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Getting wind pumping going

Wind powered water pumping has failed to take off in developing countries despite the technology improvement efforts of the last two decades. A recent study concludes that a major cause is the mismatch between what the users need and what most manufacturers are able to supply. The available windpumps are often either unsuited to the local water needs and climate or they have been insufficiently adapted to local manufacturing capability and specific market conditions.

The study*, carried out for the Dutch government, looks at markets in developing countries from the point of view of the users' needs and what the manufacturers can provide. Twenty-two developing countries with wind pumping activity were surveyed. A wide variety of market conditions were discovered and these should influence the product and service provided by the windpump suppliers. However, the supply side of the market is weak and fragmented. Most local manufacturers are small businesses operating without access to capital and technical support for development.

The most successful windpump suppliers meet three important requirements. First, they adopt an integrated approach to meeting the total water supply need of the customer, providing all the necessary expertise, perhaps by linking with other companies which have skills such as well drilling. Second, they endeavour to provide an adequate after-sales service so that the windpumps are properly maintained. Third, the manufacturers supply a windpump which is technically suited to the conditions and well-adapted to local operation and maintenance capability.

The first two requirements have mostly been understood by specialists working in this field. Paths to success were the subject of discussion at a workshop on Wind Energy for Rural Areas (WERA) held in The Netherlands in 1991 in association with a European Wind Energy Association conference. The attempt to set up a WERA international association to disseminate information and provide technical support has not yet been successful. The third factor, made clear by the recent study, goes to the heart of efforts over the last 20 years to re-develop windpump technology. Clearly much of the technology development effort has not been adequately translated into the production of windpumps which are appropriate for their markets.

Three types

The oldest designs of windpumps use local materials and artisan construction skills. They are low cost but require much supervision and maintenance. Examples are the Cretan sail windpumps and similar styles found in Asia. These are generally suited to pumping at a head of a few metres for water supply or at very low heads for drainage and salt pans.

The need to pump from greater depths in order to develop cattle farms and homesteads in the USA, South America, Australia and southern Africa led to the robustly-engineered "American" or classical windpump. This design offers high reliability in remote situations and still constitutes the largest portion of world production even though the design has changed little in 70 years. However, these machines are heavy, expensive and need a high level of manufacturing skills.

Reviews of windpump technology in the 1970s led to the idea of lighter, cheaper machines better suited to manufacture in developing countries where the need for water pumping is considerable. About 20 manufacturers now have a model in production although sales are generally very few.

Many of these modern designs owe their origin to one of two European projects. The Dutch CWD organisation, funded by the Netherlands government, undertook research and development of machines with lightweight, fast-running rotors driving a reciprocating pump through a crank mechanism. Production development and field implementation in developing country workshops proved less successful. It is now accepted that this design is best suited to low and medium head pumping, say less than 20 metres, because the pump rod forces are less severe. The second project, resulting in the ITDG design from the UK, uses modern materials and manufacturing methods which can be applied in a modestly-equipped workshop. It is slower running and therefore can pump from considerable depth.

It is notable that the modern designs are now evolving so that the distinctions between the three types are becoming blurred. For example, the Kijito version of the ITDG design, manufactured in Kenya, is now very robust in order to withstand the climate and wildlife. The tower is also of welded construction so that local tribesmen cannot remove the bracing. Other modern designs have reverted to the use of a gearbox (of welded plate rather than cast iron). A CWD derivative in Honduras now drives a traditional rope and washer pump.

The right choice

The choice of windpump for a particular market will depend on the physical conditions on site, the ability of the owner or operator to maintain it and, in the case of a machine installed for community use, various social factors. For example, the high initial cost of a windpump becomes a major barrier for poorer purchasers. A little less reliability or higher maintenance needs may be acceptable in exchange for a lower initial cost provided that the windpump can be closely supervised and that spare parts and expertise are readily available.

Local manufacturing capability will influence the choice and adaptation of a design for local manufacture. Classical and modern windpumps require engineering skills and a certain standard of manufacture in order to produce adequate quality. Most manufacturers have very limited skills and machinery. Frequently, basic materials are of poor quality and some processes such as hot dip galvanising may be unavailable. An imported machine may be perfectly adequate for the conditions but if maintenance support and spare parts are not available failure will eventually occur. This has happened in several countries in South America and Africa even though the machines have a good reputation in their own country.

The best-suited design may be a classical machine, which is good for deep water pumping in remote areas where operation is unattended, such as in Africa. It may be a modern lightweight machine for medium and low head in regions without very strong winds, such as are found in Colombia and Sri Lanka. It may even be an update of a traditional artisan design where there is a history of operating these types so that local people are familiar with their maintenance needs. Peruvian manufacturers offer several of this type. However, lacking information and support, the manufacturers are unable to adopt the best-suited basic design. The basic design still needs adaptation to the particular local factors such as available materials and processes, wind regime, water resource, application and the capability of the user. The completed design then needs to be proven in the field.

In practice the manufacturer generally copies or develops a design which is then sold to local users without being thoroughly tested and proven. Poor quality copies of classical designs are made in India and elsewhere. The CWD design has been transferred to several countries without adequate development. In Colombia lightweight designs which are adequate for the light winds of the eastern plains quickly fail on the windy north coast. The inevitable failures lead to a poor reputation even if good maintenance can be provided. Many manufacturers fail to understand the design optimisation of the windpump by matching the wind speeds and water depth with the rotor and pump sizes, which leads to inefficient use. The purchasers understand this even less, along with aid agencies and government departments which buy or promote the windpumps. In India there have been continuing efforts to adopt a standard design but currently government approval is given only to a single rotor and pump size which makes optimisation impossible.

Despite all the problems, there are examples of growing markets where the image of the technology is positive. Kenya and parts of India and Colombia provide examples. Here the manufacturers are successfully tackling all aspects of the users' needs. Some of the aid projects in West Africa, such as the Canadian-funded PEEN project in Niger, are also proving successful because they adopt a long-term, integrated strategy to wind pumping for water supply in the context of rural development.

In order to continue this progress there is a need to build the capability of the manufacturers and provide them with suitable base designs. In most cases the base design already exists elsewhere. The manufacturer needs help with adaptation, production engineering, quality control and providing a service organisation. Aid projects designed to support the application of wind pumping should be sensitive to the users' needs and ensure that long term maintenance support is developed. Unfortunately, there is no universal windpump capable of meeting needs all over the world, but there are suitable designs which will provide the basis for meeting the users' needs in most situations.

*Windpumps in Developing Countries: A View of the Markets; report by Halcrow Gilbert Associates Ltd with Dutch associates Renewable Energy Development and Netherlands Economic Institute for the Directorate General for International Co-operation, Ministry of Foreign Affairs.

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