the ocean vast beautiful powerful it's easy to see why many researchers try to tap into
our planet's biggest powerhouse one group of researchers are working on a way to take full
advantage of the ocean's seemingly endless depths by harnessing the power of buoyancy
so how exactly does buoyancy work and how could you use it to store energy
could this technology hold the key to helping level out renewable energy generation like wind
and solar or is it yet another grid energy pipe dream bound to sink to the depths
we thought these questions deserve a deeper dive today on tuba davinci
special thanks to air health for sponsoring the show and this the sky what i'd call the tesla of
air purifiers more on this in just a little bit let's go out on a nice relaxing sailing adventure
ah isn't that nice just a smooth relaxing ride on top of the ocean but wait a minute why doesn't
our heavy boat sink straight down the answer is buoyancy buoyancy is an upward force exerted by
a fluid on an object immersed in that fluid in a gravity field because our boat is filled with
air it's less dense than the water it displaces therefore it floats even though it's super heavy
in fluids pressure increases with depth creating a net upward force called the buoyancy force which
fights against the gravity and is equivalent to the weight of the fluid of the object displaced
so why does this happen imagine a virtual cylinder rising up into space in space you have no pressure
but the closer to the surface you are the more air molecules you have pressing down on you air and
water are both fluids so our virtual cylinder can extend down into the ocean and the deeper you dive
the more water molecules you have above you pushing down and so when anything is submerged in
water the pressure at the lowest point is higher than at the highest point and that net difference
causes buoyancy it's this buoyancy force that researcher julian hunt and a team of global
scientists have harnessed in their buoyant energy storage technology or best but does
it really live up to this acronym you know what really floats our boat hit that like button
buoyant energy storage builds off similar principles as pumped hydropower storage but with a
few key differences traditional hydropower stores potential energy in water contained in an upper
reservoir which is then released downward using gravity to convert potential energy into kinetic
energy turning a turbine and creating electricity bes technology stores potential energy but uses
buoyancy instead of an upper and lower reservoir best has an outer reservoir any large body of
water a lake a tank or in the case of best the ocean and a floating inner reservoir as the inner
reservoir submerges it stores potential energy how does this work imagine you're in a swimming pool
in your hands you got a beach ball and you slowly lower under the water because the ball is full
of air which is less dense in water it takes a significant amount of energy to submerge the ball
holding the ball underwater would store all that power as potential energy
as the buoyancy force builds this is essentially how the bes technology works instead of beach
balls a large platform anchored to the ocean floor connects to an enormous square 100 meters per side
made up of high density polyethylene pipes full of compressed gas like air or hydrogen powerful
electric motors pull those buoyant tubes downwards storing the potential energy in the buoyant mass
just like our beach ball so once the energy is stored how do we get it out of the ocean and into
our smartphones by releasing the platform the immense buoyancy pushes the platform
upward pulling the electric motor in reverse turning a generator and sending all that power
back into the grid this technology comes with a number of advantages over other energy storage
where best could have one major advantage over pumped hydro is efficiency buoyancy
energy storage's architectural simplicity means minimal energy loss during the energy production
and the constant pressure head allows the pumps and turbines to operate at high levels
of efficiency at all given times buoyancy energy could reach levels of between 85 and 95 efficient
compared to conventional pumped storage systems which sit somewhere between 75
and 80 percent we've covered pumped hydro storage in our video all about mechanical energy storage
which you can check out here best systems could also pair with hydrogen storage and transportation
oh shoot but i might not have even known it wasn't for our sponsor this week sky by air health why do
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sky link and special 10 discount code in the video description if you've seen our video on
the solid state hydrogen batteries you know one of the major challenges in the hydrogen energy game
is compressing and transporting hydrogen best systems already use the hydrogen in their platform
materials which gets compressed as it submerged it could then be transported via large underwater
pipes a process that could reduce the cost of hydrogen storage by a factor of 30 compared to
conventional compressors another untold benefit of buoyancy energy storage is in safety for marine
wildlife while the buoyancy tubes do move compared to other technologies like tidal turbines they are
vastly safer we should probably also remember that the best technology requires no exotic
materials and isn't beholden to complex supply chains you guys probably know how much i love
this because it allows us to reserve more of the exotic materials like lithium and nickel for more
energy dense applications like cars and possibly planes while the technology may not be as feasible
in every context not every part of the world has access to deep reservoirs of water it has
major global potential around oceanic islands and coastlines it could even be paired with offshore
wind turbines and ocean current power stations so there are some pretty interesting benefits to
this technology but what about cost the cost of grid storage for lithium-ion batteries is
around 150 dollars per kilowatt hour though those prices are expected to drop in the coming years
best would be somewhere between 50 and 100 dollars per kilowatt hour not bad but things aren't quite
that cut and dry while it's easy and economic to store energy releasing that energy is much
more challenging remember that there are electric motors and cables all of which are underwater due
to a host of challenges power output from these systems comes at a much higher price
compared to other methods best systems are a question of energy capacity versus
power capacity using water as an analogy energy capacity is the size of the tank you have to fill
and the power capacity is the size of the hose that you have to either fill or empty that tank
if you have a energy capacity of one kilowatt hour in your system and a power capacity of one
kilowatt you could output one kilowatt of power for one hour before you'd be out of energy best
systems are not a great solution if you need huge amounts of power in short periods of time like in
a power outage or in england when a majority of brits all turn on their electric kettles
after watching their favorite television program all at the same time in this sort of situation
we'll need another answer but if you could instead think about charging and discharging the system
over longer periods of time let's say weeks not days hours or milliseconds then this thing
might just be an interesting breakthrough for the future installation costs are also a factor
best has an installed power capacity from four thousand to eight thousand dollars per kilowatt
for comparison a wind turbine comes in at an installed power capacity of about sixteen
hundred dollars per kilowatt and lithium ion batteries are still king coming in around 1 000
per kilowatt so in some instances best is not always best best-known researchers recognize that
their systems would likely never replace batteries altogether but could function in a system that
utilizes the strengths of both technologies switching gears to talk about efficiency we
have to address the choices of compression gas the following graph shows what happens to the density
of air and hydrogen as a function of depth in meters hydrogen has a much lower density to start
that even at 6000 meters its density only increases to 50 kilograms per meter cubed
compare this to air which increases to a density of 528 kilograms per meter cubed at 6000 meters
this is why hydrogen is so important at 6000 meters water's density is 1028 kilograms per meter
cubed and when the change in density decreases so does the force of buoyancy if these buoyancy tubes
aren't rigid members the increase in exterior pressure will also cause a drop in volume again
reducing the energy storing capacity these are the sorts of engineering challenges best researchers
have to optimize for based on these graphs showing changes in density and volume researchers have
found that the best possible system works in a range between three thousand meters and ten
thousand meters ten thousand meters about thirty thousand feet there are not many places in the
ocean that deep but that would be the ideal use case the proposed best system with hydrogen as a
compressed gas generating electricity from a depth of ten thousand meters to three thousand meters
and an efficiency of about ninety percent can store 7.9 gigawatt hours of electricity
the challenges are plenty to be sure motors electrical equipment and salt water for example
there are also questions about the impact on marine habitats system reliability and how
much maintenance would be required overall using this technology in conjunction with
other production and storage technology could create a much more flexible and versatile means
of leveling out grid energy but what do you think is best really the best way to store energy for
the grid going forward can you think of any other places buoyancy energy storage could be applied
sound off in the comments below alright so this is another one of those really interesting quirky
approaches to energy storage it has its benefits of course it doesn't need lithium or nickel or
cobalt or anything else but it's also really challenging and complicated we're talking about
really really deep parts of our ocean the labor and installation cost but as i mentioned you can
store a pretty good amount of energy just remember that the energy storage is great but the power
density is very low so this would have to be one of those more low level grid baseline production
methods but pretty cool stuff right thank you to all of you for watching and if you want to be a
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