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Fish4Fun
#12
Dec24-10, 05:30 AM
P: 247
In another forum, a member posted this information:

Dear Mr Fish4Fun

An interesting topic you mention - I believe that this specific idea was discussed in detail in the 1930's with the
so-called Madaras power project at Burlington New Jersey USA - with tall rotor towers mounted on rail wagons
running around a very large circular track

I remember once reading an article in what I believe was a copy of the United States magazine "Practical Mechanics ?
from the 1930's". and I also have an illustration in one of the books in my own library:

"Energy - Survival Scrapbooks #3" by Stefan A. Szczelkun - New York 1974 - Lib of Congress Cat. Nr. 73-82211

This project in New Jersey USA - utilized the so-called Magnus effect - and was to a great degree influenced by the
pioneering work done by Flettner in Germany mainly for ship propulsion.

However I do consider that these technologies will have a great future importance - although not exactly for direct
electrical power generation.

I believe that this is clearly indicated by the present interesting work being done by Professor Salter from Edinburgh
in Scotland with regard to the basic "Elsbett-Salter" technological approaches for introducing moisture into the off-shore
atmosphere [off-shore sea winds blowing in-land towards arid-zone coastal areas].

With greetings and best wishes to all - JF
I responded with the following and thought I would do the same here as this pretty much resolves my initial questions:

THANK YOU. You have given me a wealth of information in your post! Using the information you gave me, I was able to locate an article from Popular Science, September 1978, page 75ff:

http://www.ecocadet.com/?p=1

Further research took me to the full DOE study of the "Madaras Rotor Power Plant" in section 8 of this document:

http://www.nrel.gov/docs/legosti/old/469.pdf

For the casual readers I will outline the "Madaras Rotor Power Plant" concept, and DOE findings:

The general layout of the project is similar to my initial outline except in scale, the scales mentioned in the report included a 457m diameter closed track with 18 cable connected cars with an output of 18MW, and a 75 car, 100MW system. Further track size considerations ranged from 10.41km to 42.73km. Other figures:

Track/Cars:
track gauge = 11m
car height = 3.8m
car length = 19.2m
car width = 17.4m
gross car weight = 328,000kg

rotating cylinder:

aspect ratio = 8
e/d = 2
cylinder diameter = 4.9m
cylinder length = 38.1m
end-plate diameter = 9.8m
Rotation Speed = 186RPM

The "optimal car speed" (referred to as "track speed") was determined to be 13.4m/s. The mean wind speed used was 8.1m/s.

Comparisons were made between Madaras plants and comparable arrays of horizontal axis wind turbines. Based upon assumptions employed, plant and energy costs of a racetrack-configured Madaras system were found to be similar to costs of an equally sized farm of conventional first generation wind turbines.
Furthermore, as many have pointed out:

It is clear that the Madaras system composed of translating rotor cars is more complex than a stationary array of conventional wind systems. Thus, it is anticipated that the operation and maintenance cost for a Madaras system would probably be higher than that of conventional wind systems. Calculations based upon costs developed for the system indicated that the energy cost is similar to a conventional first generation system...
A few notes about the "Madaras Rotor Power Plant" project:

1) While my idea involved sails or wings, this project was based on rotating cylinders. The lift generated by a rotating cylinder (the Magnus Effect) is stated as being superior to sails or standard air foils by as much as a factor of 10. This assessment would seem to imply that the use of rotating cylinders is superior to sails/wings; however, while the same aerodynamic efficiency holds true for aircraft, the Magnus Effect has not proven viable in general aircraft design. This suggests that the most efficient airfoil is not always the most economically viable or mechanically reliable engineering solution.

2) The Madars system was considerably heavier than the system I envisioned. This was primarily due to the massive DC motors employed (450kW) to rotate the cylinders, the inclusion of 4 * 250kW generators on each car, and the notion of using a "conventional" railroad track which required a huge "base width" (11m). I am uncertain if using a narrower track gauge with over/under track wheels, lighter cars and an integrated car/track generator design would substantially impact the cost or efficiency and thus economic viability of such a system, but I suspect it would not.

3) The Madaras system proposed using a 457m diameter track with 27m cylinders and an estimated output of 18MW suggests an overall CP of 0.45 using the swept area = 457m * 27M = 12339m^2 and a rated output @ 8.1m/s wind speed. This lends some credence to my initial assumption that using exposed width * height is legitimate even for a very large scale VAWT. It also demonstrates that an initial CP of 0.30 is not unreasonable for a system this size. The more rigorous engineering methods employed in the DOE report stated that a "race car style track" with long straight sections normal to the prevailing winds would produce a considerably higher output than a simple circular track (assuming prevailing wind direction were predominant).

4) The DOE report proves 100% that my idea was NOT unique, furthermore, many of the precepts have been carefully studied and evaluated. While I have no memory of ever having read about the Madaras project, it is entirely possible I read the Popular Science article in 1978, perhaps seeding the notion.



*******************************************************************


In conclusion, while I still believe the concept is potentially viable, I do not have the engineering skills nor the resources to do more than outline the project, certainly not refine it past its current state. The DOE report, while slightly different than my thought, is proof that a rigorous scientific study of the concept has been completed, and the conclusion is that more conventional wind turbines hold at least a maintenance advantage over the Madaras concept.

I would like to thank everyone who has taken the time to read through my posts and respond. A special thanks to "JF" for helping me find the information to close the book on this line of thought. I hope others have enjoyed this exercise as much as I have!

I wish everyone a Happy Holiday Season!

Fish