How does large-scale power storage work?

Wind farms and solar power plants are promising sources of renewable energy, but they're not as reliable as conventional power sources. In this episode, Marshall explains how large-scale storage technologies could make solar and wind power more viable.

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Episode Transcript

Speaker 1 (00:00):
Stuff happens, just don't let it happen to your photos, music,
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dot com. That's m o z Y dot com. Welcome
to brain Stuff from how Stuff works dot com where
smart happens. I am Marshall Brain with today's question, what

(00:30):
are all the different ways to store energy? Besides using
rechargeable batteries. Human beings have been looking for a good
way to store energy for a long time. One of
the big things that's been holding up electric cars is
battery technology. When you compare batteries to gasoline, the differences
are huge. For example, a typical electric car might carry

(00:51):
a thousand pounds of lead acid batteries. Those batteries take
several hours to recharge, and they might give the car
a hundred mile range. Two or three gallons of gasoline
give the same range. Weigh less than thirty pounds, and
you can pump that much gasoline in about a minute.
There's really no comparison between gasoline and batteries. Here's a

(01:12):
list of some of the other technologies that people commonly
use to store energy. Some of these working electric car
while others are better off for stationary applications. One of
the oldest techniques people have used is the falling weight.
You lift the weight to store the energy in it,
and then you let the weight fall to extract the energy.
Many grandfather clocks and cuckoo clocks use this technique. By

(01:35):
running the string attached to the weights through a gear train,
you can use a heavy weight and let it fall
over a long period of time. This approach doesn't work
very well in an electric car, but it's worked well
in clocks for hundreds of years. Many power plants use
the falling weight approach in the form of water. The
water is pumped uphill to a lake at night when

(01:57):
the power plant has excess capacity, and then during high
demand daytime periods, the water runs through a termite on
its way downhill to a lower lake. Another way to
store energy is in some form of repeatable mechanical deformation.
This is the idea behind a spring used in a
wind up clock or a rubber band used in a
wind up airplane. You store the energy by deforming the

(02:20):
material in the spring and the material releases that energy
as it returns to its original shape. At the scale
of a car, this technology has problems because of the
weight of the spring, but it's smaller scales like a
wrist watch, it works great. Nature has been storing energy
for a long time, and if you want to think
about it this way, gasoline is really a form of

(02:41):
stored natural energy. Plants absorbed sunlight and turn it into
carbohydrates over millions of years, those carbohydrates can turn into
oil or coal, and that's a form of stored energy.
On a more human time scale, we burn wood to
release stored energy stored in the plant, or we turn
corn into alcohol and burn the alcohol. Another technique that

(03:02):
nature uses the store energy is fat, which many of
us are familiar with in a personal way. It's interesting
to think about a car that somehow eats grass or
some other form of carbohydrate and stores it is fat.
You can take energy and split water into its hydrogen
and oxygen atoms using electrolysis. By storing the hydrogen, you

(03:23):
can later create energy by burning it or by running
it through a fuel cell. You can use energy to
spin up a flywheel and then later extract the energy
by using the flywheel to run a generator, or you
can store heat directly and later convert the heat to
another form of energy like electricity. Molten salt is one
way to do this. You can use compressed air to

(03:44):
store energy, or you can compress air a lot and
get something like liquid nitrogen and use the liquid nitrogen
to power a car. One of the new technologies that
may become available in the future involves antimatter. When you
combine matter with antimatter, you get energy. You can store
energy by creating anti matter. Right now, none of these

(04:04):
techniques can hold a candle, which is really another form
of stored energy, to gasoline in the convenience sense. Fuel
cells look to be the closest competitor right now, and
they'll probably become available to the general public over the
next few years. For more on this and thousands of
other topics, is it how stuff works dot Com. Your photos,

(04:28):
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