Translator: Tamara Perry Reviewer: Martin Bermudez
I want to show you something
that I was fortunate enough to find in 2002.
At that time, I was living in Valladolid,
and I was at the school of engineering with one of my partners and friends
who is also here with us, Raúl Martín.
And well, what I found was a video that,
at a time before YouTube existed, but today is practically viral -
it is the Tacoma Narrows Bridge, or should I say, it was
in the year 1940.
This bridge was not designed to pick up energy from the wind,
and, yet, it did.
It did it so well that it began to collapse.
It collapsed due to a phenomenon all of you may know,
the phenomenon of resonance.
I'm sure that you have seen, at least once, an opera singer
who is able to break a glass with her voice.
The first thing she does is tap the glass, listen to it,
and place her tone at the same level.
With this, she is able to transmit energy from her voice to the glass.
Resonance is an excellent way to transmit force and energy
from a fluid to a structure.
Well, what happened to the bridge was something similar,
but it was not sound, it was the vortexes,
the turbulence produced behind it by the passing of the wind.
And wind has a lot of energy.
It is energy that has coexisted with us all of our lives,
along with hydraulic energy, animal power and a few others.
There was a moment in the history of mankind,
during the Industrial Revolution,
when we thought perhaps we would be able to draw energy
in a cheaper way from fossil fuels,
from oil derivatives, etc.
In good faith, we forgot to account for the huge cost involved
in reversing the damaging effects of its use.
If we do this, if we bear in mind a cost that surely will have to be paid,
that our children, grandchildren, and we ourselves will have to pay,
the cost of these energies,
is between five to eight times higher than what we say it is.
Another thing that was done during the Industrial Revolution,
at least in some countries,
was that an enormous fabric of high voltage networks were distributed
to transmit power from the points where it was produced
to the points of consumption.
In Spain, for example, without relying on cables
and only relying on metal structures,
we've had to use more than 4,000 kg of steel
to weave this infrastructure,
and we as a country were fortunate to have been able to do so.
Sometimes, these numbers are difficult to quantify and experience.
The best way is by comparing them to something we all know,
for example, the Brandenburg Gate, which is not exactly small.
If we put all its steel in a cube, the cube would be 88 meters long.
Imagine what is involved to pull all that steel from the ground, melt it,
mechanize it, treat it, bend it, install it ...
It is an immense economic and energy cost.
Another aspect of this form of distributing energy
is that, approximately,
one of out of 10 electrons introduced does not reach its destination,
regardless of whether this energy has been generated
by renewable or non-renewable energy sources.
In terms of renewable energy, the king, without a doubt, is wind energy.
In Spain, we should be very proud of what we have done with it.
Even setting that trap I was telling you about before,
wind energy is able to compete, at market price,
with non-renewable energy.
Another source of energy exists that you all know as well,
which are solar panels.
Solar panels do not produce such cheap energy yet,
though they are starting to do very well,
and the price is starting to go down a lot.
But, however, it has qualities that make it a very special energy.
Essentially, its cost of maintenance is very low,
and furthermore, its environmental impact, once installed,
is also very, very low.
Here is where the inspiration came from in 2002.
Would we be able to design a wind turbine
that captures wind energy
but includes the qualities that make solar panels
an ideal energy source
for what is known as distributed energy?
Distributed energy is generated very close to where it is consumed.
Let's give it a shot.
All of you know that as we move away from the ground,
wind velocity increases.
What is not entirely intuitive to see is that the power contained in the wind
grows faster,
it [grows with the cube of the wind speed].
This leads us to the idea that started with a horizontal structure.
Our dream wind turbine has to be slim;
it has to be vertical in order to move us as far as possible from the ground.
What shape can this wind turbine have?
We have many options, and all of these would be able to work
with the same phenomenon that worked with the bridge.
However, all of you also know
that the direction of the wind changes when it wants to.
This means that if what we want it to resemble a solar panel
and have no mechanisms, gears, ball bearings, or axes,
elements that can wear out due to friction
and would increase its maintenance cost,
this leaves us with one possible solution:
a circular cross-section.
Our wind generator is going to be slim, tall, and have a circular cross-section.
How much energy can we pull from the air?
When we collect energy from the air,
what we are doing is reducing its velocity
because what we are collecting is its kinetic energy.
In other words, we might think that what we have to do
is completely stop the air to absorb all of its energy,
but of course in the same way we want to take in the air,
we also want it to leave.
That is why we have to allow it to take some of its speed.
This causes us to reach maximum value.
That maximum value is the Betz limit.
It says, at most, we can extract 59%, a little more,
of the energy within the wind,
with any wind turbine or device.
So what we are going to do with our wind turbine
is try to increase to the maximum and bring us closer
to this theoretical limit.
For that purpose, what we have used have been wind tunnels,
because even though the answer has always had to come from mathematics,
in the case of fluid dynamics,
which is the technical area, the scientific area which studies fluids
and therefore, the air,
fluid dynamics has always had to be supported by test data.
We have also used computer simulations,
which ultimately are something like a virtual wind tunnel
that allows us to test and try things that are so hard to see in the real world.
Here you have it when we carried out one of these formulas for the first time.
At that time, we had a certain energy performance,
and with this model, we increased that maximum performance by three.
We quickly realized
that at the top we were not working well,
and there a vortex formed just in one direction
that broke, that disrupted the vortexes
that we were using to oscillate.
What we did was introduce one more formula,
and by doing this we increased its aerodynamic performance a little.
As you can see, do not tell me why, but every day it looks more like
a bottle of good local wine.
Well, the next thing that we have to do is be able to operate for many hours a year.
Of course, one knows that wind speed
constantly changes,
so we have to try to resonate a structure
that has a variable resonance frequency.
It is kind of like wanting to break a glass
whose frequency, whose tone that it gives us when we tap it,
changes over time.
Besides, we want to do this looking like a solar panel,
also looking like the bridge.
For that purpose, what we had to introduce
was a system that did not include axes, complex mechanisms.
Surely, you all have once played with a pair of magnets
and you have made them repel.
When two magnets repel, they look very much like a spring
with variable elasticity,
but you would have also seen
that its force increases very quickly when brought close together.
Introducing this type of system, what we get is that
our wind generator, changing its amplitude a little,
substantially changes its resonance frequency.
In the end, we managed to run many more hours per year,
and by doing so reduce its amortization period,
to recover the money that we invested in its installation.
This model is a field model four meters in height.
In it, we introduced an interesting geometry,
which made it very efficient, aerodynamic,
and also a system,
what we call a tuned system,
which is this magnetic system.
This other model, six and a half meters in height, more or less,
well, it was essentially the same, but with more optimized features.
We are able to draw energy from the wind
with a decent output.
We are able to run for many hours per year.
Now what we will have to do is
convert our movement, our mechanical energy,
into usable electrical energy,
which in the end is what we are all about.
But of course, we are excluding the axes.
And surely you have seen the dynamos for bikes
that we inserted, or we insert to be able to generate light.
Dynamos, alternators, almost everything, have an axis and a rotation,
and it is something that, as mentioned before, we are trying to avoid.
We have an oscillating movement and it has some characteristics:
it is slow, it is not a large movement,
and it makes the job even harder for us.
We had to try many different alternators -
we have made mistakes many times,
and well, what we are now seeing is that in the end
that principle of "divide and conquer"
also works with this problem.
And well, in recent weeks,
we are getting outputs that are starting to be truly promising.
And that is what it looks like:
A wind turbine that has different characteristics
to those of the conventional ones.
And what characteristics are these?
Some of them are expected, for example:
we have a low environmental impact - we do not damage the fauna around us.
Other characteristics have been unexpected.
For example, one day, a great day,
NASA got in contact with us and said:
"Hey, we should test it,
but the shape of your machine and the way it operates,
is likely producing very low electromagnetic interferences."
And these interferences disturb the radars -
the antennas, sorry -
that this organization uses, right?
Also, we have learned over time that, for example,
it is very rare to see conventional windmills along the U.S. coast;
you know, all military matters are taken very seriously there,
and this type of device there would force them to raise the radars.
This is something to see.
Well, it would be very good in the future
if this were a strength of this technology.
Another feature that we count on is that we do not emit noise.
Yes, it is true that we oscillate, but we do it at a frequency
that is much slower than what we are able to hear.
And the features we looked for from the start,
the low manufacturing cost and the extremely low maintenance cost,
in order to look like a solar panel.
But not all of the features are positive,
for example, the first thing we knew that it wasn't going to be
is that even if we do not have axes or mechanisms of that type,
yes, what we are doing with a component is bending it constantly.
It is a component that is made with carbon fiber,
which is a fantastic material,
but it is also subjected to a phenomenon called "fatigue," which is very simple:
simply by bending an element many times,
fissures and cracks can appear, and it can end up breaking.
We analyzed this circumstance from the onset,
both analytically, with school formulas,
and computationally,
and both methods tossed us decades of life.
There are other aspects we are engrossed in right now,
related to the economy of scale,
how many machines are we going to have to make
in order to be in the market and be competitive.
And voilà, here we have it, right?
Two systems for generating energy that capture the forces of nature,
wind and light,
both share some features that make them ideal for distributed energy
to be able to generate on a roof and consume elements one uses at home.
And finally,
I simply want to highlight the most important thing which is nature.
It is the best engineering school that exists.
From it, we learned to take advantage of sunlight with its leaves;
and we human beings use solar panels.
It also taught us how the wind can give energy to a bridge,
to a structure,
and well, that it is simply very important
to be able to take advantage of these forces that nature gives us
without damaging it.
That you very much.
(Applause)