SMALL SCALE WIND ENERGY SYSTEMS

 


Published with financial support from The Netherlands Minister for Development Cooperation

"Small Scale Wind Energy Systems" is a quarterly publication of the Regional Energy Resources Information Center (RERIC) - AIT, Bangkok, Thailand and edited by RED Renewable Energy Development v.o.f. It is distributed as a supplementary sheet with the "RERIC News" and by direct mailing. Citation is encouraged on the condition that the source is indicated.


March 1996

EDITORIAL

As you see, "Small Scale Wind Energy Systems" is back again after a one year absence. The Dutch Minister of Development Cooperation has recently renewed financial support for two more years, which is very good news! We believe "Small Scale Wind Energy Systems" can provide a platform for people working in this field to communicate with eachother and to show that small scale wind energy indeed may contribute to local development. We are particularly grateful to the Dutch Minister for giving his support since the 'big' wind energy associations have been fairly absent in the small scale world.

We would like to thank Frank Goezinne and Dick Veldkamp for their editing work until now. They recommended us (RED) to become their successors and we hope to please you as well as they did.

In this issue, emphasis is on network creation in Asia and Latin America and on market stimulation. We also have an article about the situation in rural areas in Peru.

For the following issues, we invite all of you to cooperate and write about your experiences, activities, innovations, etcetera. Small scale wind energy is simply too important to be kept silent!

Jan de Jongh and Remi Rijs, editors

 

Wind Energy for the Rural Sector in Peru

Rural situation

Unlike the urban people, rural population in Peru has not commonly access to electricity supply by the public grid. While cities and larger settlements have now been connected to the national grid fed by hydro and thermoelectric power plants, in the rural areas still exists a strong demand for small-scale energy supply that cannot be met by micro hydro electricity. Yet, 40% of the country's population live in this area, dispersed or in villages of less than 10,000 people.

As many regions in Peru have a good wind potential, their needs might be satisfied by using small wind generators of sizes of less than 1 kW upto 10 kW. Locations that are most attractive for the implementation of wind energy, are the departments of Puno, Ica, Trujillo, Piura, Arequipa, among others. North of Trujillo, at Cape Malabrigo, average wind speeds clearly exceed 8 m/s, which is also the case in Marcona, Ica. (Actually, wind speeds at these locations are such that plans are being studied for two wind parks of respectively 30 and 75 Megawatt.)

Wind battery chargers

Peru has a long tradition in design and manufacturing of wind generators, most of them using a 12 volt car alternator to charge batteries. Until now, the most effective wind charger system is the three-bladed Waira (which means wind in the Inca language Quechua), developed by Eng. Franco Canziani. It has passed a period of tests, failures and modifications that were carried out together with Grupo, and is now available in two sizes of 700 and 1,200 watt rated, depending on the local wind speed. At present, about 25 of them have been installed at various locations in the country (coast and mountains). Price of a 700 W model is US$ 1,950, while a 1,200 W model costs US$ 2,250.

It is believed that the present technology may permit to design wind generators of sizes upto about 10 kW. For larger turbines it would become very difficult to construct the rotor blades.

Wind pumping

The Peruvian coastline provides favourable conditions for wind water pumping. It is a desertic zone crossed by some rivers that come from the Andes and that are without water at least three months every year. The coast has a high wind potential with annual average wind speeds of 4 to 6 m/s, and in the areas near the valleys underground water is found between 5 and 40 metre depth.

Wind pumping is not unknown to farmers in Peru, and a number of indigenous wind pumps have been designed and installed. Most of them had a limited capacity of, at best, comparable to a motor pump of about 1 kW. It practically means that the known wind pump models can only serve a very small area of some few hectares. Given a pumping head of 20 metre, one may hardly think about irrigation of more than 2 to 3 ha using a wind pump (depending on the product and the irrigation methods).

At present, the following wind pump types are found in Peru: Miramar (Miramar, Piura), improved Miramar type (Chiclayo); Alborada; Zimic, Infantes, Segovia, Fiasa ("American" type); Matto; MCTB500 (PUCP, second generation wind pump). Large wind pumps for water flows of 4 l/s and suitable to deeper wells are not available in Perú, and an appropriate wind pump of this size would be very useful. Moreover, farmer interest in wind pumping has recently revived due to the increased fuel prices (from US$ 0.50 in 1985 to US $ 2.00 now). This makes wind pumping more competitive, but short and medium term credits for investments in renewable energy are still rather scarce.

(Ing. Ricardo Tantas, Carlos Hadzich, Grupo, Pontificia Universidad Católica del Perú, Av. Universitaria Cdra. 18 s/n, San Miguel, Lima, Perú, Fax: +51(14)61 17 85)

 

Wind Pumping Network in India

A workshop on "Development of Wind Pumping in India" held on December 1st and 2nd, 1995 at Madras and Auroville jointly by the Center for Scientific Research (CSR), Auroville, and the Tamil Nadu Energy Development Agency (TEDA) was attended by over 40 persons including manufacturers, users, non-government organizations, state energy development agencies and media. Deliberations were conducted at Madras on December 1st where it was decided to form the "Wind Pumping Network in India". On December 2nd the participants saw several types of working wind pumps in Auroville including the WP-2s made nearly 40 years ago by the National Aeronautical Laboratory (NAL) at Bangalore. The results of some of the latest research on wind pumps recently carried out by CSR under a GTZ sponsored project was also made available to them.

At the Madras workshop, the main objectives of the Network were defined as follows:

The Wind Pumping Network will be operated by CSR who has been involved in research and development of mechanical windpumps for more than a decade and has, in co-operation with the manufacturer AUREKA, developed the highly successful, direct-drive, 5.5 metre diameter AV-55. This machine was found to be the most cost-effective wind pump being manufactured in India today as resulted from a market study on wind pumps recently carried out for the Dutch government. Auroville also happens to be one of the few concentrations of working wind pumps in a country where over 80% of the installed wind pumps do not work. However, in spite of the "12PU500" fiasco (over 2,000 installed with over 90% not working), Mr. Tency Baetens and Mr. K. Raghavan of CSR found in their "End-User Survey of Wind Pumps and other Pumping Systems in South India" that there are clusters of 12PU500s still maintained and operating successfully. The Network will attempt to study the ingredients of such success stories with a view towards replication.

Besides working towards the objectives defined at Madras, the Network will organize research in methods to improve performance of wind pumps and reduce cost of water pumped. As part of a GTZ sponsored project, Robert Trunz of CSR set up a wind pump test-bed during 1995 and studied the effects of five different techniques to increase water output, especially during low winds. Two devices (floating valve and spring device) were found to be extremely promising and field trials are planned as the next step before a widespread dissemination to manufacturers and users. Water output is increased by nearly 50% mainly in low and medium winds, and the lower cut-in wind speed results in more pumping hours and therefore increased reliability of the water supply. Since nominal extra cost is very low, it is envisaged that after successful field trials, manufacturers will be provided all necessary assistance for incorporating these devices in their wind pumps. Retrofitting existing windpumps with these devices can also be easily done and possibilities will be explored.

The Network will also formulate relevant Indian standards and certification procedures for the manufacture and installation of wind pumps. Quality assurance has always been one of the major bottle-necks and the Network expects to make a substantial contribution towards the successful development of wind pumping in India.

(K. Raghavan, RENCON, E-36, IFS Appts., Mayur Vihar, Phase I, Delhi 110 091 India)

 

International Seminar on New Developments in Wind Pumps (I)

From 23-26 November 1994, a seminar/workshop was held in Santa Fé de Bogotá (Colombia) with the object to disseminate gained know-how and technology with respect to the 3-S ("Smoothing", "Starting", "Sealing") pump concept. The Universidad de los Andes (Colombia), the Technical University of Eindhoven (The Netherlands) and the University of Reading (United Kingdom) had been working on this concept in a joint EC contract between September 1992 and August 1994 under auspices of the Commission of the European Community DG XII. Title of the project was "International Scientific Cooperation Project between Colombia, United Kingdom and The Netherlands: the development of an innovative 3-S pump". Participants invited were mainly reseachers, project managers and representatives of the scientific community from various countries in Latin America, who were previously identified and invited personally. The workshop and its proceedings are expected to contribute to the effective application of the 3-S pump concept in small and medium size wind pumps worldwide.

The focus of the 3-S project has been on the riser, pump rods and piston pump components:

The main starting device that has been investigated within the project is the "floating" or "matching" valve.

The proper understanding of the basis of the 3-S pump concept is of paramount importance if in the long term these improvements are to be successfully implemented in commercially available wind pump systems. Some foreseeable advantages of this development are an increased reliability and overall efficiency (which includes increased water output) of the wind pump system as a whole, and considerably lower maintenance and repair costs.

Technical details of the 3-S project are outlined in: Smulders, P.T., et al., "The 3S-Pump Project: Piston Pump Innovation for Wind Pumps". 5th European Wind Energy Conference, pp. 1145-48, Thessaloniki, Greece (1994)

(Dr. Alvaro Pinilla, Universidad de los Andes, Fac. de Ingeniería, Dept. de lng. Mec., Apartado Aéreo 4976, Bogotá, Colombia. Fax: +57(1)284 15 70; Dr. John Burton, University of Reading, PO Box 225, Reading, RG6 2AY United Kingdom. Fax: +44(1734)31 33 27; Ir. Paul Smulders, Technical University Eindhoven, Fac. of Physics, WS 1.45, PB 513, 5600 MB Eindhoven, The Netherlands. Fax: +31(40)246 41 51)

 

International Seminar on New Developments in Wind Pumps (II)

During the 3-S workshop in Bogota (23-26 November 1994), participants presented their experiences on wind pumping. A summary:

Chile, Bolivia

Javier Gho and Carlos Garrido (Chile) reported about the experience based upon variants of the Colombian design Gaviotas MV2E. Thirty commercial Gaviotas wind pumps were imported through a donation from the UNDP and merged with a local development of the Cretan type wind pump. Eight systems with 4 to 6 m diameter are now working in the field. A similar experience of academic research being translated into commercial wind pump systems, was reported by Emilio Montaño from Bolivia.

Panama

At the Universidad Tecnológica de Panamá, a program has started to gather meteorological information. Financial resources are sought for to buy equipment for further evaluation at selected sites with known wind energy potential.

Peru

Rómulo Bisetti and David Chávez of Grupo (PUCP - Lima) gave an overview of the used wind pump types in Peru, e.g.: Argentinian multibladed type; locally developed multibladed back-geared wind pump; the ITINTEC design; the Matto and Miramar yawless wind pumps; Cretan wind pump; Dutch WOT 12PU500 wind pump. Also in Peru, a group at the Universidad Nacional de San Agustín in Arequipa has recently started to work in wind energy (Rúsbell Zevallos).

Nicaragua

Here the "bomba de mecate" is being developed, which is a rope-washer pump combined with a CWD wind turbine design. Important characteristics of the construction are its simplicity and the low loads imposed by the pump on the wind rotor resulting in an efficient low-cost system.

Colombia

Mauricio Arango from SENA (Colombian apprenticeship training body) presented a general overview of wind pumps installed there about 40 years ago. Main problem is the lack of maintenance and repair. The systems are used by the Wayu indigenous tribes (about 150,000 people). SENA has started a training programme in conjunction with the Universidad de la Guajira. The region has a strong wind, making it difficult to use another wind pump type (for instance, the Jober wind pump). It has forced local manufacturers to develop a more robust wind pump system, with some success.

Jorge Castro (Jober) was the only manufacturer represented. He gave a brief summary of the interesting development of 100 wind pumps and four models in 1994. Systems were mainly sold in Colombia but some have been exported to Venezuela and Ecuador. Most recent development is a wind pump to suit the conditions of the Guajira region.

Mauricio Gnecco (Fundación para el Desarrollo de Tecnologías Apropiadas - FDTA) showed the interesting experience of the use of wind pumps in the Llanos Orientales. FDTA is a non-governmental organisation with the purpose of increasing the use of appropriate solutions for rural needs. Strong emphasis is on energy supply from various sources, one of them being wind. At the time of the seminar, FDTA is working together with Jober to promote the use of wind pumps for water supply for humans and animals in the Llanos region.

Venezuela

Vicente Durán and Eliodoro Gómez described the work of Fundación Zumaque, which works in extension and health care in remote regions of Venezuela, and of the Universidad Francisco de Miranda. The latter has a wind energy test site on Paraguana peninsula, a region not unlike the Colombian Guajira, where a variety of vertical and horizontal axis wind turbines have been installed.

Prospects

Common points are the recurrent necessity to have more international technical cooperation projects as well as financial resources. Education is needed in the field of renewable energies, environmental problems and sustainable development in Latin America. The idea was launched for a Latin America based association for Wind Energy for Rural Areas (WERA). To carry on with this idea, Uniandes undertook the responsibility to manage the beginning of such an association for the next two years, perhaps in another country, to share the experience of implementing the 3-S pump concept in wind water pumping and to invite some more institutions from the region.

(Dr. John Burton, University of Reading, PO Box 225, Reading, RG6 2AY United Kingdom. Fax: +44(1734)31 33 27)

 

Stimulating the Markets for Wind Pumps

Articles in "RERIC News" Vol. 17 nos. 3 and 4 (1994) described work on the markets for windpumps in developing countries which was funded by The Netherlands and the UK. A Dutch study found potential for larger markets in many countries and identified the barriers to progress and a Dutch/British seminar discussed how to develop them. The challenge of stimulating some of these markets has now been taken up in a pilot project funded by the UK's Overseas Development Administration (ODA).

Market difficulties

The four major strategic problems which are found in almost every developing country windpump market are the lack of affordable finance for manufacturers and potential purchasers; information on the technology and its applications; support to users for operation and maintenance; and improvement of design and manufacture of the windpumps. However, every market is different and it is important to develop individual solutions. Another key issue is how to best use the knowledge and resources available in the industrialised countries in order to stimulate self-sustaining markets for local wind pumps in the developing countries.

ODA project

The ODA project is designed to create local networks which will encourage and assist the players in the market to co-operate in market development activities. The project is intended to develop in such a way as to maximise the benefit of contact with existing networks, technical co-operation programmes and other agencies. The project, which started in April 1995, is executed by UK consultants HGa with help from Gamos Ltd and Renewable Energy Development of The Netherlands. From amongst the countries in Asia where there is experience of windpumping, India, China, Philippines and Vietnam were selected on account of the strength of interest and the prospects for success. They are all very different from one another which provides a test for the pilot project.

The consultants looked for potential collaborators in each country amongst manufacturers and distributors of windpumps as well as a variety of NGOs, rural extension workers, government agencies, researchers and representatives of the users. It is particularly important to gain the maximum involvement of the manufacturers and suppliers as well as organisations which represent the interests of the users. In each country a workshop has been funded at which the participants have been invited to set up a network organisation. At the time of writing three countries have set up a network and the fourth is expected to do so soon. The network organisation provides a forum for the members to work together on identifying opportunities and barriers to progress. The members can then develop suitable activities, either collectively or in smaller interest groups. The network organisation also becomes a point of entry for the consultants to input information and other support to the network and its members in developing the market.

Future organisations

During the rest of 1996, the network organisations will be assisted to develop their activities and design new projects for which national or foreign support can be sought if required. Towards the end of the year, a regional workshop will be held at which the members can exchange experiences and ideas.

A wide variety of new projects is envisaged for the next phase. For example, they could include specific technical help to a manufacturer; training for designers, manufacturers, installers, operators and maintenance workers; an awareness campaign amongst funding agencies and banks; demonstration and dissemination projects; preparation of training packages for local training institutions; or setting up a maintenance organisation in rural areas.

The ODA is providing funding for the workshops and for the start up costs of the new organisations as well as for the consultants. It is hoped that the ODA and other agencies will be sufficiently interested to fund the future projects and activities. If this approach to stimulating the markets is successful then perhaps other countries can be helped to start their own network and join the regional organisation.

(R.J. Hacker, HGa, Burderop Park, Swindon SN4 0QD United Kingdom, Fax: +44(1793)81 50 20)


June 1996

Increasing the Water Output of Windpumps

Fine field testing has been reported from the Centre for Scientific Research (CSR), Auroville, India on loadmatching devices for water pumping windmills driving piston pumps. This work, supported by GTZ, Germany, is among the best on windpumping performed in the nineties.

A piston pump has obvious merits compared to its competitor the centrifugal pump: it has a high efficiency (80 %) which is more or less independent of pumping head and pumpspeed and it can be used to great depths (over 100 m). Its main disadvantage is that its load is very badly matched to the characteristic of the wind rotor.

The torque loading on the rotor during a pumping cycle is unevenly distributed as shown in Figure 1.

Figure 1: Rotor torque during pump cycle.

A running rotor has sufficient kinetic energy to take the bumps. Standing still however, a much higher wind speed is required to get the pump started than to keep it running. This represents a considerable loss of power output at low windspeeds.

Methods to improve this situation all boil down to smoothing the torque loads (and if possible reducing them) at low wind speeds.

Five load matching devices were tested by CSR, all on the same windpump, the 5.6 m diameter 24-bladed AV55 developed by CSR. This makes a comparison of the results very reliable. The pump stroke in the experiments was 140, 180 or 227 mm, the piston diameter 101 mm.

1. Counterweight balancing the weight of the pumprods and part of the hydraulic load. It is quite effective in increasing output but was rejected owing to the vibrations caused by the accelerations of the counterweight (Figure 2).

2. Cam mechanism by which the upstroke is lenghtened and downstroke shortened in time, thus smoothing the torque. Rejected, due to technical problems of the cam mechanism.

3. Spring in tension between the tower and pumprod more or less balancing the loads like the counterweight. Proved a reliable method to increase the output considerably (Figure 3).

4. Matching valve. This valve, developed by the wind energy group of Eindhoven University of Technology in The Netherlands, is lighter than water and replaces the normal piston valve of a piston pump. At low wind speeds and so low pumping speeds, the valve by buoyancy remains open; the wind rotor can turn unloaded (except for the weight of the pumprods). It can be shown that at a critical piston speed the valve will close and pumping starts. It can further be shown that the valve -if properly designed- not only eliminates starting problems but also gives the pump a characteristic which at lower windspeeds is more or less perfectly matched to that of the rotor (Figure 4). The hollow polypropylene valve was tested over more than 3 million cycles with very good results: reliable, no extra cost and greatly increased performance.

Figure 2, 3 and 4: Counterweight; Spring device; Matching valve.

5. Automatic variable stroke mechanism. This hydraulic system, designed by CSR, adapts the load at different wind speeds by automatically modifying the stroke length. The increase in water output is considerable. However, the mechanism besides adding 13 % to the price of the windpump is technically complicated and prone to a lot of maintenance.

Finally, the windpump was also tested in its conventional state, i.e. without any load matching device.

The conclusions from the test are evident (see Figure 5). The output of a windpump can be increased by 30-50 % by installing a spring or a matching valve as load matching device at low or no extra cost. The windpump starts pumping at a lower windspeed of 5 km/h instead of 7.5 km/h, meaning that water is pumped during more days than conventionally.

Figure 5: Hourly output (l/h) vs. wind speed (km/h) for a conventional pump (+) and counterweight (-) with stroke 140 mm; spring device (o) stroke 180 mm; and matching valve (+) stroke 227 mm.

Load matching devices merit further development. They can be applied successfully on any windpump driving a piston pump. The use of springs and matching valve could be combined, in which case the spring should balance the weight of the pumprods; but it should also be explored to combine the matching valve with a modest counterweight balancing the pumprod weight. Even the automatic load matching device merits further development, but should then be manufactured in large numbers. It would especially be useful if it could also reduce the stroke at high windspeeds.

Source: Robert Trunz, Field Testing and Monitoring of Load Matching Devices for Waterpumping Windmills. Centre for Scientific Research, Auroshilpam, Auroville - 605 101 - South India, Dec. 1995.

(Paul Smulders, Technical University Eindhoven, Fac. of Physics, PB 513, 5600 MB Eindhoven, The Netherlands, Fax: +31(40)246 41 51)

 

Update on the Poldaw Windpumps

The Poldaw windpumps are a range of medium-sized very low-cost machines designed and developed by Neale Consulting Engineers Ltd (NCEL) in the UK. The designers have extensive experience of appropriate technology machinery design, and carried out the final engineering of the IT windpump in the 1980s.

The Poldaw machines have a rotor diameter of 3.5 m and 5 m. They are smaller than the IT windpump, and have a considerably simplified design, thereby achieving reduced cost without compromising robustness and reliability. They also incorporate various innovations, such as the use of automotive rubber bushes as bearings for oscillating components.

The 3.5 m diameter machine has been under development since 1990, and the pre-production trials started in early 1993. Production in the UK and Zimbabwe was started at the beginning of 1995, and further manufacturers in India and Pakistan have since signed manufacturing licences. Negotiations are underway with various other interested manufacturers, and there have been over 100 enquiries to date, from about 35 different countries.

Various surveys have established that there is a large potential demand for low-cost windpumps, providing that they are reliable, and that they are capable of pumping reasonable quantities from boreholes as well as shallow wells. The designers set out to produce a machine capable of pumping from as deep as 90m (300 feet), and giving an average output from shallower wells of at least 3 to 4 times that of a handpump.

These requirements dictated a rotor size of at least 3 metres, and therefore the challenge was to produce a machine of this size with the minimum cost consistent with adequate robustness and reliability.

Most successful small windpumps with a deep well capability use a speed reduction gearbox to avoid dynamic problems in the pump and pump rods. The Poldaw designs however use a direct drive (crank, connecting rod and rocker), but have a specially developed rotor which developes high torque at low speed. This has a tip speed ratio of approximately 0.7, and sacrifices some aerodynamic efficiency, which is compensated by a slightly increased rotor size. The elimination of the gearbox reduces the overall cost and improves reliability.

Testing was carried out in the UK to maximise the control and the accuracy of data collection. After 18 months continuous testing the machine was completely stripped to examine for wear, cracks and other defects. No severe problems were found, and with a few of minor design changes, it was deemed ready for production. The first test machine was re-installed after examination, and now has over 3 years of successful operation to its credit. There are about 30 other machines now installed and operating (mainly in Zimbabwe), and none have given any significant problems.

Enquiries are welcomed from potential manufacturers anywhere in the world. Licences generally confer exclusive rights for a particular country, except in the case of India where up to 4 regional licences are planned. The development of a 5 m design is underway and will be released to manufacturers when it has been adequately tested.

(Sandy Polak and Paul Dawson, Neale Consulting Engineers Ltd, 43 Downing St., Farnham GU9 7PH, United Kingdom, Fax: +44(1252)73 71 06)

 

Problems on Small Scale Wind Energy in Albania

In Albania interest for the exploitation of wind energy began in 1992. During 1992-94 the Institute of Mechanical Studies and Design (ISPM) carried out a study on small scale wind energy systems and their applications in Albania, including the design and manufacture, and experiments with a windpump. The study was financed by the "Albanian Committee of Science and Technology" with a sum of approx. US$ 10,000. In 1995, ISPM performed a study on electricity generation using wind power, financed by the Ministry of Industry and Trade with US$ 20,000. Also, the Meteorological Institute in Tirana is performing a study on wind potential with funding from the European Community; the aim is to compile a wind map for Albania.

The introduction of wind energy in Albania involves three major difficulties. First, the region's energy demands need to be determined. The local administrations and energy specialists must be engaged in this work. In Albania the problem of heating of houses has not yet been resolved, especially in the remote zones. Until 1991 heating was done by burning wood, which caused great damages in forests. Since 1992, electric energy is being used (partly also kerosene), which causes power failure and overload of the electricity system.

Second, the regions with useful wind speeds must be identified. In our country, the meteorological wind data reveal that 50% of the Albanian territory has a wind speed of more than 5 m/s for half of the year. However, these data are based on conventional anemometry or even popular memory and need to be verified using more accurate, up-to-date devices. But such devices have not yet entered Albania. The idea is that by buying modern measuring devices and windmills from abroad, Albanian specialists can detect the promising zones, process data, and draw final conclusions.

Third, in Albania the cost of energy produced by wind power is often wrongly compared with that of conventional power generation. Nowadays this is perhaps the main issue for Albania. In fact, small stand-alone windmills are usually installed to furnish small consumers in zones far from the electric grid, where its extension would be a too big investment or be impossible. In any case the cost of wind energy in these zones is competitive with that of other small energy sources, like diesel, small coal or oil boilers, small hydro, or solar (of course, such an evaluation should be done separately for each case). The privatization of the electricity distribution in Albania may cause problems to supply the remote zones. This may give an incitement to find other manners of energy supply, one of them being wind energy.

(Eng. Eduard Papa, ISPM, Rruga "Ferit Xhajko",Tirana, Albania, Fax: ++355(42)23 681)

 

Mariano Marcos State University ANEC Develops own Windmill

The Affiliated Non-Conventional Energy Center (ANEC) of the Mariano Marcos State University (MMSU) in the northwestern part of the Philippines, one of the 19 such centers all over the country, has built its own windpump as a direct result of a workshop on "Windpump Design and Manufacture" held in Iloilo City in the middle of 1995. The workshop was conducted by the Central Philippines University ANEC in cooperation with the University of Twente and Renewable Energy Development vof in The Netherlands. The workshop was attended by the author who proceeded to apply the gained knowledge to the design of a windpump. During a second workshop on windpumps "Project Implementation and Evaluation" held at the MMSU in October 1995, the author received valuable technical advice to improve the rotor which was then being made.

The windpump has 6 blades and a diameter of 3.5 metres. The blade width is 0.45 metres, and the twist angle is between 39.7 degrees at the base and 24.9 degrees at the tip. The tower has a height of 15 metres, and is made from mild steel angle bars and round bars. The pump, which was made from parts of an existing commercial manually operated water pump, has a stroke of 10 cm. At an average wind speed of 2.5 to 3.0 m/s at ground level, the capacity is from 7-15 litres/min.

Since this is a prototype, further improvements will be done to make it commercially acceptable. The most pressing improvement is in the area of the pumping unit. As of now, the pump is fitted with a rubber cup for suction which is prone to tearing.

The windpump is presently being used to irrigate crops planted by the university nearby. These include, corn, garlic and tobacco.

MMSU-ANEC's long-term plan is to install several windpumps as promotional units in highly visible, technically and economically feasible areas in the province of Ilocos Norte, Ilocos Sur, and Abra.

(Rudy P. Bareng, MMSU-ANEC, Mariano Marcos State University,Batac, Ilocos Norte 2906, Philippines)

 

150 Thousand Small Wind Generators in China

China has put emphasis on the development of small wind generators in the exploitation of rural energy sources. The Sixth (1981-1986), Seventh (1986-1990) and Eighth (1991-1995) Five Year Plans allocated special investments for research and development of small wind generators, while preferential loans with low interest were given to manufacturers to improve product quality and expand production. Some local governments also have granted subsidies to users for many years; in Mongolia, a manufacturer receives a US$ 25 subsidy from a local financer after selling a unit.

In more than ten years of its development, the Chinese industry of small wind generators has accumulated ample experience on design, manufacture, testing, and product check, which has improved product quality and performance. The annual output is about 20,000 units now. In 1995, about 150 thousand units were in operation all over the country, of which 130 thousand in Inner Mongolia.

In addition to social benefits, economic development and energy savings have been achieved. The Shangdu Pastoral Machinery Plant of Inner Mongolia, producing 100 W and 2 kW machines, has seen its output increasing at an average annual rate of 58 percent. The annual profit has more than quadrupled and amounts now to several 10 thousand dollars. The 15 thousand 50 W units in Inner Mongolia produce yearly 2.4 million kWh, while 70 thousand sets of 100 W machines produce 18.2 million kWh. This is equivalent to a saving of 19.5 thousand tons of standard coal.

(Long Zequiang, Chinese Wind Energy Development Centre, Huayuan Road 3, Beijing 100083, China, Fax: +86(010)201 28 80)

 

Progress on Wind Pumping in Gujarat

The first attempt of wind energy utilization in the agriculture sector in the country began in 1952 under the Council of Scientific and Industrial Research (CSIR). The National Aeronautical Laboratory (NAL), which later came into existence, developed the WP-2 Water Pumping Windmill Model. R&D on various models indicated that for favourable places, wind pumps proved to be attractive as they are three times cheaper than the nearest renewable alternative, the wood-based gasifier. A comparison of cost-effectiveness with diesel and electric pumps indicated that given favourable wind conditions the cost of water pumped by windmills can be much lower. Most wind pumps can draw about 10,000 to 20,000 litres of water every day for a head upto six metres. Applications include domestic water supply, water for livestock, irrigation drainage, fish farms, small ponds. The Gujarat Energy Development Agency (GEDA) therefore initiated the Water Pumping Windmills Programme in 1980 with financial assistance from the State Government. In coordination with the Central Salt & Marine Chemicals Research Institute (CSMCRI - Bhavnagar), in 1980-91, ten experimental prototype windmill models of different designs were evaluated; of them, six were identified as suitable to local conditions in Gujarat. Unfortunately, sufficient data on theire performance could not be collected as these windmills were severely damaged during the cyclone that hit the state that year.

The programme received a major impetus with the introduction of the National Windmill Demonstration Programme (NWDP) launched by the then Department of Non-Conventional Energy Sources (DNES). It mainly concentrated on the fabrication and installation of the 12-PU-500 Windmill model. During the Seventh Five Year Plan it received priority attention so as to generate extensive user response, create awareness about the technology and provide inputs for its subsequent extension to private farmers. As these windpumps were primarily installed for drinking water supply and small-scale irrigation, the development of other models was intensified.

Meanwhile GEDA had begun experiencing problems with most of the 95 12-PU-500 wind pumps installed in Gujarat since 1985. Major faults were detected in the pumping system, as well as in the transmission and the furling mechanism. Moreover, this wind pump was designed for shallow wells upto 10 metres and low wind velocities, whereas several parts of Gujarat have deep water tables and high wind speeds. Therefore, GEDA decided to stop the programme for the time being, and subject the 12-PU-500 to systematic testing before further trials in the field.

The Sardar Patel University (Vallabh Vidyanagar) was given the assignment to adapt the existing model to Gujarat conditions. The modified design used a chain transmission for better flexibility; a four-bar mechanism to guide the reciprocation motion; a leaking piston with a spring load to control the chain tension; a piston guided by brushes on both sides to avoid misalignment; and a drum-type brake connected to the furling mechanism. Two of these modified 12-PU-500s were field tested at Vallabh Vidyanagar and Porbandar but suffered technical problems which could not be sorted out because of short supply of spares.

Five other wind pump models have since been installed for evaluation. Four of them are indigenous designd, while one has been adopted from the Australian "Yellow- Tail". The four Indian models are: Nityanand developed by OM Engineering Works (Anjar - Kuchchh); EM-2 model developed by the Rural Engineering School (Rojmal - Bhavnagar); DW-300 developed by Autospares (P)Ltd (Pondicherry); and the 12-PU-500 model redesigned by the Rural Technology Group of the Sardar Patel University (Vallabh Vidyanagar).

These models are now being monitored. Users report they are satisfied with their performance but state that the costs are a major constraint, even at a 75 % to 80 % subsidy provided by MNES and GEDA. As an average a user is required to spend about Rs. 15,000/- per wind pump of a total cost of Rs. 50,000/- . If the windpumps are to be used by farmers on a commercial basis, the initial and maintenance costs need to be reduced substantially. The need for models with a larger capacity has also been voiced.

The Saurashtra and Kuchchh areas in Gujarat are ideal for wind pumping. A major application in coastal Gujarat is for draining in the large-scale salt panning industry. About 50 % of the Indian salt production is in Gujarat. Now draining is done by large diesel pumps, but wind pumps could be used as well because panning is generally done in summer when the wind conditions are fairly good. GEDA hopes to stimulate the use of windpumping and has set a target figure of 500 wind pumps for the Eighth Five Year Plan.

(Pradib Rajeshirke and Daksha Vaja, Gujarat Energy Development Agency (GEDA), IInd floor, Suraj Plaza -II, Sayajigunj, Vadodara - 390 005, India, Fax: +91 (265) 333 120)

 

 


September 1996

EDITORIAL

As you can see, the September issue of "Small Scale Wind" is dedicated exclusively to windpumping. We have got news from Egypt, India, and The Philippines. We have also got an interesting article from Dan Davies, UK, who has recently concluded a Ph.D. work on the reduction of pump rod forces.

As the editors we feel that not everybody is acquainted with the backgrounds of windpumping and small wind electric business. We have therefore decided to start with a series of introductory notes, each of them dealing with a tiny bit of "small wind basics". Don't hesitate to give us your opinion about this and don't forget mailing us your news!

Jan de Jongh and Remi Rijs, editors

 

Windpumps and Drip Irrigation: Success Stories from Gujarat, India

In continuation on the article in the previous issue of "Small Scale Wind", Mr. Pradib Rajeshirke reports about the experiences of some windpump users in Gujarat. Users should not passively await once another government programme, but take intiatives and get familiar with windpumping. Only direct user involvement, he concludes, can make windpumping in India successful.

Mr. Kantibhai Kataria, a small garment merchant in Rasulabad (Vadodara) reports an average monthly income of Rs. 5,000/- on his plantation since he started using a windpump to irrigate his 1.5 ha farm in September 1995. He smiles: "I have no electricity and neither is a connection in the near future within my reach. But that's no longer a problem, and now that I have learnt to use it correctly and manage it on my own, it is a blessing in disguise".

Inspired to install the windpump on the advertisement released by GEDA in that year, Kataria decided to invest Rs. 15,000/- as a contribution to the total cost of Rs. 44,000/- given as a central and state subsidy. He replies that this is a one time investment. Before, he paid a daily amount of Rs. 250/- in winter and double the amount in summer to water mango, coconut, papaya, banana, lemon and other seasonal vegetables.

Kataria's perseverance and personal initiative have played a crucial role. In the first year of installation, the manufacturer (Marut Energy Equipment, Pune) came regularly every three months to service Kataria's windpump. He taught him how to take care of basic maintenance, greasing of moving parts, changing oil, changing washers, and so on. Kataria proudly states: "I can do all these things myself. I am alert to any abnormal sounds and carefully watch the water output so that I can spot problems before they magnify into major issues. But the real secret is the careful use of the water pumped by the windmill. I have coupled my wind pump with a drip irrigation system. An even moisture supply in the soil is critical for good crops to convert this barren orchard into a prosperous abode.

In Dediapada village, Bharuch district, another farmer coupled his windmill with a drip irrigation system to water his 'ber' orchard. He claims a profit of Rs. 40,000/- in just one season. His success has led to a boom in the demand for windpumps in this area. His neighbour who cultivates a rose garden, has recently invested in a similar system. As both plants require steady water supply for promising yields, the drip technology meets the needs perfectly.

Mr. Balubhai Bhadani, a farmer in Junvader village (Bhavnagar district), irrigates his 1 ha farm to produce three-seasonal crops (pomegranate, bajri and chillies) since he installed his windpump in August 1993. The micro-irrigation application today, fetched him an economic return of over Rs. 40,000/- in the last two years and reduces the drudgery of watering the crops. He is very pleased with his windpump as it demands low maintenance and his operating expenditure amounts to about Rs. 200/- for the expenses on oil. "I would advise every farmer to install such a device where you have to only rely on the wind god".

(Pradib Rajeshirke, Gujarat Energy Development Agency (GEDA), IInd floor, Suraj Plaza -II, Sayajigunj, Vadodara - 390 005, India, Fax: +91 (265) 333 120)

 

The Reduction of Lift Rod Forces in Piston Pumps

One of the greatest barriers to the uptake of windpump technology is that of reliability. This is particularly true of the smaller, lighter "second generation" of machines which tend to run at much higher speeds than their larger, multi-bladed, counterparts. This high speed operation can make the loads in the lift rod excessive. For example, the French organization GRET (working in Mauritania) reports that 42% of failures on their 2.5 m diameter machines are due to overloading of the lift rod.

During the pump cycle, at a point after the bottom dead centre the piston valve closes. Suddenly the upward moving lift rod has to accelerate a stationary mass of water up the rising pipe. The peak loads which occur as a consequence of this acceleration can be five or six times the load due to the static head of water.

Under a project funded by the U.K. Engineering and Physical Sciences Research Council the dynamic behavior of a reciprocating piston pump has been investigated. The inclusion of varying degrees of softness in several of the windpump components has been shown to greatly reduce the peak lift loads.

The inclusion of a small amount of flexibility into the lift rod, such that it stretches by around 10% of its length when supporting the static head, can be sufficient to almost half the peak lift rod load at high speeds. One major benefit of this technique for improving the longevity of a windpump is that it can be easily retrofitted to any machine.

A more complex alternative is to use an air chamber to smooth the flow fluctuations up the riser pipe and therefore prevent the accelerative loading of the system. An air chamber system, making use of the bladder from a very small hydraulic accumulator connected to a large volume of air held inside the lift rod has proven to be very successful (see Figure 1). The bladder provides storage for 55% of the swept volume. The back-up chamber holds a volume of air five to six times the swept volume. The material is impermeable to water and air and is easily sealed. The bladder is designed to survive 10 million cycles, enough to outlast the piston seal. this device has the additional benefit that it will perform better with a restricted riser pipe.

Figure 1: Pump configuration with bladder device.

 

Another solution, which is often prohibitively expensive or too complex for the smaller machines, is to reduce the speed at which the pump operates. A novel realisation of a drive mechanism originally used by the Canadian Brantford windpump at the turn of the century has been built and tested at Reading. This device translates the rotational speed of the rotor shaft into a long slow reciprocating motion using two duplex sprockets and a length of duplex chain with carrier plates.

These simple technologies can greatly reduce the peak load suffered by the lift rod and the above ground windmill structure and offer the possibility of reliable fast running wind powered water pumps.

(Dan Davies, University of Reading, Dept. of Mech. Engineering, Whiteknights, P.O. Box 225, Reading, RG6 6AY, United Kingdom, Fax +44(1734)313 327)

 

Introductory Note: The Niche for Mechanical Windpumps (I)

Small-scale water supply in the rural areas usually involves very low power requirements. In many regions in the world, sufficient wind resources are available to attain these power levels by using a small, mechanical windpump. Even at moderate wind speeds, such a windpump can be more cost-effective than its competitors, the solar pump and the diesel engine.

Applications and Power Requirements

The water requirements for a number of typical applications are summarized in Table 1. These requirements determine the effective hydraulic power output Pav, hyd given by:

Pav, hyd = r w g Q' H [watts] (1),

with r w the density of water (1000 kg/m3), g the gravitational constant (9.8 m/s2), H the pumping head in meters and Q' the pumping rate in m3/s. If Q' is given in m3/day, the formula turns into:

Pav, hyd = 0.113 Q' H [watts] (Q' in m3/day) (2).

The volume-head product (Q' H) is a direct measure of the power requirement and is expressed in m4/day. A nett hydraulic power of 1 Watt continuous (during 24 hours) is equivalent to 8.8 m4/day, and 1 kWhhyd is equivalent to 367 m4.

Application
Head
Daily

volume [m3/day]

Typical rotor

diameter [m]

 
very low

< 3 m

low

3-10 m

medium

10-30 m

deep

> 30 m

   
Community

water supply

   
x
x
20

(500 people)

2.5 - 7
Domestic

water supply

   
x
x
1 - 3

(small farm)

1.5 - 2.5
Cattle

watering

   
x
x
20

(500 head)

1.5 - 4.5
Irrigation
x
x
   
40 - 100

(» 1 ha)

2.5 - 5.5
Drainage
x
     
100
2.5 - 3.5
Saltpans
x
     
1000
2 - 7

Table 1. Indication of water depths, required daily volumes of water and typical rotor sizes for windpumps.

The requirements shown in Table 1 range from 10 m4/day to 1000 m4/day, equivalent to average hydraulic outputs of a few watts to about a hundred watts.

Windpump Output and Wind Resources

The average output of a wind energy system can be expressed by the following formula:

Pav = E/T = b Vav3 A [watts] (3).

In windpumping, Pav is taken to be the effective average hydraulic power Pav, hyd. It is related to the rotor swept area A and the average wind speed at the site Vav by introducing the (empirical) quality factor b . In field conditions, a value of b of 0.05 is acceptable, a value of 0.15 is excellent. An average value for a well-designed windpump is b = 0.1. It should be noted that a good quality factor, hence a high performance, is not obtained by choosing an efficient windpump design only. It also relies on how a windpump is matched to the site conditions (i.e. wind and water resources). And first of all it depends on the reliability of a windpump and the way it is maintained. This defines whether a windpump is actually available for pumping when it is required to do so.

The rotor area is a good indicator for the total cost of a windpump system. Formula (3) shows that, for a given rotor size, the delivered output increases rapidly with the average wind speed at a site. At higher wind speeds, a same amount of water can be pumped by using a smaller and cheaper windpump. The price of unit water will then be lower and the windpump will be more cost-effective. It is now widely accepted that windpumping is economically feasible at sites where Vav ³ 3 m/s, in some cases even downto 2.5 m/s. Such average wind speeds are very moderate and are found at many sites in the world.

A Niche for Windpumping

Mechanical windpumps can fill the gap between the smaller handpumps and the larger electrical or engine-driven systems. This is depicted in Figure 1.

Figure 1: The niche for wind pumping.

At the lower end of the scale (below 100 m4), there is no deal in competing with the simple and much cheaper handpump. At the higher end (above 1000 m4), the increased technical complexity makes mechanical windpumps less cost-effective and less reliable. In fact, 2500 m4/day is about the upper output limit feasible for mechanical windpumps.

Engine driven pumps are uneconomical at very low requirements because they are not designed for these output levels. Diesel pumps do not exist below 2 kW rated power and are used at part-load and intermittently. Solar pumps can be applied for a wide range of power requirements, due to the modular character of the solar panels.

At larger demands, wind power may be used to generate electricity to drive a motor/pump combination. Such equipment is commonly refered to as a Wind Electric Pumping System (WEPS) and can be attractive at average wind speeds of 5 m/s and higher.

Source: BWEA/RAL Workshop - "Technology and Implementation Issues Related to Renewable Energy Systems in Developing Countries", ISBN 1 870064 25 9, Abingdon, United Kingdom, June 1995

 

The GEF-ESES Windpump Project in Egypt

The Egyptian Solar Energy Society (ESES) has signed an agreement in September 1995 with the United Nations Development Programme (UNDP) through its Global Environmental Facility (GEF) NGO Small-Grants Programme. ESES, which is a non-governmental organization, will design, manufacture, install and maintain four small-size wind turbines for water pumping in remote areas in Giza and other Governates in Egypt. The project duration as originally proposed is two years and the amount of donation received from the GEF programme is US$ 28,000.

The members of the ESES team have developed a sophisticated new design of windpump which will hopefully be capable of pumping water at a rate of 3 to 5 m3/h depending on the depth of the wells and the available average wind speeds. The new machine has a 5 m rotor diameter, 6 blades each of 2 m length, and a 9.5 m tower. It is connected to the submersed piston pump by a crank-arm mechanism, and has a regulation system which prevents the wheel from exceeding 100 rpm.

Starting-up of the project is according a four-phases plan:

The Society signed a constract with the Engine Factory EF, which is considered as one of the biggest factories in Egypt. EF will manufacture under its reputed quality control the windpumps according to the specifications, designs and drawings offered and made by the Society. A variety of issues was put forward which are all related to manufacturing, and to some extent to maintenance and after-sales support. A market will only develop if the potential customers are confident that a suitable support structure such as the Engine Factory exists, for repairs and maintenance at affordable cost. This is vital to the project success.

From 14 to 16 April 1996, a wind energy workshop was held in Cairo with the objective of disseminating know-how and technology gained with respect to the new design of the new windpump. The discussion was concentrated on the advantage of having both the transmission mechanism with a reduction speed ratio of 3:1 and the spring device mounted in the piston pump to keep the piston rod always in tension. Performance evaluation of the windpump will be the next phase before dissemination to the end-users. At the end of September 1996, a meeting will be held with local authorities, villages representatives, financiers representatives, and NGOs. The focus during this event will be on the conditions for providing and setting up a windpump for the villagers, and on their financial contributions.

(Hisham El Agamawy, Egyptian Solar Energy Society (ESES), P.O. Box 487, Dokki - Egypt, Fax: (202)781 236)

 

Wind Energy Developments in The Philippines

As a step in the direction of harnessing wind resources, the Philippines' Department of Energy through its Non-Conventional Energy Division (DOE-NCED) has formulated a comprehensive New and Renewable Energy Program to accelerate the development, promotion and commercialization of new and renewable sources of energy in the country. The philosophy "awareness creates demand" has triggered DOE to conduct a massive information campaign to stimulate alternative sources of energy. To this aim several activities have been undertaken by the Department.

Recently, series of training workshops on wind energy were conducted by DOE and RED Renewable Energy Development in The Netherlands, and financially supported by the Dutch University of Twente. These workshops aim to establish institutional and technical capacity at the national level to develop the exploitation of wind energy as an integral part of the Philippines' Power Development Program. Seeing the need to address the issues on the opportunities and barriers in the development of the wind energy market, the Wind Energy Association of the Philippines (WEAP) was organized. The WEAP in coordination with the Department will be the focal point for wind energy activities. Initially, the association will concentrate its actions on windpump development and later divert to electricity generating wind turbines.

There is some tradition for water pumping windmills in the country. The most known windpump is the Reymill Windmill in Santa Rosa, Nueva Ecija. Over 200 units of this brand have been installed, which has made the village to the country's "windmill town".

Until now, the application of wind turbines for power generation in the country was limited to pilot-scale attempts. Despite previous failures, DOE together with the government-owned utility National Power Corporation (NPC) continues to harness wind energy. NPC and the Department of Science - Philippine Council for Industry, Energy Research and Development (DOST-PCIERD) have set up a 10 kW pilot project in Pagudpud, Ilocos Norte to demonstrate the viability of wind energy for village power. Likewise, field monitoring equipment was installed on several locations to collect data for future activities.

Also, DOST and the US-Department of Energy have started the "Philippine Wind Mapping Project" which will be implemented by REPSO and aims at developing a wind resource atlas of the country. Finally, the UNIDO study entitled "Assessment of Technical, Financial and Economic Implications of Wind Energy Application for Electricity Generation", will definitely contribute to a widespread acceptance of wind energy in the daily life of the Filipino people.

(Rodela Romero, Department of Energy, Non-Conventional Energy Division, PNOC Complex, Merritt Rd., Fort Bonifacio, Makati, Metro Manila - Philippines, Fax: 632-818 8614)

 


December 1996

EDITORIAL

Bits and pieces just from anywhere this time. From Peru and Nicaragua in South America, and from Vietnam and China in the Far East. (Africa, are you still there...?)

In the UK windpumping seems an everlasting research topic and we are glad to know that. I decided to write something about the opportunities the Internet may have for us. High technology, but the experts know there is nothing as complex as a windpump - not even a battery charger!

Happy Christmas and a fine New Year to all of you (please keep writing).

Jan de Jongh and Remi Rijs, editors

 

Progress on the New IT Power Windpump

The design for the new, innovative windpump of IT Power was developed under a grant from the European Commision. Since that date the project has been supported by the UK Overseas Development Administration (ODA). The second phase of the ODA project, to continue the development of the new windpump design and initiate the technology transfer to manufacturers in developing countries, began in 1995. This phase has developed the lessons learnt in testing the first prototype and incorporated them into a design for a 1.8 m to 2.0 m machine. The detailed design has been finalised, engineering drawings have been produced and the UK-based pre-production prototype is currently being manufactured. After construction and installation (January 1997) the machine will go through a test phase so that any minor problems can be identified and incorporated into the final design, and the engineering drawings modified accordingly.

IT Power already has a number of collaborators in various countries. Partners in India, South Africa and Zimbabwe are working on costing the machines in their own countries and IT Power is currently finalising the licensing agreements with these partners. Prototypes will be built by a small number of licensees before commercial production begins next year.

(Frances Crick, IT Power Ltd., The Warren, Bramshill Rd, Eversley, Hampshire RG27, United Kingdom, Fax: +44 (118)973 0820)

 

Small Windchargers for Nicaragua?

People seem to feel a compelling need to have a television and electric lighting, also in zones where electricity is not commonly available. In the central part of our country, Nicaragua, about 20 % of the rural families use a 12 V television fed from a car battery in absence of a more sophisticated electricity supply. To charge these batteries they have to travel a considerable distance every one or two weeks to a place where there is a generator or a grid. The costs of transport and charging vary between 30 and 60 cordobas per month (about 3 to 7 US dollar).

Solar Home Systems

At present the most popular technology for small-scale electrification of the rural area is undoubtedly the small photovoltaic (PV) Solar Home System. Such a system usually consists of a PV-panel of approximately 30 to 50 Wp, a battery and a charge controller and generally provides sufficient power for a small black-and-white television and one or two lamps.

It has been shown that a Solar Home System is a reliable and -on the long term- also more economical method for battery charging. Nevertheless, a Solar Home System still costs about US$ 750,- on the average, and the initial investment is recovered very slowly. For the poorer people, this amount is simply prohibitive. For Nicaragua, where the interest rates are high, these limitations certainly hold.

Windchargers

Experience and existing information reveal that electricity generation using small wind chargers involves an investment two to four times smaller than that required for a Solar Home System, provided that wind speeds are sufficiently high (average speeds above 3.5 m/s). According data and studies, a.o. from the INE Instituto Nicaragüense de Energía there are many regions in Nicaragua, where wind battery charging might be economically feasible. Until now, however, windchargers have not had much success in the country since:

Foreign windchargers with output powers ranging between 100 W and 1 kW exist in the USA, United Kingdom, The Netherlands, and China. These advanced machines are too expensive for the Nicaraguan market and cannot be produced or copied in the country.

Local designs

The only possible solution seems to intend to design small battery chargers in Nicaragua itself. Various countries have done this before, of which China (Mongolia) is the most encouraging example.

We at CESADE (Centro de Estudios y Acción para el Desarrollo) think about modifying our rope-and-washer windpump ('aerobomba de mecate') for use with a small DC generator that could easily be obtained or imported in Nicaragua. All parts of the windturbine can be produced locally (as is already done for the windpump), remaining the generator as the only part to be purchased elsewhere. By this way, one would obtain a windcharger of a familiar, accepted technology, with the same ease of operation and maintenance as the existing rope windpump. The price of a 50 W windcharger is estimated at approx. US$ 250,-, far more affordable than a Solar Home System; the cost of energy (US$/kWh) is probably less than half that of its competitor.

Finally, we believe one should make use of experiences in other countries whenever possible, and would appreciate very much to receive response, ideas and suggestions on this article.

(Henk Holtslag, CESADE, P.O. Box 3534, Managua, Nicaragua, Fax: +(505)2-277 4952, EMail: ronrive@nicarao.apc.org.ni)

 

Windpump Markets and Technical Development in Vietnam

The existing market

Vietnam with its many islands and 3,000 kms coast line, is acknowledged to have good potential for wind energy. Many settlements in the area have faced a lot of difficulties with respect to power supply for irrigation. The products grown in these areas are mainly rice, pepper and coffee. There is also industrial tree planting, prawn farming and salt production.

The market for windpowered water pumping is very large and seems to be unexploited in Vietnam. Only 5,309 hamlets of a total of 8,791 have access to electricity (about 60 %), and there are many islands out of reach of the electric grid. Domestic water supply is done by human labor or diesel pumps, which are expensive. Windpumps would provide an attractive alternative here.

The total prawn farming area in Vietnam is estimated at 280,000 ha in 1995. There is also extensive fish farming, and production of crabs, eels, turtles, and minh hai, all requiring very large amounts of water.

Finally, there is great potential for windpumps in agriculture and salt production.

Technical development (before 1990)

In Northern Vietnam, the horizontal-axis sail wind turbines and the D4 type combined with a wooden paddle pump, were built for salt production. The wheel diameter was 4 m, and the blade number between 8 and 10. This kind of windpump could not be used widely as the wooden paddle suffered frequent damages. Eight units were installed during a period of five years.

In Southern Vietnam some Australian Southern Cross windpumps were installed in Baria, Vung Tau, before 1975. These machines have been in use until 1978, when they were stopped due to technical troubles and a lack of maintenance staff.

Some Taiwan windpumps for salt production were also installed before 1975 and pumped 20 to 30 m3 per hour at a head of less than 1 m. To repair them, the farmers replaced the original rotor blades with wooden ones. They also managed to reproduce the pump rotor.

After 1990

Since 1990, the Research Center for Thermal Equipment and Renewable Energy (RECTERE) has held many state projects on wind energy. RECTERE has implemented more than 600 windgenerators and about 70 windturbines for water pumping in locations such as Xuan Loc, Duc Tring, Dong Nai, Thu Duc, and Phan Thiet. These are high head machines manufactured in Vietnam according a Dutch design (the Diever 450).

Two years ago, RECTERE designed the flexible blade vertical-axis windturbines HL300, HL250, HL200, which combine self-starting ability, a revolution regulating mechanism, and semi-aerodynamic blades. This kind of wind turbine is used for water pumping in the salt production and prawn farming. It is also used in combination with two piston pumps or to drive a wooden paddle, as is done in Vinh Hao for water circulation in algae cultivation.

Perspectives

Recently, the Vietnamese Government has demonstrated its interest in power supply for production and domestic use. On September 28, 1996, the RECTERE workshop was visited by party chief Do Muoi, minister of Education and Training Tram Hong Quan, former minister of Science, Technology and Environment Dang Huu, and other high officials. Do Muoi stimulated the people working at RECTERE to continue their efforts in wind energy research. Though RECTERE has achieved many good results in wind energy projects, it is limited in its technology and capacity. Additional efforts are therefore essential to satisfy the enormous demand for wind water pumping in Vietnam.

(Trinh Quang Dung, Vietnam National Center for Science & Technology, 1 Mac Dinh Chi Str., Ho Chi Minh City, Vietnam. Fax: +84 (8)829 5905; Duong Thi Thanh Luong, The Ho Chi Minh City Technical University, 268 Ly Thuong Kiet St., District 10, Ho Chi Minh City. Fax: +84 (8)654 355)

 

Small Scale Wind Energy and The Internet.

The Internet, the interconnected network of computer systems all over the world is quickly gaining popularity among people everywhere, also in the South. The rapid evolution of modern telecommunications technology has dramatically widened its scope. If you have a personal computer, a modem and a telephone line, a commercial provider will link you to the Internet. And if you haven't, often somebody not too far away from you may have it.

As the editor of SSWES, I have noticed that many people active in the field of renewables indeed have access to the Internet and electronic mail (E-mail), although often not without some difficulty. Lately, industry and government institutes have extended their Public Relations activities to the Internet, and have opened a 'home-site' on the 'World Wide Web'. Many of them look like a full-colored glossy magazine, and include 'hyperlinks' to guide you to other documents containing additional information.

Manufacturers of small wind generators have also found their way to the Web, especially the US-based ones. Among them are for example:

A useful guide to manufacturers and renewable energy-related businesses throughout the world is found in:

Other good entries to start searching on renewable energies are:

Of course this list gives just a few of all the entries on wind energy and renewables on the World Wide Web. There are many more, and not all of them will prove useful either. Most entries are found in the US and in Europe, but more and more institutes in the South are finding their way to the Web as well.

If you are a scientist, consultant, engineer or government person in a developing country, you can now actively search what you are looking for. The Internet may learn you about the existence of new products, or bring you into contact with you peers at the other side of the world. It contains case studies on battery chargers and solar pumping, and documents including energy policies of state governments. And not in the least, it offers unexpected possibilities to finance your projects.

So if you can have access to the Internet, don't hesitate to use it!

(Remi Rijs - editor)

 

150,000 Small Wind Generators in China

In the exploitation of rural energy sources, China has put emphasis on the development of small wind generators. The Sixth, Seventh and Eighth (1981-1995) Five Year Plans allocated special investments for the research and development of small wind generators, while manufacturers could access preferential loans with low interest to improve their products and expand production. Some local governments also have granted subsidies, for instance in Mongolia where a manufacturer receives US$ 25,- for each unit sold.

After more than ten years of development, the Chinese small wind generator industry has accumulated ample experience on design, manufacture, and product testing. This has greatly improved quality and performance. The annual production is now about 20,000 units; in 1995, about 150,000 units were in operation in China, of which 130,000 in Inner Mongolia.

The Shangdu Pastoral Machinery Plant of Inner Mongolia, producing units of 100 W and 2 kW, has seen its production increase at an average rate of 58 % yearly. The annual profit has more than quadrupled and amounts now several ten thousand dollars. The 15,000 small 50 W wind generators in Inner Mongolia produce yearly 2.4 GWh electricity, while 70,000 sets of 100 W machines produce 18.2 GWh. This is equivalent to an amount of 19,500 tons of standard coal.

(Long Zequiang, Chinese Wind Energy Development Centre, Huayuan Road 3, Beijing 100083, China, Fax: +86(010)201 28 80)

 

Structural Dynamics of Water Pumping Windmills

Research at University College London has looked at the implications of structural dynamics on several small water pumping windmills using field data and theoretical models. The motivation for this work is to increase the life of fast running windpumps by increasing the understanding of their structural response.

Modern steel water pumping windmills are developed to be lighter and simpler than their predecessors. The recently designed rotors have a low number of blades and run relatively fast. A combination of a fast running rotor and a flexible support structure means that structural dynamics play a very important role in the longevity of water pumping windmills.

A wind pump was modeled as a set of non-linear simultaneous differential equations which were then solved numerically with a finite difference time-domain approach. This approach gave the maximum amount of flexibility in the model, though not with the minimum effort. The control system, pump system and wind turbine structure were all considered in the same model. Once the initial model had been created it was a simple matter to perform studies on parameters such as the pump depth, tower stiffness or passive control system.

A modern fast running windmill has been tested while driving a 49 mm pump with a borehole depth of 36 m. With no softness in the system the topside structure receives an impact load from the pump every cycle. This typically occurs at frequencies from 1.0 Hz to 2.5 Hz, depending on the windmill and pump size. The passive control system used in small machines is not able to regulate the speed of the rotor to any great accuracy. It is therefore difficult to design a mechanical wind pump to run safely in a compliant mode. The behavior of the passive control system was found highly dependent on the friction in the yaw bearing. This is a maintenance issue that has a direct implication on the structural integrity of the windpump.

Wind loads other than direct wind pressure forces, such as vortex shedding, have been found to be significant in some cases. This is particularly a problem if structural or aerodynamic damping are very low. Measurements have been taken to show how dynamic wind-induced loads can cause significant structural response even if the windmill is not operating.

The conclusion to the work is that the life of a modern water pumping windmill can be increased by application of structural dynamic and fatigue analysis. It has been shown that the simplest and most reliable method of collecting data is to run a test rig under a range of conditions rather than to attempt to make complex simulations on a computer. The configuration of the machine and the pump is critical to obtain an understanding of the loads involved. Pumping from a deep well will load the windpump structure in a very different way from a shallow well even when pumping against the same head. It is necessary to test a machine in a variety of pump configurations because of the complex relationship between pump rod loads and pump rod length. Longevity can be improved if structural softness is considered in the transmission system. Aerodynamic and structural damping can effectively reduce the response of a machine.

This work was funded by the Engineering and Physical Sciences Research Council (UK). The field work was carried out at Silsoe College, Bedfordshire, UK, and at ECN Netherlands Energy Research Foundation, Petten (The Netherlands).

(Robert Pumphrey, nCode International Ltd., 230 Woodbourn Rd., Sheffield S9 3LQ, United Kingdom, Fax: +44 (114)275 8272)

 

Experiences with the Waira Battery Charger in Peru

'Waira' is the word for wind in the Andean language Quechua. It is the name of our project in the development and installation of small wind energy conversion systems which has now almost six years. The first designs were intended to power a sailboat or a small house. In the following years, new designs were introduced reaching to 1.2 kW, sufficient for lighting of a small group of houses or for domestic water pumping. Recent installation has been mostly in the highlands (3,500 meter above sea level) within a state funded programme to supply power to community houses for lighting and television sets equiped with a parabolic antenna. Other interesting projects were related to the lighting of fishermen's piers in remote harbours and also in some farms.

We have had satisfactory results in most of the project but trouble in some others. The main problems were the following:

At present we are working on some improvements in the electric components in order to make the system more reliable and resistant to mishandling.

(Grupo, Pontificia Universidad Católica del Perú, Av. Universitaria Cdra. 18 s/n, San Miguel, Lima, Perú, Fax: +51(14)61 17 85)

 


 

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