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Don’t forget that in your considerations, the shape of the roof is important, in terms of wind acceptance (from which direction it generates reasonable power), in terms of structural integrity, and in terms of ease of manufacture.

Imagine two poles of bamboo parallel to each other.

Bend them in the same radius, planting both ends of each pole in the ground.

Stretch burlap or canvas between them.

Plaster them with concrete. They will sag in the middle when you do this.

When it dries you will have a natural concrete shell in the shape of an arch with double curvature throughout.

Now put another next to it (and another and another)…

The structure is arbitrarily long.
The roof shape that the wind sees is a vastly more aerodynamic hump with a longitudinal profile that looks like it was designed for installation of small darrius rotors laid down horizontally.

Refer to “The Owner-Built Home” by Kern , I think this was initially developed in India.

I wouldn’t want to have to get council to sign off on it though

respectfully
BJ

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I did get that you liked the idea in the right context. Still I reckon I can take a pat on the back for thinking of a concept that only one other person seems to have thought of.

I haven’t seen anything that uses the rotor design of my wind sculpture. I’ll have to put my thinking cap on and work out a test rig to see whether this “thing” actually produces any power. It doesn’t really matter if it doesn’t work, the process of discovery will make the effot worthwhile.

Followed your link and did a bit of googling and found this UK paper “The Feasibility of Building Mounted /Integrated Wind Turbines (BUWTs)” at http://www.eru.rl.ac.uk/pdfs/BUWT_final_v004_full.pdf

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You may have missed that I actually liked the idea at the end of all that, for the purpose of cheap access to small amounts of electricity in areas where the winds are more or less predictable and more mild mannered than the boisterous stuff here in Welly. It DOES have possibilities.

respectfully
B J

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Aircraft jet engine technology would be better for what you are thinking about. Must be a million odd engines lying around from which to scrounge parts from.

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“Incidentally, how about a carbon fiber Archimedes screw in a boiler smokestack? Lightweight and heat and acid resistant.”

While carbon fibre is heat resistant (it is only a nylon filament – an oil derivative – burned at high temperature) the resin holding it together is not. Has a temperature range to about 100 to 150 C before it melts.

Also the resin tends to be flammable.

Not to say a resin could not be developed to be heat resistant but then you would have problems in an autoclave getting a proper cure. You need pressure and a little heat to get the resin to flow through the matrix and then a final cure at the right temperature to set it.

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B*gger, there goes my dream of following in the footsteps of Edison and Westinghouse. That’s pretty much the concept I had in mind. I wasn’t thinking of using a darius turbine. I’ll have to see how they plan to transfer the energy from the each turbine to the generator. Serious amount of torque being transmitted along the drive shaft if they have a single generator.

Incidentally, how about a carbon fiber Archimedes screw in a boiler smokestack? Lightweight and heat and acid resistant.

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The trick is to use them where their strengths count.

Trevor.

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Yes, it is good that it is a flow battery, but the problems are seem to be just different, not less.

respectfully
BJ

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Google “vanadium flow battery” for a new type of battery which has inert electrodes and about a 70-78% cycle efficiency and can take deep cycling without damage. Not really suitable for portable or vehicle applications but ideal for peak load shedding or smoothing tidal generation output.
http://en.wikipedia.org/wiki/Vanadium_redox_battery

Trevor.

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And there is (I think) prior art for the roof ridge thing as well.
http://eeru.open.ac.uk/tdg.htm#wind

BJ

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Energy storage.

Cyclical and Intermittent generation.

During the any time the wind blows hard enough to make a surplus, any time the tide is flowing but demand is light…. compress air into tanks at very high pressures, this will make the air and the tanks quite hot, but it can be released from the tanks ( through much the same hardware) to run generators. At night when it is cool liquify the compressed gas, during the day or using ocean water to provide the heat, boil it off for power. The combined cycle is complicated but burns nothing to achieve storage, and by using a phase change it achieves a higher energy density than the compressed gas can offer. A big compressed gas tank may (I think) smooth load vs production curves better than batteries do.

? So… can it work ? I have to learn somewhat more about compressor efficiencies and costs to get an answer. Got to take this idea somewhere else…. homework…

bj

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When developing new technology, there are countless wrong approaches, but much is learned going down these wrong approaches and techniques learned which can be applied to other problems. Back yard inventors don’t gain the same peer support and don’t spread what they have learned so others can build on their findings.

Trevor.

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If I understand you correctly you might be better with an X or star shaped house design, utilizing the cheap (exceedingly so) jute(canvas)-concrete formed curve construction to create an upper surface that is curved. (no peak)

At the center put a vertical axis turbine. Built the reinforcements needed into the structure at the center as well. The X captures and channels wind over the center from most directions… the vertical axis takes power from any direction. Most of the bits that want maintenance are down where they can be maintained easily. If you are sensible you don’t leave it running in hurricanes (which are relatively rare and predictable compared to the typical weather in Wellington, where you probably should be applying for an alarm permit if you want to put up some wind chimes) .

The structural problem doesn’t come from the inertial mass. It comes from the fact that the power coming from the wind requires that you must in some manner have reduced the velocity of some portion of that wind. There is a resultant force that does not go away no matter if you had no inertia whatsoever. Assume you had somehow managed to create an electromagnetic charge on it, and then ran it through an empty tube ( as in magnetohydrodynamics ) … you still wind up with resultant forces in the foundation structure, or the whole thing blows away.

Smaller is most assuredly easier to deal with though, and what you are talking about does sound smaller than I thought you were aiming to build.

Some of the links may prove useful to you, but if I understand your proposal you are thinking about a horizontal axis, but one that is at right angles to the wind, which is the same power generating profile that the vertical axis turbine uses, but with a vastly different arrangement than usual. Assuming that you are trying to extract energy from “trade winds” which are relatively consistent and predictable in direction you could be onto a winner. Your moment arm is not the length of the vertical axis but the width. This is pretty clever…. it gives up omni-directional acceptance but it becomes relatively much simpler to support the structure.

Interesting problem in computing efficiencies. I would recommend, barring any commercial interests you have that I don’t know about, that you see if someone at one of the universities could be interested in helping. This’d be an ideal masters’s thesis project to model and analyze wind-tunnel performance with different roof forms and with different rotor configurations.

You have what I think now, is a pretty good idea. It doesn’t suit every purpose, but it does suit some. An ounce of experimental data is worth a truckload of theory.

Only thing is, I don’t agree much about the batteries. Battery tech has not gotten a lot better than moderately horrid. Better to compress and liquify some gas and then expand it to get your storage (what’d I just say?)

respectfully
BJ

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I must admit the question of dynamic loads on the building frame has had me rather confused. I am familiar with the complex nature of heavy vehicle interactions with pavements but couldn’t really get to grips with exactly what stresses would be placed on a building when the force of the wind is transfered to a rotating mass and then converted into electrical energy.

However, the design I have in mind would have to have a very low inertial mass as the intention is to utilise the gentler winds typically found on the Pacific islands and African continent. For these low income countries I see small power output/small capital cost as being the right balance. If it is cheap to install and can drive a car or truck alternator for a significant number of hours on most days that IMHO is going to be an important step forward to improving the quality of life in these nations without creating a dependcy on fossil fueled generators or needing an immediate investment in a full grid system.

The application was for remote baches and farm sheds where the grid is an uneconomic and inefficient way of supplying power.

The modular nature of what I have in mind is intended to make it easy to fit to any size roof and easy to install for anybody skilled to home handyman level, ie semiskilled or supervised unskilled. That’s important for the developing nations but in developed nations the building consent process will probably prevent this from becoming the next big DIY craze. If it actually did become a DIY craze the biggest benefit would be the attitude change regarding energy rather than the modest amount of renewable energy generated.

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Where I work now the shifts are arranged to coincide with the end of the school day, so one parent can work days and the work evenings. That means start/finish times of 7.30, 3.30 and 11.30 so none of the factory staff commute during peak periods.

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I was dubious about the benefits of the flat plate at normal wind speeds. However one of the objectives was for the turbine to be inconspicuous, or at least sympathetically blended into the existing structure, and to be protected from UV depending on what material the rotor is made of to be inexpensive and have low inertial mass. The small radius should mean that rigidity is less of an issue than with conventional rotors.

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