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close this book Local Experience With Micro-Hydro Technology
close this folder E. PROJECT EXAMPLES
View the document 1. SALLERI-CHIALSA MICRO HYDEL PROJECT, NEPAL
View the document 2. BHORLETAR TURBINE IRRIGATION PROJECT, NEPAL
View the document 3. NAM DANG HYDRO-ELECTRIC PROJECT, THAILAND

2. BHORLETAR TURBINE IRRIGATION PROJECT, NEPAL

a) Organisation and Management

b) Benefits

c) Project Execution

d) Technical Details

e) Investment Cost

 

This project, for which a feasibility study was done jointly by the Agricultural Development Bank, Nepal (ADB/N) and the turbine manufacturing company BYS, is of quite a different nature as compared to "standard" rural electrification projects. It was financed by ADB/N on commercial terms as one component in a package of measures, and executed jointly by the local people, ADB/N and BYS. As an introduction, passages from the project proposal report (ADS/N, Lift Irrigation Project for the Development ...) are printed here:

The project area is located at Bhorletar and Aarikosi village panchayat in Lamjung district in Western Nepal. The Midim Khola, with perennial water flow, separates the two villages. The area is roughly 20 km from the nearest road head e.g. only accessible on foot in a 4 to 5 hours walk. This, for Nepal, is a very favourable access situation.

At present irrigation facilities are limited to some areas in Karaputar permitting two or more crops a year, whereas a major part of the land at Bhorletar and Bhatbeshi has no access to irrigation facilities. As such, hardly a single crop is grown in these areas i.e., paddy under the coverage of monsoon rains. Crop productivity is presently very low.

Paddy and maize are the principal crops in the area followed by wheat, mustard and potato.

An increase in crop production and productivity of land is envisaged with the provision of irrigation and other supporting services under the proposed project.

Out of a total population of 3000, the project envisages to benefit about 100 households directly comprising 500 to 600 people. The project aims to provide a complete technological package of services and institutional support to the farming community of Bhorletar area for intensive agricultural development, mainly based on the development and installation of an effective irrigation system. Other activities which are identified feasible and therefore incorporated in this proposal include: crop-production, agro-processing facilities, credit and agri-inputs, distribution and marketing arrangements for farm produce. A second project stage envisages electricity supply to the nearby bazaar for lighting and electric power supply for running a small cottage industry.

The first project phase comprises the following integrated activities:

· Development and installation of lift irrigation facilities to cover a command area of about 50 hectares of land, 25 hectares each at Bhorletar and Bhatbeshitar areas. This will involve the following components:

- The water of Midim Khola will be diverted to a 4000 meter long 1.2 m x 0.5 m headrace canal to channel 570 to 630 l/s flow to two sets of water turbines via a 40 cm diameter penstock pipe.

- Two sets of water turbines capable of generating a total of about 70 to 80 kilowatts of power output (35 to 40 kW output each) will be installed under the roof of a permanent power-house. Both the water turbines will be purely mechanical-power generating units, which will be used to lift water up to the head of 22 meters at Bhorletar and 42 meters at Bhatbeshitar.

The first turbine will be used to drive two units of water pumps (15 l/s capacity and consuming about 13 kW power each) which will lift up about 30 l/s of water to Bhatbeshitar area through a conveying canal, to irrigate about 25 hectares.

Similarly, the second turbine will be used to drive another two units of pumps in order to supply 30 l/s flow of water to Bhorletar to irrigate another 25 ha of land. The water supply pipes will be carried across from the power house to the newly constructed suspension bridge over Midim Khola to a height of 22 meters at Bhorletar irrigation command area.

Field channels will be constructed to convey irrigation water from the point of main supply to the farmers fields located both in the Bhorletar and Bhatbeshitar area.

· The establishment of an agro-processing unit is proposed to provide milling and processing facilities to the farmers of the project area in view of the expected increase in agricultural production. A paddy huller, a flour grinding unit and a small oil-expeller will be installed within the power house. The estimated power consumption will be about 10 kW when all three processing units are operated at a time. The mechanical power required for running these agro-processing units shall be directly supplied through either of the two sets of water turbines via belt drives.

· A storage building having a capacity of 100 metric tons will be constructed at a suitable site nearby the turbine and mill house. Locally available materials such as stones and river boulders will be used for most of the construction works.

·A Bank-guided co-operative society would be registered and established in the project area. A technical officer with a degree in Agriculture would be assigned by the Bank as a manager of the society. The cooperative would provide management and operational guidance to all project activities. It would also provide agricultural inputs, including production credit and other credit requirements for operating cottage industries. The co-operative will also arrange marketing of agricultural production of the farmers.

a) Organisation and Management

To execute the project, a Co-operative Society is proposed to he set up in the project area. The Co-operative Society will be governed by the Board of Directors. The manager will be assigned from the Bank and the management supervision of the Co-operative Society will be done by ADB/N up to the period of the loan. During this period, ADB/N would help the farmers to build up their own management skill. When the loan amount is fully recovered and effective operation of the project is ensured, the Bank will hand-over the management of the project to the farmers.

Besides the Board of Directors, a project implementation committee is envisaged. The committee will function as an advisory unit to the Board on operations relating to project implementation. The committee will consist of 3 progressive farmers and 2 group leaders. The latter will be elected by/among the farmers.

Balaju Yantra Shala (BYS) will be responsible for manufacturing, fabricating and installation of the irrigation and agro-processing system. BYS will manufacture the water turbine and generating equipment and will install the complete system including the agro-processing unit and then hand-over to the Co-operative Society. Construction of canals, forebay basin and pump/turbine house will be completed by the joint effort of the Co-operative Society and the farmers under the technical supervision of BYS and ADB/N.

On the operational level an effective water-distribution system would ensure optimum utilization of irrigation water. For this purpose, within the two farmers groups to be organized, specific water-users groups comprising several subgroups will be established. Their function will be:

· To ensure equitable supply and distribution of irrigation water to member farmers.

To arrange distribution of water to its members as per water distribution schedule worked out in consultation with all farmers within the group.

· To initiate the member farmers to level and improve their land structure and construction of water distribution channels so as to have optimum water utilization and minimize water losses.

· To promote cooperation among members sharing irrigation water and other inputs and to encourage the farmers for the adoption of improved farming methods.

· To help the Co-operative Society realise its loan installments and irrigation water charge from the member farmers.

· To settle disputes among member farmers in the utilization and distribution of irrigation water.

· To promote other activities related with irrigation and agricultural development within the groups.

The main canal will be constructed through joint efforts of the farmers groups whereas sub-channels will be constructed by the participating farmers themselves. Proper operation and maintenance of the turbine, main canal, agro-processing machinery and pumps etc. will be carried out by the mechanical section of the Co-operative Society, aided by staff from BYS where necessary.

b) Benefits

The project benefits envisaged may be summarised as follows:

· The project would benefit about 100 farm families of Bhorletar and Bhatbesitar by irrigating 50 hectares of "tar" areas.

· It will provide permanent employment for 11 persons and would generate additional employment to about 100 farm families at the full development of the project.

· It would provide easy access to processing of foodgrains by providing processing facilities to the farmers of Bhorletar, Bhatbesitar, Karaputar and other nearby villages.

· The project will help to utilise the water resource of Midim Khola to generate power to render irrigation and processing facilities to adjoining areas.

· Provision of storage facilities would improve distribution of agri-inputs, minimize losses and facilitate marketing of farm outputs.

· The crop production would increase from the existing level of 456 metric tons to 752 metric tons at the full development stage (5th year onwards).

· Expected implementation of the project activities set for phase 2 would benefit the local community from the proposed supply of electric power to Karaputar Bazaar and the extension of irrigation facilities to Bhorletar and Kainbote areas.

So far the project proposal! What one may note that is different from other hydropower projects, are the following points:

· Rather than rural electrification per se, the project is based on other criteria, namely increased agricultural production.

· The development of hydropower is only a means to achieve a much broader goal, e.g. integrated rural development.

· Local participation has not been included as a theoretical requirement but is in fact a decisive factor in the implementation of the project.

· The project had to be viable from its inception in terms of qualifying for loans from a bank.

· The bank involved, on the other hand, realised after studying the local situation, what additional inputs would be required from their side and consequently included these in the proposal.

· By the development of a hydropower resource for a specific productive use, a second project stage that provides for the amenity of electric light must not be economically self-supporting, but can be done as a social measure.

c) Project Execution

During project execution it became clear that many of the problems occurring elsewhere did not exist, largely due to the integrated approach and the ultimate goal of the project. The scheme was understood and supported by local people from its inception. A farmer naturally knows what access to irrigation water all through the year means in an area where even a single rainfed crop sometimes fails due to the lack of rain. In fact, it was the local people who pushed the project all along; even though at several stages they lost courage for a while, when technical and administrative problems came up. Local participation was strong. At one point, the womenfolk of the area declared that they would take care of all material transportation. And so they did without much fuss. Cement, equipment parts, penstock and irrigation pipes were all carried on womens' back to the project site.

The men, meanwhile, were working on canal excavation and power-house construction. There were delays and difficulties largely due to the fact that, for all parties involved, it was the first time that a project on this scale was taken up. Today, the project is in operation; still in an early phase though, with agricultural production slowly developing. This was anticipated in the requirements of loan repayment with a sufficiently long grace period.

d) Technical Details

Some remarks on the technical configuration of the project may be of interest. The original idea during project prefeasibility studies was to generate electrical power with the water turbines and to operate water pumps with electricity in a pumping station at the river side. This would have resulted in a geodetic head of about 53 meters to pump water up to Bhorletar. Also, an additional civil engineering structure would have been necessary on the river bank, with intake and sedimentation tank for the water to be pumped.

In the configuration finally adopted, water to be pumped is taken from the headrace canal with a separate sedimentation arrangement in the forebay so that there are still fewer suspended particles as compared to water supplied to the turbine. This necessitates a separate supply pipe parallel to the penstock, to bring water to the pump sets with positive pressure. With this arrangement, the static pumping head to pump water up to Bhorletar amounts to 22 meters only, as can be seen from the schematical profile in fig. 61. On the other hand, a relatively long (about 1 km) delivery pipe is necessary, which involves conderable friction losses. Still, the dynamic head with the existing arrangement amounts to only 49 m as compared to 58 m with a pumping station on the river bank.


Fig. 61: Schematical Profile of Bhorletar Irrigation System

Source: BYS, Nepal

There were three criteria that helped in deciding which system to adopt, namely: technical feasibility, cost, and overall system-efficiency. The two possibilities studied were both considered technically feasible but the use of a mechanical power drive must be considered an advantage because it involves a considerably less sophisticated technology as compared to electricity generation. On the cost side, it was a comparison of cost of electricity generating equipment, including transmission and the construction of a pump-house with intake and sedimentation basin in the original configuration, versus a larger head-race canal section, a longer delivery pipe, and the cost of bringing the pipe across the river, in the final configuration. It was here possible to use an existing suspension foot-bridge to which the water delivery pipe could be attached and this cost item was therefore minimal. Adding all cost up and comparing them, showed a slight but not decisive advantages for the second system. Really of major importance, and at first surprising, was the comparison of efficiencies: The mechanical system with the pumps in the turbine building showed roughly an efficiency that was better by a factor of 2 as compared to the electric system, even though it involves a more than 600 meters longer delivery pipe..

To explain this requires perhaps some elaboration: In a comparison of the overall efficiency, all components that are equally required in both systems, need not be considered. These are: Turbines, step-up transmission, and water pumps. In the mechanical system, additional losses accrue from pipe friction only, while the electrical system involves losses in the generator, in electricity transmission, in electric motors and pipe friction. Input energy in both systems is equal, and what is of interest in terms of output is the amount of water pumped, e.g. if input energy is multiplied by all additional equipment efficiencies and divided by the dynamic head, the result will be mass flow rate of water at the irrigation outlet. A numerical comparison is thus very simple and may be presented as follows:


Fig. 62: System-Efficiency Comparison Bhorletar, Nepal

The relatively long canal of 400 meters made a number of different sections necessary, depending on terrain. At two places, rectangular wooden flumes were made to cross gullies. Another seasonal rivulet with quite a broad bed had to be crossed also. This was done by covering the canal with stone-slabs to prevent the bed-load being deposited in the canal. The photograph in fig. 63 gives an impression of canal construction that was all done manually and mostly in unlined execution.

The equipment in the power house comprises two turbine sets of type T1 to which water is fed through a common penstock, branching in two, above the turbines. The two turbines, working under a net head of more than 20 m may be operated independently of each other. Each set supplies power by chain-drive to an intermediary shaft from which two pumps (e.g. totally 4 pumps) are driven with vee-belts. A third intermediary shaft in front of the turbines may be connected to either turbine, to operate the agro-processing machinery. A 10 kW alternator, envisaged for the 2nd project stage, will be operated from this shaft alternatively. Fig. 64 shows the turbine sets installed, with construction of the power house - in local mud-mortar masonry - under progress.

A speed governor is not required for the system, because the operation of water pumps constitutes a constant load. Instead, turbines are equipped with a mechanism for manual operation of the gate. With this, it is quite simple to operate the pumps. To start, the pump inlet valves are opened with the turbine still at a standstill. Because of positive pressure on the inlet side, the delivery pipe fills without operating the pumps up to the level of the head race. Ther the turbine gate is opened and the pumps are run at reduced speed just sufficient to fill delivery pipes completely. Only thereafter is speed increased to develop full dynamic head and full flow. The optimal turbine speed can quite simply be read from a pressure gauge on the delivery pipe. This procedure prevents any water hammer in the pumping system from developing.

The pumps used are of centrifugal spiral-casing type. With the concept to use local technology to the largest possible extent, a number of enquiries for pumps were made first in the region, since Nepal itself does not produce any. By comparing characteristics of pumps from the regional market with those of pumps from Europe, it was found that much more water could be pumped with machines imported from overseas, due to better matching of the latter with the actual flow/head conditions and generally higher efficiencies. Consequently, pumps were imported from Europe, although it was clear that getting spare parts would be more difficult.

e) Investment Costs

Total investment costs were initially estimated to be Nits. 540'000.-. Successively, due to inflation and not foreseen technical difficulties, the overall costs finally reached about Nits. 700'000.-(estimate at cost level of 1979, 12 Nits. = U.S.$ 1). This is the amount for the integrated project including several other activities in addition to hydropower generation. It is not possible to separate the actual cost for hydropower development alone but on the higher side, an amount of NRs. 530'000.- seems reasonable. Fig. 65 gives a rough breakdown of cost into the systems components. Since the use of power is only possible with auxiliary equipment such as water pumps, piping, and milling machinery, this is also included.

It should be noted that costs as given here are not fully representative. Canal construction is relatively low due to involvement of partly voluntary labour. Also, supervising personnel of ADB/N and an expatriate expert of BYS have not been accounted for. From the side of power end use, it is of interest to note the cost of lift-irrigation on a unit of area basis, since in the existing situation, 50 hectares of land are irrigated, cost of development per hectare amounts to $ 886. This, however, does not include such additionally possible irrigation from head race overflow and tail race water.


Fig. 65: Cost Breakdown of Bhorletar Project

Source: ADB,/N+BYS Project proposal, and own estimate based on project progress report 1979