RECONVERSION OF TRADITIONAL WATER EXTRACTIONWINDMILLS IN MALLORCA TO PRODUCE ELECTRICAL

POWER

José Pascual TortellaDoctor Ingeniero Industrial

IDOM Ingeniería, Arquitectura y ConsultoríaAv. Conde Sallent, 11 –4º .- Palma de Mallorca (España)

Phone +34 971 42 56 70 e-mail: jpascual@barcelona.idom.es

(paper 4292)

Abstract :Traditionally, windmills have been used in the

agricultural area of Mallorca (Spain) and especially at Camposarea, to extract water from wells and use it for watering.

During the Middle Ages the number of windmillsgrew. Most of them were for flour although some were alsoused for water. . From this moment on their growth wasspectacular (in Palma there were 36 in 1872, 200 in 1891, 897in 1951 and 1308 in 1958). There were easily over 3000 in allof Mallorca Island.

With the arrival of electrical mains and the explosionmotor, motors that extract water replaced the windmills. Manywindmills have disappeared, others are in precariousconditions.

One aspect that hasn’t been dealt with until now is thetechnical analysis and the project of reconverting these slowrotational speed Machines moved by the energy of air inmovement to take advantage of it in obtaining electrical power.The specific objectives that can be summed up as the following:

. Reconvert and adapt a technology and means oftaking advantage of the wind energy existing on this island, yetforgotten, and introducing the novelty of the production ofelectricity on a small scale in order to take full advantage of it,save and replace other sources of power in the agriculturalsector (lighting, water extraction, watering, climatic adaptationof greenhouses, desalting brackish water, etc.) All of thisimproving the present visual and environmental impact, giventhe progressive state of abandonment and deterioration whichthe 3000 installations of this sort which are calculated to existon the island of Mallorca and which are object of our attention.

1.Introduction:Traditionally, windmills have been used in the

Plá of Mallorca, in the agricultural area in the North ofMallorca and especially at Campos area, to extract waterfrom wells and use it for watering. This is why we havechosen the name “Molcamp Project” for this attractiveproject.

Mallorca is a land of windmills. They are ausual sight in all the different municipalities, in thevalleys, on a hill or in a village itself. The first graphicdocument of a windmill dates back to 1468, appearing inthe Sant Jordi altarpiece by Pere Niçart, in the DiocesanMuseum of Mallorca.

During the Middle Ages the number ofwindmills grew. Most of them were for flour although

some were also used for water. All had a rotor and sailsor fabric. Windmills started being fully used for waterextraction in 1845, by the Dutchman Paul Bouvy deSchorrenber. He had the intention of cutting down thedrying out of the Plá of Sant Jordi. From this moment ontheir growth was

spectacular (in Palma there were 36 in 1872, 200 in 1891,897 in 1951 and 1308 in 1958). There were easily over2000 in all of Mallorca.

Aeolian power is an infinite and non-pollutingsource of energy. Its main drawbacks are its intermittenceand low density.

With the arrival of electrical mains and theexplosion motor, motors that extract water replaced thewindmills. Gradually, these mechanisms andconstructions deteriorated ending up creating the currentdepressing scenario. Many windmills have disappeared,others are in precarious conditions, and only a smallpercentage of them continue in acceptable conditions.They have either been rebuilt to continue extracting waterfrom the subsoil or they have been restored purelyaesthetically in order to improve the visual impact, whichtheir beauty undoubtedly has on both foreigners andlocals.

One aspect that hasn’t been dealt with until nowis the technical analysis and the project of reconvertingthese slow rotational speed Machines moved by theenergy of air in movement to take advantage of it inobtaining electrical power.

2. Environmental problem which the projectrefers to:The only autochthonous electrical power resources of theBalearic Islands are those that are renewable and thosederived from the biomass. Among the conventionalresources the only ones worth mentioning are thelignite deposits in Mallorca, which have been inactivesince 1991. Thus, 99% of the island’s power productionis obtained from importing power resources from outside,45% of the total production corresponding to oil and itsby-products and the remaining 55% to coal.

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For the production of electrical power 95% ofthe heavy oil products and the totality of coal producedon the islands.

The use of autochthonous power resources is verylimited. In spite of this, the Balearic Islands are the firstAutonomous Community regarding the surface ofinstalled solar panels and the second in solar power inrelation to the income per capita. The development ofwind energy has been much less impressing, in spite ofbeing traditionally the one and only renewable powerused since the late eighteenth century until the late 50s inthis century.

Especially important are the development ofpilot experiences and the demonstration effect, which canbe achieved with the use of renewable power.

As was pointed out by the WorldwideCommission on the Environment and Development “theefficient use of electrical power must be the focus pointof the electrical power policies in order to achieve avalid development”. The efficient use of electrical powerand the increasing importance that renewable sourcesmust take on are the two main aspects of the Conventionon Climatic Changes signed in Rio de Janeiro.

Making use of wind power has the greatadvantage of safeguarding the environment in a farsuperior manner than any of the conventional powers.

3. Project ObjectivesThe project being presented, in the case that it

has a satisfactory result from the financial technical pointof view that allows its relative generalisation to similarinstallations, is directed to achieve a series of veryspecific objectives that can be summed up as thefollowing:

. Reconvert and adapt a technology and means oftaking advantage of the wind energy existing on thisisland, yet forgotten, and introducing the novelty of theproduction of electricity on a small scale in order to takefull advantage of it, save and replace other sources ofpower in the agricultural sector (lighting, waterextraction, watering, climatic adaptation of greenhouses,desalting brackish water, etc.) All of this improving thepresent visual and environmental impact, given theprogressive state of abandonment and deterioration whichthe 3000 installations of this sort which are calculated toexist on the island of Mallorca and which are object ofour attention.

. Increase, to a certain extent (small yet worthwhile), thecontribution of wind energy to the current electricalpower offer on our islands.

. Develop this technological innovation as a productionsystem of electrical power by using the traditionalMallorquín at water extraction windmills at Campos área,betwen Campos Village and the "Trenc" beach, as well as

rationalise the use and consumption of the use andconsumption of this power.

. Promote among the different consumers affecteddirectly and indirectly the rational and efficient use ofelectrical power, introducing the “expense” factor ofelectrical power in the conscience and mentality of theresidents on our island, familiarising the consumer withthis concept.

. Recuperation of a historical patrimony (until well intothe nineteenth century windmills have been the onlymachines capable of providing mechanical energy for theservice of industry or agriculture), reducing the currentlynegative visual, aesthetic and environmental impact ofmost of the windmills in the area and increasing theirenergetic and touristic interest; in the event that thisinvestigation and development project is successful andits extrapolation to the rest of the areas of Mallorca.

The use of these aeolic devices to extract water andproduce electrical power, it also has the doubtless interestof its energetic use in a merely environmental way,applied investigation technological development anddemonstration. The rehabilitation of the windmills, whichwe have discussed and its use with this objective wouldalso be an innovating practice in our country which is notvery respectful of our industrial patrimony in general andwhat they represent, sometimes with a senselesseagerness to destroy and others due to the financialimplication their upkeep entails.

It would be a good idea to stop and think that atechnology which in our eyes may be old-fashioned, moreakin to poets and painters than to engineers and in a wayfar from the productive world, was, for centuries anavant-garde industrial and agricultural activity, since theywere the most powerful, fast and technically perfectmachines of those days, paving the road for“mechanisation” and the current Aeolic technology.

This is the technical base that supports the presentation ofthis project: bring these aeolic devices closer to thepresent providing them with a current technology inorder to carry out their role of making use of the windfor the production of electrical power, resolving thetechnical problems that are a part of it, at the same timeas improving its visual, aesthetic and environmentalimpact in the area where they would be put to use.

4. Technical Nature of the Project:There is nowhere on the Balearic Islands where the windblows at more than 7m/sec. On yearly average (measuredat 10m height). For this reason, and other technical ones(isolated electrical system and low potency regarding thedemand) it isn’t possible to replace other power sourceswith aeolic energy. It is only feasible as a complement toa conventional system or when a continuous use of theinstallation isn’t necessary (water or power extraction orstorage).

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Windmills make use of the wind’s kinetic energyto convert it directly into mechanical energy. To extractwater one adapts a piston pump and the intention behindthe development of this project is to fit an electricalgenerator for the production of electricity, analysing theaeolic, mechanical, electrical and system controlparameters which intervene, carrying out the completeproject of the installation, analysing the possiblealternative solutions, propose the system with mostchance of success and, with it, implement to a 300perfectly restored windmills at Campos area (MallorcaIsland). All of this, to, finally, obtain the final conclusionsand the “know-how” necessary for its eventualgeneralisation to 3000 traditional windmills existing atMallorca Island.

The windmills we are discussing have amultiblade type (18 blades) harnessing surface of a 8 mdiameter, slow speed (between 10 and 30 r.p.m.) whichthe wind blew on perpendicularly thanks to a rudder ortail, perpendicular and fixed to the before mentionedsurface and parallel to the direction of the wind. With thisa torque is generated in the axis which originates itsturning movement, if this is superior to the resistanttorque supplied by the piston pump which the system hasfitted to it by means of a excentric mechanism and whichis in charge of transforming the rotating movement of therotor in a linear way (swinging).

Its optimum functioning is obtained for acharacteristic speed ( λ) between 1 and 2. The maximumobtainable power (theoretic) is deduced, approximatelyby the expression (Les Gourrieres, 1974):

P=0,15 D2 V3

Being D the diameter of the rotor in meters; V, the windspeed in m/s and P, the power obtained in watts.

These parts will be analysed briefly in order toprovide a global vision of the existing technology and thetechnical improvements to be incorporated to achieve thegoals that have been marked. a) Energy reception: Rotor

The most characteristic element of the windmills are theantennas or blades which, attached to the bushing,constitute the rotor. There are two types, wood pieces andmetalic blades.

The wood pieces rotor is unique to the windmills used forwater extraction. Its structure is wood polygon of six,eight or twelve sectors, with a radius of between 4 and6m.

The blade rotors are of a diameter of between 6 and 12metres. Its structure is based on three steel circular hoopsand circular section, concentric which axially support theblades (divided in six or twelve sectors) which convergein the centre of the bushing (“Star") where they meet; the

blades are warped circular sectors. There are between 18and 26 of them made of tin or galvanised iron plates, thefirst of which was installed in 1934.

In order to permit the adequate automatic orientation ofthe rotor in a perpendicular direction to the wind, thehave a mobile tail. This structure can be oriented in therange of 360º to allow catching the wind whateverdirection it may blow in.

Its total longitude, including the support bar is around 1,2times the radius of the rotor and its surface around 15%of the rotor surface.

b) Movement transmission:The transmission system is in charge of transforming thisrotating movement (up to a maximum of some 30 r.p.m.)in a linear swinging movement that sets a piston pump inmotion. The excentric armsystem is the necessary and most simple transformationsystem. It appeared in the late Middle Ages and its use inwater extraction windmills became popular.

It is based on the main axis having an excentricity(crankshaft) perpendicular to the axis itself, supported onboth ends by a galvanised iron structure (wood in theolder ones) in the shape of a “U” called “fork”,

The crank is between 8 and 12 metres long, from thetrunnion of the connecting rod to the articulated pointwhich is joined to the rod of the pump, which it sets inmotion.

b) Work execution: Pump or “Cupet”.

The alternative movement pump used is an updatedversion of the Cresibi pump, used in the times of theRomans with human power. It consists of a cylinder(“Cupet”) with two orifices provided with theircorresponding clamp valves, through the interior of whichmoves a piston (Paneret o Pistó). When it rises itprovokes a depression inside the cylinder, and which,being shut by a valve in the outgoing orifice it suctionsthe water from the well, filling it completely with thewater that has been extracted. When the piston lowers,the valve that closes is the entry one, opening theoutgoing one and thanks to the pressure from the piston’smovement, the water that has been stored in the cylinderis impelled and expelled into the storage deposit (themaximum aspiration depth is 10.33m).

Originally the cylinder was made of pinewood althoughmost of those nowadays are cast iron or bronze.

The technical characteristics of these pumps are thefollowing: the cylinder has a diameter of between 0,15and 0,60m. The piston stroke is of 0,40m or 0,30m,giving the cylinder a volume of between 0,005m3 (5l)and 0,11 m3 (110 l).

d) Support System: Building and Tower

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A tower with a cylindrical or square base, of some 2 to 3meters in diameter or on the side and 5m tall supportedthe first windmills used for water extraction. In this caseit is known as the “narrow tower”.

Normally, these constructions have a square or circularbase and are made of sandy stone typical of the island(marés) or of stone.

The whole group of transmission components aresupported by a hollow metallic structure (made of woodin the older ones) “Box” (“Caixó”) to allow thealternative movement of the tizo???, thus sustaining thewhole thing. Moreover, this structural tower must havethe possibility of turning on itself to permit theorientation of the blades in the wind. This is why it isimbedded in the supporting building itself with the hoopor the roller bearing which is resistant to axial efforts of alarge interior diameter (30 to 40 cm), and is supported byanother as a base, known as “Grabaldina”, which is incharge of holding the weight of the entire construction,keeping it straight.

5. Project dimensionsIncorporating this system of electricity production to bedeveloped and the restoration of the traditional windmillsfor water extraction located in the flat areas near the coaston the island of Mallorca could reach a considerablenumber, easily reaching 950.

The dimensions of the project, if its advantages areproven and it was used in all these 950, would guaranteeits results in other areas of Mallorca itself. It would alsomobilise the infrastructure and create the minimumindustrial network of mechanic workshops to makemetallic parts, put them together and up-keep, whichnowadays virtually doesn’t exist or is in the process ofdisappearing.

6. Expected resultsOnce the power curve which has been validated withdifficult calculations and contrasting work withexperimental results has been determined; it has beenconfronted with data concerning wind speed fromdifferent sources (National Meteorological Institute,European Wind Atlas, Aeolic Map of the Balearics, etc.)

The speed of the wind in the area where the windmills arelocated is characterised by breezes that are especiallycommon during the hottest semester owing to theoverheating of the land in respect to the sea (this wind isknown as “Embat”). This guarantees the phenomenonwill repeat, and thus the annual power needed will beknown.

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The average annual speed is between 4 and 5 m/s, towhich applying the distribution of probability of thedensity of the speed of wind of Weibull with a K of 2which corresponds to a low variability:In these conditions, the distribution of wind speedsconclude that between 19.000 and 25.000 m3/year ofwater could be extracted per windmill per year, whichmeans a savings of between 9.000 and 12.000kWh/year/windmill.If the number of windmills to be rebuilt rises to some900, the mentioned quantities become some 22,5 millionlitres of water per year, which represents about 10 millionkWh (10 GWh) of conventional power replaced per year.This energy is equivalent to 860 Tep/year (1 Tep = 0,086Mwh), which, in other types of fuels would come to:

-Coal:-Solid residues:-Agricultural fuel:- Diesel oil:

The energy produced with these means could represent0,043% of the total power consumed in the Balearics in1996, 1% of liquid petroleum gas distributed (99.816Tep) and 4% of the gas manufactures in the same regionand year.

The installed power of windmills (2.700.000) w.Approx.) would represent some 70 times the fotovolcaicaPower installed in the Balearics in 1996 and would equalthe total installed of this sort since 1986.

7. Viability and financial interest of theproposed technique:

It is fair to admit that the viability of this Project cannotbe evaluated objectively as totally positive, if it is donefrom a purely energetic point of view, due to its lack ofspecific weight, however, this does not imply that theseenergy resources, quite considerable on this island, beignored.

Thus, it is necessary to point out thedemonstration character of this project, with itsrepercussion due to the possibility of it extending over aconsiderable, mainly rural, surface, with a great numberof visitors. Its value as an example or testimony to greatenergy savings as well as the innovative aspect of theproposed technique, without spoiling the traditionalaspect and function of Windmills, all this makes itsviability possible, involving the industrial sector on asmall scale, energy, agriculture and tourism with theabsolutely necessary attention to the environment.

These reasonings, as well as the environmentalbenefits already mentioned compose a favourable andhighly interesting scenario.

Acknowledgement

We aknowledge to the supporting Entities:

Ministry of Environment of Spain Campos Municipality Gesa-ENDESA IDAECampos Agricol Cooperative

IDOM Engineering, Architecture and consultant is theenginnering that has been carried-out the project.

C U R V A D E P R O D U C C IÓ N E N E R G É T IC A E S T IM A D A

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CAMPOS Windmills ENERGY PRODUCT ION SCHEDULE

WIND SPEED HRS / YE AR POWER PROD./YE AR AVAILAB. PROD. YE AR E ST.

m/s hrs watios kWh /year WINDMILL kWh / y ear

0 - 1 ,5 960 0 0 0 0,02 1027 0 0 0 0,03 1458,1 68,4 100 0,9 89,84 1458,6 219,6 320 0,9 288,35 1268,2 1518,3 1.926 0,9 1733,06 980,7 2385 2.339 0,9 2105,17 683,3 3763,8 2.572 0,9 2314,68 432,2 5930,85 2.563 0,9 2307,09 249,4 6712,2 1.674 0,9 1506,6

10 131,8 6930,9 913 0,9 822,111 63,9 7570,8 484 0,9 435,412 28,5 8201,7 234 0,9 210,413 11,7 8832,6 103 0,9 93,014 4,4 9463,5 42 0,9 37,515 1,5 9803,7 15 0,9 13,216 0,5 9797,4 5 0,9 4,417 0,14 8645,4 1 0,9 1,118 0,04 9410,4 0 0,9 0,019 0,01 8788,5 0 0,9 0,020 0,00 9790,2 0 0,9 0,0

TOTALS : 8759,99 1517,232 13291 0,9 11961

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