

Technical advances that could make wind power viable everywhere - tambourine_man
http://arstechnica.com/science/2015/06/making-wind-power-work-even-in-low-wind-locations/

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Al__Dante
One thing to bear in mind is that there are theoretical Limits to windmill
efficiency:
[http://en.wikipedia.org/wiki/Betz's_law](http://en.wikipedia.org/wiki/Betz's_law)

In short, we can't extract more than about half of the available wind energy,
no matter what the design.

This is because if all kinetic energy is extracted, the air would no longer be
moving behind the windmill, so it would stop turning. Betz's law is the
optimum compromise between extracting energy and sufficient airflow to keep
the windmill rotating.

~~~
JoeAltmaier
I'm concerned about all the math being per-area, which makes bigger windmills
seem inevitable. But surely its per-dollar that determines commercialization
potential. 1000 small windmills could be the better choice if they could be
made cheaper per watt after all.

~~~
jacquesm
Wind energy economics favor: fewer blades (though the three bladed design has
some mechanical properties that make them the default choice), larger swept
area, horizontal axis turbine (even though you need to aim those at the wind
nobody has been able to produce a very large VAT that survived for even a
short amount of time), direct drive (because gearboxes are very much prone to
failure).

1000 small windmills would not be commercially competitive with a single large
machine, would not extract as much power from the same amount of wind and
would not be as safe. Small machines have to make a lot more RPMs so are
inherently higher maintenance (bearing wear), harder to operate when connected
to the grid and so on.

I'd love it if that weren't the case (which is why I built my own 5 meter/16'
machine) but ultimately wind power will be dominated by several MW behemoths.

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monk_e_boy
Living near a number of wind farms:

\- They are noisy in a very annoying way - Swoosh Swoosh Swoosh. I don't know
about you, but clocks ticking drive me up the wall. Now I can add wind turbine
blades swooshing do the same. It's not really a noise so much as a pressure
wave.

\- They strobe. Sometimes reflecting the sun. Sometimes the blade shadows fall
over you. Blink, blink, blink, blink.

\- They are efficient bird murdering machines.

I like the idea of wind turbines. Reality is not nice. Bring on solar!

~~~
JoeAltmaier
Its true solar is easier to live with. But regarding the last - solar is
efficient everything-under-them murdering machines. They sterilize the land,
similar to strip-mining but without the poison. So not really eco-friendly,
which is ironic.

~~~
summerdown2
There's still a lot of area available for solar power that doesn't involve
getting rid of plants, though. Deserts, house and car roofs, for example.

~~~
JoeAltmaier
Everybody says 'desert' as if it isn't the most delicate ecosystem on earth.
yes, solar panels covering up desert destroys that ecosystem too. Living
things there are totally dependent on the large amounts of sunlight.

As for houses and car roofs - that amounts to almost zero in the big scheme of
things.

~~~
monk_e_boy
The moon!

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enricobruschini
There are many more step forward the wind energy industry can still see. Not
only incremental ones. Before moving to SF I was at Energie Etiche, an Italian
startup that is bringing to the market an innovative wind assessment software.
By cutting the preliminary wind assessment time from 18 to 3 months and the
relative costs from $15k to $2k-$4k it's possible to open up the whole "Small
Wind Market" (aka <100KW)

~~~
Animats
Check out "Wind Prospector", which has a zoomable map and a wind model for the
entire United States.[1] It uses a climatic model and topography data to
calculate wind power potential. Spend a few minutes with that and you can see
where the wind industry can and can't grow. For the US, the big potential is
offshore and in the area due north of the Texas panhandle. California has four
good onshore wind sites, and all have big wind farms already.

[1] [https://maps.nrel.gov/wind-prospector](https://maps.nrel.gov/wind-
prospector)

~~~
enricobruschini
Yes, this is one of the possible approach to the wind assessment challenge.
Unfortunately it is not accurate below 250ft, the wind is not linear and this
kind of model doesn't count well enough all the obstacles at the low
altitudes. Therefore this model doesn't work for the <100KW turbines and when
it comes to >100KW, the investment is so big that you still want an on-site-
specific wind assessment. In conclusion this service is useful only for
curiosity or for preliminary observations

~~~
jacquesm
Local variations can be huge so you are spot on that for any site that expects
to produce power a local assessment is a must. Even so a chart like that helps
to determine whether or not going for windpower makes sense at all and how
much you can (on average) expect to get out of it indicating what your 'mix'
of renewables should be to ensure year-round power, which is especially
important for off-grid installations.

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danmaz74
> A European company is also selling a blade that is shipped in segments and
> then bolted together at the site of use.

Why is this "European company" not named? European companies are bad, while GE
is good?

~~~
jacquesm
I think that refers to Gamesa.

[https://www.google.com/search?client=ubuntu&channel=fs&q=gam...](https://www.google.com/search?client=ubuntu&channel=fs&q=gamesa+segmented+blade&ie=utf-8&oe=utf-8)

~~~
danmaz74
Thanks for the link.

By the way, what really irked me is that I notice more and more how EU
companies are very often shunned by US based media, which we in the EU use
ourselves as reference. This was really a blatant case.

~~~
mikhailt
US based media are highly tuned to what their readers want to read and just
focuses on American names/companies that their readers know most about in
addition to not caring about what companies are doing in EU.

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iaw
Did I miss a segment of that article on energy storage?

One of the most difficult components of making wind energy practical on a
large scale for any grid is it's lack of predictability. I suspect that things
are somewhat more predictable at higher altitudes but not so much so that it
mitigates the challenge of having a turbine that isn't necessarily going to be
spinning when you need it.

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jerven
There is a nice picture of a new 4MW Enercon model in
[http://www.enercon.de/p/downloads/WB_012015_GB.pdf](http://www.enercon.de/p/downloads/WB_012015_GB.pdf)
Showing most of these advances.

~~~
jacquesm
Enercon is absolutely incredible in how they steadily ramp up their production
capacity and improve the yield and size of their machines. They're engineering
marvels.

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toomuchtodo
Is there anything preventing us from fabricating rotor blades on-site at large
wind farms?

~~~
jacquesm
Rotor blades are extremely high tech, fabricating them on-site is
theoretically possible by using a mobile factory but that factory would be
several times the size of the blades that it produces, would need specialist
operators, very well controlled conditions for the curing phase of the blades
and a testing facility to ensure the end product is safe to install.

Compared to that fabricating them centrally and trucking them to the site
(usually at night using 4 rigs, one for the nacelle and 3 for the blades) is a
no-brainer from an economics perspective.

If an extremely large wind-park would be funded and planned many years in
advance you could possibly build a windmill factory near it at an advantageous
location and keep running it after the park is completed to supply other
localities nearby.

~~~
ars
What about using an unmanned, hydrogen filled, dirigible?

Either conventionally powered, solar powered, or simply towed from the ground
along roads?

I'm liking the towing idea. To deal with bridges have two cables, and some
drones to carry the cable over the bridge and back to the towing truck.

~~~
pjc50
Wind farms are usually built in windy areas. Dirigibles are less controllable
in windy conditions.

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joshdance
I can see how 3d printing could really help wind power. Printing rotor blades,
and maybe even towers onsite could have drastic savings. The same type of
powered platform that 'builds' cranes could be affixed to the tower with 3d
printing capabilities. At the end, after it has climbed up the tower it build
and printed the rotors, a crane could take it down, and install the mechanical
components.

~~~
jacquesm
The forces on rotor blades are _not_ in any way friendly or easily assessed,
3D printing 35 to 70 meter long structures with very well defined properties
and extremely high tensile strength as well as resilience against fatigue is
currently (and for the foreseeable future) not an option.

Windmill blades are limited in size by current materials science and requires
a very large amount of high tech composites such as carbon fibre, resins and
so on.

Towers are high grade welded steel, foundations are huge compared to the bit
of the tower that pokes out above ground and none of all of that is currently
made from a material that can be 3D printed.

