DaveS,


"Lifting a rhinoceros is your original contribution" you agreed on your precedent post by writing "Mothra can do all the things you ask, and more."

I advice you to make less personal attacks and more electricity production or at least more correct analysis of AWE within its environment.

PierreB

All questions are complex and require an analysis of environment. For example in European countries the density of population is such as implementation of tethered-AWES or dense array or arch on most places would mean tethers and wings flying above or among people. I live out of town, I see an important quantity of wind turbines,and I do not see any place where AWES could be implemented at utility-scale. And in the end it is not me who decide of implementation or not, but authorities like city hall or country. 

In USA, in Canada, Australia, Africa...,there are important desert regions where AWES can be implemented, and where land use is only a problem of cost among others.
And also the analysis of land use is not quite the same for systems harnessing relatively low winds where all wind directions are considered, and for systems harnessing very high winds. The analysis differs also between crosswind kites (greater risk factor) and _more or less_stationary devices.

PierreB

DaveS,

"What you wrote against kite buggying as a kite sport somehow beneath "serious players" is simply not true. KiteShip first took me to NABX in the Mojave desert, all expenses paid, to teach me how to kite buggy..." No, I qualify as serious the players who definite a purpose ,here producing electricity since this is the main subject of the forum, but there making buggies, and try to realized their goals rather than anything being able to make everything. 

PierreB

DaveS,

I hello your and JoeF's work in such tragic conditions. Note also contributions from me or DougS try raising some truths about AWE, even if they are not so agreable to hear. Positive contributions can take also unpleasant forms.

PierreB

Harnessing High-Altitude Wind Energy

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"Wind speed maxima (WSM) is mentioned in joined C.Archer's paper "Airborne Wind Energy Optimal Location and Variability".

An extract: "

In this altitude range, 200-3000 m AGL, wind speed generally increases

monotonically with height, with higher gains (shear) in the boundary layer and more

modest increases above it. However, a variety of weather phenomena can

invalidate the general rule-of-thumb that better AWE resources are available at higher

altitudes, for example low-levels jets (LLJs). LLJs are narrow, nocturnal wind speed

maxima with cores centered below 1000 m that form at a several locations worldwide due

to a favorable combination of synoptic conditions, regional topography, and local

stability , discussed later. Here we include LLJs as a subset of the broader category of

wind speed maxima (WSM), defined as jet-like wind profiles centered below 3000 m

regardless of the formation mechanism and diurnal variation. Our hypothesis is that

locations with WSM are ideal for AWE applications because wind speed and wind power

densities near the WSM are as high or higher than those normally found elsewhere at

greater elevations, but at much lower altitudes. The height of 3 km is not based on

physical properties of the atmosphere, but rather on practical limitations of current and

near-future AWE systems. Since tethers longer than 5-6 km can weigh more than a ton,

flying altitude will not exceed 3 km as tether angles remain lower than 30°. As such, only

jets that are located below 3 km are of practical interest for AWE applications and are

therefore the focus of this paper.

The most well-known WSM are the nocturnal LLJs that form below 1 km AGL

(and often below 500 m) at several locations worldwide , both inland

and along coasts ."

(PierreB)

A farm of units with their respectives tethers is too difficult to manage, does not allow a maximization of worked area, and generates important hazards. Solution? : several,even a multitude of linked (finding appropriate means) devices, only one tether. Perhaps also some hydrogen balloon keeping lift.
If it is possible such an AWES can meeting some qualities being stationary (so safe as TARS, less stress in materials, better possibility of maximization of worked area, less land used), and scaling-up by conglomeration.

PierreB

A farm of independant units is too difficult to manage, does not allow a maximization of worked area, and generates important hazards. Solution? : several,even a multitude of linked (finding appropriate means of links) devices,avoiding collisions between units, and allowing maximization of space.
If it is possible such an AWES can meeting some qualities being stationary (so safe as TARS, less stress in materials, better possibility of maximization of worked area, less land used), and modular scaling.

PierreB

Hi MikeB,

I read your analyses in AWE and I generally agree. AWE is now far to provide usefull production in reliable way, and actual designs do not seem to be performant actually. But other designs or combinations are possible... 

Sometimes AWES are presented in the same level as fancy wind turbines making also not usefull production. But here is the problem. Fancy wind turbines compete with good turbines in the same resource,while high altitude wind energy (HAWE) 300-10 000 m) is another energy resource than current winds harnessed by HAWT (50-200 m). HAWE has been recently identified by C.Archer and Ken Caldeira as thick and huge reservoir.

Then AWES are expected to harness it. What is the difference? Fancy turbines will make zero production for ever. AWES can make zero, then 1% 25 years later. If a device involves a new resource, the new resource must be considered in first. So ground-based wind turbines progress in the world, the cost becoming competitive. HAWE and AWES will add their own contribution when the will become mature, without replacing HAWT (both not the purposes and not the same sites) but improving the percentage of the whole renewables. The better way to push AWES is ...to continue to critize them, obliging the concerned researchers to meet on a method making the unanimity.

Best,

PierreB

Yes DaveS,

I agree. As you say AWES must sweep the whole frontal area of the space used. The maximization of space is a key point you rightly teach. I think Dr.Beaujean makes a "simulation" of what are features of an utility-scale AWES: a stationary rotating great set instead of a farm of independant unities sweeping a small effective area and being able to collide between them.

An arch has two anchors. So it is more stable but not naturally rotating, so being not able to follow quick wind changes. And an arch lifts but does not convert by itself.

PierreB