AWE Confusion

AWE Confusion

  1. What is AWE?

Vestas HAWT 9MW first test, set a world record for 24 hours generation at ‘rated power’ output (216MWh), see

Makani M600 Offshore first test -> no power generation results

What could the Makani AWE world record have been for 24 hours maximum power output?

  1. “Base Load Capable Renewable Energy” (Enerkite website quote)

Wind is an intermittent power source. AWE YoYo and FlyGen are erratic power generators, even when the wind is blowing.

  1. “save 95% of the material at the same power rating.” (Enerkite website quote)

The Enerkite schematic shows AWE CAPEX > 4000 €/kW - more expensive than HAWT. So to put it another way, AWE uses only 5% of the materials but costs more (see 4).

An idea that is along the same lines as :
“The concept of swept area is the key to extracting energy from the wind. The larger the swept area, the greater the amount of energy that is available to the system. Our system sweeps through a large amount of area – as much as eight times that of a relatively-sized surface-based turbine” (Joby Energy quote from the distant past).

  1. Performance (ref A) : Cosine losses of 35 -> 55%, and erratic power output, averaging 30 -> 40%, together, put AWE at ~20% of HAWT. Doubling (unrealistic) the Capacity Factor (CF) gives only ~40%. To get the same ‘rated power’ output, wings need to be bigger, generators need to be bigger … and it costs more.

  2. Power Curves (predicted)

Enerkite : rated wind speed = 8m/s, CF = ~70% (Onshore) (Enerkite website)
Makani : rated wind speed = 11.5m/s, CF = ~60% (Offshore) (Patent 20190154003)
Ampyx : rated wind speed = 15m/s, CF = ~40% (Offshore) (The Sea-Air-Farm Project)

Pick the winner(s)?

Note : at higher altitudes there are generally stronger and more consistent winds.
Note : the higher the rated wind speed, the lower the CF (and vice versa).

  1. Onshore or Offshore

There is no wind advantage for AWE Offshore (wrt HAWT), the wind shear is small, so CF is roughly the same (ref A). Makani M600 with a ‘rated power’ output of ~250kW, would need 48 units to match one 12MW HAWT.
Installation : 48 sets of cables (extra long due to spacing), 48 boat trips with crew (weather permitting). Maintenance (OPEX) : 48 …

So ‘Scale Up’ to MW, but the FlyGen & YoYo designs don’t scale (see M30 -> M600).

  1. Is it safe?

Safety is the top priority. Making a System safe can be expensive.

Tether breaks will occur occasionally. Single tether systems will incur high costs to demonstrate detached Safe landing in a farm, under adverse weather conditions.

Automated Launch & Landing will not always be successful during a unit’s 25 year service life. Kite crashes (and unparked kites) will have to stay within the unit’s land/sea farm space, under all conditions. Commercial viability will be dependent on the number (and cost) of kite/tether replacements per unit lifetime. Keeping the kite on the ground (safe) or in an unproductive state will decrease CF, and also affect viability.

  1. Levelised Cost Of Energy (LCOE)

LCOE is the metric used to differentiate between potential solutions.

The new Offshore HAWT GE 12MW, predicts < ~9 cent/kWh (current Offshore benchmark) in the near future, and Onshore HAWT is already at 3 to 5 cent/kWh (Lazard LCOE v13 2019).

The two most widely studied AWE designs (YoYo and FlyGen) give no evidence that they can compete with diesel at ~30 cent/kWh, let alone with HAWT.

  1. Miles Loyd ‘Crosswind Kitepower’ (1980)

The paper is well worth a read, because it introduces the concepts of ‘lift power’ (YoYo) and ‘drag power’ (FlyGen) using a quantitative analysis. These designs were plausible alternatives to the HAWT of the period.

HAWT has moved on, higher Capacity Factors, bigger size MW, much lower LCOE.

AWE needs to move on. AWE needs new designs that can compete (on LCOE) with the new HAWT.

  1. AWE Standard Design

The ‘Standard Design’ for AWE is still to be found, although some things seem obvious.

Imagine your first day at a new AWE Company. You are given a blank piece of paper and tasked to create a new design. The boss says “Where do we put the generator?” :
a) on the wing
b) on the tether
c) on the ground

Makani a), Altaeros b) and Ampyx c) have spent millions on different solutions.

There are no experts in AWE, just good ideas and bad ideas …

ref A) Offshore Comparison : Makani vs HAWT


Everyone agrees with what you say, but no one takes it into account.

Concerning crosswind single-line yoyo and flygen AWES, all go to dead end unless they size increase in regard to the tether length: their very low power/space ratio is the killer, their dangerous working preventing any secondary use.

The original error was to consider the power in relation to the wing area, not to mention the rope of one km stretched to several tons and moving at high speed.

Other concepts are discussed, comprising rotating devices.

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I share your opinion Derek. Sorry to say it again but I truly think AWE will remain low power units but with the great capability to harness almost permanently.
Another advantage will be mobility and low environmental impact. Concrete foundation is a huge issue to wind energy

I would be most interested to hear which parts of a standard AWE design which are most obvious.

I agree to your analysis, but it will not make sense to compare pricing for prototypes with well establishes HAWT. These HAWT are some really impressive pieces of engineering. No AWE team could build one from scratch. It takes a company years to get to that level, and so many engineering hours, runtime hours, refinements, scaling projects etc etc.

I think the reason to be in AWE would be to look past today and see what possibilities AWE entails. Some people (most) would call us fools, but others (like me) believe there’s a real possibility that AWE will be a real option for utility scale electricity production AND transport.

Wish I could chase both those at the same time :slight_smile:

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The more one learns about AWE, the less confused the picture. There have been claims on both sides of every major engineering option. Time is sorting it all out.

This is not a “either/or” choice. I pick both door number one and door number two.
The main cause of the cited “confusion” is the profusion of delusion - people who don’t know wind energy from baking cookies. By the time you’ve had a hundred or so wind inventions destroyed by the brutality the wind entails, it becomes a lot easier to see at least the things that probably will not work. But from the comfort of a desk, given the profusion of delusion, amounting to a whole lot of bad information floating around out there, it is easy to be fooled by stuff that is unworkable, let alone stuff that could work, but never achieve cost parity.
Example: The solar mirror arrays shining sunlight on molten-salt steam-turbine generators were “workable” but were almost obsolete by the time they were built, due to falling solar panel costs. Thank God there will probably not be any more built because no matter how far out into the desert they locate them, they are so ugly and disturbing to look at I think it’s only a matter of time before the two giant solar thermal electric plants out near Stateline (Nevada/California) along the 15 Freeway will be dismantled. They look like a UFO landed - so bright the air itself glows. Also, they not only kill birds, but barbecue them before they hit the ground. They work as advertised, and yet I do not think another one will ever be built. Then you have the solar-power-tower that was supposed to create a strong updraft in a tower for wind turbines to turn to electricity. Sounded “nice” - ya know, save the planet and all, making for years of convincing press-release-breakthrough articles, but somehow I don’t think the idea was ever compelling enough to ever actually build one, at least a full-scale version. Spain was supposed to be the site of one. People like me just looked at it, shook our heads and thought “Boy there sure are a lot of gullible people out there”. Out of the thousands of press-release breakthroughs you’ve seen, how many have panned out? One out of a thousand? No, that is a high estimate. How many new methods for wind energy? Zero? Try being ultra-skeptical, find the holes in these proposed “solutions” instead of just believing them, and your confusion will greatly diminish. Next press-release breakthrough you read, just say “no it won’t” and you will be right. No more confusion. :)))
PS: Bloomberg TV today announced Page and Brin leaving Alphabet (Google). It was noted by this financial news outlet that there is concern among investors that Google’s side projects have mostly not worked out and increasingly show signs of probably never becoming successful, appearing to be far less promising than previously anticipated. Not that we know about any such projects here… :wink:

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