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Nuclear or solar? Fracking or tar sands?
Pipelines or no pipelines? And what the heck
is a kilowatt-hour anyway?
Confused? You’re not alone. The world of
energy is a strange and complicated place,
and like any unfamiliar land, it has a language
all its own.
In order to become an energy-conscious citizen,
you’ve got to speak it, so today we’re
going to take a look at the essentials of
energy.
[MUSIC]
Often we use the words energy and power interchangeably,
but they mean very different things. Energy
is a quantity,and we can use that energy to
do lots of different things. Power is the rate
at which we use that energy.
Energy is measured in units like Joules, calories,
or the ever-popular British Thermal Unit.
Power is measured in watts, kilowatts, megawatts…
or gigawatts.
Energy isn’t power, but power times time
equals energy, which is why when your bill
lists the amount of energy you used in a month,
you see kilowatt-hours.
If power is energy over time, how much energy
would it take to time travel?
Accelerating a DeLorean close enough to the
speed of light to experience time dilation
or simply warping the fabric of space and
time at 88 mph would require a lot of energy.
In "Back to the Future", Doc Brown explains
that the flux capacitor requires 1.21 jigga-watts
to do its thing.
1.21 JIG-A-WATTS!
But that’s power, and without knowing over
how many seconds those 1.21 gigawatts are
being applied, we don’t know how much energy,
whether it’s from plutonium, lightning,
or garbage-fueled nuclear fusion, is required.
Everything from light bulbs to toasters has
a power rating, the amount of energy it needs
to consume at any given moment to emit photons
or cook pop tarts or whatever.
A 100 W light bulb uses 100 Joules of energy
every second. Turn it on for an hour, it uses
100 Watt-hours.
Newer bulbs have lower ratings because they
use less energy to make an equivalent amount
of light in the same amount of time.
An adult male like me eats 2,500 food calories
every day, or about 10.5 megajoules of energy.
Burning through those[k] calories over 24
hours means my body operates at about 120
watts.
And even though a fifth of that power goes
to my brain, I can’t use it to light any
actual light bulbs…
because even though energy is all around us,
and it comes in many forms, not all of it
is available for us to use.
And, although we can’t create it, we can
move it around from one form to another.
It’s energy conversion that drives our energy
world, whether it’s turning chemical to
electrical, thermal energy to motion, or mechanical
to electrical.
Unfortunately, the second law of thermodynamics
tells us that highly ordered forms of energy
will be converted[o] to highly dis-ordered
energy. Basically we can’t turn heat and
ash back into wood.
Because every energy conversion has losses,
and because of entropy. That’s a complicated
physics answer for why Earth's energy supplies
are bound to decline.
A-ha! But luckily our planet isn’t a closed
system!
The sun’s radiant energy can power solar
cells, create wind, and drive precipitation
to fill rivers and lakes. As long as there’s
a sun, we’ll have these renewable resources.
But renewable or not, there’s inefficiencies
at every step of converting energy, and the
more times energy is converted, the more those
losses multiply. For every 100 units of energy
produced by coal, we only get 1.6 units of
light energy in our homes.
And overall, for every 100 units of energy
produced in the US, we lose 60 to waste.
ENTROPY!!!!
To lower that number, we need to develop more
efficient ways to use energy and move it around,
better appliances, better vehicles, more efficient
buildings, and most of all, more efficient
ways to harness energy in the first place.
Like how Doc Brown used a lightning strike
to power the DeLorean in 1955!
Lightning strikes the Earth around 1.4 billion
times per year, each bolt can carry 5 billion
joules of energy… 30 millionths of a second
per bolt… that’s enough to power 137,741
flux capacitors, capable of taking us anywhere
we want to go.
I wonder what kind of future we'll decide
to make.
Stay curious.
