Translator: Eriko T Reviewer: Denise RQ
My name is Danielle Fong
and my mission is to provide the technology,
so that people can have abundant, sustainable energy
everywhere for everyone.
So my first message, and possibly my most important one,
is that we are at a critical time
because we really see a ray of hope.
Technology to produce power from solar and wind has improved so much
that the price of solar power has fallen like a meteor.
It is now competitive with oil, with liquefied natural gas.
It is incredibly cheap.
It's not quite the cheapest in areas where people are producing or burning coal
but in many places in the world,
in Europe, increasingly across the world, it is cheap.
It's only a matter of time
before it is the lowest cost source of power almost everywhere.
And there's a lot of it.
There's more than we could possibly need.
It's well distributed in places where people need power,
there's a lot of sunlight.
But there is one challenge that must be overcome:
renewable energy - solar and wind - is intermittent.
Here's a picture of the Earth
and as you can see, part of it is in shadow.
There's no solar power at night.
So the problem that I'm going to speak about
is the problem of how do you store energy economically enough
so that it's lower cost than power from fossil fuels?
Before I do that, a message on how urgent the problem is:
because carbon dioxide stays in the atmosphere for a very long time,
you can make a carbon dioxide budget beyond which if you burn more,
you just have increasingly difficult climate problems you have to deal with.
That carbon budget is exceeded by the amount of carbon dioxide
already accounted for in the reserves
of the fossil fuel companies and the countries that ship it out.
So, actually if you go through
those fossil fuels already discovered resources.
In business as usual,
you burn through the carbon budget in just 17 years.
Just to review, that means flooding: flooding of Amsterdam, and then New York
if we surpass the safe limit
of two degrees centigrade and temperature increase;
you have heat waves that kill people,
desertification becomes a huge problem,
coral reefs are a problem - they mostly bleach or die -
less food, stronger storms, and species going extinct.
So now is a really critical time to get in front of this.
And one way that I put it is
that since power plants last a long time too,
the power plants being built now will define the biosphere
for the next 5,000 years.
So it's really critical that we get this right.
So how did I get involved? What's my personal story?
And I should get into this, a word of warning, it's a little unusual,
but I think there are lessons for a lot of different people.
The way i like to justify it
is I have patience for people, but I don't have patience for systems.
For me personally, when I went into high school,
I felt it was just moving too slowly, and it wasn't focused enough
on teaching people real skills to make a difference in the world.
So when I left, I found actually to my surprise,
I could enter university at a very young age, 12 years old,
and I studied Physics and Computer Science.
Thank you; hold the applause.
Starting early I think is something that a lot of people can do,
but the most important thing is
that they use their energies and move as quickly as possible to do something
that they find truly important, that they can make a difference in.
When I chose what I needed to do for graduate school,
I knew that I wanted to make a difference in energy,
which I saw as the problem of my generation,
it had to be solved in this generation.
And initially, I started working on nuclear fusion,
but again, I felt it wasn't moving fast enough.
This is a picture of the large nuclear fusion project in France;
this is a graduate school student for scale; it's a huge project.
I felt it was too big and moving too slowly to make a difference.
The first power plant was anticipated in 2050,
which, obviously, would be too late
to solve the climate problems that I cared about.
So I left again,
and I decided to try to develop my own capacities
and to start a company.
I moved to Silicon Valley, where strangely enough,
after I started posting essays, people reached out to me
including a lot of extraordinary inventors and entrepreneurs.
I worked odd jobs, and slept on couches,
and eventually, I met the people who would fund and and join my startup.
Now what was that on?
So I noticed the cost of solar and wind were coming down so quickly.
I'm back to this problem;
I knew that there was a missing technology,
and I started focusing on the energy storage problem.
Most people think energy storage is to store energy so you can use batteries,
but the problem is to really best fossil fuels in terms of cost,
batteries are too expensive, and they don't last long enough.
Basically, you dissolve and replay ions over, and over, and over again;
and it grows these strange structures,
which reduce efficiency and reduce capacity.
Everybody who has a cell phone knows
that they don't last as long after too short a time;
that degradation eats up the batteries, and you need something else.
So I have the idea to store energy and compressed air.
I'm not the only one to have had this, but the advantages are well-known.
You can store energy in tanks with compressed air very inexpensively,
and the tanks last for a very long time.
Why hadn't people used compressed air to store energy all across the world?
People said that it must be inefficient.
And there's a simple reason for this.
When you compress air, it gets hot.
And as you know from hot air balloons,
hot air wants to expand; it fights you.
And if you compress air to a decent enough pressure
to store energy densely,
it would increase in temperature dramatically.
So the pressure we use, 200 atmospheres of pressure,
it would increase in temperature more than 2,000 degree Celsius.
All of that extra heat, unless you can capture that efficiently,
that's a loss.
So our focus was on increasing the efficiency of that process.
And that's what we've done, and I'll tell you how.
But basically, it's a really big improvement in efficiency.
You can see that red bar there;
that's the thermal loss that we've really shrunk down.
That about doubles the efficiency of the round-trip process.
So when compressing, you want the air to be as cool as possible,
and when expanding, you want it to be as warm as possible.
We figured out how to do that using water spray.
Basically, as you compress the air sprayed directly into the compressor,
we inject water, which keeps the air cool,
and then you separate the water from the air
- just in this mesh-filter thing - you store the air in air tanks,
you store the heat in hot water tanks
- which you can insulate, and it's really cheap -
then you spray the warm water back in during expansion.
So that was the idea.
I started a company, "LightSail Energy" - this was in 2009 -
and in 2010, we showed that this process would actually work
- we did a proof of concept -
and we proved a vastly improved thermodynamic efficiency;
then we started working on the product.
Here are some of the pieces we put together,
and this is what it looks like.
In the process actually, my partner pursued a method
of making really low-cost air tanks using carbon fiber,
so those are some people for scale.
I should point out the compressor here: this is enough to power 500 homes.
The tank there - if you have 8 of them - powers the 500 homes for an hour.
So, that's the scale. It's a pretty large scale.
Here's some of the data
- I don't know if I should really go through all of this -
but basically, the process is as you draw air in, the volume increases
- this is pressure and volume -
as you draw air in, it fills up the cylinder - a valve closes -
and it compresses as it goes up here,
and increases the pressure all the way up to 200 atmospheres.
Then the valve opens, you push that air out,
and the process repeats.
Then, to get energy back from the compressed air,
the whole process runs in reverse,
and it turns into mechanical energy and then electrical energy,
right to the socket.
This is the graph that shows the process actually working.
So basically, how to describe this is that the red line here
is how efficient it was before,
and how far it moves up
is how efficiently we compress without it heating up.
The green is the absolute thermodynamic ideal.
The blue is the water spray, the yellow is our efficiency following it.
So the compression process occurs;
as soon as the water sprays in, the efficiency dramatically improves.
So that's how the process is working.
What does this mean?
Remember this formula that I showed?
On the left here, this is up top.
This is the cost of energy from renewable sources
plus the cost of energy storage.
Then on the right, that's the cost of energy conventionally.
So if I just compare this here,
this is roughly the cost of energy from conventional sources
during times when it is most needed.
And on the left is previous batteries,
and you may have heard of Tesla Motors
that released a dramatic improvement in battery cost
and that's on the right here.
All of the different costs are added up here,
and you have the cost initially;
the fact that you're paying a little more for energy usage
from inefficiency, and so on, degradation over time,
and that's added up.
As you can see, it's a serious improvement,
but it is not quite competitive yet.
So I'm looking forward to them improving that.
But right now,
we have a method that we believe will be able to produce power
at a lower cost than power from conventional sources.
So basically, what that means
is that people can go on to our website,
ask for energy from solar power whenever they like it,
and we will go and install it;
it will save them money and provide power sustainably.
We'll split the savings with them.
So that's basically our story and our progress so far.
We will be releasing a product in 2017, piloting in 2016.
(Applause)