Can Underwater Turbines Solve Our Energy Problems?

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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Posts created 40981

100 thoughts on “Can Underwater Turbines Solve Our Energy Problems?

  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. Lets build them all underneath the Gulf Stream. That way we can finish off the revolution our forefathers started and finally destroy Europe once and for all.

  3. wait so if the size of the turbine is proportional to the density of fluid why don't we just replace the oceans with honey? energy crisis solved

  4. No. These have similar problems to wind turbines in that you're potentially destroying the environment in order to save it.

    The answer to our energy needs is nuclear.

  5. Stupid stupid stupid. You need a constant source of work.
    The fluctuations in ac not only makes a practical design hard to obtain, but the mechanism used to convert the ac into a grid compatible frequency, be it a battery or some crazy transformer, will cause huge losses.
    Dams work well because they have a constant rate, as do nuclear power plants and gasoline generators.
    The next thing down the list would be hydrothermal vents. Not the whims of Poseidon you idiots… That is the first stupid.
    The second stupid is for the potential of millions of these turbines being placed in the sea slowing down currents so that the mineral rich lower layer doesnt mix with the top layer causing death of algae and thus warming of the top layer which will further separate the layers causing the ocean to stagnate and die.
    This is just too toddlerish to me, did you get this idea from Bob the builder? "The ones on the surface are chopping up birds, I've got an idea, lets put them under water".
    Stupid numero three. I know you don't care about whales, but if they die, than there will be an explosion in seal and sea lion populations, and guess what they cary. Diseases! Yaaay! Tuberculosis! And ecoli.

  6. Ocean energy is not wasted energy. The gulf stream is because of the ocean energy. The weather patterns is due to the ocean energy. We don't need millions to turbines for a so called renewable system. That is just going to create more waste and just even makes those turbines in the middle of the sea will take huge amounts of energy.

  7. What is wrong with you people? It's not enough that wind turbines killing birds? You want to kill sea life as well? Only solution available now is LFTR.

  8. So windmills slaughter birds, guess we want to slaughter ocean life to.

    Nuclear will solve our energy problems, once we get clean fission fully instituted

  9. The units you were using for the amount of power was terawatt hours per year. There are already a set number of hours per year, you unnecessarily increased the amount of power by a factor of 24*365

  10. No, don't mess with the oceans. Just go nuclear. It's the cleanest, best source of energy. Solar and wind are terrible for the environment. Go nuclear or go home.

  11. Creating energy can produce heat and with a load of them could slowly increase ocean temperatures which is destroying marine plant life like the coral reef!? 😯

  12. Great video, as always! I'm an engineer from Italy and I find your channel incredibly intresting. I could suggest a topic for a next video.
    What do you think about MO.S.E. project in Venice?

  13. its not about our energy need ,it s about human greed, we will go to war for the petrol dollar, ask again in 50 years,

  14. "Can Underwater Turbines Solve Our Energy Problems?" May be with a lot of research, infra-structure, engineering, etc. But you know what could solve our carbon-free energy problems right now? Advanced designed……..NUCLEAR…….energy! The safest form of generation now in use, including wind and solar, not to mention it is on-demand/base-load power which renewables certainly are NOT!

  15. We had this in environmental science over 20 years ago. Problem 1 is cost. Problem 2 is it's not that efficient-lots of equipment req'd & suitablility of location. Not going to happen off Florida or Cal b/c of tourism. Tidal power is low & only 2x/day. Current power-would have to go way out. Wave power-negligible at low tide-just not enough power. People can't imagine the massive machinery required to install offshore. Also an ecosystem effect.

  16. The actual problem is not energy deficit, the true problem is increasing energy demand due to growing human population. Solution to energy demand lies in limiting the growth of human population.

    Also… Turbines underwater might calm the waves near coast and change the ecosystem on coast. But Im somewhat sceptical of this.

  17. There is a solution; underwater turbines or otherwise. But nothing will ever happen in a worthwhile capacity in a systemically rotten system.

  18. you start putting these things in the water and we all die the currents will slow or change marine life will die. Stupid fucking idea………..

  19. why use a system that looks like a wind turbine? why not use a blade setup like a ship screw or propeller? wouldn't that give you a better power output?

  20. But, but, but it will change ocean currents and chop up fish and happy smiling dolphins … so BAN IT NOW! Baaaaaaannnn it! Hail Saint Thunburg, amen.

  21. I’m commenting this before watching video: how would we do any of this without having a possible negative effect on the ecosystems?

  22. Salt water is very corrosive. The so called protection isn't perfect. Moving parts are very difficult to seal without a pump which uses electricity. Not to mention the constant force put in the metal. It doesn't seem feasible at this time

  23. I wish you would explore the oscillating water column technology. The moving parts are not in contact with the seawater and ecosystem impact is greatly reduced. Wavegen.

  24. @Real Engineering, You forgot the Annapolis Royal Powerplant in Nova-Scotia, Canada, its been open since 1984 with a 50GW/h annual output! And also, in the Bay of Fundy, there was a project for large scale tidal turbines called Cape Sharp Tidal.

  25. Stop misusing 'renewable'.
    To be renewable, something needs to be depletable.
    How do you deplete or renew wind or solar?
    You don't.
    Trees are renewable.
    Sun, wind, hydro, wave and tidal…
    Non-depletable or naturally sustained would be coherent classifications.
    Credibility requires coherence.
    Words need to mean things.

  26. This is one of my favourite channels, and this is my favourite video. I love how it addresses all of my concerns and sets realistic expectations, and yet maintains the excitement of the technology. Can't wait for the next vid.

  27. I am surprised this has not been done already. Designs were drawn up years ago which would have both underwater turbines and wind turbines used together on the same structure.

  28. Disrupt the ocean currents by sticking thousands of turbines in their path will likely slow, and or alter their path around the globe and will in itself be the cause of major climate changes.
    If you want to know about climate change start by studying the thousands of changes both major and minor over all of the planet earths history and the many different known causes of them.
    Without a number of past climate changes Humans as we know them would never even exist on the face of this planet.

  29. Saw a environmental paper written by an sustainable energy ecoscientist who said mass scale energy from the ocean could never profitably happen.

  30. I find solar to be most effective way, without affecting the physical stuff happening around us…

    Turbine in dam makes sense.. since the gradiant is artificially made…

    I mean these turbine will slow down, air current or waves and affect animals in borne

  31. As a environmental scientist and engineer in the industrial and municipal water filtration industry i find this very interesting. Thank you for the content. Great job

  32. I hope Scotland, my home, makes the most of this kind of technology. We have the perfect geography for renewable energy production.

  33. As a scholar who is all about renewable energy, this would and does have a negative effect on the tides themselves. In a Canadian study on underwater turbines in the Bay of Fundy in the North Atlantic, they saw a diminished tide and on computer analysis and tests they expected a still tide unlike the powerful tides the bay has. Taking the energy that drives the tides only will diminish said tides over time.

  34. dont do anything with ocean water….Ask Germany…. they installed all those wind machines and the maintenance from the salt water and the transport cost to get it into Germany failed…they now have gone back to strip mining coal and the World Body has given them until 2030 tio figure it out for their energy demands aren't being met. One big wast of "new clean energy money.

  35. Now if only political environmentalists actually cared about the environment instead of using it to push communism, maybe these lads and lasses could get some extra funding to help with projects like this.

  36. I thought that offshore Wind turbines were beaching whales because they were ridiculously loud at low frequencies . Now, lets put the noise maker directly into the transmission medium that is 700x more dense . Have you ever heard someone clap underwater from across the swimming pool ? Brahhhh, This is not the correct answer.

  37. No. We have wind turbines killing millions of birds every year, so do we really want something to do the same to ocean life?

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