cost / MWhr?
20th April, 2012 @ 7:19 a.m. (California Time)
20th April, 2012 @ 1:48 p.m. (California Time)
May be better to suspend your Turbine from beneath a dirigeable, at least then they can be dropped and raised without damage to the envelope (this design has bare blades inside one).
Also in crosswinds a dirigeable can easily turn into the wind, the current design looks stable only when it is turned into the wind direction, being only semi rigid I would not like to see what happens when it is buffeted from the side and the envelope meets the blades.
In short get a blade housing.
21st April, 2012 @ 12:24 a.m. (California Time)
It has fins that will keep it turned into the wind.
Given the blade clearance and the stiffness of the inflatable structure any additional blade housing should be unnecessary. However a rigid housing that provides for smoother airflow might be worth the cost.
21st April, 2012 @ 11:34 a.m. (California Time)
why don't they use hydrogen? this way they could transport deflated from site to site and inflate onsite rather than what they showed in the video, not to mention the supply of helium is finite.
21st April, 2012 @ 7:38 p.m. (California Time)
This design is really bad, complicated, and inefficient. They should have kept it as a typical balloon with the generator suspended underneath, and instead of a prop it should have had a large spiraling ribbon hanging on a double joint hanging from one end of the generator. Then it would not matter how, which, or when the wind is blowing because the the ribbon would always be flowing with the direction of the wind and away from the cable while the balloon would have no negative angles or unnecessary turbulence due to its shape.
21st April, 2012 @ 8:27 p.m. (California Time)
Re; Dennis Klanac
The supply of helium is effectively infinite because it is produced by radioactive decay and trapped in shales. We have far more than it is possible to ever use, but it is all wasted because there is no market. It is a normal byproduct of natural and shale gas production.
22nd April, 2012 @ 1:11 a.m. (California Time)
The aerostat is tethered by a single cable and it has fins to keep it pointed into the wind.
Between the stiffness of the inflated structure and the wide clearance the envelope will not meet the blades except in conditions that make the thing fall out of the sky the good option.
The contour of the air channel could be improved.
re; Denis Klanac
Hydrogen leaks a lot faster than helium, and the supply of helium is not near as limited as you think.
22nd April, 2012 @ 1:12 p.m. (California Time)
Slowburn, don't forget that the Hindenburg flew across the Atlantic. I know it had an unfortunate end, which killed off hydrogen balloons( the fire was mostly caused by the aluminium paint) Hydrogen is a lighter element than Helium, but is a lot cheaper, and this device is unmanned, so safety is not so critical.
23rd April, 2012 @ 8:45 a.m. (California Time)
Articles as this and their presentation is why this site is so great.
Obviously a favorite that stimulates the imagination.
23rd April, 2012 @ 12:33 p.m. (California Time)
Actually I agree that they should use hydrogen for lift. My posting on the previous article about this windmill was to question how much of the generated electricity it would take to keep it full of hydrogen.
23rd April, 2012 @ 9:24 p.m. (California Time)
I could suggest making the whole gas envelope as a pair of contra-rotating helical units. The axis would be the sole rigid component, and the location for the alternator. Tail fins at one end (spinning in unit) would ensure it faces into the air-stream.
Utilize dual LTA gasses with helium (more expensive) at the core, and the cheaper hydrogen as the blanket.
24th April, 2012 @ 6:46 p.m. (California Time)
In the past, thousands of migratory birds,as well as birds of prey using stationary turbines as perches have been killed. Was there any consideration given, or tests done in this regard?
30th April, 2012 @ 11:43 a.m. (California Time)
Outside of the turbine actually spinning, with something that large in the air tethered to the ground, it would be interesting to see what potential would develop with respect to ground, assuming the tether was electrically isolated from ground contact.
The electrostatic field and the difference of potential of the earth field according to investigations, is in summer about 60 to 100 volts and in winter 300 to 500 volts per meter of difference in height, a simple calculation gives the result that when such a collector is arranged for example on the ground, and a second one is mounted vertically over it at a distance of 2000 meters and both are connected by a conducting cable, there is a difference in potential in summer of about 2,000,000 volts and in winter even of 6,000,000 volts and more.
1st May, 2012 @ 12:18 p.m. (California Time)
Re; David Mott
That is Tesla technology, free power from the Atmosphere itself. You would not believe how quickly airborne turbines would be scrapped if they start using it, every Jack would be launching their own home brew version.
Superb post, thank you !.
13th May, 2012 @ 2:03 a.m. (California Time)
If it was really practical to harvest "free" energy from the atmosphere, we would have been doing it by now. The static electricity produced is essentially useless. Aerostats have been used for years as barrage balloons, antennas and other uses with no real success in harvesting energy.
As for floating wind turbines, the technology will eventually filter down to the consumer level. As a pilot, I would worry about hundreds of "home brew" wind turbines floating high above the countryside.
31st May, 2012 @ 4:28 a.m. (California Time)
Re: Bruce Williams
Why I can't let this be, I can only wonder. At any rate, here are some numbers for you and anyone else that might be interested to ponder:
A number of studies have been done using lightning detection networks located in some countries and using a couple of satellites that have optical detectors designed to recognize lightning flashes. The most recent data suggests that the long used statistic of around 100 flashes per second globally is close to being correct, of which 80% are in-cloud flashes and 20% are cloud-to-ground flashes.
This gives us approximately 20 flashes to the ground per second globally and therefore 1,728,000 flashes to the ground per day. This seems like a huge number, but it is necessary to maintain an electrical balance between the Earth's surface and the atmosphere.
Lightning can occur with both positive and negative polarity. An average bolt of negative lightning carries an electric current of 30,000 amperes (30 kA), and transfers 15 coulombs of electric charge and 500 megajoules of energy. Large bolts of lightning can carry up to 120 kA and 350 coulombs. An average bolt of positive lightning carries an electric current of about 300 kA — about 10 times that of negative lightning.
The average peak power output of a single lightning stroke is about one trillion watts
Static electricity, a potential, can be captured and stored in a leyden jar, a capacitor or a battery.
In short (pardon the pun), there is a tremendous unharvested potential between our charged earth and our usually oppositely charged atmosphere. I've read that during a thunderstorm, as large potentials develop and move across the sky, large opposite potentials also move under it -through the ground-. If lightning has leaders that come up from the ground to meet the charge coming down from the sky, then that means that the classic 'earth' or 'ground' or 'neutral' references usually used to denote 'no potential charge' are only relative states, not absolute. It's safe to say that these potentials exist to a lesser degree at all times even when there is no thunderstorm.
Nikola Tesla Day is July 10th!
24th June, 2012 @ 1:05 p.m. (California Time)