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CHRIS WILMER: My name is Chris Wilmer,
and I come here today wearing two hats.
On the one hand, I'm a co-founder
of NuMat Technologies, which is pursuing
the moonshot of changing the way the world stores gases.
And on the other hand, I'm a professor
with the new lab at the University of Pittsburgh,
whose research focuses on the materials that
made going for this moonshot possible.
Correspondingly, I'd like to talk today about gas storage,
but I'd also like to talk about these materials
because I think they're important and might eventually
lead to other perhaps more futuristic moonshots
like atomic scale 3D printing or molecular machines.
But let me begin by talking about natural gas.
Now compared to oil, natural gas is cheap and abundant.
It's also much cleaner than oil, which
generates a lot more carbon dioxide per unit of energy.
So given that oil is both more expensive and worse
for the environment, why do we use it so much?
Most of the world's cars, trucks,
and buses run on oil today.
And given that international tensions over oil
pose a threat to peace, wouldn't we all
stand to benefit from switching more of our vehicles
to natural gas?
Well, a problem with natural gas vehicles
is that you have to highly compress the natural gas.
This requires an expensive refueling station
and a heavy, expensive tank.
This compression obstacle has prevented
the widespread adoption of this otherwise cheaper, cleaner
fuel.
But what if we could use natural gas
without highly compressing it?
We wouldn't need the heavy tank.
We wouldn't need the million-dollar refueling
station.
In fact, if you were one of 65 million US households
with residential natural gas service,
you could refuel your car at home.
This could be a reality if we could somehow
store natural gas more effectively.
But today we can't, and our inability to do so
has other consequences besides the fuel we use in our cars.
This is a natural gas flare.
There are tens of thousands of these at oil fields
all around the world.
Oil fields extract natural gas at the same time
they extract oil.
But instead of storing it, they just burn it.
They don't use that energy for anything.
But they do contribute to global greenhouse gas emissions.
Collectively, these oil fields are throwing away
over 100 billion cubic meters of natural gas, which is about 1%
of global energy demand every year.
Why?
Again, the problem is storage.
Natural gas, like all gases, is difficult to store
and transport.
Today, we either have to highly compress natural gas
or compress and refrigerate it, both of which
require energy and infrastructure.
So today we mostly don't bother shipping it from oil fields.
We mostly don't use it to power our transportation vehicles,
even though it's plentiful, cheap,
and we really need that energy.
Now, in principle, there is a solution
to storing gases without resorting
to very high pressures or refrigeration.
A universal physical property of all gases
is that they highly concentrate at the surfaces of things.
So for example, in the room you're in right now,
the density of air is slightly higher
at the surface of the floor, the walls,
and even on your skin and clothing.
We can apply this principle to storing gases
by using sponge-like materials with very high surface areas.
A common example is activated carbon.
At the nanoscale, activated carbon
looks like sheets of highly crumpled paper which
have many small but randomly-sized spaces
that gases can enter inside and stick to.
Some of these spaces, or pores, are
too big to really help concentrate the gas.
And some of the pores are too small,
smaller than the size of the gas molecule itself.
But some of the pores turn out to be just the right size.
And so you do get a concentrating effect
from activated carbon.
However, this effect is modest and so far has
been too small to be useful for natural gas storage,
as evidenced by those thousands of gas flares
that are still burning today.
So how do we solve this problem of efficient gas storage?
Well, in this glass file in my hand
are little blue green crystals of a new class
of porous materials discovered a little over a decade ago
called metal organic frameworks, or MOFs.
And if you were to zoom in to the nanoscale,
you would see that each crystal contains trillions
of identical nanoscopic pores.
And because of their perfect, regularly-spaced pores,
MOFs have extremely high surface areas, significantly beating
the previous world record held by activated carbon.
But what's really exciting about MOFs
is that unlike activated carbon, you can custom
design the pores of a MOF to be sticky preferentially
to certain gas molecules over others.
This makes MOFs perfect not just for storing gases
but also for separating them.
Now, before I talk more about MOFs
I'd like to take a step back and briefly talk about plastics.
You'll see why in a minute, I promise.
Prior to the 1950s, nothing in this world was made of plastic.
But today, it's hard to find anything
that's not made of plastic.
Our cars, our phones, our clothing, and of course
our packaging materials all are made of
or contain some amount of plastics
or, as they're more precisely called in chemistry terms,
polymers.
But what is a polymer?
At the nanoscale, a polymer looks like a piece of string
which is made of repeating molecular units called
monomers.
When many of these strings clump together,
you get a kind of stretchy, solid material that
could be made into a shopping bag or a contact lens.
The genius of polymers is that by carefully choosing
the monomers to be, say, a little bigger or a little
smaller or with a different electrical conductivity,
we can make the resulting solid very soft like rubber,
very hard like a helmet, or transparent like a pair
of goggles, and so on.
Plastics became a miracle material class
because we could so easily engineer their properties.
The one drawback to polymers, perhaps,
is that when the individual strings clump together,
the process is somewhat random.
And so we don't know their precise relative arrangements.
Now, that may not matter for a lot of applications.
But you'll see in a moment why I mentioned this.
So MOFs are made of repeating molecular units just
like polymers.
But whereas polymers grow in one dimension,
MOFs grow in all three dimensions.
So instead of floppy strings, you
get rigid, three-dimensional structures or frameworks.
And just like polymers, we can vary the monomers to create
materials with widely varying material properties-- softer,
harder, red, green, glow-in-the-dark, you name it.
But here's the really unique thing,
the thing that makes MOFs so new and exciting for scientists
like myself.
Because the framework grows rigidly in three dimensions,
there's no random folding or clumping process
like with traditional polymers.
And that means that in the resulting material,
we know precisely where every atom is.
And so for the first time, we can
engineer the atomically detailed geometry of our materials,
and in a way that's scalable.
So imagine in the future using MOFs as scaffolds
to build three-dimensional molecular circuitry
or scaffolds to construct advanced molecular machines.
These would be far-off applications,
but I'd be remiss if I didn't point out the potential of MOFs
beyond just gas storage.
That being said, hopefully you can
see how MOFs are ideal for gas storage.
Rather than the random pores of activated carbon,
we can design a MOF that has pores the exact shape
and size for a gas in question.
And having identical, atomically precise pores
that you can control the size and shape of
has a huge effect on gas storage performance.
So let's come back to natural gas.
We can now make, with MOFs, natural gas tanks
for cars that store almost the same amount of fuel
but at only a quarter of the pressure.
This means we can build inexpensive, low-pressure
refueling stations.
But the tanks themselves can be lighter, cheaper,
and can be molded into any shape.
So now, instead of designing the car around the tank,
we can design the tank around the car.
And beyond cars, low-pressure storage
could enable lawn mowers or golf carts
or drones to use natural gas as a cheaper fuel source.
And if we can store natural gas inexpensively,
maybe operators of oil fields will actually ship natural gas
rather than just burning it.
Inefficient gas storage and separation
is a pervasive problem beyond natural gas.
Medical oxygen is very expensive,
largely because the tanks don't have much oxygen.
And so you have to frequently deliver new ones.
Hazardous gases used in semiconductor manufacturing
are stored today in tanks that use activated carbon.
So they have to be replaced often,
leading to downtime and safety risks.
And if we want to capture carbon from the air,
we're going to need an efficient way to separate and store it.
We're trying to make efficient gas storage and separation
a reality.
Last year, we went from producing-- well,
so MOFs are a brand new material class.
Last year, we went from producing milligrams
in our university labs to tens of kilograms
in our small facility.
And this year, we're in the process
of going from kilograms to metric tons.
I'm excited about what MOFs will let us do in the future
because I think they just might be
the plastics of the 21st century.
Thank you.
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