this video is brought to you by click up batteries and energy storage are one of the
most important sectors this decade everything from grid storage to electric cars laptops and
phones hinge on their very development but that historically means Lithium-ion batteries which
requires exotic materials and we can't build them fast enough the what if we could store
energy without mining or building batteries but instead by storing it in a rotating flywheel
let's talk about flywheel energy storage and some game-changing breakthroughs and materials
that could really take flywheels to the next level I'm Ricky and this is Two Bit da Vinci
I'm all about replacing fossil fuels with clean and renewable energy but unlike coal and gas that
you can modulate to produce electricity predictably The Sun Shines differently
throughout the day and the wind speeds vary too so renewable energy is equal parts energy
production and energy storage to help level out the variance in output a recent study published
by the international Journal of renewable energy suggests that we'll need to store at least five
percent of the total renewable energy production capacity in order to replace fossil fuels
completely that means a lot of batteries to give you an idea in 2019 alone we consume roughly 173
000 terawatt hours of energy 85 percent of which came from burning fossil fuels so we
would need approximately 7 350 terawatt hours of energy storage to run a stable grid assuming for
the sake of argument that all that energy was used as electricity that's an insane amount of
energy capacity enough to power 1 million average homes for almost 700 years or charge a million
model all three performance Teslas from zero to a hundred percent almost ninety thousand times each
considering that the worldwide energy capacity of today is approximately nine terawatt hours
which is only point one two percent of what we would need we have an uphill battle in front of
us and we need to take advantage of every storage technology available and one promising solution
is flywheel energy storage additionally given that over ninety percent of our storage capacity
comes from pumped hydro and there are many places where this simply isn't an option like Delaware
and Mississippi for example we need alternative ways to store energy in places where pumped Hydro
isn't an option thermal energy batteries are the main competitors followed by compressed air and
flywheels coming in fourth with a total deployed capacity of only a little over 97 megawatt hours
this would only be enough to power 3 300 average US homes for one day speaking of powering homes
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month huge thanks to click up and you for support in the show flywheels have amazing potential and
their storage capacity is growing exponentially only a few years ago Beacon power built one of the
world's largest flywheel energy storage systems in New York that can pump out 20 megawatts for
15 minutes for a storage capacity of 5 megawatt hours another even bigger storage facility that'll
hold 80 megawatt hours with a power rating of 20 megawatts is set to be built by a company called
aberkinetics in Fresno County California now these are mostly bulky and heavy flywheels made for grid
storage applications but as we'll see later in the video newer technology can make them lighter and
more energy dense making them ideal for mobile applications like EVS in fact flywheels are
already used in Formula One cars to store excess mechanical energy but what exactly are flywheel
batteries flywheel batteries are more accurately flywheel energy storage systems or Festus for
short are a type of Electro mechanic technical energy storage system these systems transform
one form of energy like electrical energy into rotational kinetic energy at a fundamental level
a flywheel is pretty easy to understand electric motor uses energy to spin a massive rotor or
flywheel storing that electrical energy as kinetic energy in the spinning Mass these things can spin
really fast a modern flywheel is designed to spin its speeds upwards of 50 000 RPM while the engine
on a standard sedan will rarely go over 3000 RPM while cruising on a freeway the rotational
kinetic energy remains in the flywheel as long as it spins at a constant speed then when we want to
discharge the flywheel we used a generator to slow it down and convert the kinetic energy back into
electrical energy just like an ev's regenerative braking system does by slowing down the car it's
as simple as that but how good are flywheels at storing energy one way to know is by looking at
its energy density so let's see what that looks like for a flywheel thankfully this is also quite
easy to understand and it's only based on a couple of simple equations to get a better feel for this
let's put on our engineering hats and set to work on designing the world's greatest flywheel energy
storage system by looking at how to maximize its energy density as I just said in a flywheel energy
is stored as rotational kinetic energy which is given by the equation you see here where I is the
moment of inertia and Omega is the angular speed or how fast the flywheel is spinning as in hertz
or RPMs this little formula basically tells us that we can increase the flywheel's energy by
increasing in the inertia or the angular speed but the latter is more effective because it's squared
this means that if we double the speed we'll multiply the kinetic energy by a factor of four
the moment of inertia on the other hand depends basically on the flywheel's design or shape its
dimensions and what it's made of and it's usually a fixed quantity so to store more energy we want
to increase speed as much as possible because kinetic energy increases with the square of
the angular speed and we want to also increase the radius of the flywheel as much as possible
because the moment of inertia also increases with the square of the radius but there's a
problem you see spinning faster at increasing the radius generates a great deal of tensile stress
on the material that tries to rip it apart if that stress becomes too high the material will fail and
the flywheel will really fly into pieces that is this is the typical optimization problem we want
to increase a good thing like maximum speed and radius for more energy but as we do something bad
also increases like tensile address in this case Engineers already found the optimal solution for
this problem and had summarized in a very simple equation that determines the maximum energy per
unit mass of a rotating flywheel or its specific energy density in this equation K is a constant
that depends exclusively on the rotor's shape its highest possible value is one for a special
theoretical shape called the level disk but we can get real values in the range of between 0.8
and 0.95 if we trim the level disc and add a rim here's some examples of K for other rotor
shapes the rest of the equation is the ratio of the material's maximum tensile resistance
or yield strength Sigma Max to its density rho so the stronger than lighter the material the
more energy a flywheel can store while spinning at its maximum velocity without failing we should
note here that the real limiting factor in flagal energy density isn't so much the flywheel's design
which in the best case would double the energy density but rather the construction material so
what should should we make our flywheel out of if we want to maximize energy density this table here
ranks flywheel construction materials based on their expected energy density calculated with the
previous equation notice how a strong lightweight metal like titanium offers an energy density of
just 32 Watt hours per kilogram which is about one tenth of the energy density of Tesla's new
4680 cells on the other hand a cylindrical rotor made of T-1000 carbon fiber composite can reach
theoretical energy densities of 254 Watt hours per kilogram making them as good as the best
lithium-ion battery packs so in principle we could potentially even use these kinds of flywheels to
power EVS but it doesn't stop there notice how I blurred out the top row of this table that's
because I don't want to give away the number one spot just yet but we'll get back to that in a bit
first let's talk about the pros flywheels are encased in an inert frictionless vacuum meaning
they require very little maintenance and can easily withstand 20 or more years of constant
use this makes them and almost set it and forget it energy storage system secondly we can charge
them with a high round trip efficiency of 90 percent and more in a matter of seconds to minutes
depending on the total capacity without generating almost any heat you can't do that for example with
lithium ion batteries thirdly flywheels can withstand a hundred thousand to a million
charged in discharge Cycles including both shallow and deep Cycles without a hiccup but one of the
best things about flywheels though is their power density which is second only to Super capacitors
you can draw almost as much power as you want from a flywheel without overheating it making them
great for covering Peak electricity demand and power grids and other applications but of course
flywheels aren't perfect most common flywheels have low energy densities compared to the best
chemical batteries they require Precision milling and construction techniques to ensure the rotor is
adequately balanced and the vacuum chamber doesn't have any leaks this makes this technology rather
expensive up front especially concerning the cost of high tensile Sprint carbon fiber and other
novel materials but of all these issues pertaining to flywheel energy storage The Worst by far is
their energy loss in standby mode which ranges from three to twenty percent per hour this is a
limiting factor that prevents using Flywheels for long-term energy storage and it's also the number
one reason why we don't see flywheels absolutely everywhere even in the best cases losing three
percent of the charge per hour means losing all the charge in a little over a day however
this still works for some mobile applications like EVS or the 1940s Swiss gyro bus was charged for a
couple of minutes in every station I made a video about this that you should really check out links
in the description in spot these limitations there is a new material called carbon nanotubes that is
helping make flywheel batteries better than ever before this is a form of carbon arranged into
a hexagonal honeycomb structure rolled up into a tiny tube one to two nanometers thick that's
about one ten thousandth of the thickness of the thinnest human hair it's also super light and
incredibly strong that said it's time to unblur the table I showed you earlier as you can see on
this table carbon nanotubes have the highest yield strength known to man reaching a staggering 30
000 megapascals along their axis that's over 20 times stronger than the strongest Steel
this unique combination of tensile strength and low density is just what the doctor ordered
to maximize a flywheel's energy density which can reach almost 2 700 watt hours per kilogram
that's 10 times more than the best chemical battery to date increasing a full order of
magnitude incapacity will totally change the game in energy storage and possibly shift a large chunk
of funding towards improving other components of the system even further there are still some
challenges to address like making these nanotubes long enough and in large enough quantities but
researchers are already able to produce forests of carbon nanotubes 14 centimeters long these could
be long enough to build some pretty epic flywheels if we manage to make them at a commercial scale
we'll have hit the flywheel of Fortune jackpot but the real problem comes down to scale of how
much carbon nanotube material we can produce also we need really long nanotubes because you don't
want to have a bunch of little flywheels because that means you have to have generators Motors
power control rollers for thousands of different flywheels the way this scales up and becomes cost
effective is by having large flywheels that store a ton of energy so to make a larger flywheel with
a larger radius you have to have these materials that can be built and stretched out longer than
they currently are today so while this is truly a theoretical promise a future where we have carbon
nanotubes means we'll have amazing flywheels they are still practical today with current technology
so for flywheels to really take off and to be one of the most energy dense forms of storage we got
to make carbon down tubes really big to make larger and larger flywheels otherwise the cost
just won't scale up but even today as it is with carbon fiber and with lightweight materials like
titanium we can make some pretty amazing flywheels and their power response is an amazing application
for grid storage to be able to take the Peaks and valleys of energy demand and fulfill that
with renewable energy and so no you wouldn't want to flywheel home battery because hours later when
the sun has gone down it's probably going to be slowing down and slowing down and lose all that
energy but it would make a ton of sense for grid operators so that's where you'll most likely see
it but what do you think do you think flywheel is going to come back do you think we're going
to see a ton of new projects in development there are some already all around the world
I'll let them know what you think and if you thought that was really cool you got to check
out our video on the gyro bus next I'm Ricky tuba DaVinci we'll catch you guys next week