Solar irrigation pump for smallholders
Position: Research & Development Engineer at Practica Foundation
This solar steam pump was developed as an affordable solution for small farmers to irrigate their fields. It can pump up ground water by boreholes up to 20 meters of depth.
As it is fuelled by sunlight only, it saves the variable cost of a fossil fuel, as spent with a petrol or diesel pump. How it works: a parabolic collector reflects the light to its focal point, where a water boiler is placed. This water is conversed into steam, which drives the engine and so the pump.
This project had reached its final stage when I joined; I was asked to optimize product parts and help prepare for production. Design issues concerned user ergonomics, construction details, design for manufacturing and assembly, choice of materials, optimizing cost price etc. In cooperation with a manufacturing agent in India we redrew the final assembly from the original Autocad files into SolidWorks and ordered production moulds and tools.
Need for a tracking system
A problem that was untackled at this stage was the need to regularly redirect the collector to the sun, in order to keep the engine working. Closer analysis of the sun paths in target areas taught me that the maximum interval between these required handlings was too short to fully benefit from the 'automatic' pumping; the user had to stay near. Consequently, I examined the possibilities to develop an additional solar tracker; a device that could steer the collector continuously in the direction of the sun.
From the beginning I questioned the efficacy of the chosen concept. Despite the ingenious engineering work that created this wonderful piece of art, I wondered if the result would not be a bridge too far for its purpose and intended users. In my experience, many smallholders in East Africa hardly used any means of irrigation at all; a human powered solution like a hand, treadle or bicycle pump would be a great start. Even for those who can afford more, I thought the complexity, the many parts and required maintenance would make the product vulnerable, and therefore a risk factor to the promise of prosperity such an investment would imply.
As the price of solar panels dropped during the years, a solar photovoltaic (PV) solution became more and more within reach as a workable alternative, and was eventually adopted. The problem of too much handling was solved right away, as exact pointing to the sun is of less importance for a PV panel. The solar irrigation pump is now introduced in various countries as the Futurepump.