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Storing wind-generated energy as gravitational potential energy? - Page 34

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Posted by Derek Geldard on December 9, 2008, 7:59 pm

ITYF it was a disused slate quarry, of which, everywhere one you don't

A singular aberration in time and money.


Posted by The Natural Philosopher on December 9, 2008, 11:52 am
Dave Liquorice wrote:

about 70% at Dinorweg.

If heat is what you want.

Low grade heat -> electricity is the worst efficiency of anyhting.

Posted by Neon John on December 7, 2008, 5:05 pm
 On Sun, 7 Dec 2008 07:31:41 -0800 (PST), John Nagelson

Ahhhh, another liberal arts major :-)  OK, smart-assed mode off.

there are two answers to this question:

A) we already are.  It's called hydroelectric power.  More specifically pumped
storage power.  Unfortunately it takes a whole lot of water to make a little
bit of electricity.  Research TVA's Raccoon Mountain pumped storage facility
to see just how much water has to be pumped how high to store just a partial
day's worth of output of the nearby Sequoyah nuclear plant.

B) gravity is very weak force and therefore it's very ineffective for storing
energy.  Back in the summer there was a scandal at Purdue University when some
kid announced that he'd invented a gravity powered lamp.  Supposedly a person
could lift up the built-in weight and  its gradual drop to the ground would
power the lamp the rest of the day.

Their public relations department failed to do even the most basic fact
checking before stumbling over themselves and releasing a press release.  We
ripped it apart pretty well in this group. I calculated that his specified
weight would have to be raised to approximately the height of the Empire State
Building to produce the amount of light he claimed.  In response, Purdue
public relations department issued yet another press release in which they
admitted that the kid had not actually built the lamp, but only simulated it,
but they still had confidence in his work.

This was sad testimony to just how bad the current educational system is.  Not
only did he make a huge mistake in his simulation, but he knew so little
physics of the real world that he didn't recognize the magnitude of his
mistake.  Many orders of magnitude, actually. There was egg on a lot of faces.
I should add that the amount of light that he claimed his lamb produced wasn't
all that much, certainly not as much is a good hundred watt equivalent compact
fluorescent lamp.

I don't recall whether his weight was 20 pounds or 20 kg but in either case it
demonstrates just how little energy is stored by raising a weight to a
reasonable height.  His first claim was that the weight only had to be lifted
to chest level to operate the light all day.


John De Armond
See my website for my current email address
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
There is much pleasure in useless knowledge. —Bertrand Russell

Posted by John on December 7, 2008, 5:29 pm

The hydraulic accumulators in Tower Bridge are interesting.


Posted by Tim Jackson on December 7, 2008, 6:03 pm
 John wrote:

They are, but did you know that the hydraulic service ring main around
the City of London of which this was originally a part, and which sat
unused for 100 years or so, got recycled in the '90s as comms fibre
ducts for the financial institutions?

Tim Jackson

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