Hi Pierre:
I can’t say I disagree with anything you are saying here. I guess one main point is, if you can figure this out so easily, how were thousands of supposedly “really smart” people fooled by Altaeros? Just goes to show you, there’s something in the air, that is causing large numbers of people to lose their sanity in a complete departure from reality!
Having said all that, I still leave room for the possibility of some configuration that might include lifting gas and make some sense. And if Altaeros was worth all those millions and all that fanfare, a system using a regular blimp would be twice as good!
BTW the 10 kW turbine here weighs over 1000 lbs. That may seem too heavy, but there are a couple of factors to consider:
Turbines you see for sale on the internet, especially manufactured in “the world’s factory” are of questionable quality, and prone to failure.
Heaviness is actually good for turbines, in the sense that the heaviness can help them withstand extreme winds. Remember the story of Little Red Riding Hood, and the Big Bad Wolf saying “I’ll huff and I’ll puff and I’ll blow your house down!” Which house survived? The one made of bricks! Bricks, not sticks! I hope I’m not mixing up my fairy tales. I mean, we also have The Three Bears, and their porridge, what was it, too hot, too cold, of “just right”?
I don’t know - you tell me. And if it is that easy for you to declare blimps invalid, what does that say about a team from MIT making their own HOLLOW (donut) blimp that would hold maybe half (1/2) the helium of a regular blimp of the same size? What you are saying just goes to prove the general insanity of the entire AWE ecosystem - thousands of people, including many PhD’s, engineers, “journalists” (who typically know nothing) and government agencies, ALL UNANIMOUSLY celebrating Altaeros for close to a decade! With new articles explaining how many homes “it powers”, years after the project was abandoned !?!?
When one guy (Pierre) doing “back-of-the-envelope” calculations, in his head, can see it won’t work out. Where were you 13 years ago Pierre, when all the hype was about the donut blimp with a turbine in the center? All those magazine articles! All that celebration ahead off any facts? Why didn’t YOU declare it a non-starter way back then, like me? Well, maybe you did, and, as usual, I just don’t remember.
But what I DO remember is, out of ALL these thousands of suckers, I was the only one who placed a free long distance phone call to the newspaper in the little town in Alaska where it was SUPPOSED to be powering the local grid, to find out that they didn’t even know what I was talking about and didn’t even remember publishing the article!!! (I guess all those “journalists” were too busy googling and staring at their phones to ever check an actual source!!!.)
I’d rather have a REAL donut with a chocolate or vanilla cream center!
Could any sort of blimp have a place in AWE? How would anyone know? I definitely see the issues, but at the same time, I’m not ready to completely rule out the concept, perhaps in some form nobody has thought of yet.
This makes things even worse for the two simplest AWE ideas.
I believe the small volume relative to surface area has already been discussed. In addition, I am not in the habit of dwelling on projects that are destined to fail. I’m trying to do some digging to see if anything might work. Some of the current companies may be on the right track.
@dougselsam I am acting as a broken record again, bjt it must be said: Don’t «Das Kind mit dem Bade ausschütten» [Throwing the baby out with the bathwater].
There are a lot of people in the world who are totally incapable of ever creating power from wind. Still many of these posess the will and opportunity to try. These people outnumber the people who could actually do something really useful.
Its hard for others to separate one from the other. Maybe as many are incapable of telling the two groups apart as are unable to «do».
That group is of no importance. Focus on where the possibillities lie.
The Kitewinder system has the additional benefit of operating at a high tether angle without incurring cosine cubed losses because the turbine is oriented to directly face the wind. In addition, the with the Kitewinder system, all the functions of launch and land are performed by the lifter kite only without the assistance of the turbine. This enables construction of the turbine to maximize power output and doesn’t compromise its efficiency.
The Kitewinder system eliminates almost all of the above drawbacks. The weight / power ratio is decreased because the generator and gear reducer are on the ground. There is no electric tether. Pendulum effects are eliminated by having a stabilizing wind vane, and for multiple turbine systems, an aerodynamically designed frame to support the turbines.
I think Kitewinder did a great job, including executing their rope drive concept, but I’m not convinced it is better or lighter than just attaching a generator to the rotor. The rope drive and gearing add friction (lost efficiency), cost, wear points, and complication - more parts, more expensive, more stuff to go wrong. So if it is lighter, great, but I’m not convinced of even that. I’m also not convinced that running electricity down the tether is a showstopper. The thing is not that high to have a huge tether weight, even including some copper (or aluminum).
Perhaps some arrangement like the following would facilitate an implementation, because the Sharp rotors accumulate aerodynamic and aerostatic lift, and allow to carry the turbine instead of hanging it.
At first I dismissed the idea. However, after some research it seems that methane or natural gas could perhaps be a possibility compared to hydrogen.
In French language:
Risque de fuite : la petite taille de la molécule d’hydrogène lui permet de s’échapper à travers des ouvertures de taille extrêmement faible. Le risque de fuite est donc plus élevé avec l’hydrogène qu’avec les autres combustibles.
Risque d’inflammabilité : lorsqu’une nappe d’hydrogène se forme, le risque d’inflammabilité est nettement plus élevé que pour une nappe d’essence ou de gaz. L’énergie requise pour l’enflammer est environ 10 fois plus faible que pour le gaz naturel.
Risque de formation d’une nappe explosive : l’hydrogène se disperse plus rapidement que les carburants traditionnels. Il se dilue 4 fois plus vite dans l’air que le gaz naturel et 12 fois plus vite que les vapeurs d’essence. Cette volatilité est un facteur protecteur limitant la formation de nappes d’hydrogène.
Translation:
Risk of leak: the small size of the hydrogen molecule allows it to escape through extremely small openings. The risk of leaks is therefore higher with hydrogen than with other fuels.
Risk of flammability: when a hydrogen slick forms, the risk of flammability is significantly higher than for a gasoline or gas slick. The energy required to ignite it is approximately 10 times lower than for natural gas.
Risk of formation of an explosive slick: hydrogen disperses more quickly than traditional fuels. It dilutes 4 times faster in air than natural gas and 12 times faster than gasoline vapors. This variant is a protective factor limiting the formation of hydrogen layers.
I will try to put together a few elements to try to find out if @Kitewinder Kiwee could be an advantageous alternative to a conventional wind turbine as both scale up.
To do this, let’s try to know the mass of the blades (which could be similar for the two types of turbines) in relation to the nacelle of a conventional wind turbine which contains the hub as well as the generator and the gear multiplier, plus some other elements.
To put it simply, we will assume that the mass of a rope drive transmission would be similar to that of a simple tether including the electrical cable.
Likewise, we will assume that the mass of the hub (very heavy part) would be equivalent to the mass of the Kiwee hub transmission pulley system.
We can roughly deduce that the aloft mass of the conventional wind turbine will be approximately that of Kiwee plus the nacelle without the hub, or approximately double for large dimensions.
Of course, it remains to be seen whether a giant Kiwee would be feasible and reliable.
Description of an 8 MW reference wind turbine, Cian Desmond et al 2016 J. Phys.: Conf. Ser. 753 092013 (see table 1 for the mass of the elements):
Georgios Sieros
P.K. Chaviaropoulos
John D Sørensen
Peter Jamieson