Power on the farm

Press, 2 August 1979, Page 17

Power on the farm

The water that ftows from the foothills down the streams and races of the Canterbury Plains is a potential source of power for rural communities. For very small schemes, however, the cost of machinery and equipment to generate and use the power is a barrier to its exploitation. But a water-driven turbine for small-scale proluc- , , tion. which has been tested, assessed and improved in the civil engineering department of Canterbury University, does show promise. Only three metres long, it can be placed in streams and, depending on the volume and speed of the watqr, develop up to one kilowatt. _ Mr E. P. Giddens, a senior lecturer incivfl engineering, who has tested and developed the turbine, says that with small systems the initial Cost is a

matter of primary significance. The exercise of harnessing these small water resources is largely One of finding technically sound and socially appropriate solutions which are economically possible, especially as far as the initial cost is concerned. The turbine was originally devised by Mr R. Martin, of Dunedin, as a cheap and simple device to be coupled to a small water pump for lifting some of the stream water for use on New Zealand farms or for water supply purposes in developing countries. The original design has been improved and its potential increased while retaining its simplicity. The Plata pump, as it is known, is being manufactured by a Dunedin company. It is coupled to a reciprocating water pump suited to the requirements of a New Zealand one-man farm or for overseas use.

The possibilities of electricity generation are now being investigated. The turbine section consists of a fibreglass cylindrical casing with a bell-mouthed Opening and a short outlet chute at the lower end. Inside is a set of identical axial-flow rotors mounted on a shaft. When set in a natural stream bed at a point where there is a fall, the water flows through the inclined tube, partly filling it and driving the ro-

tors. It can deal with flows in the range of 50 to 200 litres a second and has been tested for slopes of up to 30 degrees. Additional research on small-scale water power, is being undertaken by senior students in the fluid mechanics laboratory into intakes, water hammer, governing, turbine design and the matching of turbines with pumps. Close relationships are being maintained with industry and care is being

taken to ensure that the results are realistic.

Mr Giddens says the fluid mechanics laboratory has excellent testing facilities, probably, the best in New Zealand, for this research. The equipment is adequate for the present programmes without substantial capital investment. Funds are required Only for the consumable materials for the building of these small prototype systems.