

Dubai Tower generating 10x more energy than required to power it - themichael
http://www.designgeist.org/2008/06/rotating-tower-dubai-positive-energy-building-10x-by-dynamic-architecture.html

======
pingswept
This is ridiculous.

The designer, David Fisher, makes more detailed claims here:
<http://www.dynamicarchitecture.net/dubai-project.htm>

Judging by the drawings of his tower
(<http://www.dynamicarchitecture.net/schema/schema_big.htm>), it's about 300 x
50 m. Ignoring the narrowing of the tower as it rises, roughly 20% of the area
is devoted to wind turbines. That's around 15000 x 0.2 = 3000 m^2.

He claims that the average wind speed in Dubai is 16 km/h, or 4.4 m/s.

Assuming a Rayleigh distribution for the wind speed, the average power
available as kinetic energy in the wind is (6/pi) * 0.5 * (density of air) *
area * (average velocity)^3.

The density of air is 1.2 kg/m^3.

That's (6/3.14) * 0.5 * 1.2 * 3000 * (4.4^3) = 290 kW. If the wind turbines
were 30% efficient, which would be pretty good for a vertical axis turbine
stuck in a building, the yield would be 100 kW.

This ignores the narrowing of the building, the lack of wind near the ground,
and obstruction from other buildings.

The building has around 50 m * 50 m * 60 floors = 150000 m^2 of floor space,
so the areal power density is about 0.67 W/m^2.

To meet the claims of a 10x ratio between energy generated and used, the
building can budget 67 mW/m^2. That might be enough to light a single LED in
each room.

Oh, and the average temperature in Dubai is 27 C. I guess they can run the air
conditioning when all the LEDs are off.

~~~
michaelneale
Excellent and humorous analysis. Thanks !

~~~
pingswept
No, thank you, my good man.

As I've been thinking about it more, the most disturbing part of the tower
design is not the low energy yield. It's far more alarming that this gets
picked up as an exciting direction for development (judging by the discussion
of the tower on TreeHugger, Inhabitat, and similar sites).

I desperately want us to figure out how to capture energy from renewable
sources in an economically viable manner. If we don't do that, we are royally
screwed. However, the central problem is not, for example, that we have no
land for wind turbines or solar panels. The core problem is low power density.
We need to be putting up the most efficient, cheapest turbines we can build in
the windiest areas, not less efficient turbines in a not very windy area with
the added costs of building integration.

It's not a good idea that won't quite work-- it's a terrible idea that's
headed in the wrong direction. It's morons like David Fisher (the designer)
who give conservatives a reason to say "Bah, that renewable energy stuff is a
load of crap."

~~~
michaelneale
I agree. What we have with energy is a supply side problem. Yet all the
thought energy of the public is directed toward the demand side (either
reducing/conserving things, or changing the sourse). Yet if we were to solve
the supply side in a sustainable manner, we would solve a whole lot of other
things very very quickly.

~~~
michaelneale
Sourse? What the heck was I thinking ;)

------
willarson
I think "is expected to generate" is much more appropriate than "generating"
since it doesn't exist yet. I would have been suitably more interested if it
was real instead of a prediction.

------
tlrobinson
_"It will be continually in motion, changing shape and giving residents the
ability to choose a new view at the touch of a button. The form of the
building would constantly change as each floor rotates separately giving a new
view of the building as it turns."_

 _"Each floor, made up of 12 individual units, complete with plumbing,
electric connections, air conditioning, etc., will be fabricated in a
factory."_

[http://www.inhabitat.com/2008/06/09/rotating-wind-powered-
to...](http://www.inhabitat.com/2008/06/09/rotating-wind-powered-tower-to-
begin-construction-in-dubai/)

 _"In our buildings you can have breakfast facing sunrise, and dinner in front
of a sunset over the ocean... without moving from your room."_

<http://youtube.com/watch?v=RzQazjw-4jI>

Sooo... what happens when the residents on _both_ sides want to have breakfast
in front of the sunrise and dinner in front of the sunset? Maybe they need a
social-voting aspect to the building...

Anyway, this is still ridiculously cool, whether or not it's practical. I want
one.

------
sanj
This doesn't pass a minimal sniff test in terms of accuracy.

The solar energy impinging on the building will top out at 1kW/m^2, with an
insanely optimistic 50% conversion rate, I can't imagine it generating more
than 7500kW from solar.

That, by the way, isn't enough to run the hand dryers.

------
henning
Don't worry about all that environmentally efficient stuff going on in the
tower, most of the people who enter the building will drive there in $300,000
supercars that get 6 MPG.

------
wheels
There's the link with some actual info:

[http://www.inhabitat.com/2008/06/09/rotating-wind-powered-
to...](http://www.inhabitat.com/2008/06/09/rotating-wind-powered-tower-to-
begin-construction-in-dubai/)

------
xlnt
And how much extra did it cost to build the tower? This isn't free energy. It
has a cost. Any serious analysis would consider how much energy we could get
spending the same money on additional power plants.

