Eco-friendly smoke-free ovens

In 2010 Project Aid started to develop eco-friendly ovens, which are meant to replace the traditional open fires people use to cook in the villages. The ovens save a lot of fire wood and make cooking more comfortable as the smoke does not longer cause diseases of eyes or irritations of the respiration path. They also decrease the risk of burn injuries among children. By now about 150 such ovens have been built in Jahaly and Madina.

The project was supported – amongst others -by donations of a Gambian Foundation. Through the chimneys of the ovens, the “skyline” of the two villages has visibly changed. The village population is purchasing the necessary sand for the construction of the oven and send a laborer. The construction of one stove incl. building material and labor costs for the Project Aid’s mason costs about 25 Euro.

The women of the villages are very excited about the ovens. For the first time since the existence of Jahaly Health Centrein 2014 the clinic had no longer to treat burns,  especially small children have suffered from afterb falling into the open fire places.

For the construction of a first prototype in 2010, only self-produced clay bricks were used. Clay as a building material is sufficiently available around Jahaly. In order to keep the costs per oven low, we wanted to not purchase  burnt bricks, fireclay bricks and iron rings for the “hotplates”. Apart from the costs of transporting these materials to Jahaly these materials are even difficult to buy in The Gambia.

Each oven consists of two fire places (“stove-plates”) with access to a lateral chimney. Double-cookers have two fire places on each side of the chimney placed in the middle.

For all components required forms of iron were produced, so that the components could be pre-produced in large quantities and the oven could be assembled on a modular basis. But the clay failed as building material for the construction of firebox, fire hole and the flue to the chimney. Through the use of heavy pots and due to the great heat parts of the clay construction quickly broke out, making the oven unusable.

Another challenge was the cooking pots, which are used in The Gambia. There are different sizes – most have a three-legged stand, so the pots can be placed in the traditional open fireplaces. For smaller pots could be used, we produced rings made of concrete (only without, then with reinforcements made of structural steel) in various sizes for the round stove openings. But the concrete ring constructions did not survive the practice test: they were too heavy and broke after a short time.

Finally, we had the idea of ​​the fire chamber (and thus the stove opening) to make in triangle shape. The big pots fitted with their tripod feet exactly into the opening. To cover the triangle ends when using smaller pots matching concrete parts were produced, covering pot and open corners completely. So no or only very little smoke leaking from the fireplace into the cooking hut. The smoke is travelling almost completely through the chimney.

The second prototype components for the triangular fire chamber, the fire hole and the flue to the chimney then were made of concrete and also composed on a modular basis. The fire hole – where long wooden sticks  are pushed through to fuel the fire – was doubly reinforced. Around the components clay bricks were installed to give the oven a form. A “cook top” made of concrete with recesses for the fire openings was applied at the end.

Even the 2.Prototyp had to be abandoned. The use of clay and concrete led to cracks and crashes at the contact points of the different materials. The construction of the fire chamber as a “Hasenwinkeler triangle” (named after the street in Bochum, where the idea was born) had proved to be valuable.

Again a few months later, there were material fatigue due to the use of heavy pots and of large wooden sticks pushed through the fire entrance. The cement that is available in The Gmbia is unfortunately of poor quality, and so are sand or gravel. Regular maintenance and repair work are still required.

Update February 2021: Despite various structural improvements, the design of the stoves has turned out to be unsustainable. Since the stoves are not working reliably, the women no longer use them. With a heavy heart, we therefore decided not to pursue this idea and the project any further. We make mistakes too. Not every project succeeds.