Metrics or equations? Power curves or simulations?

Recording a power curve (power vs windspeed graph) is normal in wind turbine development. However, since kite-reeling does not deliver continuous power, it could be a little more complicated. But for utility-scale wind turbines, the windspeed is averaged over ten (10) minutes, so I don’t see anything preventing the generation of a power curve for any system that operates for five hours at a time. Over the years, I’ve experienced developers of vertical-axis drag-based machines wanting to be taken seriously just on the basis that they rotate, without even having a generator attached. Some of us also may remember Santos postulating that the wind industry had become too dependent on power-meters, when responding to demands that he back up his various claims of kite-power breakthroughs with no numbers to back up his claims.
Certainly, at some point, since the entire point of any of these clean-energy projects is the production of energy, the most relevant question is how much energy is being produced. Not all companies may want to share that information, but the data should be there in some form, I would think.
In general, I would say, if a wind energy system developer can go on for years without sharing output data, there is probably a reason, since power output is the main goal. Experience would suggest that no publicized power output data could indicate a lack of impressive numbers to share, which could indicate a general problem with power generation.

Interesting information. If you can reply, do you mean that for Kitemill prototypes the shareholders are well informed about the schedule of the company, not content to demand production at the moment T, but participating in the development process of the complete project?

The shareholders would get information about progress and delays, while the public would only be notified when something is ready to be shared in public. There is nothing special here. Sharing information in public is not straightforward due to rules on insider trading, not particular to Kitemill. I am not the one dealing with this, so maybe direct further enquiries down the proper channels.

If you are looking for admitting that Kitemill is in some way «playing» the public, I can only say this is far from the case. I would testify that any news Kitemill shares reflects well what happens inside the company. But of course not everything is shared with everyone. And you guys seem a good example why that is maybe not a good idea.

So if you want the most detailed and updated status update from Kitemill, I suggest you look at the news section of the home page. It should be quite accurate.

You are referring to «mature technology» windmills, where you make a windmill with a slight or no changes from previous iterations. In that case the windmill will probably go straight knto 24/7 operation and after a year or so you will have a power curve.

I was referring to the days when windmills were not mature technology, and once build maybe broke down after just a few days worth of use. Or maybe was never used. Even though they contained useful innovations that were later commonplace.

The experimental wind farm in Balaclava (in Crimea) with capacity of 100 kW was developed under direction of inventor Yuri Kondratyuk and installed there in 1931. Before the war, it produced electricity for the Balaclava-Sevastopol tramline. During the war it was destroyed.[7]

Actually, it is easy to get a power curve in an afternoon, if you have good winds that day. It is a very simple thing, using wind speed and electrical output sensors, and feeding the data to an excel spreadsheet. The spreadsheet will feed you back a graph with a typical shaped cloud of data dots, and a superimposed average power/windspeed line (power curve). In truck testing, I can take a power curve in about 1 minute, driving with my left hand while writing down output and speed with my right hand. Well, it does help to make a few runs in each direction, so let’s say 5 or 10 minutes for a good quality power curve using a truck.

Also, I’ve never heard much about wind energy in Russia, but, the Danish Concept, which is how windfarms got their first real start here in California, resulted from farmers that needed power, building the simplest design anyone could imagine, and they worked right away. The first home powered by a windmill was by a guy named “Brush” who made a giant (but low) version of a typical farm water-pumping windmill, and I believe it found immediate use powering his home. Some wind systems just work the moment they are put up, and keep working.

Classic “Only 2 types AWES” BS references
If you want another
Ollie published a power curve for the tests on early Daisy Kite Turbines in his PhD
The early soft ones weren’t very impressive power or efficiency admittedly. Rigid ones were impressive.

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Yes, and there are a lot of documents with metrics and power curves or power data for Daisy and showing high efficiency. Similarly I mentioned in my initial post:

It looks like rotary AWES (Kiwee, SuperTurbine ™, Daisy) go well with metrics and power data, perhaps because there are closer to the regular wind turbines than crosswind AWES, in first the ones which use reeling mode.

And because you can leave them running unattended without needing a control system to keep them in the sky, this gives you time to get more than a couple of loops worth of data

One problem to finding a power curve for an AWE rig; what is the wind speed? If the rig is of some size, the one option would be a LIDAR, already out of the budget scope of many AWE companies I suppose

I thought there was some equation by a guy called Tallak which could tell how windy it was just by looking at some string in the sky

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Very nice example of stone-age instrumentation, Roddy. See? Stone-age people were smarter than we think! :wink: I’ve long imagined an analog meter for windspeed. Take a visible arrow hanging down like a pendulum, and place a graphic scale against it, then use an anemometer to calibrate what angle = what speed, and voila - instant easy-to-read windspeed sign. It would have to pivot like a weathervane, so you would also get wind direction out of it. Very much like the rock, it could also show rain if it was wet, sun if it casts a shadow, etc. But seriously, it would be an easy way to show windspeed and direction, at whatever height it was mounted. Or one could just mount an anemometer and wind vane up there are take the data. If you are flying at a higher height than the instrumentation, that can either be factored in and the higher windspeed estimated, or just specify that the power curve is based on the windspeed at height X. if you are comparing your powercurve to a turbine at height X, that could work out OK.

Having access to LIDAR data I can only say the wind gradient only holds as an average. Today wind was constant on the LIDAR 100-500 m, then much less. Other times, there are «rivers of wind» at some altitudes…

You would need a second kite or drone at the correct altitude to do it right without LIDAR. But most AWE developers probably dont care too much because we are still just learning to fly at all, and it doesnt make sense to make a power curve until control strategies have matured to a minimum level.

AWE is not like windmills if it is computer controlled. The job is not done the moment the blades come out of the mold.

Anyways. I support the demand for power curves. WHERE ARE THEY? I DEMAND ANSWERS!

Sure, I like power curves or power data. I know what Kiwee and Daisy are up to, providing continuous power at an assumed known altitude, above all for Daisy where the wind speed measure is easily made at a correct altitude by using a mast, while an anemometer on Kiwee could do this job.

For crosswind reeling (yo-yo) or fly-gen devices it is a bit more difficult, and there are very few power data. For them putting on the kite a good old anemometer measuring airspeed when the kite flies (as it is already done), and measuring wind speed the times when the kite is stopping (between the zig-zag turns during power phase when figure-eight is applied, between reel-out and reel-in phase), then cross-check the data, such like deducing wind speed by kite airspeed when the kite glide ratio is known in the concerned range.

There’s a power curve at the end of this prospectus document from kitepower

They’re crowd funding
Have you got €10 for this venture?

Perhaps only for a valid power curve :grinning_face_with_smiling_eyes:, unlike the operation schema mentioning likely an estimate of the power:

Here the journalist takes the information from the Falcon page already linked above: 100 kW, 150 households supplied. On the other hand the website provides also the value of 450 MWh (not the incorrect “100 kW per year”), which allows a high capacity factor to be expected.

But useful metrics should lead to real power curves, not only the manufacturer’s information.

@dougselsam if a small household is careful 1kW is sufficient in most of the world. North America hmmm not so much because you wouldn’t be able to leave the bbq cooking, while heating the pool and shampooing the car… Whatever it is you do with all that energy

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Hello Roddy:
If your location were powered by wind energy, like our facility, you would know better than to say that.

  1. There is a huge difference between a wind energy system with a rated power of 1 kW, and 1 kW of continuous power. No wind energy system achieves a 100% capacity factor.You have to multiply the rated output by the capacity factor of, say, 0.3, to get the actual average output, which, for a 1 kW wind turbine, should be about 300 Watts. (Then again, how many people would put a 1000-Watt turbine on a high enough tower to get a 30% capacity factor? Also, almost no house is located in a good wind resource.)
  2. It is well-known here in the U.S. that you need a 10 kW system, whether solar or wind (assuming you have a REALLY GOOD wind resource) you will have the equivalent of 2-3 kW continuous power from a 10 kW system.
  3. Yes I am somewhat aware that the smaller houses in Europe use less power than homes in the U.S., but if you think any will be self-sufficient with all power provided by a 1 kW wind turbine, you are dreaming. And you are always working, you need vehicles large enough to carry a lot of materials, lumber, paint, tools, lawnmowers, chainsaws, weedwhackers, fuel, oil, people, etc. Real living requires real energy.
  4. Average power used by houses around the world would include many mud huts and minimal shelter in undeveloped areas, often with no heating or cooling systems, cooking with dung as fuel, etc. It makes no sense to include such minimalist living conditions in a discussion of powering developed areas. (not that I don’t appreciate minimalist lifestyles, but if you want to get a lot of stuff done in the modern world, you are going to need energy.)
  5. I’ve noticed Scottish clean energy people seem jealous of our standard of living here. To me, it feels bare bones. I’m not living high on the hog. I bust my ass for very little reward. All I can say is thank heavens for LED light bulbs. This place has something like over 70 light bulbs of outdoor lighting. Many of the light fixtures have 4 bulbs. I can barely manage to turn all seven switches on and off every day - I usually miss at least one, due to getting sidetracked. I had quite an electric bill when our second Bergey 10 kW wind turbine failed, until I replaced it with Bergey Turbine #3. That took a large crane, many skilled workers driving over 100 miles, with trucks full of tools, and used a lot of energy. Nice to know the latest turbine is usually putting out a few kW. Almost always spinning. Brings my bill down to near zero most years, and once every few years we go over our use and they send me a small check, which is a tiny sum compared to the cost of even just maintaining the wind energy systems.
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I think with benefit of the doubt… As I only mentioned consumption…
Yeah fair points. Hold my hand up. Spot on @dougselsam The article is waaay over claiming on houses supplied equivalent, without considering capacity factor

I was just outside in about a 30 mph wind (hard to walk in) when suddenly it hit me:
My friend who was the head of Anemometry for GE Wind lives with his wife in a small cabin in a remote location on a hill near the GE windfarm, and their small cabin WAS powered by a 700 Watt wind turbine and batteries when I met him. Heating was from a wood-burning stove. They ran everything else off that 700-Watt turbine and batteries. They had to be extremely careful using minimal lighting, small appliances, teeny TV, little laptop computer, etc. Their lifestyle was so spartan it was really almost like camping. Most people would never put up with it. At some point he started adding solar panels. About ten years ago he told me “Doug, wind sucks, solar is the way to go”. The wind turbine wore out. He gave me his tower for one of my test sites. These days he has all the (solar) power he needs. He buys big lots of solar panels at auctions and sells them off in small batches. He has all the power he could ever use, no more skimping, just lots of solar.

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