Laddermill

Rodread · February 12, 2019, 2:16pm

200 years is how long a molecule of CO2 stays in the atmosphere. There are way too many there already. So - We have to go to zero emissions. total cut. end of emissions.
I’m still going to fly. I want electric planes. (had a lovely family snowboarding holiday in Austria last week … melted another polar bear )
I’m still going to heat. I want electric heat-pump heating.
It’s bloody windy where I live and it’s similar at altitude in a lot of places. (Austria is wind dead apart from the foehn) The energy density of solar has massive implications for the area we need to use. High wind is massively energy dense.
If it’s viable to have massive turbines it’s viable to have working AWES.
Chat about Daisy (A very simple - multi kite - scalable - AWES ) was removed from

The
AWE prognosis .
basically says… AWES could happen if we just pull the finger out and get on with it.

Rodread · February 12, 2019, 2:20pm

@Tom
Do you consider all systems apart from Makani and KitepowerBV (By the way neither of whom contribute shit £&£* all to any public forum…) a pivot?
To me, It just seems like their basic architecture can be so massively improved on fundamental levels.

derek · February 12, 2019, 3:09pm

An AWE system is essentially, kite(s) + generator, or blade(s) + generator, or mixtures of both.
Whatever the flavor, there’s always a generator, so a generic system = wind energy extraction design + generator.
Where the design could be YoYo, Laddermill, HAWT etc.
The design defines how efficiently the generator is used.

A design that is 100% efficient will generate the maximum power all of the time 24/7.

YoYo has a very erratic power output over the cycle, giving it an average power of about 30% of the maximum. The design is 30% efficient.

For comparison, HAWT has a steady power output over the cycle, and the average power is close to the maximum. The design is about 95% efficient.

Comparing ‘rated power’ is easy, a 10MW HAWT is the same as a 10MW YoYo, they have the same ‘rated power’ output. They could both light 10000 1kW lamps 24/7.
But
HAWT nameplate generator size is 10.5MW @ approx 95% efficiency
YoYo nameplate generator size is 30MW @ approx 30% efficiency

So we have to build a 30MW sized YoYo, to get a 10MW ‘rated power’ output.

Note : nameplate power output is the maximum power output of the generator, just like in the hardware stores for sanders/grinders etc (labels attached to the machines).

Laddermill (Doug, Rod & Christof) is a better design than YoYo and FlyGen, because Laddermill promises a steady power output.

The reason that there are no products yet (of any design) to buy in the hardware store or for utility scale customers is simple. Launch and landing. Companies can not endurance test their products day and night, if a dedicated support team have to live at the field month in month out, to manually do this.
Automated launch and landing isn’t reliable yet.

Windy_Skies · February 12, 2019, 5:00pm

I used to think that too. But no, it is much worse. Current estimate is that one-fifth would stay in the atmosphere for tens of thousands of years. And a big percentage of the absorbed CO2 goes into the ocean, leading to ocean acidification. Together with ocean warming and overfishing this will lead to dead oceans in a little while, where now already the situation is dire.

Tom · February 12, 2019, 7:01pm

Not sure if I understand the word correctly anymore. I’ve figuratively interpreted it as performing a major change in direction. I have not seen any of those. So the non flygen or yo-yo can only be a pivot if they have previously worked on something different.

I’d be happy to see anything in economically viable operation. Improvements can still be made after and probably better funded and with more data.

Tom · February 12, 2019, 7:39pm

The natural interpretation of 100% efficiency is that the machine outputs 100% of the work put into it, which is impossible. In the case of awes that would be 100% of the wind in a defined volume or swept area. @PierreB seems to know most about these things. Betz limit and power available in the wind

But let’s go with your definition:

There is no physical law dictating, that the relationship between average and maximum power. We’ve got the one paper you quoted, but we don’t know the estimates of other developers. For example reel in phase might have become shorter.
By the way: It looks like they weren’t actually generating electrical power in that Article but only measured line length, and tether force and calculated the power from that.

By your definition of efficiency that holds true.^^ I doubt the relationship between maximum power and average power is meaningful. It would be better to just compare average power of systems which cost the same.
Seemy like you’re talking about the capacity factor. Solar, for example has a very low capacity factor of about 0.3 and is still one of the best ways to generate electricity.

Yepp. Automatic operation in general. Would need to be a damn large system to make it economically viable to have people there and then they couldn’t just move it manually.

derek · February 18, 2019, 10:49am

I propose a challenge, a video demonstration of the first commercially viable AWE design. Of course, the prize would only be a place in history.

It’s a simple challenge, run your Laddermill for 1 hour, and collect the wind speed and power output every second (or a faster sampling rate). Then plot the results on a graph, horizontal axis is time, and vertical axis is 2 plots, power output and wind speed.

If the power output is steady (for a given wind speed), you have won. If the power output is erratic, the system performs like YoYo and FlyGen.

Note that the wind speed and power output measurements should be collected as pairs, so taken at the same moment.

dougselsam · February 19, 2019, 7:40pm

Roddy: You and I are some of the few people who know what it’s like to live in a very windy location. I hear about storms and hurricanes and think “That’s a normal day in this mountain pass”. The last couple of storms brought us snow in the local mountains for skiing, and

Rolled a 25-foot-tall wood and steel “oil-derrick” style tower (laying on the ground, not upright) weighing hundreds of pounds across the yard;
Flipped over a cast-iron-and-wood “park bench”
Blew cast-aluminum chairs across the yard;
Caused a failure requiring at least a service call of a 22-foot-diameter 10 kW turbine on a 120-foot tower, all weighing several tons;
Blew over many many trees in the high winds with wet soil, to various downwind angles, requiring weeks of work to pull upright and secure with stakes, ropes, etc., and severe trimming far beyond what would be normal.
Blew over long woden fence requiring more stakes and lumber to push it back upright in several places
Water leaks on not only roofs, but windows and doors facing to windward including flooded garages from water being blown in under the doors
I’m sure I’m leaving a lot out, but you get the idea.
When you’re outside in it, you can barely walk.
Yup, windy areas: almost impossible to just live in…
Mostly, it’s a battle for survival.
People have no idea.

dougselsam · February 19, 2019, 8:04pm

I’d say without going into specific numbers, capacity-factors, Betz limits, intermittent cycles, storage, nameplate-this-and-that, something useful or promising will be self-explanatory, probably not requiring a lot of explanation or analysis to convince anybody.

derek · February 21, 2019, 12:58pm

Some commercially viable generators :

Type			Fuel

solar panel 		light
hydropower 		water
HAWT 			wind
diesel generator	diesel

The goal is to put an AWE entry into the list.

Given a constant fuel supply, none of the generators in the list has an erratic power output.

The ‘challenge’ isn’t optional, it’s part of the development process. YoYo and FlyGen have taken the challenge, and failed, the results (erratic power output) are in the first AWE book by R.Schmehl et al (Springer 2014). If the competition is weak, an inefficient design can still succeed, but Solar and HAWT grow stronger each year.

Utility Scale generators use LCOE (Levelised Cost Of Energy) to differentiate viability. LCOE basically means price and performance. One is no good without the other. A cheap system that produces very little power, or a high performance system that costs a small fortune, will both have a poor (high) LCOE.

Of course, there are different markets and competitors (see Lazard yearly report for LCOE).
a) onshore small/medium scale : diesel generator (LCOE approx 30 cent/kWh)
b) onshore utility scale : solar (LCOE approx 5 cent/kWh), HAWT (LCOE approx 5 cent/kWh)
c) offshore utility scale : HAWT (LCOE approx 10 cent/kWh)

YoYo and FlyGen have benefited from big investments. If another AWE design (e.g. Laddermill) is demonstrated to produce 3 times the ‘rated power’ output using the same generator (hence a lower LCOE), the investors will arrive.

PierreB · February 21, 2019, 1:51pm

The erratic power for both yoyo and flygen systems is due to the crosswind motion, as the elevation angle varies during the figure. Adding the reel-in phase for the yoyo system where some energy is spent.

Rodread · February 22, 2019, 11:10am

Smooth constant power for grid energy normally comes from gas or steam turbines… polar arrays of multiple small blades on wide diameters and multiple stages too… Which AWES rig does that remind you off?
The tilted hollow axis, multi stage, ring mounted multi kite rotor
Well I call it Daisy

Annoyingly - There’s a company called kite turbines http://kite-turbines.com
(Must have realised their blades would be better off in tension)

Diesel generators are noisy and reciprocal piston motion is inefficient.

I think the laddermill vs single kite problem is kinda analogous with transistors…
You can still make a transistor from a vacuum tube (and some people pay a fortune for that https://hackaday.com/2019/02/20/retrotechtacular-how-not-to-design-with-transistors/)
but just try packing them by the billion into a useful, reliable arrangement, which is easy to use and portable. modular silicon cellular structures won

dougselsam · February 22, 2019, 6:50pm

Also annoying:
https://www.solarturbines.com/en_US/index.html

Rodread · February 24, 2019, 2:24pm

Unwind - release the pressure
That’s the key to kite survival

PierreB · May 14, 2022, 12:35am

Laddermill with Magnus cylinders.pdf (139.5 KB)

tallakt · May 14, 2022, 7:21am

I think if we consider L/D of 3 for the sharp rotors, if you also consider the drag of rotors in the return phase, the L/D for a pair of sharp rotors may be as low as 1.5. This gives an unloaded elevation angle of max 55 degrees approximately not considering gravity and the lifter kite. If you load it by spinning the pulleys, that reduces that angle to 20-30 degrees I suppose. In which case gravity will hit you very hard in particular for low wind operation.

Seems to me you need a quite large lifter to support the concept. So the large lifter combined with <50% utilization of the sharp rotors I think for me it puts the concept under the not worth it line. This because existing wind power can do the same job simpler and cheaper. my 5 cents

PierreB · August 21, 2022, 8:19am

A cableway looks a little like a “Laddermill” (see the video below, at 0:10):

A more or less vertical cableway where cars are replaced with crosswind kites flying almost vertically on both sides:

tallakt · August 21, 2022, 9:53am

That airborne pulley will never convince me. Any airborne structure should be rag’n’string™ or carbon fiber flying at high speeds.

I am attaching the straightforward solution to this. I have drawn only one kite but there should be several. If each kite has two tethers attached to the “carousel” they may also depower automatically.

Also to make much sense the kites should spread out to either side.

wind blowing in this direction

PierreB · August 21, 2022, 11:39am

Laddermill projects by not crosswind kites going downwind to power, and depowered kites going upwind without tension led to multiple issues: more complexity, high risk of tangle between the two rows of kites, low power as for yo-yo aligned (nor crosswind) kites…

Spidermill variant intended to improve it by adding a crosswind component, but by adding still complexity.

So, in my message I intended to take a cableway as an example: all cars are powered, as for crosswind kites going up and down in the crosswind Laddermill. So the geometry is a bit different: the two strands of the rope drive system are facing the wind.

As shown on the drawing, the kites are offset from the strands to avoid tangles and the problem of passage to the pulleys.

As the drawing suggests, the upper pulley is actually an aerostat or kytoon reinforced around its circumference. I prefer to have an airborne top pulley in this way (although the proof of feasibility remains to do) rather than a tower supporting the top pulley. For the lower pulley, the question is open. I think this aerostat or kytoon should be large enough to prevent the kites from slowing down, and also to support the system.

Thus, each kite has its own tether(s) attached to the rope drive system, so that a control pod allows it to go as vertical as possible.

Re-edit: the aerostat-pulley should rotate with the rope drive because it cannot counter its torque. As a result it cannot be a kytoon.

I think my two last comments include a lot of wrong things, but it is not too important for any Laddermill.

dougselsam · August 21, 2022, 3:23pm

Thanks guys: I’m not really quite understanding the 2-D drawings here. It might help to add an arrow designating “wind direction” since a term like “facing the wind” doesn’t tell us much.
The original laddermill-type concept, both in my original design from the 1970’s as a teenager, and the subsequent Ockels versions (as far as I recall) utilized the same passive geometry that would SEEM, from looking at drawings and thinking about it, to tend toward avoidance of tangle between upward-traveling and downward-traveling parts of the apparatus. While the opposite direction of travel is certainly worth considering, at this point I’m not convinced it reflects a best, workable configuration or even necessarily a workable configuration at all. Of course if anyone had had sufficient strength of their assertions for so many years, and had put a small fraction of the effort into building even a single, miniature “laddermill”-type configuration, we might have a better idea of actual operational characteristics and parameters. By this point I don’t expect any such thing to happen unless I can get to it, meanwhile the ongoing brainstorming is welcome and interesting in my opinion.