SERl/TR-211-1911 

UC Category: 60 

DE84000087 

Oscillating Wind Energy 

Conversion Systems 

Peter South 

Richard Mitchell 

December 1983 

Prepared under Task No. 1067.10 

WPA NO. 171-83 

Solar Energy Research lnstitute 

A Division of Midwest Research Institute 

1617 Cole Boulevard 

Golden, Colorado 80401 

Prepared for the 

U.S. Department of Energy 

Contract No. DE-AC02-83CH10093 
Printed in the United States of America 

Available from: 

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

Price: 

Microfiche A01 

Printed Copy A02 

NOTICE 

This report was prepared as an account of work sponsored by the United States 

Government. Neither the United States nor the United States Department of Energy, 

nor any of their employees, nor any of their contractors, subcontractors, or their 

employees, makes any warranty, express or implied, or assumes any legal liability 

or responsibility for the accuracy, completeness or usefulness of any information, 

apparatus, product or process disclosed, or represents that its use would not 

infringe privately owned rights. 
PREFACE 

The informaticrn in this docriment sui:qcst!; t:!je C)sci!!n :.in;: [.!iiigJ E~?el-,zy Conversion SysCms 6:-I not appear to have si~rjificn!~r atlv;~r.tn!re:; over ecl~ii\.- 

alent conventional rotatinr-llenent wind t3nt.rgy conversion svstc>ms. In fact, 

in most cases it appears that they have scvcral disaclvantagt3s. Tnc doc~:mi?nt 

addresses the oscillating cable-type wind energy conversion svstclrl its well as 

the oscillating vane and the oscil lnting wing. I i~dv;lnt;lgrss and disadvantages of each type of system are evaluated, and in each case a comparison 

is made bctseen it and a convetltiorlal rotati-ng-element wind c-nt-trfy collversion 

device. It appears unlikely that any of the: oscillating element corlcepts can 

compete with the present generation of conventional wind enerfy systems. 

Approved for 

S0LP.R ENERGY RESEARCH INSTITUTE 

.- 

Donald Ritchie, Planager 

Solar FJectric Conversion Research 

Division 
s=n I 

;+ TI?-1911 . 

TABLE OF CONTENTS 

.. 

Paqe 

1.0 Introduction ........................................................ 1 

2.0 Oscillating-Cable WECS .............................................. 7 

3.0 Oscillating-Vane WECS ............................................... 11 

4.Q Oscillating-Wing IJECS ............................................... 15 

5.0 Conclusions ......................................................... 17 

6.0 kferences ......................................................... 19 

LIST OF FIGURES 

1-1 Cross Section of a Typical Oscillating-Airfoil WECS ................. 2 

1-2 Oscillating-Cable WECS .............................................. 2 

1-3 Oscillating-Vane WECS ............................................... 3 

1-4 Rigid Wing Oscillating in a Supporting Track ........................ 4 

2-1 Comparable Skipping-Rope (Darrieus) and Oscillating-Cable WECS ...... 10 

3-1 Oscillating-Vane WECS (Rielawa Model) ............................... 12 

3-2 A VAWT Comparable to the Oscillating-Vane WECS ...................... 12 
SECTION 1.0 

INTRODUCTION 

Interest in oscillating-element wind energy conversion systems (WECS) was 

generated when it was suggested that these systems could be built with relatively simple elements. Because the main part of the structure would be 

extracting energy from the wind, the cost of that energy would be relatively 

low. Figure 1-1 shows a cross section of a typical oscillating-airfoil WECS. 

Three basic types of oscillating-element WECS have been proposed. In the 

first type, the oscillating-cable WECS, the "galloping" characteristic of a 

stretched cable is enhanced by various aerodynamic shapes. The structure is 

mainly made up of a set of cables stretched between two anchor points, and 

power is extracted from either the lateral or axial motion of the cables. The 

oscillating-cable WECS is shown schematically in Figure 1-2. 

The second type of oscillating-element WECS uses an active element that is 

cantilevered fron a base. The aerodynamic properties of this active element 

are controlled to produce the appropriate oscillatory forces. Thi.s type of 

oscillating WECS, the oscillating-vane WECS, is shown schematically in 

Figure 1-3. 

The third type of oscillating-element WECS uses a wing that moves in a direction normal to the wind. This notion is constrained by some form of track, 

and power is extracted from the motion of this wing. This type, the oscillating-wing WECS, is shown in Figure 1-4. 

The benefit of a WECS, energy production, must be compared with the cost of 

building, installing, and maintaining the WECS. The effectiveness of any WECS 

depends on its overall benefit-to-cost (B/C) ratio. Thus, the most important 

parameter of interest in evaluating a WECS is this ratio. It is usually possible to obtain a reasonably accurate power coefficient (C ) based on swept P 

area (the space occupied by the rotating or oscillating blade), but this 

parameter has little meaning unless it is divided by the cost per unit of the 

swept area of the WECS. Hence, comparing widely different WECS solely on the 

basis of obtainable power coefficients does not accurately compare the cost of 

the energy that they produce. 

The power coefficient based on swept area can be particularly misleading when 

it is applied to devices like the oscillating-element WECS, where the swept 

area is proportional to allowed motion as well as to the size of the structure. For example, if in a given situation, doubling the amount of the element's motion produces 1.5 times the power obtained previously, the Cp would 

only be 75% of what it was before, hut the power output from the structure 

would increase. Since costs pertain to the structure and not to the amount of 

motion it allows, in our example it is obvious that the cost of energy would 

be reduced by using a lower power coefficient. 

A more practical parameter is the power loading parameter, TAP. Power ot~tput 

is divided by the power flowing in a stream tube having a cross-sectional area 



equal to the area of the active structural ~lcnent. :laximizing the pomr 

loading parameter, then, maximizes the power available frm the str:lcture. 

The power loading parameter, however, is not a useft11 tool. for co~~~pari.np 

widely different WECS. Irt fact, it could he argut?d tlli~t the only relevant 

parameter of real interest in eval.uatinp a IECS is the cost of huilding and 

maintaining one for a given energy output. %vlouslv, i.t is not possible tn 

estimate costs accurately at a very early stnae in the clevelopment of a 

concept. Regardless of how good any particill.nr parmeter appears to he, the 

concept is valuable only if: it produces a B/C riltio better than that of any 

comparable device. Probably the best method i.s to conpc?re the device with a 

comparably designed conventional system and then analyze the wav in which 

their associated costs and benefits differ. 

The power coefficient hased on swept area can be useful as an indicator of 

performance and can be used to determine tile lipper limit of the device's power 

output. If the calculated power coefficient based on swept area exceeds, or 

even closely approaches, 0.59, it is a good indication that either the calculations are idealized or there has been an error. 

Tine primary power extraction mecharlism in a VECS can he either aerodyna.,i r. 

lift or aerodynamic drag. However, aerodynanic drag is associated with re1.atively low speeds, large forces, and large active areas, and it results in a 

relatively high energy cost, except in very specialized applications. Hence, 

the following discussion is concerned prinari1.y with devices that rise aerodynamic lift as the primary power extraction nechanism. 

With aerodynamic lift, power is extracted from the wind by movinp the lifting 

element across the wind. A general characteristic of lifting acti.ve-element 

WECS is that for a given Cp, the required solidity (the ratio of the blade 

area to the swept area) is related to speed ratio. The hi~her the ratio of 

lifting element speed to wind speed, the lower the required solidity. At low 

solidities and high speed ratios, the required solidity n is approximately 

inversely proportional to the square of the speed ratjo for an identical Cp. 

For any. IJECS with liftinp elements, the choice, then, is between hzving a 

relatively large active area noving at a low speed or a relatively small 

active area moving at a high speed, or any combination of these between these 

two extremes. The choice is a fundamental one, hcca~~se high-soliditv, 

low-speed airfoils are subjected to fairly low pressures and csn be made relatively crudely frorn low-grade materials; low-sol-iditv, high-speed airfoils, 

however, require nore sophisticated design, manufactt~re, an(! materials use. 

3 (Note that, while the aerodynanic pressures (N/mL) are quite different, aero- --- dynamic loads (K) are similar. ) 

The cost of conversion to electrical power usually increiises :>it!? tile naximun 

force or torque produced by the primary device. On I.arge nac:>iqes, tlic power 

conversion mechanism is a significant fraction of the overall cast of the 

machine; hence, power conversion costs tend tc prc?do~nignte and to ?enalize 

high-solidit y machines. 

SECTION 2.0 

OSCILLATINGCABLE WECS 

The phenomenon of cahle oscillation has been a ma:jor ?ro\len for users of 

transniission lines for sometime. It beco~.rles particu!.arly severe when the 

shape of the cahle changes because of the accretion of ice. 'iurnerous investi.- 

gators have studied this problen, hoping to find some vay to all.eviate its 

adverse effects. Although investigators understood that this oscillation 

necessitates an extraction of energy from the wind, no serious proposals tc 

use the phenomenon as a practical wind energy extraction device were put forth 

until Payne did so in 1977 [I]. Payne also suggested that very large, oscillating-cable WECS might be feasible and advantageous when natural terrain is 

used for support. 

Other investigators may have been deterred from pursuing cable oscillation as 

an energy extraction mechanism because it is not very efficient when coupled 

with the geometry and aerodynamic mechanisms that operate in a natural 

environment. In any case, their efforts were aimed at suppressing this 

phenomenon. In fact, using cable oscillation as an energy extraction mechanisa requires a look in the opposite direction, i.e., enhancing the natural 

phenomenon so that it becomes a viable (more efficient) enerCqy extraction 

mechanism. In a study funded by SERI [2], Payne analyzed hot11 cable oscillation and the binary flutter of a cable structure modified to form an 

airfoil. 

That analysis of cable oscillation suggests that reasonable power coefficients 

based on swept area are obtainable at relatively high cable flutter frequencies. To simplify the analysis, the velocities that wou1.d be induced 

normal to the wind direction are usually ignored. And in fact, the dynamic 

pressure virtually ignores that normal component because of the ].ow cable 

velocity. Hence, the analysis strictly applies only when the lateral velocitv 

of the cable is small compared with wind velocity and when the cable's 

diameter is small compared with the lateral motion. Along with these qualifications, the analysis also shows that a simple cable WECS presents some 

formidable practical probl.er!is. 

A more interesting possibility that Payne investigated is the binary flutter 

WECS, in which a device that acts as an airfoil is stretched between two 

cables. It has been suggested that an inexpensive material could be stretched 

between the t$iO cables to provide the surface of the airfoil. This is a 

quasi-steady-state analysis in which the velocities that are induced normal to 

the wind direction are ignored and the angle of pitch is assumed to he 

small. 'he assmptions also imply that the airfoil velocity is small compared 

with the wind velocity. 

The analysis also suggests that, ideally, the device can have a Cp thnt 

reaches the Zanchester-Betz limit. However, in order to achieve a hi,gh power 

coefficient, the effective chord (the distance between thc two cahles) nust 

greater than the vertical motion and the verti,cal velocity of the airfoil mist 

exceed the wind velocity. The high vc1oci.t~ and relativel:,~ 1.arge chord or' the 

airfoi.1 tend to violate some of the initit31 assumpti~ns of the analysis nilci 
make the results somewhat q:~es ti.onable; however, the results indicate that 

some general trends exist. As with any other lifting-element WECS, we must 

elther have a high relative speed or a large surface area. Because stretching 

the airfoil between two cables makes high speeds impossible, a large surface 

area is required. 

Payne's analysis suggests power outputs from such a device based on a power 

coefficient that approaches the Lanchester-Retz limit. Realistically, the 

obtainable power would probably be significantly less, after various losses 

are taken into account. 

The power extraction method proposed would emanate from the reciprocating 

axial motion of the ends of the cable. This axial motion could be used to 

pump a working fluid through some conversion mechanism to produce usable 

power. The initial conversion, however, from an enormous force traveling a 

short distance at a low speed presents a significant technical problem. 

For example, if the average wind speed normal to a cable is 6.7 m/s (15 mph), 

a stretched cable wing 1524 m (5000 ft) long with a 152- (500-ft) chord that 

operates at a Cp of 0.4 would produce an average of about 10 MW of power 

(assuning that the device operates efficiently over a wide range of wind 

speeds). The installed power would be about 70 MW. The airfoil would be 

cycled through a 46m (150-ft) range at midpoint and would produce an axial 

motion of about 3.7 m (12 f t) at one end of the cable if the other end were 

fixed, Assming a frequency of 0.07 Hz and two power strokes per cycle, an 

8 average force of about 13.3 x 10 N would be exerted on the power conversion 

mechanisn. To make the change in cable length caused by power loads relatively small compared with the displacement, a stress level of about 6.9 x 10 7 

N/m2 (10,000 psi) would be indicated for a steel cable (the overall stress due 

to pretension would be much greater). Hence, a total cable cross-sectional 

area of 1.9 m2 (3000 in.2) is indicated for a cable mass of about 

22.7 x lo6 Kg. 

The skin stretched between the two cables would carry an average pressure difference of a few newtons per square meter at maximum power. For a distance 

between cables of 152 m (500 ft), a tensile load on the order of 454 kg/m 

(1000 lb/ft) of length would be expected; this is a cyclical loading. There 

would also be loads caused by rain and snow, and material would be subjected 

to ultraviolet radiation. Taking all these factor3 into ace unt, the minimum 5' weight of the skin would probably be about 96 ~/m (2 lb/ft ). For a 1524- 

(5000-ft) by 152-m (500-ft) area, the total weight of the skin would be about 

5 million pounds. 

6 If the wing structure weighed about 22.7 x 10 Kg, as these rou h calculations 

suggest, a dynamic pressure of about 888 N/m2 (18.5 lblft ) at a lift 

coefficient of 1.3 would be required to support the weight statically. A 

dynamic pressure of 888 ~/m~ (18.5 1b/f t2) corresponds to a wind speed of 

about 37.7 m/s (843 mph). Oscillations can occur at wind speeds much lower 

than that, but a significant amount of time would be required for the amplitude to build up to the optimum. Ihe great weight also implies that, unless 

great care is taken to reduce internal friction, there would be little net 

output at moderate winds. 
T:- ~le ilbo;re cal.cufstion was carried out for a large-scale system to include the 

advantages that have Seen claimed for large systems. It does not imply that 

an airfoil stretched between two cables can never be economical, but it does 

suggest that the well-known square cube law becomes burdensome at a span of 

1524 n (5000 f t). If the span and chord were reduced by a factor of two, 

power output would be reduced by a factor of four; the structural weight, 

however, coul.0 he reduced by a factor of eight if the stress levels were the 

same. Hence, the structural weight per unit of power would he halved. If the 

oscillating cahle WECS is to be competitive, then, it would have to be at 

sizes rnuch smaller than 100 MW. 

A hi.gh-modulus, low-density cable material with low internal losses could be 

an alternative to the steel currently proposed. At present, though, materials 

that have properties superior to steel tend to be expensive. 

The stretched-cable, oscillating WECS is analogous to the conventional curvedblade Darrieus machine; a simple comparison between these two night prove 

instructive. At high tip-speed ratios, the aerodynamic performance of the two 

devices should be very similar at the same tip-speed ratios and solidity. At 

the same maximum tip speeds and the same maximum dimensions, the maximum 

acceleration of the blade would also be similar in both WECS. The motion of 

the Darrieus-type bECS would be similar to a skipping rope (Figure 2-1). The 

major differences between the two devices are (1) in the Darrieus-type WECS, 

there is no need for energy to be stored to reverse the direction of motion of 

the wing, and (2) power in the Darrieus WECS is provided in the form of rotary 

motion. Thus, for small kXCS, these two advantages indicate that the Darrieus 

type WECS would he more technically and economically viable. For large WECS, 

the previous analysis indicates that oscillating cables would not be 

practical. At no size, however, does the oscillating cable, galloping or 

bimary flutter, appear to be competitive with the conventional horizontal- or 

vertical-axis WECS. 

SECTION 3.0 

OSCILLATINGVANE UECS 

Like the oscillating cable, the osci 11-ating-vane WECS has its origins in an 

undesirable phenomenon. It is directly related to the flutter plicnomenon that 

has caused the destruction of a number of aircraft, although T~iornycroft's 

wind motor proposal hears little resemblance to the flutter. of a wing 131. 

Again, the wind energy approach has been to enhance the phenomenon, rather 

than to suppress it, by means of concepts like the oscillating vane. 

The advantage claimed for the oscillating vane is that if the vane is cantilevered from a base, then the most effective part, the tip, is in the highenergy area of the flow farthest from the ground and thus is aerodynamically 

most effective. It is also argued that (1) the ~nain part of the structure is 

involved in the primary extraction of power, (2) this structure can be manufactured with relatively low-tolerance construction techniques, (3) the power 

conversion mechanism is located at ground level, and (4) the concept is 

inherently self-starting. 

The major disadvantages of this WECS are that (1) because it is an oscillatine 

system, the foundations must be designed to withstand oscillating loads; and 

(2) the power-conversion systen, which uses the oscillating motion and produces constant-frequency AC power, could be expensive. 

Rielawa has studied the oscillating-vane concept [4] and reported on the 

results of some tests on a small model (Figure 3-1). The measured power coefficients were quite small, less than 0.1. The power loading, Lp, was also 

low, with a maximum value of about 0.45. As with the oscillating cahle, the 

blade area required for a given power output was much preater than that 

required by conventional high-tip-speed-ratio machines. 

It seems reasonable that further developnent work could be done to raise that 

power coefficient to a !?:,re respectable value, and that the power loading 

could also be increased substantially. It is unlikely, however, that it will 

be possible to reach the tip speed required to maintain a high power-loading 

coefficient even at moderate wind speeds. 

The oscillating-vane WECS can be directly compared with a vertical-axis wind 

turbine (VAWT) (Figure 3-2). Assuming that, at the same tip speed and the 

same inaxirnum deflection, the oscillating vane would have an aerodyna~xic performance similar to that of the airfoil (which rotates about a pivot at the 

base), and the maximum accelerations and stresses would be similar, the two 

blade designs would be quite similar. However, as long as tlie tip-speed ratio 

is sufficiently high, the rotating vane does not need a cyclic pitch co:ltrol 

to achieve reasoriable aerodynamic efficiency . 

It appears that the design and manufacture of a tapered vane that cants outwards at an angle of 45' from the base and has a tip solidity nf i!. 15 wg,.??d 

not be difficult for tip speeds on the order of 30.5 m/s (10;1 ft/s). 1.f tha 

rotating vane is compared with an oscill.atirl~: vane t!lat operates tlhrouz'i! a 

range of f45" at the same maximum tip speeds, and the vane c!esifn is sim-il.ar, 

the maximum stress levels due to the acceleration would also be siailar. Ho-dever, with an osci1.Lating vane, the direction of the scress rt?verses 

cyclically; with the rotating vane, it remains constant, although the aerodynamic forces are cyclical. The loads on the fo:~ndations ~7oul.d he si;qil.ar in 

magnitude in both cases, altholigh wi-tli the oscillating vane, the forces wou1.d 

occur in one plane. If, however, the oscillating vane is designed for omnidirectional winds, the foundations will he similar in the two cases. The 

essential difference between the two systtms is that an oscillating vane would 

require an elastic hinge and an oscillatory power conversion nlech~nis+,, while 

a comparable VAW would have a rotary bearing artd a rotary power conversion 

mechanism. 

On both the oscillating vane and the comparable V.4\7T, the dynamic forces and 

moments can be reduced by the use of tuned masses or balance weights, respectively. Regarding the comparable VAWT, methods are available to dramatically 

reduce the bending moment on the vane and thereby reduce the cost of the 

structure. Also, rotary power conversion devices are more readily 

available. It appears, then, that most of the advantages of the oscillating 

vane are the same as those of the comparable VAWT, and that the rotating vane 

has advantages that the oscillating vane does not have. 

SECTION 4.0 

OSCILLATINGWING WECS 

It appears that the oscillating-uiug syste!n concept originated in the hel-ief 

that maxinun power can he extracteti from a lifting element if it is allowed to 

rilove in the direction of the !if t force. On the surface, this is a very reasonable :zss:lmption, since the work one i.s the force multiplied hv the d-istarice traveled in tlle directior: of the force. With the airfoil, l~owever, the 

lift force is normal to the relative velar-ity; any notion normal to the wind 

causes a tilt in the lift vector. Assurning 2 co:lstant lift coefficient, the 

magnitude of the lift force is proportional to the square of the relative wind 

speed. At high relative speeds, the power-ex~ractin): capability of an 

isolated wing is nearly proportional to the square of its relative speed; it 

is then noving in a directisn that is nearly normal to the lift vector. 

Even if the basic premise is not correct, the oscillating wing should be 

examined 03 its om nerits as a !i-EGS. Tt is reasonable to heli.eve that for a 

carefully designed oscillating ving, a power coefficient can be obtained t!;aC 

is not much worse than that obtaiiled for n convenciona!. WECS. However, the 

power ioading coefficient x.il.1 be dependent upo!~ both the solit'iity and the 

speed ratio, 3,e bending monents that exist as the direction of motlon ii: 

reversed ac the linits of travel i~ili govern the maximum speed attainable. 

Rence, as in other oscillating concepts, a relatively large, low--cost wicg is 

indicated. 

To convert the power to a useful fom, some ariven system must he attache5 to 

the wing. .Although conceptual mechanisms exist, a reliable. efficient power 

co?iversion mechanism must still be producsd at a cost comparable to that of 

conventional devices. 

The 3sci.llatii;g-wing inCS is analozo;ls to the Cironill [5]. k t?lc sme total 

sc.!.idi ty , :naxii::-m -ti~--sr;e?d ratio,^, 2nd ovsrali di~enatons, the aer~dynairi c 

p~~';:-r~iance of 'i:e two dey;-iz?s s!.oi?:ri 5e qs.iite similar. fdkewise, at tile same 

ri~:.::.nvz ~izg FP~~C~S the ;naxF-v.>n dyrlanic Ioadi: an2 stresses shn!;? d he si.:?iIar 

".!; f.,?t:*. :he <:irvmiii tiie osc-:; l:..~inp ~.iinc.~ <-, - ?!owr.ver, for the fixed-pit 2'r; 

G<r.=.?;:i.l1, ar_c..c.lerat-ng f::~ccs an: :<tresses -9i:.ld :?e corlscant; f;?r :he oscil.- 

~.*~z-%,-. 9. i.,,z -..-, %::-18- the.: t.oui.4 .r\*:erse =YC:<CR?~V 2.32 2o::Tt Lead to f~tls~e problems, 

qsi.,=, :. , _.,?ZC -A 7 :ill . . . - -. ~~C~~~:SF ;;r, ;j;? <;ironill is ,?:p.> tf12 firs: stsize :jf the . . . - p35~~: st,, Tt i: ::5rft<:;,.i2.: ~2 t~ac:5zz ;li: 3sci:-lzti~g ~rl.52 

. . sue'!l a ~j<z;7~le s~;pi3.,yyt a:?C: I:~Z!:ST".~S~~;:!; in+;fi.!q=< '71f ?~:~i?:j~?.ii)n gild 

.- . .--,,. ,.. R;IP>D:~ ~t~zi:::$.?r- of the c;~.~:1.~aj:.:-i:g-.winp :.:.;.,-.. wo~-??J have to he :!~.sijzneci for 

s<r,S.I.:;r cor;di-;ions. Ttics, zs wit!- t;?e osci!:.;tinp Irnne, oscili.acing-wing iLTCS 

zcise~r . . to offer no s ignir'icant adb.:?n;a~es over ::o:.~ventional !.?rECS, whiii-. ;laviz.;g 

several signlf icant disadvantages. 

ST.: 

j :,> .. . ._ 8:sciIZa t5r.i~-clemi;~t. '_. 'YTCS are interesting enzrgy-extrac tion r~ec?~anisms. TI-. fa t!:ey appear to have no clear-cilt advanta~e over cor3parahle 

rcr.zting MECS; in fact, they appear to have scme signfficant disadvantages. 

iint? ci tile arjpli:!t.ilt~ in f~vor of such s:~scttns is that oscil.lating-elenent WECS 

e:-.lpl~y 2 ., rr -. ;:-.ea of low-cost material, whfch represents an overall cost 

savir?.~ over tl?e smller, relatively expensive material now used. This is ail 

arg:in!eni. tl:zt car, be applied equally well to IECS sing rotating elemezts, On 

rotatizq-element I\ECS, in fact, using relatively sinall-size, sophisticated 

eicnents has proven to be more economically viable than using large-size, lowcost .r?lments. Since oscillating-elemcni. WECS dc not appear to have any significant advarttizges Over equivalent rctatir:g-element WECS, it is unlikely that 

they can coi-il~e te with che present generation of conventional wind energy 

systems. 

SECTION 6.0 

REFERENCES 

1. Payne, P. R., "kolian Windnill," U.S. Patent 4,024,409, ?.lay 17, 1977. 

2. Payne, P. R., ,A Theoretical Analysis of Oscillating Cable Wind Enerw Systems, SERI/TR-0-9173-1, Golden, GO: Solar Energy Re~arch Institute, 

September 1951. 

3. Tnornycroft, J. I., "Wind Motor," U.S. Patent 1,490,787, April 1.5, 1944. 

4. Bielawa, R. L., Development of an --- Oscillating Vane Concept as an Innovative Wind Enerw - Conversion System, SERI/TR-?~~O~~-~, Golden, CO: Solar 

Energy Research Institute, March 1982. 

5. McConnell, R. D., Giromill Overview, SERI/TP-35-263, Golden, CO: Solar 

Energy bsearch Institute, Play 1979. 
1 Doc~ment Control I 1. SERI Report No 1 2. Nils Access~on No 1 3. Recipient's Accession No 1 

Page I SERI/TR-211-1911 I I 

4. Title and Subtttle 1 5. Publication Date 

( December 1983 I Osci 1 lating Wind Energy Conversion Systems I 

I 

I 

7 Author(s) 1 8. Performing Organization Rept. No. 

12 Sponsoring Organization Name and Address 13. Type of Report & Period Covered 

Peter South, Rick Mitchell 

9. Performing Organization Name and Address 

Solar Energy Research Institute 

1617 Cole Boulevard 

Go1 den, Colorado 80401 

Technical Report 

14. 

15. Supplementary Notes 

I 

10. ProjecVTask/Work Unit NO. 

1067.10 

11. Contract (C) or Grant (G) No 

(C) 

16. Abstract (Limit: 200 words) 

The information in this document suggests that Oscillating Wind Energy Conversion 

Systems do not appear to have any significant advantages over equivalent conventional rotating-element wind energy conversion systems. In fact, in most 

cases it appears that they have several disadvantages. The document addresses 

the oscillating cable-type wind energy conversion system as well as the oscillating vane and the oscillating wing. The advantages and disadvantages of each 

type of system are evaluated, and in each case a.comparison is made between it 

and a conventional rotating-element wind energy conversion device. It appears 

unlikely that any of the oscillating element concepts can compete with the 

present generation of conventional wind energy systems. 

4 

17 Document Analysis 

a.Descriptors Airfoils ; Cables ; Girornill Turbines ; Oscillations ; Power 

Coefficient ; Vanes ; Wind Power ; Wind Turbines 

b. Identifiers/Open-Ended Terms 

I c. UC Categories I 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, Virginia 22161 

.r 

k 20. Price 

18. Ava~lability Statement 

National Technical Information Service 

I I J 

Form ?lo. 0069 (3-25-823 

19. No. of Pages 

2 5