TWP and AHDESA / Fuel-efficient stoves for tortilla makers

TWP and AHDESA, not-for-profit organisations based in the USA and Honduras, have enabled the installation of efficient wood-burning stoves for cooking in Honduras. About half have been installed in and around the Honduran capital, Tegucigalpa, where demand for fuelwood has led to severe deforestation in the nearby hills. The other half have been installed in rural areas. Although the work of TWP originally focussed on decreasing fuelwood use in order to reduce deforestation, the need to prevent the damage to health from smoke has become increasingly urgent.

The organisations

Trees Water and People (TWP) is a non-profit organisation established in 1998 and based in Colorado, USA. It works to protect the environment and welfare in Central and South America as well as the USA, with a focus on tree planting and the development and dissemination of fuel-efficient stoves.  Asociación Hondureña para el Desarollo (AHDESA) was founded in 1992 and is a registered Honduran non-profit organization working to help the poor through training, technical assistance, and implementation of projects.
The effective partnership between TWP and AHDESA has been the foundation of the success of this work. AHDESA is responsible for the day-to-day operation of the programme in Honduras. TWP initiated the programme, continue to source most of the funding, and maintain contact through regular working visits to Honduras.

The technology

How does it work?

The stove technologies used by AHDESA in Honduras are based on the ‘Rocket’ concept which was developed by the Aprovecho Research Centre in Oregon, USA. The key features of the Rocket are that it provides efficient combustion and efficient heat transfer. It also discourages the use of excess wood and, by using a chimney, removes smoke from the kitchen.

TWP brought technicians from Aprovecho to work with AHDESA and community leaders on the stove design. One of the leaders, Dona Justa Nunez, was particularly instrumental in providing the designers with an understanding of what would be most appreciated by the users of the stove. In recognition of her contribution, the Justa stove carries her name.

The Justa stove is built into the kitchen by AHDESA technicians, with assistance from the household.  It is made on a raised platform, which is normally used for cooking in Honduras.  The body of the stove is built from standard masonry bricks, with ceramic bricks used for the combustion chamber.  The dimensions of the combustion chamber and the air gap under the plancha are critical, but other dimensions can be more flexible, depending on the space available and the wishes of the user.  Pumice or ash is filled round the chamber to minimise heat loss. The hotplate is large enough to fit several pots and can also be used to make tortillas.

The technology in more detail

Efficient combustion is achieved by the elbow-shaped combustion chamber, essentially a horizontal pipe which bends round to a vertical pipe. The wood sits on a shelf at the bend, so that air is drawn from underneath it and upwards.  This air flow provides a high air-to-fuel ratio, thus promoting efficient combustion and reducing the production of carbon monoxide, unburned particles and other products of incomplete combustion, which are damaging to health. The small size of the chamber prevents the use of large pieces of wood, and therefore means that wood is not left burning when cooking has finished.  Efficient heat transfer is achieved by forcing the hot combustion gases through a narrow gap under the hotplate or ‘plancha’.  The chimney which then carries the gases out of the kitchen both enhances air flow and removes about 95% of the combustion gases from the house.

How is it manufactured, promoted and maintained?

AHDESA works on the stove programme with local community groups, many of which are led by women.  The group leaders are the key stove promoters and are crucial for the success of the programme.  AHDESA technicians train the group on stove use and the environmental benefits of stoves before the programme starts, as well as providing training during construction of the stove.

Users are trained to clear ash from the chimney every day and to clean the surface of the plancha every week. For each installation programme, AHDESA technicians make follow-up visits after one month and six months, to check that all is going well. The good initial design and careful construction mean that very few problems arise.  The Justa stove lasts at least five years.

Benefits

By the end of 2009, about 20,000 stoves had been installed in Honduras, and another 15,000 provided with the help of partners elsewhere in the region, including Haiti.  New independent studies confirm a carbon saving of about 1.5 tonnes/year of CO₂ per domestic stove, so the total saving for TWP stove programmes in Honduras and elsewhere is about 53,000 tonnes/year CO₂.

Other studies have confirmed additional benefits: a PhD thesis from Colorado State University quantified the reduction in indoor air pollution and impact this has had on health. It found that a well functioning Justa stove cut particulate concentrations in the kitchen by 83% and CO concentrations by 98%. There was also a statistically significant (p<0.01) reduction in coughing, wheezing and headaches among women with Justa stoves compared to traditional stoves.

As well as benefiting from health improvements, Justa stoves also save users time. The stove lights up and gets hot quickly, and the plancha can accommodate nine or ten tortillas at once, so a skilled cook can substantially reduce the time she spends cooking. This further reduces smoke exposure.

Environmental benefits

Standard laboratory tests carried out by the Aprovecho Research Centre suggest that the Justa stove reduces fuelwood consumption by 50%. However, an extended field survey carried out in Tegucigalpa found that fuelwood use was actually reduced by an average of 70%, because the design of the combustion chamber allowed users to burn some agricultural residues (such as maize cobs and sugar-cane stalks) instead of wood.  It is observed that fewer fuelwood trucks visit the communities that have had stove programmes.  The countryside around Tegucigalpa is heavily deforested, so this reduction in wood demand is a great benefit.

Economic benefits

The Justa stove brings financial savings, since most wood in Tegucigalpa is purchased.  Avoiding 70% of the daily fuelwood cost of about US$0.50 (10 HNL) is a significant benefit, since the typical household income is only about US$2 (38 HNL) per day. Some Justa stove owners are increasing their earnings through tortilla production, but the tortilla market in Tegucigalpa is saturated, so this is probably not a significant financial benefit.

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