Making Rocket Stoves in China
Dean Still, Aprovecho Research Center, March 28, 2008

Hi Stovers!

A lot of the folks on the List saw the Rocket stoves that we are making in China at ETHOS. John Page and I just spent ten days at the factory near Shanghai. Here’s a quick update on the China project.

The big news is that the lightweight, refractory ceramic combustion chambers are now being extruded at the rate of about one thousand per day. You can imagine that John and Dean were grinning ear to ear, watching the materials being mixed three times in the big grinders. When thoroughly mixed, the clay is extruded into the combustion chamber shape, pushed by a 100HP motor, and every twenty seconds or so, another combustion chamber is ready for drying. (There are photos of all this.) Drying takes about 30 days and then firing takes place in the huge coal fired kiln, as big as a supermarket. I think that we can fire about 20,000 combustion chambers at one go. The kiln is being fired and emptied simultaneously. The clay deposit is located one kilometer from the kiln.

The cast iron stove top was adjusted; raising the pot supports two millimeters, after further emission testing in the lab showed a reduction in CO and PM with a little higher clearance.

We have the first order for a container of stoves, which is going to India. The factory has arranged for a good set up price (about $600) for the packaging. The six sided box can be printed in the local language with desired designs and logos.

We are investigating shipping costs to and duties for all countries. There are different duties for whole stoves and for stove parts. We’re going to write up our experience and send it around to everyone, bit by bit, trying to share what we learn from this project.

You can contact me for the stove catalog, questions, etc…

All Best,

Aprovecho Research Center
541-767-0287 Oregon, USA

New Factory Under ConstructionNew Factory Under Construction

Dean Still, June, 2005

download the Insulated Rocket Stove for Charcoal pdf
Preliminary Fuel Use and Emissions Test Results:

    Wood Stove
WFP Wood
(with Skirt)
Time to Boil min - 22 29 22
Fuel to Cook g 850 604 675 733
Energy to Cook kJ 15,000 23,983 26,089 12,579
CO to Cook g 20 12 74 15
PM to Cook mg 1500 81 85 1289

Dean Still, June 18 2002

Prototype Ecuadorian earthen stove with Baldwin sheet metal skirt around partially submerged pot.

Dean Still, Lanny Hensen, Peter Scott June 2002

Dean Still and Brad van Appel, Aprovecho Research Center, January 1, 2002

The Effect of Material Choice on the Combustion Chamber of a Rocket Cooking Stove: Adobe, Common Brick, Vernacular Insulative Ceramic, and Guatemalan Floor Tile (Baldosa)

The Search for Vernacular Refractory Materials

Multiple tests of the Lorena stove beginning in 1983 at the Aprovecho Research Center have shown that placing thermal mass near the fire has a negative effect on the responsiveness and fuel efficiency of a cooking stove. In 1996, Leoni Mvungi built a Rocket stove from earth, sand, and clay that was a replica of a low mass Rocket consisting of metal chimney parts. His version weighed hundreds of pounds even though the Rocket internal chimney was only eleven inches high. Tests of a low mass sheet metal version scored around 30% fuel efficiency. But the best result achieved by the Mvungi stove was around 15%.

Building Rocket stoves from sand and clay showed little promise of improving on the three stone fire which was scoring around 18% in repeated boiling tests performed by Jim Kness and Dean Still (1994). Unfortunately, metal stove parts also have a major drawback in that the high heat in the combustion chamber quickly destroys thin metal. Consultants were in agreement that a good stove should last for years without requiring maintenance. Replacing metal parts as they wear out was not considered a viable solution.

A women's co-operative in Honduras (Nueva Esperansa) makes ceramic stove parts that have a reputation for working well in stoves. Aprovecho consultants Mike Hatfield and Peter Scott contracted with this group to produce combustion chambers for the Dona Justa plancha stoves that they helped to design. This material seemed to work well and, in fact, the Rocket elbow made by Nueva Esperansa has been successful in Honduras and Nicaragua. It is difficult, however, to deliver the fragile combustion chambers without breaking them. Also they are relatively expensive, costing about eight dollars each.

Don O'Neal (HELPS International) and Dr. Larry Winiarski have shown that cast iron combustion chambers, which do last, also have problems. Tests showed that the very conductive cast iron made the fire hard to start. In fact, a group of indigenous Guatemalan women stove testers living in Santa Avelina were unhappy with the expensive cast iron combustion chamber and asked for it to be replaced. They wanted a more responsive stove that started quickly, and quickly cooked food in the morning. Don and Larry eventually found an alternative material: an inexpensive Guatemalan ceramic floor tile (called a baldosa in Spanish) which seemed to function well when cut up to make the walls of the Rocket combustion chamber. The baldosa was about an inch thick so the combustion chamber only weighed eighteen and a half pounds. Like all Rocket combustion chambers it is surrounded by insulation, either wood ash or pumice rock.

The baldosa tile has done well in test stoves. It seems to be durable, lasting a year so far, and the group of testers from Santa Avelina reported that their stoves are much improved. The ceramic material made the stove much quicker to heat up. The women approved the improved stove for general dissemination to neighbors and other villages. The HELPS molded griddle stove now uses a preformed ceramic combustion chamber made by a local baldosa manufacturer. Unfortunately, all baldosa are not equally resistant to heat and it's important to test tiles before using them in stoves.

Appreciating that ceramic seemed a promising material for Rocket combustion chambers, Ken Goyer, an Aprovecho Board Member and consultant, spent a year, 2000-2001, testing ceramic mixes. His research resulted in a vernacular insulative ceramic material (VIC) that is refractory, insulative and can be home made. Six bricks made from this material combine to make a complete Rocket combustion chamber. Making the chamber from separate bricks has resulted in a greatly reduced tendency to crack. The bricks have held up so far in durability tests and they seem to create a very active fire.

The purpose of this paper is to describe the results of experiments involving same sized brick combustion chambers made from adobe, the insulative ceramic mix and common ceramic brick material. All bricks shared the same dimensions. Six bricks (11 ½" high by 2 ½" thick) made up a hexagonal cylinder surrounding a four inch in diameter chimney. Sticks of wood entered the bottom of the chimney through a hole sawn in the bricks. A combustion chamber made to similar dimensions was constructed using baldosa tile bought in Guatemala. Vermiculite filled in around the baldosa creating a combustion chamber with approximately the same dimensions as the brick stoves.

Protocols for Standard Stove Tests Using PICO Software

Dean Still, May 2010

Hi Stovers!

As Paul says

Stove Camp is July 26-30 here at Aprovecho Research Center

next to the river in beautiful Cottage Grove, Oregon.

The theme of Stove Camp this year is "Tuning TLUDs" using the emissions hood.

Dean Still, Aprovecho Research Center, April 25, 2008

Dear All,

Stove Camp this year will take place August 4-8 here at the new lab which is on 4 beautiful acres with a nice river on two sides of the property. Folks are invited to camp here near the river! We will cook on wood burning stoves for lunch and dinner and bake tasty bread in a Rocket bread oven. We can have bonfires at night and figure out how to distribute one billion stoves.

Paul Van der Sluis from Philips may be able to attend. Friends in India are trying to buy and send us a BP stove. Can anyone in India assist them? I'll pay costs, shipping, etc.

Pam Baldinger, now in Darfur with USAID, very much supports this year's theme and contest. The team that cooks corn flour using the least fuel, etc. wins the more and more coveted Dr. Kirk Smith Cat Pee Award and $250! The most effective solutions will be sent to Pam.

Let's prove that cooking with wood can be done with very little fuel! It's important! Let's help refugees.

There's room for 25 participants. Book early!

ETHOS Stove Camp costs are:
Instruction/Participation: $100 students $200 others
Camping (5 nights): $25 students $50 others
Five dinners cooked here with wood on Rocket and other stoves: $25



Aprovecho Research Center
Fred's Island
Cottage Grove, Oregon
541 767 0287

Aprovecho research Center, July 18, 2005

Download the full report Stove Performance Report: Mayon Rice Hull Stove

Laboratory Comparison of the Global-Warming Potential of Six Categories of Biomass Cooking Stoves

Aprovecho Mass Producing Stoves
Dean Still, Aprovecho Research Center, September 4, 2007
Officials from Shengzhou Stove and Aprovecho Seal the DealOfficials from Shengzhou Stove and Aprovecho Seal the Deal


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