Topic: Articles

Clay Culture: Ceramic Rocket Stoves

One particular area in which developments in ceramics can contribute to a cleaner world and better health is by limiting air pollution from cooking.

According to the World Health Organization, around 3 billion people cook using polluting open-air fires or simple stoves fueled by kerosene, biomass (e.g., wood, animal dung), and coal. These cooking techniques emit large quantities of health-damaging particulate matter, and each year close to 4 million people die from illness attributable to these pollutants, the majority of whom are women and children.

Most of the 3 billion people relying on solid mass for fuel live in developing and emerging countries, so any proposed stove design to limit pollutants must be affordable, accessible, and easy to use. Due to these requirements, gas stoves are not always an option because of challenges with affordability and accessibility (for example, in Northern Ghana and India). Instead of turning to gas, some researchers are working to improve the burning efficiency of solid-mass-burning stoves—with a little help from ceramics.

1 On-site assembly of an insulating ceramic rocket stove in Tanzania.

Rocket stoves are a type of low-mass stove designed to burn small pieces of wood very efficiently. Larry Winiarski, technical director of Aprovecho, developed the rocket stove design in the 1980s, and now over 10,000 variations based on Winiarski’s rocket stove principles have been introduced into over 30 developing countries on five continents.

One of those variations comes from ceramic industrial designer Reid Harvey. Harvey, a senior scientist at TAM Ceramics, spends his free time working on humanitarian projects in developing nations. In an email, Harvey says his experience with top-loading, cylindrical kilns in firing mold-cast, decorative ceramic containers helped him envision his adaptation of the rocket-stove design: the insulating ceramic rocket stove.

Unlike other stoves that have metal components, Harvey says his design uses only small, curved bricks consisting of 50% clay powders and 50% combustible materials, such as fine sawdust and rice husks. Charcoal could be used, but “we prefer a more environmentally responsible, fine-grained combustible,” Harvey adds.

2 A set of four plastic master molds allow people to create insulating ceramic rocket stoves of varying sizes.

3 Pouring gypsum plaster over a master mold produces a working mold, used for forming the bricks.

Harvey says using clay instead of metal in his stoves makes them not only cheaper than other rocket stoves, but fabrication can also be done on-site by clay workers using local clays and combustibles, meaning there is no need to import stoves. “All that might come from outside would be [the] chicken wire wrapped around [the stove], which tends to be very inexpensive,” says Harvey. “This will make the stoves a little more durable as well as being semi-portable.”

While the ultimate goal would be proliferation of these stoves to all areas in need, Harvey is working with an Anglican priest, Father Bartholomew Segu, to begin spreading the stoves around Tanzania. “Bart Segu and others have recently established Advocates for Social Cohesion Foundation, the Tanzanian organization that will implement the stove project(s) [sic],” says Harvey. “[There] will also be a training center for proliferation of projects.”

One drawback to the stove—as with every rocket stove—is the fact only one size pot can fit in the stove. “The pot fits down inside with only a narrow gap all around,” says Harvey. “[As such], a given stove will accommodate only one diameter of cook pot.”

4 Interior view of an insulating ceramic rocket stove under construction. Photos: Reid Harvey.

To tackle this drawback, Harvey and the others are creating four master molds. These molds will allow stoves to be fabricated for cook pots of any diameter between 9½–19 inches (24–48 centimeters). According to Harvey, this flexibility is crucial because markets at the project site in Kibondo, Tanzania, and other such markets sell cook pots of any diameter in one-centimeter increments between those measurements. Additionally, master molds will mean more people can be trained to create the stoves and not just local experts.

However, before the master molds come into effect, Harvey says they need to secure more funding. “Bart Segu and I have been communicating with several prospective supporters for continuation of the project and prospects look good,” says Harvey. “At the first real indication of new support, I’ll be engaging a local plastic factory, nearby Niagara Falls, to put together plastic master molds.”

Harvey explains that plastic master molds are a springboard for even further projects. “[People] will be able to produce master molds themselves using gypsum plaster or concrete, given their new understanding of model and mold making [from using the plastic molds],” he says.

Insulating ceramic rocket stoves can be made without any metal parts, meaning they are cheaper than other stoves and can be fabricated on-site by local clay workers. Photo: Reid Harvey.

In addition to insulating-ceramic rocket stoves, Harvey is working on bringing ceramic water filters to developing countries, which you can read about in the January/February 2019 issue of the American Ceramic Society Bulletin (https://ceramics.org/bulletin-issue/january-february-2019). “Between ceramic water filters and ceramic cook stoves, literally thousands of lives will be saved every day,” says Harvey. “This will be the case in the event that the technologies are properly embraced and managed.”

For more information on the insulating ceramic rocket stoves project, visit http://tzenvirohealth.wixsite.com/tzenvirohealth.

the author Lisa McDonald is associate editor and science writer at The American Ceramic Society. Prior to this position, McDonald worked at the American Institute of Physics: FYI and the ATLAS Experiment at CERN. She has a master’s in science communication and specializes in communicating science to nonspecialist audiences.

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