Burning biomass is critical to the lives of half the world’s population, providing essential food and warmth. Unfortunately it is also a major cause of poor heath, with about 1.6 million deaths each year caused by smoke from cooking. It also contributes to deforestation as areas are stripped of trees, and to climate change as greenhouse gas emissions mount up.
At the heart of the problem are the many inefficient and polluting stoves used across developing countries.
“Paraffin used to take most of our family income. We are not all employed. We used to spend lots of money and sometimes ended up borrowing to pay for paraffin. At first I was worried about the stove. I did not trust it and thought maybe they had given us something which doesn’t work. But after lighting it, I felt so good and happy. There is a big difference between the paraffin stove and this one. The children are no longer coughing. I use it day in and day out with no problems at all.”
Esther Kuneme, Alexandra Township, South Africa
Aprovecho Research Center (ARC) is a non-profit established in 1976, which designs, tests and promotes improved stoves and other technologies, and had an annual turnover of US$195k and five staff in 2008. SSM is a private family business specialised in producing ceramic coal-burning stoves. It had an annual turnover of US$2.1m and 100 staff in 2008.
Three different stoves designs have been developed, in consultation with users. All are portable and based on the ‘rocket’ combustion chamber. The most popular stove burns wood only, and has a single door for adding the wood: this stove is available in different sizes. A similar stove has been developed that burns either wood or charcoal, with a lower door for controlling primary air, and an upper door for fuel entry. These stoves are designed to last between three and five years.
A very low cost all-ceramic stove has recently been developed, in response to feedback from GTZ, the German Development Agency working in Southern Africa. This stove is supplied without metal parts, so that it can be finished in the country where it will be used.
One of the main purposes of the stoves is to reduce fuel wood use (although some replace kerosene and electricity) and hence greenhouse gas emissions. Cooking practices and the sustainability of wood supply vary between countries and regions, and ARC has used several different methods to assess savings, including both laboratory and field studies. All these methods agree that, compared with a cooking fire, the stove without a pot skirt saves about 40% of fuelwood. If the skirt is used, this figure increases to about 50%. The stove also reduces particulate emissions by 50 to 70%, and carbon monoxide emissions by 50 to 60%.
How much wood is saved depends on how frequently the stove is used, and for what purposes. For example, an Indian study of 100 cooks found that families cooking two meals per day saved an average of 0.73 tonnes/year of wood.
Converting fuelwood savings into greenhouse gas savings depends significantly on the sustainability of the wood source, and also on which emissions are included in the calculation. ARC studies suggest that, if CO2 and all the other Kyoto greenhouse gases are included, then these savings represent between 1 and 2 tonnes/year CO2 (equivalent) per stove.
Users benefit directly because the reduction in indoor air pollution results in less respiratory and eye disease. The risk of burns and house fires is also much lower with an improved stove.
SSM has taken on about twenty extra staff to manufacture the improved stoves. Many are skilled, and earn up to $430 (RMB 3,000) per month, well above the minimum wage of US$90 (RMB 600).
The ARC/SSM partnership has shown that it is possible to mass-produce an efficient, durable and affordable fuelwood stove. Given that about half the world’s population cook using biomass on open fires or basic stoves, there is a huge potential market for such stoves. There is plenty of opportunity to complement local artisanal stove manufacturers, and not compete with them.
ARC and SSM are working to apply the mass-production approach to other types of pots and stoves, including a fan-assisted stove that burns wood as cleanly as kerosene and greatly reduces greenhouse gas emissions.