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(Richard Alley) Humans need energy.
We always have, and always will.
But how we use energy is now critical for our survival.
It all began with fire...
Today, it's mostly fossil fuels.
Now we're closing in on seven billion of us
and the planet's population is headed toward 10 billion.
Our cities and our civilization
depend on vast amounts of energy.
Fossil fuels-- coal, oil and natural gas--
provide almost 80% of the energy
used world-wide.
Nuclear is a little less than 5%.
Hydro-power a little under 6.
And the other renewables--
solar, wind and geothermal about 1%
but growing fast.
Wood and dung make up the rest.
Using energy is helping many of us
live better than ever before.
Yet well over a billion and a half are lagging behind,
without access to electricity or clean fuels.
In recent years, Brazil, has brought electricity
to ten million,
but in rural Ceará some still live off the grid.
No electricity, no running water,
and no refrigerators to keep food safe.
Life's essentials come from their own hard labor.
Education is compulsory,
but studying's a challenge when evening arrives.
The only light is from kerosene lamps.
They're smoky, dim and dangerous.
Someday, this mother prays,
the electric grid will reach her home.
(translator) The first thing I'll do
when the electricity arrives in my house
will be to say a rosary and give praise to God.
(Richard Alley) More than half of China's 1.3 billion citizens
live in the countryside.
Many rural residents still use wood or coal
for cooking and heating,
although most of China is already on the grid.
China has used energy to fuel the development
that has brought more than half a billion out of poverty.
In village homes there are flat screen tvs
and air conditioners.
By 2030, it's projected that 350 million Chinese,
more than the population of the entire United States,
will move from the countryside to cities...
a trend that's echoed worldwide.
Development in Asia, Africa and South America
will mean three billion people will start using
more and more energy as they escape from poverty.
Suppose we make the familiar if old-fashioned
100 watt light bulb our unit for comparing energy use.
If you're off the grid,
your share of your nation's energy
will be just a few hundred watts, a few light bulbs.
South Americans average about 13 bulbs.
For fast developing China, it's more like 22 bulbs.
Europe and Russia, 5,000 watts, 50 bulbs.
And North Americans, over ten thousand watts,
more than 100 bulbs.
Now let's replace those light bulbs
with the actual numbers.
Population, shown across the bottom
and energy use, displayed vertically,
off the grid to the left,
North America to the right.
If everyone, everywhere, started using energy
at the rate North Americans do,
the world's energy consumption would more than quadruple,
and using fossil fuels, that's clearly unsustainable.
No doubt about it, coal, gas and oil
have brought huge benefits.
But we're burning through 'em approximately
a million times faster than nature saved them for us,
and they will run out.
What's even worse,
the carbon dioxide from our energy system
threatens to change the planet
in ways that'll make our lives much harder.
So why are fossil fuels such a powerful,
but ultimately problematic, source of energy?
♪