
Hydraulic Rock Storage – an efficient system for large grid scale storage [pdf] - nkurz
http://www.cleanenergybusinesscouncil.com/wp-content/uploads/HeindlEnergyPresentation.pdf
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Animats
From the article: requires _" Possibly compact, homogeneous rock with little
tendency to fracture."_ That's rare geology. It's rare for a tunneling project
to find nice hard homogeneous rock through which a tunnel can simply be bored
without supports. Both the Gotthard Base Tunnel in Switzerland and the NYC
East Side Access, although in areas where such rocks exists, ran into
incompetent rock.

In practice, they'd probably have to line both the hole and the plug with
something like tunnel lining segments.

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csense
> It's rare for a tunneling project to find nice hard homogeneous rock through
> which a tunnel can simply be bored without supports

Obviously you've never played Dwarf Fortress.

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Animats
"Rock is dross or nedross. Dross does not crumble; it is rock to trust, grain
pure throughout. Nedross rock cannot be trusted, even if it looks solid and
pure in grain. It fails. It is -- not truth."

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brudgers
Hydraulic Storage in general:
[https://en.wikipedia.org/wiki/Hydraulic_accumulator](https://en.wikipedia.org/wiki/Hydraulic_accumulator)

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jimmcslim
Similar concept to ARES that has been discussed here before;

[http://www.aresnorthamerica.com/](http://www.aresnorthamerica.com/)

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pontifier
At first this looked a bit weird. It may be a bit more land intensive, but the
idea is sound, and would be able to expand to full capacity gradually. I like
it a lot better than the hydraulic storage for the near term.

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Gravityloss
Earlier this was for a much larger cylinder, say kilometers across, where you
could leave the nature at the top intact. They have explanation here.

[http://www.authorstream.com/Presentation/heindl-958931-hydra...](http://www.authorstream.com/Presentation/heindl-958931-hydraulic-
energy-store-system/)

(Edited to change info it was the same guy, added url)

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ChuckMcM
That is so cool. Now I want to install a hydraulic piston under my house.
During the day excess solar production lifts the house, at night as the house
slowly sinks it provides power. Zero foot print chemical free energy storage.

Would make for an interesting front walk, that basically would turn into a
staircase as the house went up :-)

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brudgers
Install a stationary gatehouse with an elevator.

Plumbing? You're on your own.

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onetimePete
Could the same system be implemented with a column of concrete and a tank of
water under the surface of the ocean?

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hollerith
interesting idea.

if the seal breaks, then most of the energy stored in the system might over an
interval of only a few minutes go into kinetic and potential energy in the
form of water flowing over terrain and water gushing high into the air, so at
the least it seems like a bad idea to have a road containing through traffic
as close to the facility as depicted in the final image in the OP (the PDF).

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JoeAltmaier
Why r ^ 4th power? The weight of the rock is ~r ^ 2. Potential energy is
weight X height lifted. I'm confused.

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dragonwriter
> Why r ^ 4th power? The weight of the rock is ~r ^ 2.

No, because, as shown on the fourth page, the length of the cylinder is ~r
making the weight ~r^3 (if the length was constant, the weight would be ~r^2.)

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daveloyall
I am not a physicist... Why is setting a rock atop a column of water better
than an unadorned column of water?

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JshWright
The basic idea is that you are storing energy by lifting something heavy. The
more mass you can lift, the more energy it can release as it falls back down.
Rock density varies, based on the type of rock, but it is generally 2-3 times
heavier than water for a given volume. The limiting factor for water energy
storage systems is how much space it takes to store all the water. So the big
chunk of rock on top of the water column means you can store more energy in
the same space.

