Tyson Turbine: The firsthand experience in Nepal

Tyson Turbine:

The firsthand experience in Nepal

Dr. C. B. Joshi

Associate professor

Research Center for Applied Science and Technology

Tribhuvan University

INTRODUCTION               

Nepal, with its per capita energy use of 22 KOE, (World Bank, 1995) belongs to one of the least per capita energy consuming countries in the world. Because of the lack of any mineral deposit it has been relying mainly on the fuel wood which has already destroyed its forest and damaged the environment and. Ecology leading to an ever increasing economic and human losses. It is only the recent phenomena that the importance of developing alternative energy resources has been realized. Among them micro-hydropower resource is the most suitable one for a country like Nepal as it is abundantly available and both technically and financially. Besides it is environmentally friendly and can be used for producing both mechanical as well as electrical power. In view of these advantages a few types of micro-hydropower devices have already been operating successfully in the country. These devices, however, can be run only under a certain head of water need civil strut urges like canals, foundations, sheds and land for their installation an operation. Moreover they are immobile and prone to regular repairs and maintenances. Because of these disadvantages such devices have not been fully able to harness the energy hidden in the big micro-hydro power resources of Nepal. A need of devices had always been felt in which the necessity of all these prerequisites do not exist. This is precisely the idea incorporated in the so called Tyson

Turbine.

TECHNICAL FEATURES

Tyson Turbine is a run of the river, axial flow type device. It is similar to a horizontal wind mill and is the exact reverse of a ship propulsion system with propeller type of blades operating in a set of mutually perpendicular axes to the river f low. The natural water f low power of a river moves the blades and they, by means of right angled coupling, rotates a pulley above the water to drive a pump or generator or both. The revolutionary turbine is supported below water level by two pontoons.

Several models of Tyson Turbines are available. The one, which Research Centre for Applied Science and Technology (RECAST) of Tribhuvan University had recently installed, has a propeller of 1.5 meter diameter. The turbine made of molded polyethylene is mounted to an input shaft, on a right angled gear box, to transfer shaft power to the surface on the platform. There is an adjustable stroke crankshaft at the top of the vertical output shaft, connected to a positive displacement (piston) pump. The pump, manufactured from corrosion resistant materials is adjustable to match the power to the head pressure in water delivery pipe. The output shaft from the gear box transmits the rotational power to a large pulley mounted on the frame of the water level. The pulley in turn drives a 12 pole, 3 phase, 48 \bit permanent magnet generator of 3.3 kW capacity. Both pumping and generator units are loaded on the platform above the water level by means of two floating pontoons made of molded polyethylene filled inside with foam.

The power output is a 3 phase AC, variable the voltage and frequency supply which is rectified to DC to charge a 48 V battery bank made from 2V, 24 numbers of Individual cells. This battery bank serves the purpose of both off peak energy storage and controlling the voltage fluctuations that occur due to the varying speed of water. The recommended battery bank is 1350 Ah (Horwood Bagshaw Australia, 1994).With the help of a Sine wave Inverter, the DC power is converted into steady 240 volt AC. The box with batteries and inverter are installed a little away from the turbine set and the power at suitable voltage is supplied right from there.

INSTALLATION SITE

In order to install the turbine the site has to be technically feasible. In other words the current and depth of the river have to match with the turbine to be installed. In the case of turbine installed and operated by RECAST, it was 2.5 - 3.5 m/s and 2 m respectively. Similarly, the site has also to be economically viable. For that the site should be easily accessible and as near as possible to the settlement. Further, there should be something for anchoring the turbine which increases the cost for additional structure. Taking these aspects into account RECAST has chosen a site near Fishing - a small settlement on the Prithvi Highway at a distance of 90 km from Kathmandu. The next bigger settlement is Mugling which is 15 .km ahead of it. One more advantage of this site is that this area has no electricity supply yet, plenty of fertile land is available for irrigation, a rope for anchoring the turbine already exists and the people at this place are very cooperative.

POWER SUPPLY AND

MANAGEMENT

The management of Tyson Turbine and the power supplied by it is in the process of handing over to a local consumer committee. A technician from among the local residents is trained to perform the day to day operations and maintenance works. A watchman safe guards the turbine and its accessories. The power is being supplied to the Bazar areas form 6 P.M. In the evening to 6 A.M. in the morning. For this purpose 25 electrical bulbs of 100 watts each Installed on either side of highway (RECAST, 1995) along the Fishling Bazar. The power is yet to be distributed for the domestic purpose.

TURBINE PERFORMANCE

The turbine was generating maximum 2 KW of electricity only. In dry season it even dropped to a minimum of 1.5 KW. The battery is able to store only 912Ah which is markedly less than what it is expected. At the maximum stroke the pumping unit could lift 3852 liters of water to a head of 20 meters. There was a drastic drop in electricity when the pump wasin operation.

The turbine was stable only when the current was smooth. With the rise in current and tides in the river it became very instable and even  overturned. There were               practical difficulties in moving the turbine side wards when the river became turbulent. On the other hand if the turbine is run only during the winter and dry season its economic viability become very low as compared to the alternative technologies. In addition to that the question, whether the maintenance cost remain within the affordability of the local people, is not yet answered properly.

CONCLUSIONS

Based on the data collected by RECAST on the operation of Tyson Turbine following conclusions can be drown. :

·         Technically Tyson Turbine can be run only during the dry season.

·         Suitable sites for the turbine would be diversion channels of hydro power station and large irrigation canals.

·         Prohibitive cost of battery banks and inverter makes the turbine hardly feasible for Nepal.

·         Further studies are necessary to see how these devices can be best used to harness Nepal’s vast hydropower resources.

Bibliography

1.       Horwood Bagshow Australia Ltd.,Assembly, parts and Service Manual, Australia.

2.       RECAST, Testing of Tyson Turbine- An Executive Summary of Final Report. December, 1995, Kathmandu, Nepal.

3.       World Bank, World Development Report 1995, Oxford University Press.