1st International Conference: Renewable Energy - Small Hydro

3-7 Feb 1997, Hyderabad, India

 

THE DEVELOPMENT OF TRADITIONAL HIMALAYAN WATERMILLS FOR SUSTAINABLE VILLAGE-SCALE MICRO-HYDROPOWER.

 

 

O.Paish, IT Power Ltd, The Warren, Bramshill Road, Eversley, Hants, RG27 0PR, UK

R.Armstrong-Evans, Evans Engineering Ltd, Trecarrell Mill, Trebullett, Launceston, Cornwall, UK

R.Saini, Alternate Hydro Energy Centre, Roorkee University, Roorkee - 247667

D.Singh, T.E.R.I, Darbari Seth Block, India Habitat Centre, Lodi Rd, New Delhi - 110 003

D.Kedia, Industrial Consultants, GS Road, Bhanga Garh, Guwahati - 781005

 

 

ABSTRACT

The Watermills Block of the Hilly Hydro Project has set out to demonstrate technologies for upgrading and replacing some of the many thousands of traditional watermills, or gharats, in the Himalayan regions of India.

The paper covers:

  1. the conclusions of site surveys, identifying the range of local circumstances across the regions,
  2. the major design issues and different technologies proposed to meet the needs of the mill-owners
  3. elements of the strategy planned to ensure the projects undertaken are successful and sustainable.

1. Introduction

1.1 The Hilly Hydro Project

The UNDP-GEF Hilly Hydro Project is an ongoing initiative supported by the World Bank Global Environment Facility and the Government of India to demonstrate and promote the use of small-scale hydropower in the 13 Himalayan states of India.

The principal existing use of hydropower in the Himalayas is through the use of traditional wooden vertical-axis watermills (gharats) for grinding grain. These operate off 2-6m head, developing typically 0.5kW. There are believed to be up to 200,000 mills in the Indian Himalayas, a further 25,000 in Nepal, and many more in Pakistan, China, Afghanistan, Myanmar and parts of Turkey. This indigenous technology is built and maintained by the miller himself using local materials. However in recent years, gharats have started to fall into disuse: owners have descended to the plains to seek more lucrative employment, more effective diesel powered mills in nearby towns have reduced their market, and major deforestation has caused some water supplies to disappear. Yet, if this abundant and renewable waterpower resource could be exploited more effectively with appropriate and modernised equipment, it could play a key role in driving sustainable economic development in the hilly regions. This is the task which the India Hilly Hydro Project is now endeavouring to address.

The Watermills component of the project is seeking to upgrade and develop 100 watermills in different regions with improved technology which will serve as prototypes for upgrading the remaining watermills in the region. The upgrades will cover two different types of development:

1.2 Background

1.2.1 The Himalayas
The populations of the Himalayas, from Afghanistan to Myanmar, still live predominantly in agricultural economies, often at subsistence level. The market for milling is reasonably well served by traditional watermills spread throughout the region, but most other essential agro-processing services (rice-hulling, oil-expelling, juice-extraction, etc.) are non-existent and have to be done manually (ie. by women), or by many hours’ walk to electric or diesel machines in town. In Manipur, an alternative waterpower technology has been identified: the Pani Dhenki, a drop-hammer used for de-husking rice.

1.2.2 Beneficiaries
Improving traditional watermills is intended to benefit :

1.2.3 Traditional technology
It is important to note the advantages inherent in the indigenous watermill technology, in particular it is:

At the other extreme, a state-of-art mini-hydro plant may be able to increase the useful energy output at a watermill site by several times, but will inevitably involve:

Such modern installations can prove to be unsustainable in the longer-term without accompanying advances in local and regional infrastructure, local skills and engineering facilities, and major technology transfer initiatives. For example, once the crossflow (Banki) turbine had been proven and demonstrated by Swiss engineers in Nepal, it took 7 further years of concentrated promotional activities to establish a workable level of dissemination [1].

A sustainable approach to developing and transferring appropriate technology therefore implies a compromise strategy, where modern know-how (eg. on hydraulics and turbine technology) is applied in the local context. This approach, adopted from the start by the Watermills Block [2], encourages local manufacture and support of the technology, and designs that are simple both in concept and in construction.

1.2.4 Nepal experience
Nepal is the only country where significant progress has been made to upgrade watermill designs, where developments occurred in 2 phases. Initially a packaged steel assembly was developed by a local workshop which incorporated a vertical-axis impulse turbine made with fabricated steel buckets and a penstock pipe [3]. This became known as the MPPU (Multi-Purpose Power Unit) and in the early 1980s this system outstripped the sales of crossflow turbines being promoted through foreign aid programmes because of its simplicity, its similarity in principal to the traditional watermill, and its low cost [1]. When the manufacturer ceased production of MPPUs to take up more profitable business, GTZ of Germany supported a programme to develop a cheap ‘construction kit’ which involved supplying the MPPU runner and a few components to enable millers to install upgrades themselves [4]. This ‘improved ghatta’ programme ran from 1984-1988, with further support from 1991-1993, and there is now a steady market for these kits of over 100 per year, providing improved milling plus a rice-hulling option. GTZ however recognise that there is scope for developing and improving the technology, which still has a number of limitations, in particular:

1.2.5 Indian experience
There has been more than one attempt in India to copy and disseminate the Nepali design of watermill upgrade [5] [6] but these initiatives have failed to make a significant impact, through either institutional reasons (highly subsidised, no training or technical support, owners not helped to develop their businesses), or technical reasons (designs were copied, not understood and transferred, so systems were inappropriately specified and installed).

2. Site & equipment surveys

2.1 Overview

In the first phase of the Watermills project, the team from IT Power, UK, the Alternate Hydro Energy Centre at Roorkee University, the Tata Energy Research Institute in Delhi, and Industrial Consultants, Guwahati, has completed numerous site surveys in the Northern and North-East states and studied the needs, capabilities and aspirations of mill-owners through both one-to-one interviews and an organised forum of mill-owners in March 1996. A standard questionnaire was developed for completing each survey. A census is also ongoing which is attempting to quantify the total number of gharats in the region and therefore the potential for implementing new technology.

A broad conclusion from the surveys has been that nearly all sites are technically feasible for upgrade machines to be installed, but the more critical questions in selecting a viable site are:

  1. is the owner willing and motivated to invest in, operate, and maintain an upgraded system ?
  2. will there be sufficient new business to justify the cost of the upgrade ?

ie. the priority is less on finding the right sites, but more on identifying the right owners.

2.1.1 Case study - Gadora Bridge
The Gharat Owners Association in Chamoli District (UP) have nominated a site at Gadora Bridge for demonstrating a multi-purpose system to replace the existing, traditional gharat. The site is an attractive choice for a demonstration scheme since it is directly by the roadside on the tourist route to Bhadrinath, and the bridge is also a crossroads for local movements. The miller is young and enthusiastic, and keen to adopt changes if it is worth his while.

The existing gharat is one of 5 at Gadora Bridge, and one of 21 on this stretch of the river. It was therefore agreed by the Association that this gharat should be converted for uses other than milling, so as not to take business away from the other millers.

An available head of 8m and design flow of 150l/s implies a gross potential of 12kW, therefore a working capacity of around 6kW.

Discussions on possible end-uses concluded that the following activities might be feasible and profitable in the context of the businesses operating locally:

The existing mill-house would have to be demolished and replaced with a new building to accommodate the proposed end-use equipment plus café, and a small amount of work would have to be done on the channel. It was agreed that these civil works could be carried out by the Association.

2.1.2 Case Study - Dehra Dun
Another typical example is a 1.5m head site near Dehra Dun in Uttar Pradesh. The owner mills with a traditional watermill by day, but also wants to generate electricity to be able to run a jam-making business from the produce of his farm. He also wants power for lighting, TV, and fan in the evenings and night. He has a flow of 150 litres/sec and power potential of 2kW. He would be keen to invest in improved hydropower technology, but has found nothing available to meet his need. In this case the miller’s requirements would be served by a modernised gharat-type system which could still be used for milling, but also adapted to allow an add-on generator to provide electrical power.

2.2 Establishing Local Contacts

A further important issue during the 1st phase was the need to identify local organisations to support the technology at the local level and to take responsibility for managing and supporting new projects.

The Himalayan Environmental Studies and Conservation Organisation (HESCO), an Indian NGO based in Chamoli District, UP, was responsible for setting up the Gharat Owners’ Association in Chamoli and has been working with them to design and implement simple upgrades for traditional gharats. The improvements have involved lining the open chute with galvanised steel sheet, using a Teflon bush for the top-bearing (at the centre of the bed-stone), and using a fabricated ball-bearing assembly as the footstep bearing at the base of the rotor.

About 12 gharats have been upgraded to date in Chamoli District. The component and material costs are about 1500Rp and the upgrade work is undertaken by the miller himself. Increased output of 2-3 times has been experienced, with stone speed increasing typically from 70 to 120rpm.

2.2.1 Gharat-Owners’ Meeting
On 17th March 1996 a meeting of the Association’s 30 members was staged by HESCO. The meeting enabled the owners to express their outlook on their current livelihoods, as follows:

2.3 End-use equipment survey

A brief survey was also carried out to establish the current costs and power ratings of end-use equipment relevant to the setting up of multi-purpose watermill upgrades. The following table summarises the general conclusions from a survey in Saharanpur (U.P.):

Equipment Rating Price
Good quality single-phase generators 2-5kW 4000-9000Rp
Grindco Mills 1-4kW 1000-2500Rp
Rice huller 1.5-3kW 1500-2000Rp
Oil expeller 3-4kW 5500Rp
Spice-grinder 0.75-1.5kW 1300-1800Rp

2.4 Technology needs

The general engineering strategy for upgrading the mills should be to establish the very best systems that can be coped with by the mill-owners. The needs and capabilities of the person who is going to install and operate the equipment should have as much bearing on the overall design as the hydraulic and engineering criteria.

It is proposed that there are two general approaches that can be applied successfully in the local context:

  1. a simple upgrade that can be maintained locally, either by the miller himself, or a local craftsman.
  2. a design that is still simple in concept, but is well-engineered and sophisticated enough to be maintenance-free for at least 5 years.

The danger lies in adopting a half-way solution which is both unreliable and too sophisticated for local expertise to repair. The need for sustainability would indicate that the designs for upgraded gharats should be maintainable locally (approach 1), and the multi-purpose units should be designed to be robust and maintenance-free (approach 2).

3. Design Issues

Because of the great diversity of the sites and the economic and personal preferences of the millers, the array of possible detailed design choices is large and there are virtually no areas which are totally clear regarding either the general approach or the precise selection of equipment.

Outline designs for the first demonstration units are proposed in Section 4. Some of the main issues which have been considered are as follows.

3.1 Cost vs Quality

Most areas are characterised by the phrase ‘Pay now or Pay Later’ i.e. either a lot of time and effort is expended at the outset to achieve little or no maintenance, or minimum capital is spent, accepting that there will be regular on-going maintenance efforts and costs. For example, an intake structure can be an expensive but permanent concrete structure, or it can be a seasonal low-cost diversion weir which needs to be re-built every year.

3.2 Manufacturing Strategy

3.3 Maintenance Strategy

3.4 Rotor Design

3.5 Bearings

3.6 Drive train

3.7 Flow Regulation

3.8 Load Governing

3.9 End-Use Issues

Perhaps even more critical than the design of hydropower unit is how the power will actually be used.

3.9.1 Mechanical vs electrical
Although the local viewpoint may often be in favour of electricity generation as part of a new scheme, this may not be the best use of the hydropower resource to meet local needs and guarantee the success of a project. In most cases using the majority of power for mechanical end-uses has proven to be more cost-effective and sustainable; almost all of the 1000 micro-hydro schemes in Nepal operate one or more agricultural machines. The key issues can be summarised as follows:

3.9.2 Charging and income-generation

3.9.3 Electrical generation

3.10 Areas for Development

The technology for village-scale hydropower is generally under-researched and could benefit from R&D in a number of fields, for example:

4. Proposed system designs

4.1 Overview

The preliminary designs proposed for the demonstration units, are as follows:

4.2 ‘New Gharat’ Watermill Upgrade

Layout and Upgradability
A principal aim behind the proposed design is that millers should be offered a simple concept, but one that can be upgraded. Therefore the layout of the first demonstration units will continue to be vertical-shaft systems, replacing the existing wooden construction, and used primarily for milling in the traditional manner; the millstones, mill-house and open chute can remain the same during the upgrade process. However options for driving other machinery (either an electrical generator or a rice-huller, spice-grinder, etc.) will also be immediately possible by removing the top mill-stone and replacing it with a single pulley and belt-drive. Further sophistication can be achieved by replacing the open chute with a penstock pipe and control valve. In the longer-term, greater options can be opened up by using the same rotor but with a horizontal axis and belt-driving two or more machines off the main shaft in an enlarged mill-house.

Rotor design
The traditional wooden rotor is less than 20% efficient. The steel runner design used in Nepal is limited hydraulically to about 50% efficiency, and contains two-dimensional curvature which requires laborious fabricated manufacture. Efforts have therefore been made to design a runner which can exceed 50% efficiency but have a geometry suitable either for casting, or low-cost welded fabrication. This would have major implications on its suitability for both low-cost mass production, and for being replicated at local-level. Casting also guarantees the quality of the runner construction. Furthermore, this design of runner is suitable for converting to a horizontal axis layout at a later date.

Speed
Traditional watermills run at less than 100rpm. The Nepali design increased the speed to around 150rpm, which was insufficient to be able to attach a standard 1500rpm generator with a single belt-drive, since 6:1 speed-increase is generally regarded as the maximum. The proposed rotor design is intended to operate in the region of 250-300rpm. This is an important advance in enabling electricity generation, plus other faster-running agro-processing machinery, to operate with a single belt-drive from the main shaft.

Figure 1 shows a schematic of a simple ‘new gharat’ upgrade, and Figure 2 illustrates the same runner used with a horizontal axis in multi-purpose mode.

4.3 ‘Open Crossflow’ Multi-Purpose Schemes

The ‘Multi-Purpose Unit’ will be appropriate where there is adequate head and flow to produce at least 5kW of power at the shaft. These projects will require considerably greater engineering and financial input than the simple mill upgrades. The key features of this unit must be robustness and very low maintenance. The competitive advantage of these ‘Multi-Purpose Mills’ must be so marked that the enterprising millers that have set up diesel and electric mills, will want to get back into watermilling because it is cheaper and better than diesel.

The open crossflow design is recommended for a number of reasons: the crossflow turbine is well-disseminated through publications by SKAT and others; it can be replicated in modestly equipped workshops; and the ‘open’ arrangement allows the technology to be more transparent and it is also significantly cheaper (and more efficient) without the casing. Furthermore the unit needs to have a horizontal axis because of the horizontal alignment of most end-use equipment and the desirability of avoiding twist belts wherever possible.

Figure 3 and Figure 4 illustrate the main elements and proposed layout of the multi-purpose design.

It is not proposed that the components for such a system should be manufactured in the remote areas, but that ‘benchmark designs’ should be built at a centralised workshop, at least for the first batches. If village workshops wish to assemble or modify the units in the future, this should be encouraged. Small diesel engines are now assembled by hundreds of small workshops using components and spare parts supplied by larger companies in the regional centres. The original engines from which the designs were copied were long lasting and the same approach could be adopted with the manufacture of turbine components.

The ‘overhung’ layout allows the wet components to be kept outside the mill building, with the bearings inside. It is important that the bearings and shaft are of adequate specification and that the overhung loads are kept as close to the bearings as possible. Running the end-use equipment off the main shaft is intended to keep the system compact, cheaper and safer to operate.

5. Conclusions and Implementation Strategy

The Watermills Block is addressing the immediate requirements of rural people by aiming to demonstrate the best technical solutions to meet their technical capabilities and economic needs. The technology must be both affordable and locally acceptable - technically and culturally. The history of small hydro shows that ignoring these factors has sometimes led to the transfer of efficient and powerful technologies which have had no chance of being replicated, maintained, or owned by local people, and have therefore been unsustainable unless propped up by foreign aid programmes.

The upgrading of traditional watermills is an effective and sustainable way of meeting the energy needs of a major section of the rural poor. Rather than attempting overly ambitious leaps in technology, the need for sustainability means starting at the current point of development and moving forward in steps that can be understood, afforded, and bring immediate and worthwhile benefit. There is a danger in adopting ‘half-way’ solutions which are too simple to be reliable, but too sophisticated for local expertise to repair.

The danger with any ‘Short Term Development Programme’ is that a lot of effort is put into establishing as many projects as possible within the time and budget allocated, without making provision for the long term training and backup. The Watermills programme is endeavouring to ensure that there will be groups of trained local engineers who are well-equipped to attend to problems as they occur. Gharat-owners will also need training (eg. via a local Association) to maintain their own mills.

If unwisely managed, one negative impact of watermills development can be anticipated (from experiences elsewhere) as occurring through market forces. If one watermill increases its business, other millers may suffer and come to resent the new technology. The Hilly Hydro Project is already taking active steps to prevent this problem by supporting the setting up of Watermill Associations, adding to the existing one in Chamoli. Groupings of local watermill owners in a valley or region will agree by consensus which mills to upgrade and what services should be provided so as to minimise any local conflicts of interest. Past experience [7] has shown that conflicts can be avoided by involving local people in the decision-making process and ensuring private purchase and ownership of the new technology.

There is also a danger of making the pilot projects too sophisticated, so that they are then too difficult to replicate. The project aims to keep the technology simple, robust and transparent, while providing appropriate levels of training and backup.

References:

1 Micro-hydropower in Nepal: development effects and future prospects with special reference to the heat generator, D.Jantzen, K.Koirala, FAKT, 1989

2 Engineering small waterpower schemes from traditional mills, R.Armstrong Evans, O.Paish, India Hilly Hydro Project - Brainstorming Conference, New Delhi, November 1995

3 Multi-purpose power unit with horizontal water turbine: operation and maintenance manual, A.Nakarmi, A.Bachmann, UNICEF/Nepal, 1984

4 Improved ghatta construction manual, Manfred Bach, GATE Publications, 1985

5 Performance testing of modified gharats in Kumaon region, R.Saini, N.Ahmed, Non-Conventional Energy Development Agency, Lucknow, U.P., 1989

6 Rural Technology Manual - improved water mill, A.Ahmad, CDRT, IERT, Allahabad, India, 1992

7 Key Factors for the Success of Village Hydro-Electric Programmes, N.P.A. Smith, World Renewable Energy Congress, 1994

 

Figure 1 : New Gharat, traditional layout

 

 

Figure 2 New Gharat runner used in horizontal-axis, multi-purpose mode (plan view)

 

Figure 3 : Open crossflow (elevation)

 

 

Figure 4 : Open crossflow; general layout of horizontal shaft mill