NMT Smallholder Energy Development


NMT Trustees have been developing energy producing devices as a means of reducing the requirement for wood fuel for cooking in a smallholder context.
Cookstoves Solar troughs

Efficient cook stoves

A cook stove made from simple materials has been designed using a lid and small chimney that enables solid fuel to be burnt with a gasified flame without smoke, efficiently and at a high temperature.
The July and August 2016 news items show the work done at the Home of Hope in West Malawi.
The first one built there using materials and tools brought with the youth group from the U.K. was lit in 5 minutes. A phrase became very popular at the Home of Hope, reflecting the potential of what could be achieved for the benefit of the country:

Malawi Opanda Utsi!
Flame Without Smoke!

Further work for building a reliable and permanent cooking setup for the Home of Hope is required.
Macadamia shells have been very successfully used and tested as an alternative solid fuel. Measurements in the U.K. showed that 800 g of macadamia shell could burn for over 1 hour at a heating rate of 0.5 kW (heating 8 litres of water to over 60C).

The stove burns the fuel from the top down, leaving charcoal/biochar in the can as an extremely useful by-product.
Further information about biochar and NMT work.

Solar troughs

A comprehensive summary of the Solar trough work including designs, builds and measurements of successful water boiling can be viewed here and also downloaded as a PDF document from

Materials brought in the August 2016 trip (reflective foil, chipboard forms and hardboard) were assembled to demonstrate that water can be boiled using the typical Malawian sunlight.

Chipboard frame and cut with a parabolic curve.

Constructed solar trough.

Solar trough pipe lit up to near white as it receives focused sunlight.

Water was boiled in the vertically aligned pipe in Malawi.

Further work in the U.K. has produced a horizontal aligned pipe connected to a tin can, in which 1 litre of water was boiled at a rate of upto about 150 W in U.K. sunlight. The efficiency was around 25%.

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