Three stone cooking fires, 3-stone cooking fires or 3-rock cooking fires are fires which, unlike open fires, have the cooking vessel placed very close to the fire itself, limiting excessive waste of heat. With 3-stone cooking fires a superheated space is effectively formed between the cooking vessel and the fire. Sometimes, a circle of stones is placed besides the fire itself, to keep the fire from spreading into the environment, and to keep wind away from the fire.
In addition to using additional stones as windbreaks and to increase the thermal properties of the cooking fire, it is also possible to burn the fuel more efficiently, using three pieces of wood, and pushing them slowly into the fire, burning only the ends of the sticks.
Use in the developing world[edit | edit source]
Rural cultures around the world depend on the three rock fire for their cooking needs. Although more efficient than the open fire (in which the cooking pot or container is generally hung well above the fire), it is still an inefficient method of cooking and thus places the environment in jeopardy. This as over-harvesting of fuel for cooking can cause damage to vegetation and wildlife. Understanding traditional cooking methods can help explain why improved solid biofuel stoves are an important appropriate technology. "Most cooking fires are surrounded by three of more stones, bricks, mounds of mud of lumps of fireproof material – thus the common name of three rock fire"
Benefits[edit | edit source]
Three rock fires have benefits not found on improved stoves such as:
- Space heating
- Domestic lighting: one of the important uses of three rock fires, a function that the improved stove cannot perform. "Three rock fires provide light, heat and a social focal point for family and friends."
- Protection from insects. A three rock fire producing lots of smoke in a riparian or wetland environment might have the added benefit of preventing insect bites.
- Flexibility to use a wide variety of fuels in different seasons.
- "It cost nothing and no special materials, tools or skills are needed to construct it".
Because of these benefits, open fire possesses important advantages compared to an improved stove. If the other functions of the three rock fire are not replicated with its replacement, then the improved stove is not being judged and evaluated fully.
If the fire is used to provide heat or light at times when cooking is not taking place, then its efficiency can hardly be judged only on the basis of how well it heats pots.
Critiques[edit | edit source]
A large population of people in developing nations depend on traditional three rock fires for cooking; this primitive form of cooking negatively impacts the health of people using the stove and the well being of the natural environment. Two billion people use biomass for cooking and heating worldwide. Traditional three rock fires are used inside the persons dwelling, usually located on a dirt floor. "Over the last 30 years awareness of the environmental and social costs of using traditional fuels and stoves has grown." Traditional three rock fires pose major obstacles to the environment, social health and sustainability of society.
The most important concern with traditional three rock fires is indoor air quality. Biomass fuels release large amounts of air pollutants when burned on traditional three rock fires. These pollutants become concentrated in inadequately ventilated homes and dwellings. "Several recent studies have identified prolonged exposure to biomass smoke as a significant cause of human health problems." Biomass burned on three rock fires produces harmful soot and ash that become concentrated when confined inside a dwelling, resulting in harmful indoor air conditions. "According to recent estimates by the World Health Organization, up to 1.6 million women and children die every year from breathing polluted air in their homes." Respiratory and vision problems occur in mostly women and children because they spend significant time indoors tending to cooking fires.
Another critique with traditional wood fires is the inefficiency in fuel consumption. Traditional wood fires are very efficient at turning wood into energy. However, traditional wood fires are inefficient at transferring the released energy into the cooking vessel. Most of the released energy in the wood is wasted heating the surrounding air rather than heating the cooking vessel. The inefficient transfer of energy requires the user to use more wood fuel, increasing the amount of wood harvested from the surrounding environment. The increased demand for wood can further deplete the already stressed local natural environment.
The third critique of traditional wood fires is childhood burns. "Burns are quite common in homes using fire and can be fatal or horribly disfiguring."Children can easily fall into the fire because traditional wood fires are located on the floor. Burns disfigure and scar their victim and the experience can be very painful for the child.
References and notes[edit | edit source]
- Innovation from Constraint (the extended dance mix), Ethan Zuckerman, 10 Nov 2008.
- Foley, G., P. Moss, and L. Timberlake. 1984. Stoves and Trees: how much wood would a woodstove save if a woodstove could save wood?. London and Washington D.C.: Earthscan. This publication addresses the very political nature of improved stove programs. The book informs the reader of: domestic fuels, current and past stove programs, and why improved stove programs should be used. The main advantage of this publication is the focus on stove programs success and failures and the books ability to refer to African societies past experiences with improved stove design. The books main disadvantage is the lack of any design or construction ideas for rocket stove design. Sections are included that refer to measuring efficiency and testing performance.
- Bryden, Mark., Dean Still., Damon Ogle., and Nordica MacCarty. 2001. Designing Improved Wood Burning Heating Stoves. Creswell, OR: Aprovecho Research Center.
- Barnes, D.F., K. Openshaw., K.R. Smith., and R.V. Plas. What Makes People Cook with Improved Biomass Stoves? World Bank Technical Paper No. 242. Energy Series. Washington, D.C.: World Bank. This publication from the World Bank gives a comparison of stove programs throughout the third world. The paper gives an overview of the general lessons from stove programs: consumer preferences, stove design, role of government and donor agencies and the role of subsidies. The paper presents the role of politics in improved stove programs; considerable information regarding the emergence of government based stove programs is included in the paper. Advantages of included the stove market and consumer preferences section. This topic was not specificity addressed in any other publication. The main disadvantage of this publication is the role to the publisher. The World Bank has provided this paper with good intentions that must be questioned.
- Witt, Mark., Kristina Weyer., David Manning. 2006. Designing a Clean Burning, High Efficiency, Dung Burning Stove: Lessons in cooking with cow patties. Creswell, OR: Aprovecho Research Center.