Naked Science Forum
General Science => General Science => Topic started by: Floating Badger on 29/06/2015 00:59:24
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So I've had an idea for a while now, (while its already been made by Altaeros Energies)
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I want to create a High Altitude Wind Turbine... or 'HAWT' for short. However there is a bit of a snag... i need to find an alternative to helium, while its all well and good using it to provide lift, we are 'running out' and currently there is no feasible way to produce helium here on Earth.
I'm trying to find an alternative that will provide lift for a sustained period of time so they can be deployed in areas of disaster to provide crucial sustainable power in times of need where the main source of power has been disrupted or destroyed. Recent Examples include Fukishima and Nepal. This invention could revolutionise sustainable power and also disaster help efforts.
Getting back on topic i have a comprehensive list of all lighter-than-air gases (thank you user damocles):
gas Buoyancy (relative to He = 100%) Drawbacks
hydrogen 108% explosively flammable
helium 100% slowly leaks from container
methane 52% explosively flammable
ammonia 48% highly toxic, corrosive, high affinity for water.
neon 36% prohibitively expensive
acetylene 12% flammable
6 others <5% various, but mainly not enough buoyancy.
note that hydrogen is lighter than both air and helium (EDIT) and obviously hydrogen is flammable, but only to a certain degree, hydrogens UEL/UFL is actually 74/75% concentration so theoritcally you can use upwards of this to provide a theoretically non flammable source of lift (end of edit), now obviously being so bouyant it will leak from the container. here is the other snag, i would need to find a way to contain the gas with minimal leakage.
So this is what i need:
1) a SAFE lighter-than-air alternative to helium
2) a way of containing said gas
(open for discussion)
Thank you
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The police may have just answered a question however lift via propulsion isnt my area so some of you will have to validate it, say for instance that the turbine is not lifted via gas but by rotor instead, would that work out better or is it just because its 2am that im thinking these crazy things, mayhaps it uses part of its own produced energy to provide said propulsion...?
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... say for instance that the turbine is not lifted via gas but by rotor instead, would that work out better ... mayhaps it uses part of its own produced energy to provide said propulsion...?
There would be two conversion-losses (https://en.wikipedia.org/wiki/Energy_conversion_efficiency) converting wind to electricity, then electricity to a helicopter rotor. A kite/wing would be more energy efficient, and cheaper to make, see ...
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wouldnt this require some form of high wind speed though? whereas a floating wind turbine could continuously provide power with low wind speeds
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I think hydrogen would be the way to go. It is the cheapest, most abundant, easiest to make, and most buoyant.
Yes flammability is a potential problem, but it should be operating high enough that if it exploded it wouldn't hurt anybody, and it wouldn't be any more likely to fail because of the flammability (any scenario that led to a fire or explosion would have compromised a similar vehicle using helium...)
The small molecules will leak out of most anything, but using an aluminum envelope would keep it in quite well, and a small amount of water with a tiny electrolyzer could use a small portion of the energy captured to generate more hydrogen as needed.
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Yes flammability is a potential problem, but it should be operating high enough that if it exploded it wouldn't hurt anybody, and it wouldn't be any more likely to fail because of the flammability (any scenario that led to a fire or explosion would have compromised a similar vehicle using helium...)
I strongly agree. Not to mention these things can be put in large fields which people don't have access to. Then if there's an explosion (and I can't see any way that it could ignite so it'd be a rare event) nobody would be in harms way, so long as the proper precautions are taken during maintenance.
Why do you say that helium and hydrogen are leaky when that depends on the fabric/plastic used? The balloons used for flying instruments use plastic and they don't leak to my knowledge.
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Yes flammability is a potential problem, but it should be operating high enough that if it exploded it wouldn't hurt anybody, and it wouldn't be any more likely to fail because of the flammability (any scenario that led to a fire or explosion would have compromised a similar vehicle using helium...)
Why do you say that helium and hydrogen are leaky when that depends on the fabric/plastic used? The balloons used for flying instruments use plastic and they don't leak to my knowledge.
the balloons used for flying instruments are lined with aluminium, be cause the helium and hydrogen molecules are so small, they will leak through everything, hence why party balloons die after a while.
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the balloons used for flying instruments are lined with aluminium, be cause the helium and hydrogen molecules are so small, they will leak through everything, hence why party balloons die after a while.
If that is the case can't you still use helium to line the container in the same way? That way it won't 'slowly leak from container'.
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Hydrogen is definitely the route to take - if there's an accident with it, it goes upwards and burns away safely, quite unlike petrol which we happily use in cars despite it being more dangerous. Hydrogen isn't so safe if you mix it through with oxygen in the right proportion for it all to explode instantly, but if it's just hydrogen surrounded by air, it will burn off much more peacefully at the point where it's leaking out.
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The viability of the project seems dubious. You need to get a specialist crew, the winch system, and your gas supply, to the disaster area, and keep watch on the blimp, shortening the cable as the wind speed increases. A simple lattice tower windmill doesn't require continuous attention, can work for several years with no maintenance, and can be assembled by a "local" with just one spanner.
It's often a good idea to start a disaster rescue by clearing the airstrip. One short fixed tower can be a navigational aid and radio station as well as a power generator but the last thing you want near a landing ground is a barrage balloon on a long flexible tether!
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The viability of the project seems dubious.
Dubious or not, it's already being done. See: http://www.altaerosenergies.com/bat.html
You need to get a specialist crew, the winch system, and your gas supply, to the disaster area, and keep watch on the blimp, shortening the cable as the wind speed increases.
I don't see why the cables would need to be shortened. From the images in the above link it appears that they use a system of cables so as to keep the balloon in a fixed position in the sky.
It's often a good idea to start a disaster rescue by clearing the airstrip. One short fixed tower can be a navigational aid and radio station as well as a power generator but the last thing you want near a landing ground is a barrage balloon on a long flexible tether!
I also don't see why anybody would want to place this near an airstrip. In fact it seems to me that'd be a bad idea. But the balloon isn't on the kind of tether that I think you have in mind. Even if the balloon is 1/4th of a mile away from the landing strip then its perfectly safe for planes to land.
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However many cables you attach to an aerostat, it will be blown downwind. With multiple fixed-length cables, the most-downwind one will become slack and trail along the ground, causing more havoc as it drifts from side to side, and applying a shock load to the aerostat when the wind drops and it becomes taut again. So you need to constantly monitor the cables and either increase the length of the upwind ones or shorten the downwind ones as the wind strength increases.
I wouldn't want to tether a balloon within a mile of an airfield - in fact it is generally forbidden to fly anything unmanned above 500 ft within 5 miles of the traffic zone center, with the safe height obviously decreasing to zero at the threshold, so at 1/4 mile your limit for a tethered balloon is 25 ft. A fixed tower inside the airfield boundary and 100 ft from the runway center, however, is no problem because planes can't turn into it.
The reason for establishing your emergency power supply near an airstrip is I think pretty obvious: it can quickly restore transport and radio communication with the rest of the world when all other infrastructure has been rendered unusable, a functional airfield provides a helicopter base for reaching otherwise-inaccessible areas, you can coordinate a heck of a lot of traffic if the radios and lights work, and most airfields are, by design, exposed windy places where turbines work very well.
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PS and of course if you are flying any sort of aircraft in and out (especially one large enough to carry the balloon, turbine, winch, gas bottles and crew) you may as well deliver a 100 kW diesel generator and let the locals run it off cooking oil or jet fuel - no aeronautical skill required. Or just use the APU of the plane.
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PS and of course if you are flying any sort of aircraft in and out (especially one large enough to carry the balloon, turbine, winch, gas bottles and crew) you may as well deliver a 100 kW diesel generator and let the locals run it off cooking oil or jet fuel - no aeronautical skill required. Or just use the APU of the plane.
The whole purpose of the project is to provide the.essential power WITHOUT using non remewable energy, and as specified i wouldnt be using hydrogen canisters to pump the balloon, i would use electrolysis to seperate hydrogen from a main water supply or something alike. You would need minimal crew and the end project would be mostly automated to allow more personel to the relief effort.
And also the balloon isnt only for disaster situations it can be bought and deployed to rural areas or remote work situations, pretty much whatever you read in the links supplied throughout this thread. The main difference is that my balloon will be more efficient and sustainable...
Any critisisms and or discussion is more than welcomed, i don't want to start work on my project if its only going to be a flop
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There's no question that it will work, but engineering begins where physics and chemistry end.
In a nondisaster situation you need to consider the initial cost per kilowatt and the cost per kWh of maintaining and replacing the equipment for ever. Then compare it with other renewables such as a conventional "turbine on a stick", solar panels, and an ordinary generator powered by wood, camel dung, methane, or any other combustible waste. The latter is best because it will produce electricity always and only when you want it, and in a predictable quantity.
You also need to think about the consequences of failure. In addition to lightning strike, damage by turbulence (try flying a hot-air balloon on a summer day), and tether-drag (try flying a tethered hot air balloon in even a gentle breeze - my crew managed to launch a Landrover) you must consider the worst case of the balloon uprooting the tether platform or the tether ropes or the power cable breaking near the ground. Within living memory we had a rogue barrage balloon dragging its cable through Magdalen College - admittedly not a rural area, but cows and sheep are as valuable as arts students, and a modern barn is just as important as an ancient college if you are a farmer.
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You also need to think about the consequences of failure.
In addition to the ones Alan mentioned, some turbines have burst into flames!
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And once you have resolved the engineering questions, think about the ethics.
What do you mean by a rural area?
A. Some part of East Anglia or Oklahoma where farmers have million-dollar combine harvesters but no mains electricity? Be sure they already have all the diesel and wind generators they need, until you invent a 1000 horsepower electric tractor. But they will probably run that on chicken poo and barley straw.
B. A Nepalese valley where they have been farming successfully for the last 20,000 years without depending on alien technology, and are unwilling to get into debt or take college courses in aerostatics, upper atmosphere meteorology and electronics just because you think they should be using wind instead of cow dung for heating and cooking?
C. It probably makes scientific sense for an Arctic exploration, but given the amount of fossil fuel you need to get there and resupply the base, a few more gallons of JETA1 for the generator won't make a lot of difference to global warming. And the natives have been using sustainable seal blubber lamps since the Stone Age.