Google-X Makani Wind Turbine Kite

[jai mitchell]

http://www.businessinsider.com/google-x-is-putting-giant-wind-turbines-in-the-sky-next-month-2015-3

Google X is putting giant wind turbines in the sky next month

AUSTIN, Texas -- For its next trick, Google will begin flying 84 foot-long airborne wind turbines, said Astro Teller, the head of Google X, the company's lab of moonshot projects.

Google has been working on Project Makani, as these wind turbines are called, since buying a company of the same name in 2013, but until now, the search company has only been testing 28-feet long test models. The new kite turbines set to be introduced next month will be full scale

The Project Makani kites look like the wingspan of a large airplane minus the cabin in the middle. Each kite has eight propellers that it uses to take off and a tether that keeps it attached to the ground. After the kite ascends to the limit of the tether, which is more than 1,400 feet, the propellers stop climbing, Teller said. At that point, they begin serving as flying wind turbines and the kite starts doing large circles in the sky. Combined, this generates 600 Kilowatts of energy that is continuously sent down the tether.
 

A good concept video with demonstration of the prototype made by Makani in 2011 is here:



600kw of continuous power sounds pretty good to me, I wonder why they don't go higher than 1,400 feet elevation?

[Sigmetnow]

600kw of continuous power sounds pretty good to me, I wonder why they don't go higher than 1,400 feet elevation?

Interesting concept.

Depending on the location, 1,400 feet can easily be an aviation hazard.

[Neven]

Cool video. I read about these kites years ago. Good to see that they're still working on them.

I wonder how much better these things could get compared to wind turbines on the land, and also whether their resource footprint would get lower. It takes a hell of a lot of concrete, steel and rare earth metals to build wind turbines.

[LRC1962]

Wikipedia, Airborne wind turbine
Airborne wind turbines are not a new concept. In theory they should be more productive because you can get into more dependable winds. Two major problems are, they all have their own technical hurdles that as yet have not been solved and because they go into the more nontraditional realm of research, lack of adequate funding. As Google is funding it that side of the equation should not be an issue.
The Technical side is always a wait and see. Many good ideas have look very good until that last little problem that needs to be solved and there it ended.
But as Edison said.

I have not failed. I've just found 10,000 ways that won't work.

[jai mitchell]

Cool video. I read about these kites years ago. Good to see that they're still working on them.

I wonder how much better these things could get compared to wind turbines on the land, and also whether their resource footprint would get lower. It takes a hell of a lot of concrete, steel and rare earth metals to build wind turbines.

I did a calc once and found out that the amount of concrete for a wind farm that is comparable to a 1970's era u.s. nuclear reactor is almost twice the concrete in the nuclear plant.

[Tor Bejnar]

I did a calc once and found out that the amount of concrete for a wind farm that is comparable to a 1970's era u.s. nuclear reactor is almost twice the concrete in the nuclear plant.

Sorry, Jai Mitchell, but this isn't clear to me.
In those calculations, did a wind farm use twice the concrete of a (similar output) nuke plant?
Or is the concrete in the nuclear plant twice the concrete in the equivalent wind farm?

[jai mitchell]

For the same kwh generation, the volume of concrete for wind was double.

[Tor Bejnar]

Thanks for the clarification.
The bad news, of course, is that concrete production is a significant contributor of atmospheric CO₂. (for reference: http://www.global-greenhouse-warming.com/cement-CO2-emissions.html)

[GeoffBeacon]

Tor

That's why we need a decent carbon price, rather than subssidies.  The embodied CO2 in wind turbines would soon be much less. e.g. magnesium cement. What about wooden blades - we had wooden propellors - perhaps I need to check if that's looney.

[ghoti]

Carbon in the form of carbon fiber is sequestered in the turbine blades not released. This should count as an additional GHG offset credit.

[ghoti]

Oh! Just realized ALL the sources I found immediately when searching for concrete usage for windmills were anti-wind looney sites. Not only do they use practically infinite amounts of concrete the final product causes every illness known to man.

So for now i'm not inclined to put any faith into the concrete usage comparison. When/if I can find reliable numbers I'll revisit the conclusion.

[jai mitchell]

http://www.awea.org/Resources/Content.aspx?ItemNumber=5083

In 2012 alone, the U.S. wind industry installed over 6,700 turbines. To install that number of turbines, the U.S. industry required 20,100 blades and the same number of tower sections, approximately 3.2 million bolts, 36,000 miles of rebar, and 1.7 million cubic yards of concrete (enough for more than 7,630 miles of 4 foot-wide sidewalk). There are over 8,000 components in each turbine assembly.

American Wind Energy Association

[ghoti]

So 2012 saw 60 gigawatt of wind installed in the US using 1.7million cubic yards of concrete. I think that's 28,000 cubic yards per gigawatt.

The concrete construction report on Hinkley Point says

The work is typical, even though Hinkley Point is the world’s
largest nuclear station, with an output of 500,000 kilowatts for the two
reactors. The total quantity of concrete placed exceeded 300,000 cubic
yards.

http://www.concreteconstruction.net/Images/Construction%20of%20Nuclear%20Power%20Stations_tcm45-344339.pdf

That's 600,000 cubic yards per gigawatt.

With all this I've forgotten what the point of this discussion actually was but it doesn't seem to me that concrete and the one time CO2 it generates isn't the driving factor when switching to renewable energy which requires no fuel and generates very small amounts of waste.

[jai mitchell]

New capacity installation for wind in 2012 was 13.2 GW  to compare to a nuclear power plant the capacity factor is about 1/3 the installed capacity.  so nuclear equivalent is 4,400 MW of capacity.

Don't forget realization rates,

Ground based wind turbines have about 31% capacity factor while nuclear is closer to 97% capacity factor.

so 1.7 million cubic yards of concrete is 386 cubic yards of concrete per MW for wind

According to nuclear industry records, the concrete per nuclear power station is 400 cubic yards per MW.  So it is certainly comparable.

http://www.nei.org/Master-Document-Folder/Backgrounders/Fact-Sheets/Nuclear-Power-Plants-Contribute-Significantly-to-S