Can Underwater Turbines Solve Our Energy Problems?


This episode of Real Engineering is brought
to you by Brilliant. A problem solving website that teaches you to think like an Engineer. Next time you’re near the ocean, listen
closely to the waves. That sound you hear? That’s wasted energy. The energy from waves, tides and currents,
known collectively as ocean energy, is a massive resource just waiting to be tapped. The total energy available along the American
continental shelf could potentially provide roughly half of the current total US energy
supply. [1] With an estimated 250 TWh/yr for the West Coast, 160 TWH/yr for the East Coast,
60 TWh/y for the Gulf of Mexico, 620 TWh/y for Alaska, 80 TWh/yr for Hawaii, and 20 TWh/yr
for Puerto Rico. [1] Harassing all of that energy, while transporting
it to population centres and finding suitable locations along the coast that will not affect
coastline ecosystems and property values would be a difficult if not an impossible task,
but if we could find a suitable way to harass the power of the tides and waves off our coasts,
it could provide the final push needed to convert out grid to a 100% renewable system
[2] There are many methods to gain energy from
the sea. Wave power is created as the wind pushes the surface of the ocean. Ocean currents
provide power driven predominantly by wind and heat from the sun. Some systems have even
utilized the differences in salinity between rivers and seas to produce electricity. However, today we are going to investigate
one of the most promising technologies in this sector, Tidal Energy. It has huge potential
in the renewable energy market thanks to its predictable and consistent availability. Tides
change four times a day, every day. This is a result of the Earth rotating through
bulges of ocean water formed by the gravitational influence of the Sun and Moon. We experience
greater tides, called Spring Tides, when the Sun is aligned with the Moon allowing their
gravitational influence to combine. [3] This corresponds to the New and Full Moon phases
of the Moon. And we experience smaller tides, and smaller differences in high and low tide,
during Neap Tides. This occurs when the Moon is at a quarter phase, offset to the Sun by
90 degrees. Meaning our tides are not only smaller in total, but the changes in tide
are minimised. While their intensity does vary, these tidal
changes come 4 times a day and result in a flow of water that will look something like
this for a Spring Tide and this for a Neap Tide. [4] With the Spring Tide not only resulting
in a higher tide, but a faster flow of water, which means more energy is available for extraction. These patterns can be projected well into
the future thanks to the predictable movement of the Sun, Moon and Earth. Which definitely
cannot be said for the unpredictable weather here on earth which affects Wind and Solar
energy. Despite this steady and reliable flow of water,
ocean power provides the smallest percentage of renewable energy. With only two large scale
tidal energy plants, a 240 MW system [5] located in the estuary of the Rance River in Northern
France, and a 254 MW system in Sihwa Lake in South Korea [6]. Both are tidal barrage
systems, which work similarly to dams by opening and closing sluice gates to control the flow
of water through their turbines. This is a proven technology, proving they can generate
electricity and operate in seawater without corrosion being a massive issue thanks to
cathodic protection. [7] So why are there so few of these systems in
the world. The problem is two-fold. First, the cost of installation is incredibly high
requiring a very large structure to control the flow of water. It simply makes more sense
to use other forms of renewables like wind and solar. And second, a large barrier like
this has a significant effect on the local ecosystem. One company, Simec Atlantis, is looking to
improve on both of these points with their underwater turbines which look remarkably
like normal wind turbines, but thanks to water’s higher density can be much smaller. Their first prototype system was placed here
in the mouth of Strangford lough in Ireland. This area benefits from some of the fastest
flowing water in Ireland, as tides force their way in and out of the bottleneck of Strangford
Lough. Millions of tonnes of water flow through the channel every day. [8] The system consisted of two 16 metre diameter
turbines with a nameplate capacity of 0.6 MWs each. [8] For reference an equivalent
wind turbine would have a diameter around 40 metres. These turbines reached full capacity
in November 2008 and were decommissioned in May 2016. [9] If that 1.2 MWs ran continuously
at full capacity for all that time it would result in about 77-79 GWhs of power, however
it only produced 11.6 GWhs. [10] Enough to power around 1 thousand American homes for
1 year, but that’s just 15% of its full potential. That percentage is called a capacity
factor and 15% is a very low capacity factor, with Ireland’s 5 year average wind energy
capacity factor standing around 28%. [11] However this was a prototype which did not
run continuously and was routinely taken offline for inspection and research. In their best
month, SeaGen produced 522 MWhs with a capacity factor of 59% and Seagen claim that is reproducible
year round. [12] With a capacity factor of 59% year round this would make tidal energy
an incredibly reliable energy source with only minimal storage needed to smoothen out
the peaks and troughs between the tides. With a short time between peak power generation
and minimum power generation, this form of tidal energy could use cheaper short-term
energy storage solutions like mechanical batteries to create a desperately needed renewable baseload. This project was decommissioned in 2016, as
part of the research process. It was vitally important to test whether these machines could
be effectively removed from the environments with minimal impact. [13] And this is of course
a major concern for any machinery being placed into a marine environment. Seagen satisfied
this requirement having no significant effect on the local ecosystem, and they have since
moved onto the next stage of their technology with Meygen, installed in between the Island
of Stroma and the North East coast of Scotland. Their original lease agreement was for up
400 Megawatts, provided the initial testing phase with 4 turbines satisfied the environmental
impact requirements. [14] The latest version of the underwater turbine
now has 3 turbine blades, allowing for an increase in capacity to 1.5 MegaWatts with
only a slightly increased diameter turbine over the 16 metre 0.5 MegaWatt turbines of
their previous project in Northern Ireland. This turbine is also completely submerged,
so it is not an eyesore for local residents. Seagen previously had actuators to lift the
turbine out of the water to allow maintenance to occur, but the new generation of turbines
are designed so the actual turbines and generators can simply be placed and removed from the
substructure in about 30 minutes. [15] Making installation and maintenance vastly easier
and cheaper. Environmental impact has been a central focus
for the project and this started with a comprehensive survey of the surrounding ecosystem from seaweed
and shellfish to the whales that occasionally visit the area. The area thankfully has such fast moving water
that the seabed was stripped of sand and silt, so the installation had little impact on ecology
of the rocky seafloor. The impact the installation could have on
local marine mammals was of much larger concern with surveys showing a large population of
both seals and dolphins, with several haul out areas for seals nearby. [16] Both of these
mammals are sensitive to noise and will likely avoid any area with excessive sound. The noise
levels these turbines emit are not terribly high, as they move relatively slowly through
the water. Their 544 page long environmental report, which I read to the best of my ability
in the 1 week of research I did for this video, indicates that seals will have a strong avoidance
of the noise within 38 metres of the structures, while mild avoidance may extend as far as
168 metres. [17] With seal haulouts over a kilometre away this was deemed acceptable.
While dolphins are expected to avoid the noise up to 100 metres and filter feeders like whales
up to 500 metres, which may remove a small section of sea from use, but will not act
as a barrier to any significant feeding ground. A significant improvement over tidal barrages. This theory is backed up by surveys conducted
during Seagen’s operation which found little evidence that the two turbines had a significant
effect on the numbers of seals and dolphins during operation, but did have an effect during
the construction phase where noise was much higher. [18] Area avoidance would be useful in the fact
that it would prevent the animals from straying too close to the turbines and being struck
by them. Potentially hurting themselves and damaging the turbine. Once again we can garner
some positive data from Seagen, which examined all carcasses discovered near the site and
found no evidence that any deaths were caused by impacts to the turbines. [19] This seems unlikely but they theorize that
these animals actually avoid the areas while the turbine is operating not because of sound,
but because the water is flowing fast enough to make it too difficult to swim and catch
prey. The last major worry for these types of devices
is the fact that they need to use toxic anti-fouling coatings to prevent marine growth on the turbines.
However Meygen uses a clever low friction paint that self cleans as soon as the marine
growth grows large enough where the drag overcomes their ability to adhere to the slippery paint. Additionally they trialed a sonar detection
system that would allow them to track and potentially stop the turbines when larger
animals occasional pass through the area. Without a doubt, these types of turbines would
have less of an impact on the environment than tidal barrages seen in France and South
Korea, but only time will tell whether this system in the far reaches of Scotland will
have a small enough impact to encourage additional systems to be installed. Cost will still be a massive factor. Based
on their companies financial reports the Meygen project generated 2.7 million dollars of revenue
for the company in 2018. That’s 0.675 million dollars of revenue from each turbine. Based
on their estimated cost for a further 49 turbines at 540 million dollars, we can calculate that
each would come with an installation cost of around 11 million dollars, so that would
require 16.3 years to recoup the cost of installation. Which is better than the 20 years it took
to recoup the costs of tidal barrage system in France, and those numbers will likely continue
to drop if the company manages to start manufacturing these underwater turbines on a larger scale. But it’s slow going. Iterating and improving
on designs for tidal power is much more difficult than other forms of renewable energy. Testing
has to take place in coastal waters, most of which are public spaces, requiring extensive
permitting and testing. It’s unlikely that these underwater turbines
will ever compete on cost with onshore wind turbines or solar, but thanks to the predictability
of the tides this form of energy could provide a reliable baseload when combined with low
cost batteries. If this project succeeds if could justify
large scale manufacturing of these turbines and transform tidal energy from a small niche
industry, to a huge player in the renewable energy industry. After all, Meygen is just one small section
of a larger 1600 MW ocean energy project earmarked for Pentland Firth and Orkney, with mixes
of both wave and tidal energy.[20] A colossal amount of energy which could go
a long way to diversifying Scotland’s power usage, and we will delve into the world of
wave energy in a future video. In the meantime, you can learn more about
other forms of renewable energies like solar by watching some of my past videos on the
topic, or taking this course on solar energy on Brilliant. Or even better mark off one
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100 Comments

  1. Have you watched our new video on Real Science? When we posted it we only had 30k subscribers. Somehow it now has 1.4 million views. Madness https://youtu.be/Bh4jKXsquWA

  2. What is the cost per kilowatt hour of the power produced? As everthing comes down to economics of user cost of the power.

  3. Now this is interesting potential tech and there are plenty of places to put them to generate power. They also have the advantage of being able to be pulled out and taken ashore to be serviced at a depot, meaning that maintenance would not be too difficult.

  4. We actually have one of these in our harbour from the local university, but there is a HUGE backlash against it, I saw a billboard a while back titled "Grinding Nemo" so we have another stupid people problem.

  5. Like wind turbine kill massive amounts of birds and have to be de Iced to work in the winter, water turbines kill massive amounts of fish and sea mammals and require costly maintenance done by ship and divers crews who’s fleet of ships and equipments carbon production make its far more expensive then nuclear. We have clean energy it’s called nuclear.

  6. 9:20 it would be very interesting to see how these areas would behave in the long term – i could imagine that certain species might actually seek refuge in areas like this, where their hunters might not follow them.

  7. Heres a thought…how many tidal generators would be needed to extract enough energy to calm a storm? 2cd thought… Could the generators be reversed into motors? Could enough strong motors and turbines act as a barrier reef to quell storm surge?

  8. Oh! you don't use batteries to store the power. It's cheaper and cleaner to use large air compressors to store energy.

  9. Is there any research into what the impact of removal of energy from currents will be? I've read somewhere that the abundance of wind farms in northern europe already has impact on the local climate because it slows down surface wind.

  10. Its amazing seeing one of the first engineering projects I visited as an engineering student being talked on real engineering.

  11. Liquid hydrocarbons ARE RENEWABLE! Grow feed stock (hemp requires NO PESTICIDES and grows almost anywhere) 1 ACRE = 50 BARRELS OF OIL EVERY 90 DAYS!!! Process the feed stock with its own energy ( see pyrolysis) and you are carbon NEUTRAL!!!!! In other words, the plants feed on CO2, so when it is turned to oil, hydrocracked into gasoline and diesel, and used in your car or genset.. ta fuckin da YOUR RENEWABLE AND GREEN!!!! This shit is nothing but a RIPOFFFFFFF. Stop falling for this bullshit, seriously. This is all about a money scheme to funnel government funds, people I know your smarter than that.

  12. ive always wondered what scale of hydro electric turbines, would influence a stream like the gulf stream enough, to significantly drop the temperatures throughout europe

  13. Maybe we have “unpredictable weather” because of military projects to control the weather.

    Projects that were made illegal decades ago, that is most definitely, ignored.

  14. путин в шоке. Там не только с червяками проблемы будут, но и с дельфинами.

  15. No they can't we lack power storage systems, wiring and other factors like the fact that these systems would likely kill fish. Face it nuclear power is our current best option.

  16. I think the need for battery capacities large enough to level out the curve was glossed over, but this is definitely an area that should be developed. Out of sight, low impact, reliable.

  17. Theres a tidal turbine near me at the mouth of Strangford Lough in….

    Never mind you did talk about it aha. It's massive when you see it and the tidal rate in the mouth of the Lough it astonishing

  18. A stable genius with great and unmatched wisdom might surmise that these turbines will give sea-life cancer. Ever thought about that you smarty-pants scientists out there? 😜🤪

  19. There is no Tera W.h/year because time units will cancel each other and will be left with W with some number beside it

  20. "Waves are wasted energy." … You don't know much about the nutrient cycle, do you?

    Specifically, gravity draws mobile nutrients to the oceans, and eventually, to the ocean bottom. Currents, and especially tidal flows, are the primary things that transport those nutrients back up to the surface and onto land.

    Seriously, I'm worried that large-scale harvesting of this could have catastrophic ecological consequences. Sure, we could harvest a lot on our current scale and it'd be a drop in the ocean, but that's also the same mentality people had for air pollution, deforestation, ocean pollution, and many others. We tend to scale up quickly. It wouldn't be long before we were harvesting enough for some serious impacts to be possible.

  21. This kind of discussion gives me spielkis. Gastric upset. I remember reading that the energy cost of producing a solar panel is NEVER recovered by that panel. So here we have that proposal scaled up AGAIN!! Imagine the huge energy outlay for large mechanical systems to harness wind, wave, and solar sources. THAT IS WHY CLEAN ENERGY IS A FALSE HOPE AND PROMISE. The answer, in my opinion, is large scale nuclear energy plants. I read that at its height the nuclear weapons production had 70,000 warheads in inventory. 70,000!!! my god!. where is all this potential now? Get a grip people, and lose your fear of nuclear energy. It is our only future hope.

  22. Hey, I wanted to say something about one of your older vids. The one about artificial gravity.

    You forgot a problem that maybe puts all other problems to shame.
    How are we supposed to spin this large an object, most probably with a much smaller motor (of sorts), in space? We don't have to deal with the conservation of rotational momentum on earth, where the large object intended to be spun is attached to the smaller object that spins is, which in turn can be fixed to the ground.
    As the smarter ones of you can guess, the earth has a much (much) larger moment of inertia than the object to be spun, and therefore what happens is, it's the object that will we spun. But in space, we have nothing to attach our motor to. And that being the much small mass, and therefore having the much lesser moment of inertia, will be the object that is spun, while our station stays more or less station ary. The smaller the the motor, the easier it can be spun, meaning our station spins even less. So one way to get about this is to make s station with two contra rotating ring sections, so that it's equally easier (I mean, harder) to get them rotating.

  23. Yes it can! And It already did!

    By giving life to lots of critters millions of years ago which are now juicy, delicious crude oil :).

  24. I've wondered if San Francisco will have to install a tidal barrage system as sea levels rise. It would serve to protect property during high tides (relevant in a few decades) while also offering energy generation, including potentially using the SF Bay as a huge battery.

  25. Keep your Greeny crap out of the oceans! Oh and stop dumping all the container ships garbage from foreign shores on Canada’s shores! Use Mother nature’s fuels oil/Gas/Lumber/ Coal/ humans/etc! Wind mills never result in green energy, takes more to build and repair then anything they “Save”! OIL/Gas/Coal etc is the make up of Real Earths Normal and most Green Energy ever produced! Oh and transgender ain’t produced in Nature! Leave the KIDDs alone! Freaks!

  26. I saw a documentary on a tidal generator to be placed in the Bay of Fundy in Canada. They had the system ready to install but the installation was cancelled while it was sitting on the barge that was being moved into position.

  27. and then a whale or shark or some other large mammal swims by to get sliced open, Nuclear power is and has been the best source of electrical energy

  28. Before watching this, because i dont have time right now, I'm going to ask if putting thousands or 10's of thousands of whatever items into the ocean to use it's energy would destroy the currents and have other unforeseen effects on how the oceans work. taking energy from them to use for ourselves seems selfish since the energy of the oceans seriously effects the weather and distribution of heat around the world.

  29. Dear retards. We are literally living on a giant ball of energy. We don't need oceans. We have geothermal energy. Stop fucking up the oceans with poorly thought out engineering. How are you going to build and maintain the infrastructure underwater ? The only way is lots of specialized equipment and personnel. A HUGE waste. What a stupid idea.

  30. Wow, what a novel idea. Instead of killing birds with wind turbines, let’s kill our fish and anything that swims. The wind turbines in the ocean now are affecting all life in the oceans already. Oh, and by the way most of our oxygen comes from the ocean.

  31. We need to get behind these technologies urgently. We rely on fossil fuels too much. The more alternatives we have, the better. Next up, would making all roofs white or reflective help there environment at all? Why not a green/ vegetation roof? Why not require new buildings in cities to have green space?

  32. Simply no. If you want to solve climate change. Best not to waste time developing new ideas. A process that takes decades. Best to use what we know how to build and what we know is quick and effective. Light water reactors.

  33. A project like this relies on a relatively rare circumstance where high tidal velocities exist. And, at this rare location, the project will generate about a tenth of the output of a typical fossil fueled power plant. So, I cannot see this project offsetting or replacing a conventional boiler/turbine-generator. So, no, this power source cannot, by itself, solve our energy problems. In the more common tidal power set up, where you would rely on the tidal rise and fall of the surface, you would need the rise and fall of an acre of ocean to run you blow dryer. I just don't yet see the numbers working out for this power source.

  34. There's a massive water sink in the north sea isn't there? Millions of tonnes of colder water sinks to the bottom, just a thought, we put turbines in that.

  35. Of course they can, but then that would be free energy, so maximizing our efforts in wind and water energy will never be done.

  36. So bird chopping wasn't enough… We also need to kills countless schools of fish in our "already ecologically stretched" oceans and seas too?
    So kill off more of our food supply to feed our computers which still will be made using fossil fuels… Sounds a lot smarter than feeding plants with our additional CO2.

  37. Tesla already figures the problem out 100 yra ago. The real Tesla that called out all the frauds like einstein and company. .

  38. Do people realise that when they take energy from one thing then that energy is no longer present to do what it was doing before? Wind turbines lower the velocity and strength of wind by extracting energy from it, as will ocean current turbines.

    Air and water currents (including tidal currents) perform a function in the balance of our environment and degrading those currents by extracting energy from them (through wind or water turbines) will have a consequence.

    So here's my prediction, people will do these things (harnessing air currents using wind turbines, and harnessing water currents using ocean turbines) and in 30 years time the environmentalists will be protesting the damage they do to the environment (yes, the same type of environmentalists that caused these technologies to be adopted in the first place). Yes, a single turbine likely does little measurable damage to the environment – but how much cumulative damage might exist if there were 25 to 50 turbines in an area?

  39. As soon as i hear an Irish accent I think this guys got the answer, go and plant some potatoes bog trotter leave it to the English, it ain't going to be you.

  40. I love the idea of tidal energy, since it takes its energy from gravitational potential rather than solar. However, it's than environmental impact that I'm worried about. I'm still not entirely convinced that global warming is as bad as everyone says it is, but I think the impact of wine turbines is far worse than most people think. I'm concerned that tidal turbines would be similar. I'm glad to see that Seagen is thinking carefully about this and I hope that others will do the same.

  41. Build it in Malabo, Martha’s Vineyard, Kennebunkport, Carmel, San Bernardo, Portland, Seattle, Key Biscayne, Scituate, Stinson Beach, Newport Beach, Massapequa, Bodega Bay, and Westport just to name a few. Anyone want to take bets what would happen if it was even tried in these liberal bastions of wealth and power?

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