Is it possible to develop a home use version? 3. I assume the tide is going to be consistent, but need to dig deeper into this.
- jszymborski 3y ago
  > Is it possible to develop a home use version? I suspect that these things are heckin' dangerous unless they are far from humans, so that would be a challenge I think.
  - hnthrowaway0328 3y ago
    Good point.
- moffkalast 3y ago
  > a home use version > 28-ton, 1.2-megawatt tidal kite Yes, one for your shower drain.
  - hnthrowaway0328 3y ago
    I was thinking a much smaller version TBH, or a big one for multiple homes.
_whiteCaps_ 3y ago
This would be great in the https://en.wikipedia.org/wiki/Skookumchuck_Narrows https://en.wikipedia.org/wiki/Skookumchuck_Narrows
taldo 3y ago
Kinda reminescent of Makani, Google/X flying kite-turbine-generator-thingies. https://x.company/projects/makani/ https://x.company/projects/makani/
tlbsofware 3y ago
Reminds me of the the wind based KitePower that was shared here a month or 2 ago https://spectrum.ieee.org/micro-wind-power-kitepower https://spectrum.ieee.org/micro-wind-power-kitepower
vitiral 3y ago
What happens when a 28 ton kite slams into a whale or shark?

282 points by bornelsewhere 3y ago

The sea is a harsh environment, but the energy it contains, in the form of waves (basically concentrated wind) and tides is enormous (partly thanks to the density of water.) Of course, like with all renewable, location matters. But there are lots of places with strong tides, and lots of places with reliable waves. Harvesting this abundant energy at scale, with reasonable maintenence costs will be the next breakthrough in green energy.

mywacaday 3y ago
I've often thought why not dam a whole estuary or bay and use hydro to collect the energy on the the fall and rise of the tide. I know the environmental impact wouldake it unpalatable but are there any reasons it wouldn't work?
- flipbrad 3y ago
  https://www.gov.uk/government/publications/1-severn-tidal-power-feasibility-study-conclusions-and-summary-report https://www.gov.uk/government/publications/1-severn-tidal-po...
  - hardlianotion 3y ago
    That Severn project has on-again, off-again cycles that are typical of so many UK infrastructure projects. It's a little depressing.
- lelag 3y ago
  It's been done. Biggest one is Sihwa Lake Tidal Power Station[1] and France had a 240MW tidal plant since the 60s [2]. This type of project has been few and far between and I would guess they might be very costly to build and maintain compared to the harvested energy. [1] https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station [2] https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station
  - macNchz 3y ago
    This is interesting–it made me wonder if this had ever been considered on NYC's East River, which is a tidal estuary with strong currents. Turns out there's been a company working on it for a while, with free-moving turbines rather than something that spans the whole thing: https://www.energy.gov/eere/water/articles/tidal-testing-underway-new-yorks-east-river https://www.energy.gov/eere/water/articles/tidal-testing-und...
- KeplerBoy 3y ago
  Meet project Atlantropa, a proposed plan to dam the Mediterranean (or more accurately the atlantic ocean) at the strait of Gibraltar. A project so absurd and gigantic it would deserve its own thread really. https://wikipedia.org/wiki/Atlantropa https://wikipedia.org/wiki/Atlantropa
  - bagels 3y ago
    Meanwhile, Egypt wants to expand the mediterranian: https://en.wikipedia.org/wiki/Qattara_Depression_Project https://en.wikipedia.org/wiki/Qattara_Depression_Project
    - KeplerBoy 3y ago
      That's interesting,I have never heard of it before. It seems outright feasible and sensible in comparison.
- himinlomax 3y ago
  https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station 240 MW, built in 1966.
- theropost 3y ago
  Where I'm from they have some of the highest tides in the entire world and there's an area not far from here that has always been sort of a local talking candidate for such a huge project. https://earthsciencesociety.com/2014/05/01/a-tidal-power-lagoon-in-nova-scotias-scotts-bay/ https://earthsciencesociety.com/2014/05/01/a-tidal-power-lag...

IshKebab 3y ago

Definitely seems more feasible than a lot of crazy energy ideas! E.g. I think this makes more sense than the air versions because you don't have problems launching/landing or when the wind stops. Probably the biggest issues I could imagine are maintenance and wildlife. They might be minor issues though. Also in most of the world (maybe not the Faroe Islands) this has to compete with solar & batteries which are getting cheaper and cheaper. If this is more than £5-10m then I think solar and batteries would be a much better option in most of the world.

Someone 3y ago
> Probably the biggest issues I could imagine are maintenance and wildlife. They might be minor issues though. Might, yes, but I think it’s unlikely all problems will be minor. Salt water isn’t kind to metal, no matter how well painted. Also, I expect barnacles will start growing on it. If you’re a filter feeder, this may be even better than sitting on the sea bed or on a whale. Question will be how much that effects their $/MWh calculation. The only real way to find out is to try, I guess.
- usrusr 3y ago
  The good news is that we do have a bit of experience with metal machines that operate in sea water for decades. We (as in humanity, I don't) know exactly what to expect. You'd want to have a permanent service operation scaled exactly to how much overhauling capacity you need to put the tide kites in a round robin maintenance loop.
  - hoseja 3y ago
    And yet, every other tidal powerplant has been rendered hopelessly useless by barnacles.
    - usrusr 3y ago
      Have they? And how many of them can be ordered to surface under tide power, for easy maintenance access and towing into a maintenance dock without involving expensive divers? I presume the tether on this would be built long enough for controlled surfacing, a longer tether means larger deadzone between inbound and outbound tide, but there won't be much energy in the flow close to the turning point anyways.

throwbadubadu 3y ago

More renewable is good.. but there is always one fear in my crazy mind about these: This isn't actually renewable but taking energy out of a huge reservoir (Same for solar if pea counting, but solar is really endless until the end of the solar system).. and if we'd scale it massively the result could be another catastrophe. (Same btw. with geothermal?). (Btw.. I maybe got tidal wrong, so if it is just taking energy from waves via wind this counts as endless solar. Still, consider systems which would really break the tides and take energy out of the earth<=>moon system). The answer to this fear is that this reservoirs are so massive they are quasi endless in regard to what we ever could take out? It is hard to find numbers for these crazy thoughts :)

HPsquared 3y ago
There's also ocean thermal energy conversion, which exploits the temperature gradient in the ocean. https://en.m.wikipedia.org/wiki/Ocean_thermal_energy_conversion https://en.m.wikipedia.org/wiki/Ocean_thermal_energy_convers...
lm28469 3y ago
> (Same btw. with geothermal?). Not a chance, we're barely scratching the surface > More renewable is good.. but there is always one fear in my crazy mind about these It depends a lot on the rate of maintenance, materials used, &c. For example small windmills are next to useless: https://solar.lowtechmagazine.com/2009/04/small-windmills-put-to-the-test/ https://solar.lowtechmagazine.com/2009/04/small-windmills-pu...
zakary 3y ago
You’re right that nothing is unlimited. Luckily in this case, the energy of waves and tides is given to the oceans mostly by the gravity of the moon pulling the water as it passes overhead. Also a little bit by the wind which is fed by solar heat energy. The moon is slowly moving away from earth and eventually, in hundred of millions of years, it will impart significantly less energy into the tides. The energy that the moon gives the tides is essentially the same as how the sun gives energy to the ground with light. That is to say: If we don’t collect it, it just gets turned into another kind of energy that is absorbed by the environment. For tides and waves that would be mostly heat, and a little sound. And most of that heat would eventually be radiated back out into space. So suffice it to say, while there is a finite pool of energy stored in the tides, it is so massive we could never make a difference, and it gets recharged everyday by the moon.

tetha 3y ago

Since the number 1.2MW didn't mean much to me, modern on-shore wind turbines seem to supply 3-4MW and offshore ones 8 - 12MW. But this seems a lot easier to transport and install compared to cranes and the nightmare of navigating turbine blades on trucks through places. And if these hold up to water and don't cause too many problems for wildlife, there would be a lot less discussions about these "messing up my skyline", while tapping a new source of energy. Quite interesting and cool.

out_of_protocol 3y ago
> too many problems for wildlife There were a meta-analysis regarding population of birds in areas with/without wind turbines, found no statistically significant difference (unlike coal, where difference was huge)
- tetha 3y ago
  Yep. I mostly meant for or rather caused by this kite. I wouldn't expect it intuitively, as it's just a big object in the water, not moving erratically or obstructing anything.
  - thfuran 3y ago
    I guess erratic is in the eye of the beholder, but it's certainly moving.
  - imzadi 3y ago
    It has a 39-foot wingspan and moves in a figure 8 pattern on a seabed tether. There's going to be at least some implication for local wildlife, but is it worse than the impacts of fossil fuels? I have no idea. It's definitely an interesting concept. I'm sure it will get more efficient and require a smaller footprint over time, assuming we invest in it.
    - duskwuff 3y ago
      > There's going to be at least some implication for local wildlife, but is it worse than the impacts of fossil fuels? For that matter, how does it compare to the local impact of other watercraft?

Benbobby 3y ago

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mukundmr 3y ago

While 28 tonnes appears to be a lot of material for generating 1.2MW of energy, it compares favourably when you look at wind turbines. How often does this need maintenance though?

pbmonster 3y ago
> How often does this need maintenance though? Moving parts in salt water? Frequently. The positive thing about this design is that maintenance is potentially much easier than on an seafloor mounted turbine: if the tether is long enough, you can just make the craft surface next to a maintenance vessel with a small crane. No divers necessary, and no giant crane platforms like for offshore wind turbines, either.
- Sammi 3y ago
  > No divers necessary, and no giant crane platforms like for offshore wind turbines, either. This is critical to the economic viability of the project.
  - pbmonster 3y ago
    It's certainly one advantage. I still worry about some of the technical aspects. The craft is going to pull it's own tether through the water behind/"under" it while it "flies" loops in the current at a speed faster than the current itself. That must induce quite a bit of drag, right? Especially because that tether is delivering several megawatts of electric power do the anchor, while holding all the mechanical load of that power being generated. That has to be a beefy cable. And the joints where that cable meets the craft and the anchor are moving parts, for all intents and purposes. I also wonder how much the craft actually resembles a full submarine. Are there ballast tanks and ballast pumps for altitude control? Full set of diving and directional rudders? What happens when any of those fail? Potential complexity is certainly higher than for an offshore wind turbine.
Mistletoe 3y ago
Yes I’m envisioning this thing covered in barnacles. Surely they’ve thought of that?

LysPJ 3y ago

For those wondering how they transfer the generated energy from the tidal kite to the shore: > The turbine shaft turns the [onboard] generator which outputs electricity to the grid via a power cable in the tether and a seabed umbilical to the shore.

bjourne 3y ago

How on earth can such a small device generate so much energy? Wouldn't 1.2 MW of power make it very brittle just like a real kite? Or else why not scale it up and make one 100 times larger that generates 120 MW of power? Since tidal currents are much more reliable (I think) than offshore wind it almost seem to good to be true. There has to be a catch.

KaiserPro 3y ago
The speed of the tide between those islands is something like 5-6mph, and in some places much much higher (think tens of miles an hour). Water is 800 times more dense, so moving water contains much much much more kinetic energy when its moving. But that also means it has a lot more drag. That drag can be quadratic, meaning that you'd need to a monster fucking cable to stop it being dragged away by the tide.
- arethuza 3y ago
  The Grey Dogs channel between the Scottish islands of Lunga and Scarba has a peak flow of about 15km/h with large standing waves - quite incredible to watch this up close and watch the sea shooting past!
  - Super_Jambo 3y ago
    And of course some lunatics will go and find a way to have fun in them! Here's a sea kayaker at Penrhyn Mawr off Anglesey in Wales. https://www.youtube.com/watch?v=l5o7qV1Gy04 https://www.youtube.com/watch?v=l5o7qV1Gy04
    - btbuildem 3y ago
      Looks like fun! FPV [1] and drone footage [2] 1: https://www.youtube.com/watch?v=Qo28x0CYBaA https://www.youtube.com/watch?v=Qo28x0CYBaA 2: https://www.youtube.com/watch?v=ehN9c7WfLMI https://www.youtube.com/watch?v=ehN9c7WfLMI
      - 3y ago

tamimio 3y ago

It’s just a matter of time before the orcas start playing spikeball with it, hopefully the team considered that.

Sammi 3y ago
Fortunately they are smart. They will learn fast. This isn't a new problem. Ships do get whales caught in the propellers from time to time. I was in a ship that had exactly this experience in 2001. Whole ship stopped and wouldn't start again until the third attempt to start it. A crew member reported he saw blood and guts at the stern.

ksec 3y ago

Too good to be true? I assume this does no harm to fish. And electricity can be easily transported back to land ( there was no mention of how this was done in the video ). Since it is portable, small, fits into a 40ft Container. And you could mass manufacture these, ship it with container. There isn't another manufacturing problem and transportation problem like wind turbine. If Yes. You could have tens of thousands of these in north of Scotland of or seas around England. Surely there has to be a catch somewhere. Right?

PaulRobinson 3y ago
I will 100% guarantee that the unique brand by Brit NIMBY-ism will rise, and some of my fellow citizens will complain about them affecting the nesting habits of the migrating lesser-spotted blue crested greeb warbler or something, and that'll be that. It's happened to many wind projects, this won't be any different (despite there being no evidence). Never mind that if CO2 in the atmosphere continues to climb, all those birds will die anyway, the global food ecosystem will go crazy, hundreds of millions of people will die and so on: that picturesque estuary has to remain unencumbered with man-made engineering, or else!
- Sammi 3y ago
  Production of the kites is partly in the UK and there are projects in the works to put them to use there: https://minesto.com/holyhead-deep/ https://minesto.com/holyhead-deep/
jokoon 3y ago
> Surely there has to be a catch somewhere. Right? Underwater things are expensive to maintain, nothing is 100% waterproof, so rust rust rust. Underwater cables are no joke either, especially if you're building a network of sea cables. Making watertight is not cheap. And there is the question of doing high power electricity under seawater. I'm not an engineer in that field, that I think it is going to being a whole lot of new headaches.
- ksec 3y ago

Eddy_Viscosity2 3y ago

I was hoping for some sort of diagram or animation about what this thing is set up and does underwater and how this movement gets converted to electricity. Does anybody know?

ljf 3y ago
Check out the embedded video in the story (link: https://www.youtube.com/watch?v=dkXinDn67Kw https://www.youtube.com/watch?v=dkXinDn67Kw ) The turbine (propeller) at the back of the kite rotates and generates electricity. Since this can 'fly' at an angle to the current, the speed of the 'kite' moving through the water, will be faster than the movement of the water - therefore the turbine can be spun faster than if it were just anchored in one spot.
- Eddy_Viscosity2 3y ago
  thank you!

DrNosferatu 3y ago

The long-term projected levelized cost of the generated electricity really has to hit that $54/MWh target, otherwise the economics won't work - unless you absolutely must use some form of offshore energy production, then I guess it's an interesting niche application. It will be interesting to see.

Sammi 3y ago
The tides are always moving so this energy is much more useful as baseload energy. They will lessen the need for energy storage for wind and solar, making wind and solar even cheaper. So tidal doesn't actually have to be as cheap as wind and solar by itself, as it will lower the total cost of wind and solar and be economically viable as a part of the mix. If you're a company operating wind or solar, then you will be able to have a much smaller battery installation, by using tidal kites for most of the baseload instead. And the kites actually generate energy instead of just storing it.
- DrNosferatu 3y ago
  This system, as presented, will be really prone to *mechanical wear*. Maybe it can be done, but I need to see long-term (price & reliability) performance to believe it.
  - Sammi 3y ago
    What type of mechanical wear are you thinking of? I can think of a propeller and generator, but those are solved problems. This is just a boat with a propeller. Only instead of using the generator as an engine to spin the propeller, the tides spin the propeller which generates power in the generator. Steering is also a solved boat problem. Then there's the tether and anchor. This is the reason it swims in a figure 8, instead of it just being a propellar anchored straight to the seabed. So the "pulling" force is actually mostly to the sides instead of directly on the tether and anchor.
    - DrNosferatu 3y ago

ederamen 3y ago

We should probably just do nuclear.

mikro2nd 3y ago
Per Wikipedia, nuclear LCOE runs to $81-82/MWh, so is not cost competitive.

h1fra 3y ago

Neat, I just didn't get why they designed it this way vs a regular turbine at the floor of the ocean? if anybody knows

Sammi 3y ago
That has been attempted in the same location in Vestmanna in the Faroe Islands. From what I've been told it pulled itself loose immediately, and the anchoring was pretty significant. This kite swims in a figure 8, so I guess that doesn't pull as much on the anchor.

titzer 3y ago

Interesting! Given the small amount of power relative to the total amount in the tides (I've seen an estimate of 3.7TW), this doesn't make a big difference to the Earth/Moon gravitational system, but I'm curious how this will affect the Moon's orbit (yes, I know it's millimeters or meters). For example, the Moon's orbit is increasing by stealing rotational energy from the Earth--i.e. Earth rotation slows down, Moon speeds up and orbital distance increases. Does this friction in the tidal system reduce the energy transfer to the Moon and therefore preserve Earth's rotational energy, or just redirect that rotational energy into our power grid? I would guess it would have to be the latter...

vikingerik 3y ago
I believe it would reduce the transfer to the Moon. The Moon's orbit increases by stealing rotational energy from the Earth -- this happens because Earth's rotation carries its tidal bulge ahead of the Moon angularly, so the bulge pulls the Moon forward. The tidal harness uses some of the motion of the water to do work, so it gets carried less farther ahead by Earth's rotation, so it pulls the Moon forward less.

dylan604 3y ago

When the wind isn't blowing, no wind generation. When the sun isn't shining, no solar. So these guys come in with a "gap" filling idea of using tidal, yet their own marketing says this "kite" parks itself when there is no tidal flow. So how is this continuous power generation?

7952 3y ago
It's not continuous, but would presumably be very predictable. And times of less movement would be different across the world which makes it possible to have some geographic resilience.

Donaldbendo 3y ago

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beefman 3y ago

For comparison, electricity was sold to the U.S. grid at about $48/MWh in 2023. This is less than any of the cost projections mentioned in the article. Howabout materials? It says this weighs 28 tons and makes 1.2 MW. That's 21g/W assuming a 100% capacity factor, no balance of plant, and assuming those are short tons. Compare to an iPhone 15, which consumes about 1W per 150g in use. That's a materials intensity multiple (EROI estimate) of ~ 7. An average automobile on an average commute dissipates about 67kW, or 27g/W for a multiple of ~ 1.

rsynnott 3y ago
That would benefit from various subsidies; from the article it _looks_ like the $54/MWh projected figure is before subsidy.
- beefman 3y ago
  Subsidies would be useful in getting it from $108/MWh to $54/MWh faster, but they don't change the underlying physics of the technology.
  - rsynnott 3y ago
    Sorry, what I mean is that the $48/MWh figure benefits from significant subsidy; it's not a realistic cost of provision.
    - beefman 3y ago
      Perhaps surprisingly, it is a realistic cost and could be much lower if the electricity market were efficient (as opposed to being an amalgam of regional monopolies with essentially no price incentives).

bagels 3y ago

Does it present a navigation hazard?

vitiral 3y ago
maybe for submarines. Pretty sure the video said the depth is 50m

User23 3y ago

The Earth’s angular momentum is the exact opposite of renewable. It’s even less renewable than so-called fossil fuels.

ars 3y ago
True, but it's being wasted anyway. The amount of power dissipated in the daily tides is around 3.75 terawatt, around 3 million times as much. And don't assume this 1.2 MW adds to that total, a good portion of it is simply substituted.
vitiral 3y ago
??? by that metric literally nothing in the universe is renewable. RENEWABLE ENERGY IS IN VIOLATION OF THERMODYNAMICS. WE ARE ALL HEADING TOWARDS THE HEAT DEATH OF THE UNIVERSE.

hnthrowaway0328 3y ago

I'm thinking loudly about three questions: 1. How does the maintenance fee and replacement fee look like, per year? 2. Is it possible to develop a home use version? 3. I assume the tide is going to be consistent, but need to dig deeper into this.

jszymborski 3y ago
> Is it possible to develop a home use version? I suspect that these things are heckin' dangerous unless they are far from humans, so that would be a challenge I think.
- hnthrowaway0328 3y ago
  Good point.
moffkalast 3y ago
> a home use version > 28-ton, 1.2-megawatt tidal kite Yes, one for your shower drain.
- hnthrowaway0328 3y ago
  I was thinking a much smaller version TBH, or a big one for multiple homes.

_whiteCaps_ 3y ago

This would be great in the https://en.wikipedia.org/wiki/Skookumchuck_Narrows https://en.wikipedia.org/wiki/Skookumchuck_Narrows

taldo 3y ago

Kinda reminescent of Makani, Google/X flying kite-turbine-generator-thingies. https://x.company/projects/makani/ https://x.company/projects/makani/

tlbsofware 3y ago

Reminds me of the the wind based KitePower that was shared here a month or 2 ago https://spectrum.ieee.org/micro-wind-power-kitepower https://spectrum.ieee.org/micro-wind-power-kitepower

vitiral 3y ago

What happens when a 28 ton kite slams into a whale or shark?