This report describes the results of tests conducted to assess the viability of an electric 3-phase 2.2kW Agsol hammer mill, imported from Kenya, for use in rural Maasai communities in Simanjiro, Tanzania. The objectives of the tests were to assess the viability of powering the mill from offgrid (solar) energy technology, and (for different mill settings), the:
- Speed of milling,
- Quality of flour output
These two indicators of milling performance were investigated through variation of (a) screen hole size and (b) maize feed rate (through varying the feed aperture). Resulting flour samples were ranked and evaluated by local cooks, and directly compared with a locally milled flour sample.
Results confirm that while quality of flour from coarser mesh sizes and higher milling rates is not suitable for use, it was possible to produce flour of a quality that was evaluated as better than an existing local (diesel) milled flour sample. Furthermore, analysis of the use cases of milling machines suggest that the slower speed of the electric mill does not necessarily cause any greater inconvenience to customers than the need to wait for the diesel mill to be operated.
The milling machine also operated without any issues from a solar-powered water pumping system, connected to the VFD (solar pumping controller) in parallel with the borehole pump. Pump and milling machine were able to operate size by side, and the milling machine could be turned on and powered down according to demand. (Note that the report assumes the milling machine included a soft-starter. It was later learned that this was not to the case, although the VFD acts as an external soft starter when running the machine).
We conclude not only that a small electric milling machine of this type can produce flour of a satisfactory quality, but that it can also be easily retrofitted into existing solar water pumping systems (provided there is 1-2kw “spare” power capacity) at minimal additional expense.