Hydrostatic Pressure Converters for the Exploitation of Very Low Head Hydropower Potential

Abstract

Much of the world's available hydropower potential has been exploited, and within the western world attention is increasingly being focussed on hydropower sites with very low head differences. These are sites where the vertical distance through which water falls is less than five metres, and remain unexploited as there is a recognised lack of hydropower technology available to exploit these low-power sites economically. The aim of this work was therefore to develop a novel hydropower machine which could be used to viably exploit very low head differences in river environments.
A review of the hydropower technologies determined that the established machinery is primarily driven by the operational principles of impulse, reaction, or potential. It was however noticed that some less well established designs appear to be driven directly by the hydrostatic pressure which could be generated by a depth of flowing water. This observation had not been previously acknowledged. It was also recognised that investigation into this operational principle could potentially result in machines that were both relatively simple, and have high flow and power capacities when compared to the established technologies.
It was identified that there could be two approaches to exploiting hydrostatic pressure, and ideal theories were developed to describe both approaches. The resulting physical concepts were called Hydrostatic Pressure Converters. Scale models of these concepts were hydraulically tested, verifying the proposed theories, and providing data from which estimates of full scale performance were made. These predicted that the two proposed designs of Hydrostatic Pressure Converter were suitable for head differences below 2.5m, normally the domain of the traditional waterwheel. They would operate with high hydraulic efficiency, at around 80%, but have a significantly greater flow capacity and power output per unit width of machine, at 500% that possible using a traditional waterwheel.
In conclusion this work has identified, analysed and prototyped a novel approach to exploiting very low head hydropower potential. The resulting Hydrostatic Pressure Converters are a significant and promising development in the field of very low head hydropower.

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