The Eastleigh Community Centre, of Nairobi, Kenya, (www.pceaecc.or.ke) is beginning production of several new products, shown in this update. The picture at the right shows a section of a pottery rocket stove, under construction. Rocket stoves are a highly fuel efficient alternative to the other stoves in the markets.
Reduced fuel consumption and portability of stoves are urgently needed, important in addressing those environmental and health issues that are implicit to cooking with such fuels as wood or charcoal. For example, in the slum of Mathare, opposite the ECC, many residents cook indoors, using less efficient stoves, and as a result there is a serious issue of respiratory illness. Outdoor space in such communities as Mathare is hard to come by and to monitor, but outdoor cooking with such fuels is always preferrable, in a well ventilated area.
The high fuel efficiency is partly because the short, chimney section of the design causes the flame to be sucked in, and the cook pot is heated both from the bottom and the sides. The sizes of the internal spaces of the stoves should also be optimized.
For the section of the stove shown, the first course of brick has been laid, using a mortar of 50% clay and 50% sand. After the sheet metal is tightened to the diameter of the stove, additional mortar may or may not be pushed into the space behind the brick. This section should be tight, with good integrity.
For the rocket stove of the ECC, the amount of fuel needed should also be greatly reduced because the curved brick used, as shown above, is insulating. The light weight of the stove sections also makes these portable. The curved brick is made to be insulating by adding a lot of fine, wood sawdust to the clay composition. This sawdust burns out in the firing of the brick, leaving voids, and this contributes greatly to the insulating properties, as well as the light weight.
For the pottery rocket stove shown below, the diameter of the cook pot is 30 cms. Note that the side of the pot is a uniform 12 cms. (~1/2 inch) from the inner wall of the stove. Thus there is very little loss of heat energy. This is one of several reasons why the amount of fuel required is very low.
The pottery rocket stove is portable in the smaller models, for cook pots of under 40 cms. diameter, approximately speaking. The environmental and health considerations of improved stoves address important issues on the household scale, just as is the case with pottery filter systems.
It is important to note that the preferred method of delivering water is when it is piped in, from a pure source. Similarly the use of wood and charcoal as fuel is not a preferred practice. Rather it would be better to prepare meals with a gas stove or a solar cooker.
But thus far, for the environmental, best practices of cooking, the issues of effectiveness, price and user-acceptability have proven to be difficult to address, so the use of gas or solar have been slow to take root. In the meantime it is urgent to reduce consumption of fuel wood and charcoal to a bare minimum, as is the case with the use of the rocket stove.