

Massive Energy Skyscraper Proposed On U.S.-Mexico Border - samsolomon
http://www.forbes.com/sites/davidferris/2013/03/26/massive-energy-skyscraper-proposed-on-u-s-mexico-border/

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brc
EROEI will kill this thing stone dead, if the world is still thinking
rationally.

Note that it is essentially a solar installation, it doesn't really say if it
works during the night. But you can safely assume that if it works on
temperature, the headline 'nameplate' figure of 500 gw is only available in
peak conditions.

It says it uses desalinated water - which is a very energy intensive
operation- so at best I figure it would be mildly energy-neutral, at worst it
would actually be an energy suck. Then there is the small matter of all the
embedded energy in the worlds second tallest structure. The costs are $1
billion for the tower, $100 million for the pipeline, and desal plants are
about a $1b a piece these days. That's $2.1 billion invested - not including
transmission lines - that's going to take a very long time to earn back.

It looks like a subsidy farming exercise to me, or possibly a stock
pump'n'dump scheme.

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richardjordan
Any time people think in terms of EROEI they get an upvote from me, as it's
the problem with so many plans.

I was hoping from the headline that this was a conc. solar tower or something
similar, as have been described in the past and which have a chance of being
EROEI positive.

Sadly few people see the world in the eyes of basic physics and energy return
on energy investment. Most of the utopians who believe we'll think ourselves
out of the energy crisis without having to make any lifestyle changes or
depopulate tend to rely on arguments that are almost always EROEI negative.

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drucken
Wait, what...

1\. massive water dependency in middle of the desert

2\. dependency on pipeline through foreign territory

3\. dependency on foreign border integrity

4\. adjunct to military territory

...mmm, what could go wrong?

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ximeng
Follow up: [http://www.forbes.com/sites/davidferris/2013/03/26/your-
ener...](http://www.forbes.com/sites/davidferris/2013/03/26/your-energy-
skyscraper-questions-answered/)

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dmotles
Do you seriously get surplus energy despite pumping water from 46 miles away
and then 2000+ ft up in the air?

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mmphosis
I was wondering about that too. Plus the energy required to desalinate the
seawater.

<http://en.wikipedia.org/wiki/Energy_tower> (downdraft)

My first thought was that they were building an updraft tower.

<http://en.wikipedia.org/wiki/Solar_updraft_tower>

[http://www.livescience.com/2644-giant-solar-tower-power-
futu...](http://www.livescience.com/2644-giant-solar-tower-power-future.html)

~~~
ndonnellan
Me too. The difference is that a solar chimney makes sense, kinda. I have no
idea what this downdraft tower nonsense is. Converting potential energy to
kinetic? 46 miles of pumping expensive water?

~~~
richardjordan
Right... I've heard of the concentrated solar towers which create an updraft
to drive turbines in a very tall chimney, and seen suggestions that they COULD
be made to be net energy return on energy investment positive. But this one is
pretty new to me. I think it's time to pop over to see what the folks on
TheOilDrum.com have had to say about this - they must have seen it and are
probably ripping it apart by now.

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racbart
I really like the idea of solar updraft tower, where air moves the other way:
<http://en.wikipedia.org/wiki/Solar_updraft_tower>

It's disadvantage is that it requires much more land, but it doesn't require
water on the other hand. As someone noticed, the water-powered downdraft
version requires pumping water from 46 miles away and then 2000+ ft up.

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fernly
"Solar Wind Energy has said... that each tower would require a permanent
workforce of 1,000 people." Doing what, exactly? That has to be a bogus
number.

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gavanwoolery
Is it wrong that the first thing I thought of was this:

<http://majorslack.com/pics/screenshots/redalert_03.jpg>

?

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jayfuerstenberg
A Canadian company, AVE Designs, has a similar idea but with an upward moving
vortex...

<http://vortexengine.ca/index.shtml>

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alimoeeny
something is not quite right here, does this make sense at all to anybody?
even if for some reason air on the top is hotter than the air next to the hot
ground, after a short while the draft itself, makes a local equilibrium, and
it is hard to believe you can over come this by spraying water and cooling the
bottom of the tower, and all of this just by testing on a 4 feet tall model in
Maryland?!

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graycat
My take was that the crucial 'energy' issue was the huge latent heat of
evaporation of water that cooled the air at the top of the tower. So, the air
falls in the tower partly, maybe mostly, because it is cooler and, thus, more
dense, not because the air is more dense because it is wetter (is air less
dense than water vapor?) but because it is more dense because it is cooler.

Then I would wonder how to recapture the water without losing a lot of energy,
that is, would be fighting the huge latent heat of evaporation again? And I
would wonder just why bothering to desalinate the water?

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chii
> And I would wonder just why bothering to desalinate the water?

perhaps it sucks to have salt deposits due to the evaporation?

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chroem
One word: corrosion.

I honestly don't think this idea is too far fetched, though it's going to need
subsidies to get going. If it all works out, then it would be pretty
revolutionary.

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Cryode
What a giant eye sore.

