True, but it should be aligned with the prevailing wind directions at the very least. And I believe the wagons should move very fast, maybe 40-50 m/s so that would put severe restrictions on which tracks to use.
And it you travel far, the wind resource will vary a lot. Again maybe not if you are crossing a desert
I am not sure about this. 40-50 m/s can be the speed of the kites as they fly crosswind by figure-eight as shown on the website. Perhaps the speed of the wagons could be something like about 15 m/s, maybe even less.
I recall a piece of information about the speed of the KiteGen carousel which is also much lower than the speed of the kites (see the document below on the next comment), a bit (but not quite) like the speed of the tether during the reel-out phase for yo-yo systems, also compared to the speed of the crosswind kites.
In general I’m not sure that such huge infrastructures lead to economically viable solutions.
Document from KiteGen:
From page 14/27:
how much energy can be generated ?
The turbine rotates at 0.16 rpm, with tangential speed of 5 m/s (18 km/h)
Simulation of a single KSU
kite area A= 100 m²
kite efficiency E= 8
wind speed We= 12 m/s
turbine radius R= 300 m
The kite flies “lying eight” at high speed (around 200 km/h)
I was explaining this and the Oceanergy concept to a wind energy manufacturer friend yesterday. Regarding Oceanergy, his comment was: “How many layers of inefficiency do they want to combine?”
Regarding the railroad track idea, seems to me we’ve been discussing this for well over a decade, including many “carousel” concepts, and of course using existing railroad lines. More “All ya gotta do is…” hypothesizing. OK, rather than building an inefficient ship With water turbines to drag thru the ocean, with Onboard energy storage (“all ya gotta do is!”), electrolysis, hydrogen storage, etc, etc, etc, at least a railroad Engine has less drag than a ship, but why is there none of these running anywhere? And if a kite was powerful enough to pull a train engine (Extracting power instead of using power), could the kite cause a derailment? Then of course you have to store the energy on maybe another car or two? Whereas a wind turbine can be connected to the grid. “We were going to build a wind turbine, until we realized how much easier it would be to build a railroad!”
@dougselsam
There alway a third rail transfer?
If you want to go the kite route?
There also rail type to consider if derailment concerns you?
Reading a circular track? Well are kite want there own particle accelerators? Truth be known it not to hard to make a oversize generator this way? You technically could build on with x dia. Powered by multiple kites? Only needing the outside radius? Simple t section track should do? It would be hard for it to derail if attracted to the underside of the t beam or I beam? Think rollercoaster operations? Depending design direction?
The track could be built like aertotrain? Reverse maglev so to speak? There is no end to scale there? Though cost per mile/km might be quite expensive? GW maybe TW? If built as a trans global generator? How big to do like Awes?
Swept area is important right?
There has been a question of how to power the world? Something that obits it might just do the trick?
Anyone else want to join in?
Or wish to add something?
How heavy is one section of rail?
Can you build a ground station with the same mass instead? If so, just do that.
@Rodread
There are many ways to go about track
There also Aluminium extrusions? That can prevent derailment? Sort of like a curtain roller system?
Power to materials ratio? Materials used vs expected output = cost of manufacturing/cost per kw?
It would be ideal in a disaster emergency situation for quick development?
Sure the more permanent structure would use more than materials than a basic ground station but really it durability we are looking at here? As that will effect running cost?
It don’t need to be heavy at all?
I had a vision of kites in a dream once powering a section of railway up the Avon causeway years ago? On the old Christchurch to ringwood branch? Never quite understood what that meant? With help it could come into sharp focus?
I’ve two pictures in my mind one is like windswept? The other it’s a kite pulled sled? With multiple units on a looping track?
Built much like film cartridges shape? With minimal passing distance accounted for? In that dream it also powered parts of Christchurch? So it must of been pretty bulky to get the council in on it?
Currently in my area
So do the math and it alot for the year? Considering there about abt. 1/2 million people Living across the conurbation. per head it’s a lot of energy consumption? Abt. 130,000 in Christchurch? Datums to how much energy it would have provided the town?
So that was abt. 2014-2015 when I had that dream?
Some variety of this might do it?
If someone willing to crunch the numbers?
It can be a possibility? It wouldn’t take all that much?
Heck it might just fit a ground station as well?
Just depends how you wish to generate electricity?
That would make it nonviable. What’s the difference in available power between this and what Pierre is quoting?
Another idea, add grooves in or on the sides of roads for your train wheels to ride in. Or initially accept the higher rolling resistance of wheels on roads.
It’s a funny problem. Now you have to develop an autonomous road safe vehicle, with height restrictions with kites that perhaps also need to quickly launch and land to go under traffic lights and overpasses.
@PierreB @Windy_Skies @tallakt @Rodread
A yo yo system might pull the kite in for just long enough? Sensors on the train and track could trigger it? Also warn of complex section where there a serious risk of entanglement with structure?
Complementary system might be required on the tricky section
Or alternatively
?
Enter the sail train.
At 0:43, we see that the wagon goes slowly while the crosswind kite flies fast. In a similar way the reel-out rope speed is (theoretically) 1/3 wind speed, so far lower than the speed of the crosswind kite. It’s a classic case of high torque by low speed.
Thats ok. I realize they are probably still in the early phase, but to normal people that video was rather unimpressive. Cross fingers things look more powerful soon
That doesn’t address the point though. That video was an illustration of the path that we assume the company, or person as I only saw one person on the about page, wants to pursue; a carriage moving downwind with kites moving crosswind. To answer a question similar to my own from before, if I’m correct for that you’d need 9/4 more kite area than if you wanted to have the carriage moving crosswind, which sounds achievable.
The alternative, something like a high-speed rail that can take significant side-load, x times longer than the alternative, with no obstacles on either side, doesn’t exist today for one, and would need both decades and infinite money to build. So I’m doubtful that is the better solution for now. Unless perhaps this high-speed rail isn’t so difficult to build after all or actually already exists.
Wing sails could also come in handy here? Much like the solid sails on ships
Yes. But that plan of moving downwind is not so good I think as power delivery of the kite will be very unsmooth, as we can also see on the video. So maybe you could move the kite slightly to remove some wagon speed but I think it still needs to move slightly fast.
Also the rail must hold side forces as the carts still need to move crosswind and upwind.
I would also like to mention that besides the book release, much of the stuff from this company seems a bit old.
The problem with side forces can probably be alleviated by tilting the track inwards towards the center. But I would think a railroad track is anyways capable of withstanding lots of side force.
I dont think building the track is the biggest problem here though.
But where the traction is stronger, as indicated by Beyond the sea, different flight modes. And moving downwind (for the tether during reel-out phase) is naturally used in yo-yo systems, the kite flying crosswind by figure-eight in the middle of the flight window, so in the more powerful zone.
This is where we see that alternative devices to the yo-yo system lead to structures that are unnecessarily heavy and even less adaptable to the parasitic forces generated by the figure-eight movements of the kite. The yo-yo kite station can pivot during the kite’s movements so that it remains in line with the tension produced by the kite, which a rigid track cannot do.
The target height I think was something like 500 meters. At that height the cone will be quite narrow. And yes, you’d still have side forces, less if you choose your tracks based on the weather prediction, but now also probably a heavier and a slower moving cart.
You’d need to account for side forces, and obstacles, on both sides I think.
Syroco and sailing boats would disagree. Although I do wonder how that changes when you start constant regenerative braking.
Erroneous statements that I had to correct were made, starting with the belief that the wagons should go at a high speed (40-50 m/s), which is contradicted by all the documents (including one from KiteGen that I quoted, 5 m/s) and videos (one of which I linked), both for KiteGen and X-Wind carousels.
The latest erroneous statement is that “Syroco and sailing boats would disagree” that the “traction is stronger” by going downwind (what I wrote), “the kite flying crosswind by figure-eight in the middle of the flight window, so in the more powerful zone” (what I wrote).
The traction force should not be confused with the speed of the boat. Furthermore, the downwind configuration with a crosswind kite (which greatly increases the swept area) is not the same as that of a conventional sailboat, which uses only the drag of the sail, possibly increasing the area with a spinnaker.
As sailors know, the crosswind is the fastest, and notably faster than the downwind. This is true for classic sailboats because the sail also uses lift. This is also true for kite-surfing and Syroco, as going downwind with a crosswind kite would lead to chaotic sailing with large jumps, and not to speed records.
Please refer to the comment I quoted about Beyond the sea.
So of course only a proper design and calculation will reveal whick wagon speed is optimal.
But as we are speaking from our «hunches» here, sailboats produce more power (fastest speed in the water, all power produced counteracts hull drag) when sailing crosswind at high speed. Also kitesurfing, its very hard to get a fast and stable sailing directly downwind. This was very similar to the wagon travelling directly downwind.
Why would you travel very slow (1/3 windspeed) and generate a large braking force on the wagon, facing friction problems on the rails and so on, when you could travel slightly faster and get smoother power outpu? Also wheeled wagons dont face the exponentional drag penalty a ship faces.
All leading to a benefit of travelling faster.
The minimum viable wagon speed would be 1/3 wind speed travelling directly downwind. But then maybe speed up a lot going upwind? The maximum wagon speed would be travelling the kite’s L/D ratio times windspeed, then slowed down by power harvesting to 2/3 of that speed.
There is no doubt in which end I would start my design
A direct conversion (kites driving the carousel by a same angular speed) would be more achievable if the carousel and the kite loop trajectory are parallel, as for The Pyramid, leading to a tilted carousel.
The X-Wind and KiteGen horizontal carousels face zero or low power zones during rotation. These zones are more or less reduced when kites realize several figure-eight during the rotation, leading to a slow wagon motion.
I don’t know how easy it would be to turn a standard rail and sleeper to a supersized radial flux generator.
Then there technically no limit to the size potential?
Also?
as possible track layout? It don’t need to be all that tall? Can be just 1m so providing a low optical profile with mine environment impact?
Basically the sleeper would double as coils? It might be possible to repurpose a only shunting yard for this job?
Healey mills is one such site? There uses to shunting yard all over Britain? Though I’d struggle to know where to start in acquiring one? There bound to be a few yet undeveloped sites? The really good thing about this design is scaling. @ Doug selsam was wondering how to deal with over speed? This might be one way? Make it really big? Bigger than any known generator today? You guys were thinking about kw/mw. Really if you found a place big enough then who knows? What would happen? Three gorges dam energy production capacity might just be exceeded?
