0:00:00.396,0:00:03.285
Nearly everyone in the world[br]is part of some community,

0:00:03.309,0:00:04.952
whether large or small.

0:00:04.976,0:00:07.998
And all of these communities[br]have similar needs.

0:00:08.022,0:00:09.202
They need light,

0:00:09.226,0:00:10.390
they need heat

0:00:10.414,0:00:11.760
they need air-conditioning.

0:00:11.784,0:00:14.979
People can't function very well[br]when it's too hot or too cold.

0:00:15.003,0:00:19.449
They need food to be grown or provided,[br]distributed and stored safely.

0:00:19.473,0:00:23.553
They need waste products to be collected,[br]removed and processed.

0:00:23.577,0:00:27.004
People in the community need to be able[br]to get from one place to another

0:00:27.028,0:00:28.202
as quickly as possible.

0:00:28.226,0:00:31.548
And a supply of energy is the basis[br]for all of these activities.

0:00:31.572,0:00:34.902
Energy in the form of electricity[br]provides light and air-conditioning.

0:00:34.926,0:00:36.900
Energy in the form of heat keeps us warm.

0:00:36.924,0:00:39.970
And energy in chemical[br]form provides fertilizer;

0:00:39.994,0:00:42.799
it drives farm machinery[br]and transportation energy.

0:00:42.823,0:00:44.793
Now, I spent 10 years working at NASA.

0:00:44.817,0:00:47.528
In the beginning of my time there in 2000,

0:00:47.552,0:00:49.552
I was very interested in communities.

0:00:49.576,0:00:52.211
But this is the kind of community[br]I was thinking of --

0:00:52.235,0:00:53.476
a lunar community

0:00:53.500,0:00:56.802
It had all of the same needs[br]as a community on Earth would have,

0:00:56.826,0:00:59.378
but it had some very unique constraints.

0:00:59.402,0:01:01.933
And we had to think about[br]how we would provide energy

0:01:01.957,0:01:03.475
for this very unique community.

0:01:03.499,0:01:04.971
There’s no coal on the Moon.

0:01:04.995,0:01:06.333
There's no petroleum.

0:01:06.357,0:01:08.034
There’s no natural gas.

0:01:08.058,0:01:09.241
There's no atmosphere.

0:01:09.265,0:01:10.526
There’s no wind, either.

0:01:10.550,0:01:12.604
And solar power had a real problem:

0:01:12.628,0:01:15.115
the Moon orbits the Earth once a month.

0:01:15.139,0:01:17.140
For two weeks, the sun goes down,

0:01:17.164,0:01:19.378
and your solar panels[br]don't make any energy.

0:01:19.402,0:01:22.670
If you want to try to store[br]enough energy in batteries for two weeks,

0:01:22.694,0:01:24.187
it just simply isn't practical.

0:01:24.211,0:01:26.335
So nuclear energy[br]was really the only choice.

0:01:26.359,0:01:29.742
Now, back in 2000, I didn't really know[br]too much about nuclear power,

0:01:29.766,0:01:31.156
so I started trying to learn.

0:01:31.180,0:01:34.536
Almost all of the nuclear power[br]we use on Earth today uses water

0:01:34.560,0:01:35.846
as a basic coolant.

0:01:35.870,0:01:38.920
This has some advantages,[br]but it has a lot of disadvantages.

0:01:38.944,0:01:42.542
If you want to generate electricity,[br]you have to get the water a lot hotter

0:01:42.566,0:01:43.732
than you normally can.

0:01:43.756,0:01:47.255
At normal pressures, water will boil[br]at 100 degrees Celsius.

0:01:47.279,0:01:51.005
This isn't nearly hot enough[br]to generate electricity effectively.

0:01:51.029,0:01:54.320
So water-cooled reactors have to run[br]at much higher pressures

0:01:54.344,0:01:55.836
than atmospheric pressure.

0:01:55.860,0:01:59.955
Some water-cooled reactors run[br]at over 70 atmospheres of pressure,

0:01:59.979,0:02:03.614
and others have to run at as much as[br]150 atmospheres of pressure.

0:02:03.638,0:02:05.131
There's no getting around this;

0:02:05.155,0:02:08.363
it's simply what you have to do[br]if you want to generate electricity

0:02:08.387,0:02:09.795
using a water-cooled reactor.

0:02:09.820,0:02:12.308
This means you have to build[br]a water-cooled reactor

0:02:12.332,0:02:13.491
as a pressure vessel,

0:02:13.515,0:02:15.889
with steel walls[br]over 20 centimeters thick.

0:02:15.913,0:02:18.175
If that sounds heavy,[br]that's because it is.

0:02:18.199,0:02:20.387
Things get a lot worse[br]if you have an accident

0:02:20.411,0:02:22.484
where you lose pressure[br]inside the reactor.

0:02:22.508,0:02:25.346
If you have liquid water[br]at 300 degrees Celsius

0:02:25.370,0:02:27.043
and suddenly you depressurize it,

0:02:27.067,0:02:28.857
it doesn't stay liquid for very long;

0:02:28.881,0:02:30.083
it flashes into steam.

0:02:30.107,0:02:34.077
So water-cooled reactors are built[br]inside of big, thick concrete buildings

0:02:34.101,0:02:35.529
called containment buildings,

0:02:35.553,0:02:39.103
which are meant to hold all of the steam[br]that would come out of the reactor

0:02:39.127,0:02:41.348
if you had an accident[br]where you lost pressure.

0:02:41.372,0:02:45.097
Steam takes up about 1,000 times[br]more volume than liquid water,

0:02:45.121,0:02:47.611
so the containment building[br]ends up being very large,

0:02:47.635,0:02:49.361
relative to the size of the reactor.

0:02:49.385,0:02:51.561
Another bad thing happens[br]if you lose pressure

0:02:51.585,0:02:53.119
and your water flashes to steam.

0:02:53.143,0:02:56.098
If you don't get emergency coolant[br]to the fuel in the reactor,

0:02:56.122,0:02:57.560
it can overheat and melt.

0:02:57.584,0:03:01.388
The reactors we have today[br]use uranium oxide as a fuel.

0:03:01.412,0:03:03.776
It's a ceramic material[br]similar in performance

0:03:03.800,0:03:06.753
to the ceramics we use to make[br]coffee cups or cookware

0:03:06.777,0:03:08.893
or the bricks we use to line fireplaces.

0:03:08.917,0:03:10.178
They're chemically stable,

0:03:10.202,0:03:12.408
but they're not very good[br]at transferring heat.

0:03:12.432,0:03:14.459
If you lose pressure, you lose your water,

0:03:14.483,0:03:16.082
and soon your fuel will melt down

0:03:16.106,0:03:18.707
and release the radioactive[br]fission products within it.

0:03:18.731,0:03:21.836
Making solid nuclear fuel[br]is a complicated and expensive process.

0:03:21.860,0:03:25.392
And we extract less than one percent[br]of the energy for the nuclear fuel

0:03:25.416,0:03:27.572
before it can no longer[br]remain in the reactor.

0:03:27.596,0:03:30.332
Water-cooled reactors have[br]another additional challenge:

0:03:30.356,0:03:32.661
they need to be near[br]large bodies of water,

0:03:32.685,0:03:35.474
where the steam they generate[br]can be cooled and condensed.

0:03:35.498,0:03:37.760
Otherwise, they can't generate[br]electrical power.

0:03:37.784,0:03:39.886
Now, there's no lakes[br]or rivers on the Moon,

0:03:39.910,0:03:42.719
so if all of this makes it sound[br]like water-cooled reactors

0:03:42.743,0:03:44.846
aren't such a good fit[br]for a lunar community,

0:03:44.870,0:03:46.359
I would tend to agree with you.

0:03:46.383,0:03:47.434
(Laughter)

0:03:47.458,0:03:50.928
I had the good fortune to learn about[br]a different form of nuclear power

0:03:50.952,0:03:52.727
that doesn't have all these problems,

0:03:52.751,0:03:53.983
for a very simple reason:

0:03:54.007,0:03:57.064
it's not based on water-cooling,[br]and it doesn't use solid fuel.

0:03:57.088,0:03:59.306
Surprisingly, it's based on salt.

0:03:59.330,0:04:01.416
One day, I was at a friend's[br]office at work,

0:04:01.440,0:04:04.297
and I noticed this book on the shelf,[br]"Fluid Fuel Reactors."

0:04:04.321,0:04:06.782
I was interested[br]and asked him if I could borrow it.

0:04:06.806,0:04:09.784
Inside that book, I learned[br]about research in the United States

0:04:09.808,0:04:10.975
back in the 1950s,

0:04:10.999,0:04:13.556
into a kind of reactor[br]that wasn't based on solid fuel

0:04:13.580,0:04:14.751
or on water-cooling.

0:04:14.775,0:04:17.440
It didn't have the problems[br]of the water-cooled reactor,

0:04:17.464,0:04:19.213
and the reason why was pretty neat.

0:04:19.237,0:04:22.448
It used a mixture of fluoride salts[br]as a nuclear fuel,

0:04:22.472,0:04:25.891
specifically, the fluorides of lithium,[br]beryllium, uranium and thorium.

0:04:25.915,0:04:28.306
Fluoride salts are remarkably[br]chemically stable.

0:04:28.330,0:04:30.519
They do not react with air and water.

0:04:30.543,0:04:33.392
You have to heat them up[br]to about 400 degrees Celsius

0:04:33.416,0:04:34.570
to get them to melt.

0:04:34.594,0:04:37.237
But that's actually perfect[br]for trying to generate power

0:04:37.261,0:04:38.415
in a nuclear reactor.

0:04:38.439,0:04:39.600
Here's the real magic:

0:04:39.624,0:04:41.903
they don't have to operate[br]at high pressure.

0:04:41.927,0:04:44.058
And that makes the biggest[br]difference of all.

0:04:44.082,0:04:47.550
This means they don't have to be[br]in heavy, thick steel pressure vessels,

0:04:47.574,0:04:49.502
they don't have to use water for coolant

0:04:49.526,0:04:51.155
and there's nothing in the reactor

0:04:51.179,0:04:53.899
that's going to make[br]a big change in density, like water.

0:04:53.923,0:04:56.084
So the containment building[br]around the reactor

0:04:56.108,0:04:57.967
can be much smaller and close-fitting.

0:04:57.991,0:05:01.162
Unlike the solid fuels that can melt down[br]if you stop cooling them,

0:05:01.186,0:05:03.401
these liquid fluoride fuels[br]are already melted,

0:05:03.425,0:05:05.066
at a much, much lower temperature.

0:05:05.090,0:05:07.381
In normal operation,[br]you have a little plug here

0:05:07.405,0:05:09.121
at the bottom of the reactor vessel.

0:05:09.145,0:05:11.745
This plug is made[br]out of a piece of frozen salt

0:05:11.769,0:05:13.795
that you've kept frozen[br]by blowing cool gas

0:05:13.819,0:05:15.209
over the outside of the pipe.

0:05:15.233,0:05:17.874
If there's an emergency[br]and you lose all the power

0:05:17.898,0:05:19.276
to your nuclear power plant,

0:05:19.300,0:05:20.980
the little blower stops blowing,

0:05:21.004,0:05:22.792
the frozen plug of salt melts,

0:05:22.816,0:05:25.180
and the liquid fluoride fuel[br]inside the reactor

0:05:25.204,0:05:27.235
drains out of the vessel, through the line

0:05:27.259,0:05:29.369
and into another vessel[br]called a drain tank.

0:05:29.393,0:05:33.279
Inside the drain tank, it's all configured[br]to maximize the transfer of heat,

0:05:33.303,0:05:35.600
so as to keep the salt passively cooled

0:05:35.624,0:05:37.496
as its heat load drops over time.

0:05:37.520,0:05:39.177
In water-cooled reactors,

0:05:39.201,0:05:41.466
you generally have to provide[br]power to the plant

0:05:41.490,0:05:44.178
to keep the water circulating[br]and to prevent a meltdown,

0:05:44.202,0:05:45.621
as we saw in Japan.

0:05:45.645,0:05:48.885
But in this reactor,[br]if you lose the power to the reactor,

0:05:48.909,0:05:52.170
it shuts itself down all by itself,[br]without human intervention,

0:05:52.194,0:05:54.814
and puts itself in a safe[br]and controlled configuration.

0:05:54.838,0:05:56.822
Now, this was sounding pretty good to me,

0:05:56.846,0:06:00.260
and I was excited about the potential[br]of using a liquid fluoride reactor

0:06:00.284,0:06:01.609
to power a lunar community.

0:06:01.633,0:06:04.662
But then I learned about thorium,[br]and the story got even better.

0:06:04.686,0:06:06.809
Thorium is a naturally[br]occurring nuclear fuel

0:06:06.833,0:06:09.898
that is four times more common[br]in the Earth's crust than uranium.

0:06:09.922,0:06:12.351
It can be used in liquid fluoride[br]thorium reactors

0:06:12.375,0:06:15.958
to produce electrical energy, heat[br]and other valuable products.

0:06:15.982,0:06:19.730
It's so energy-dense that you could hold[br]a lifetime supply of thorium energy

0:06:19.754,0:06:20.996
in the palm of your hand.

0:06:21.020,0:06:23.568
Thorium is also common on the Moon[br]and easy to find.

0:06:23.592,0:06:26.647
Here's an actual map of where[br]the lunar thorium is located.

0:06:26.671,0:06:29.887
Thorium has an electromagnetic signature[br]that makes it easy to find,

0:06:29.911,0:06:31.072
even from a spacecraft.

0:06:31.096,0:06:34.189
With the energy generated[br]from a liquid fluoride thorium reactor,

0:06:34.213,0:06:36.904
we could recycle all of the air,[br]water and waste products

0:06:36.928,0:06:38.234
within the lunar community.

0:06:38.258,0:06:41.229
In fact, doing so would be[br]an absolute requirement for success.

0:06:41.253,0:06:44.467
We could grow the crops needed[br]to feed the members of the community

0:06:44.491,0:06:46.313
even during the two-week lunar night,

0:06:46.337,0:06:48.254
using light and power from the reactor.

0:06:48.278,0:06:51.130
It seemed like the liquid fluoride[br]thorium reactor, or LFTR,

0:06:51.154,0:06:54.623
could be the power source that could make[br]a self-sustainable lunar colony

0:06:54.647,0:06:55.806
a reality.

0:06:55.830,0:06:57.180
But I had a simple question:

0:06:57.204,0:06:59.899
If it was such a great thing[br]for a community on the Moon,

0:06:59.923,0:07:02.733
why not a community on the Earth,[br]a community of the future,

0:07:02.757,0:07:04.779
self-sustaining and energy-independent?

0:07:04.803,0:07:07.968
The same energy generation[br]and recycling techniques

0:07:07.992,0:07:11.038
that could have a powerful impact[br]on surviving on the Moon

0:07:11.062,0:07:14.112
could also have a powerful impact[br]on surviving on the Earth.

0:07:14.136,0:07:15.934
Right now, we're burning fossil fuels

0:07:15.958,0:07:18.258
because they're easy to find[br]and because we can.

0:07:18.282,0:07:21.999
Unfortunately, they're making some parts[br]of our planet look like the Moon.

0:07:22.023,0:07:24.409
Using fossil fuels[br]entangles us in conflict

0:07:24.433,0:07:26.041
in unstable regions of the world

0:07:26.065,0:07:27.978
and costs money and lives.

0:07:28.002,0:07:30.636
Things could be very different[br]if we were using thorium.

0:07:30.660,0:07:34.119
You see, in a LFTR, we could use thorium[br]about 200 times more efficiently

0:07:34.143,0:07:35.584
than we're using uranium now.

0:07:35.608,0:07:38.642
And because the LFTR is capable[br]of almost completely releasing

0:07:38.666,0:07:39.828
the energy in thorium,

0:07:39.852,0:07:43.946
this reduces the waste generated[br]over uranium by factors of hundreds,

0:07:43.970,0:07:46.580
and by factors of millions[br]over fossil fuels.

0:07:46.604,0:07:49.751
We're still going to need liquid fuels[br]for vehicles and machinery,

0:07:49.775,0:07:53.659
but we could generate these liquid fuels[br]from the carbon dioxide in the atmosphere

0:07:53.683,0:07:55.512
and from water, much like nature does.

0:07:55.536,0:07:57.673
We could generate hydrogen[br]by splitting water

0:07:57.697,0:08:01.156
and combining it with carbon[br]harvested from CO2 in the atmosphere,

0:08:01.180,0:08:04.712
making fuels like methanol,[br]ammonia, and dimethyl ether,

0:08:04.736,0:08:07.271
which could be a direct replacement[br]for diesel fuels.

0:08:07.295,0:08:10.455
Imagine carbon-neutral[br]gasoline and diesel,

0:08:10.479,0:08:12.922
sustainable and self-produced.

0:08:12.946,0:08:14.301
Do we have enough thorium?

0:08:14.325,0:08:15.480
Yes, we do.

0:08:15.504,0:08:19.467
In fact, in the United States, we have[br]over 3,200 metric tons of thorium

0:08:19.491,0:08:21.267
that was stockpiled 50 years ago

0:08:21.291,0:08:23.838
and is currently buried[br]in a shallow trench in Nevada.

0:08:23.862,0:08:26.103
This thorium, if used in LFTRs,

0:08:26.127,0:08:29.766
could produce almost as much energy[br]as the United States uses in three years.

0:08:29.790,0:08:31.993
And thorium is not[br]a rare substance, either.

0:08:32.017,0:08:34.116
There are many sites[br]like this one in Idaho,

0:08:34.140,0:08:38.023
where an area the size of a football field[br]would produce enough thorium each year

0:08:38.047,0:08:39.323
to power the entire world.

0:08:39.347,0:08:41.312
Using liquid fluoride thorium technology,

0:08:41.336,0:08:44.234
we could move away from[br]expensive and difficult aspects

0:08:44.258,0:08:47.097
of current water-cooled, solid-fueled[br]uranium nuclear power.

0:08:47.121,0:08:50.015
We wouldn't need large,[br]high-pressure nuclear reactors

0:08:50.039,0:08:52.197
and big containment buildings[br]that they go in.

0:08:52.221,0:08:54.829
We wouldn't need large,[br]low-efficiency steam turbines.

0:08:54.853,0:08:56.039
We wouldn't need to have

0:08:56.063,0:08:58.751
as many long-distance power[br]transmission infrastructure,

0:08:58.775,0:09:01.234
because thorium is[br]a very portable energy source

0:09:01.258,0:09:03.564
that can be located[br]near to where it is needed.

0:09:03.588,0:09:06.803
A liquid fluoride thorium reactor[br]would be a compact facility,

0:09:06.827,0:09:08.769
very energy-efficient and safe,

0:09:08.793,0:09:11.269
that would produce the energy[br]we need day and night,

0:09:11.293,0:09:13.349
and without respect to weather conditions.

0:09:13.373,0:09:16.347
In 2007, we used[br]five billion tons of coal,

0:09:16.371,0:09:18.085
31 billion barrels of oil

0:09:18.109,0:09:20.342
and five trillion cubic meters[br]of natural gas,

0:09:20.366,0:09:23.444
along with 65,000 tons of uranium

0:09:23.468,0:09:25.351
to produce the world's energy.

0:09:25.375,0:09:27.314
With thorium, we could do the same thing

0:09:27.338,0:09:30.574
with 7,000 tons of thorium[br]that could be mined at a single site.

0:09:30.598,0:09:34.134
If all this sounds interesting to you,[br]I invite you to visit our website,

0:09:34.158,0:09:37.444
where a growing and enthusiastic[br]online community of thorium advocates

0:09:37.468,0:09:41.152
is working to tell the world[br]about how we can realize a clean, safe

0:09:41.176,0:09:42.920
and sustainable energy future,

0:09:42.944,0:09:44.539
based on the energies of thorium.

0:09:44.563,0:09:46.277
Thank you very much.[br](Applause)