A safer, more efficient stove for low-income households

13 March 2014

Working with low-income households in the HaMakuya district in Limpopo province enabled the University of Johannesburg’s Chris Bradnum to design a safer, more efficient biomass stove that is also kinder to the environment.

The Tshulu Stove, named after the Tshulu Trust who partnered with Bradnum in his project, is a safe, efficient and sustainable wood burning stove for rural and low-income households that promises to reduce deforestation while decreasing the risks of burning or developing respiratory illnesses from open fire cooking.

“The majority of low-income households in South Africa rely on open fires or use paraffin as their primary fuel source for heating and cooking needs,” Bradnum said in an article on the University of Johannesburg’s website on Wednesday.

“A recent study by the Global Alliance for Clean Cookstoves estimates that 3-billion people in the developing world cook food and heat their homes with traditional cookstoves or on open fires,” explained Bradnum, who is head of the university’s industrial design department. “More than 4-million premature deaths occur every year due to smoke exposure from cooking on open fires or using inefficient stoves in the homes.”

Bradnum said that, while gas could be an ideal alternative to electricity in terms of clean cooking and efficiency, there was a general mistrust of gas stoves, with paraffin being the fuel of choice for cooking in many areas.

However, in the Ha-Makuya, Vhembe District in Limpopo, where Bradnum conducted his research, the community tends to use wood fires for cooking – making the Tshulu Stove, which reduces both the amount of wood required and the smoke and emissions given off by fires, an excellent solution.

“The cutting down of trees is strictly controlled in the area by village headmen and the local chiefs, so households can only use wood that has fallen off the trees or specific areas that have been demarcated for tree felling.” This means that the community has to spend long hours searching for wood.

“The fallen branches are of little use in open fires as these burn up very quickly and don’t generate enough heat for cooking. However, these smaller branches burn extremely well in the Tshulu Stove,” Bradnum said.

The Tshulu Stove is based on the “rocket stove” design, developed by Aprovecho in the US, which includes a burn chamber and directed chimney of heat to the base of the cooking pot.

“The Tshulu Stove, however, includes innovations such as introducing air below the burn chamber, a removable ashtray, standing height cooking, an inner sleeve that reduces the amount of heat loss from the burn chamber, and an outer sleeve that reduces the chance of burning the stoves users,” Bradnum said.

In laboratory testing conducted at the university’s Sustainable Energy Technology and Research Centre (SeTAR), the stove’s combustion efficiency levels were 2% for paraffin, 5% for charcoal and 10% for wood (a lower percentage indicating greater efficiency) – working out at an average efficiency of 3%, a fraction above the ideal paraffin stove.

“In effect, the Tshulu Stove will save an average household, cooking three meals a day on the stove, 7 kilograms of wood per day over that of a three-stone fire,” Bradnum said. “This translates to a saving of 2 500 kilograms of wood for one household in a year.”

SAinfo reporter and University of Johannesburg