A rocket stove is a type of improved biomass stove. Improved stoves reduce the demand for biomass fuel and improve living conditions for populations who currently use three rock fires.
Widespread use of modern energy sources such as electricity and petroleum has been slow to develop in third world nations due to their large population and the limited resources and investments. The bleak outlook for modern energy systems, means that third world populations will remain dependent for some time on biomass fuels. Technical advances in energy efficiency are crucial for developing countries, especially for the many countries whose populations depend primarily on biomass fuels such as wood, charcoal, and agricultural residues. Understanding traditional cooking methods can then help you understand why improved stoves are an improvement. Most traditional cooking fires consists of three large rocks or bricks surrounding a open fire. The rocks are used to support a cooking vessel above the fire. These three rock fires may have benefits not found on improved stoves such as, space heating, protection from insects, and the flexibility to use a wide variety of fuels in different seasons. Domestic lighting is one of the important uses of three rock fires, a function that the improved/rocket stove cannot perform. If the other functions of the three rock fire are not replicated on its replacement then the improved stove is not being judged fully and evaluated.
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. Traditional three rock fires pose major obstacles to the environmental, 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. Repertory and vision problems occur in mostly women and children who spend significant time indoors tending to cooking indoors.
Another concern with traditional wood fires is the inefficiency in fuel consumption. Traditional wood fires are very efficient and 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. Because traditional wood fires are located on the floor of the dwelling, children can easily fall into the fire burning themselves. Burns disfigure and scar their victim and the experience can be very painful for both the child and family.
The main justifications for improved stoves are economical, social, and environmental. Stove programs can produce economic benefits. The stove save time and money for the users. In urban areas were people purchase biomass fuel the payback time for the cost of a improved stove is short, thus providing extra cash from purchasing less fuel.
Rocket stoves can help moderate the environmental externalities of the over harvesting of trees. Improved indoor air quality and fuel efficiency have social and health benefits, especially for women and children. In order to reduce indoor air pollution improved stoves must improve combustion of the wood fuel. Improving combustion reduces the amount of smoke and harmful emissions produced during the burning process. The key to having a efficient combustion is to burn wood at a high temperature. Several methods can be used to increases the temperature of the fire. Having a good air draft into the fire is essential to increasing combustion temperature. Insulation around the fire can help the fire to burn hotter. The most important factor in improving combustion is metering the fuel. Metering the fuel allows only the burning portion of the wood to be heated. Fully burned biomass fuel produces less smoke and emissions. In order to improve the fuel efficiency of rocket stoves you must improve the heat transfer from the fire to the cooking vessel. The crucial factor is having the hot air and gas released from the fire, contact the cooking vessel in the largest possible surface area. This is accomplished through the use of a pot skirt that creates a narrow channel forcing hot air and gas to scrape along the bottom and sides of the cooking vessel. Increasing heat transfer can also be accomplished through the use of wide pots.
Increasing the speed of the hot gases that scrape against the pot can improve heat transfer. Improved stoves are insulated and lifted off of the floor. The inability for children to burn themselves is a important improvement over traditional three rock fires. The major obstacles to the success of improved fuel stoves in rural areas is freely available biomass resources leads people to continue to rely on biomass for cooking. Stoves are not used because fuel is not purchased or fuel is easy to collect.Stove programs must be conduced in areas that have a need for improved stoves.
Ease of use is a major concern where stoves require fuel wood to be cut into small pieces. Stove users that have neither the time nor the tools to cut the wood into sizes, may result in the improved stove going unused. The high price of the improved stoves can be a fordable barrier to their adoption.
Stove programs have a better chance of success in urban areas where people buy both the fuel and the stove. Programs in rural areas succeed where fuel wood has already been harvested and people are spending extended periods of time gathering fuel. Rocket stoves that have a quick payback period generally are more likely to be adopted in poorer rural areas.
Testing is essential is rocket stove projects. Testing should happen during the entire life of a stove project. Testing stoves helps determine if the model is marketable, whether production costs are as low as possible and if improvements are needed.
Technical advances in energy efficiency alone will not ensure success, stove programs must be complemented by appropriate project design, implementation and proper institutional support. With our proper testing stove programs can have unrealistic expectation of the efficiency of improved stoves. Stove programs can over estimated the efficiency of improved stoves when tested in a controlled lab setting. Improved stoves never do as good in real households.
Many stove programs controlled lab settings achieved a 75 present reduction in fuel consumption using improved stoves. After examination of early stove programs expectations of the efficiency of stoves has been revised. The respect for indigenous culture is important in the improved stove design. Feedback and a two way interaction should be designed in any improved stove program.
Stoves need to be adapted to each region around the world. The different styles of cooking in various countries dictate different stove designs. Improved stoves are most successful were local knowledge and customs are taking into account. Stove programs do best in areas where people have an unequivocal need to save fuel and the improved stoves can be produced cheaply by local industries or artisans.
Population around the world are going to continue to use biomass fuel for the indefinite future. The use of improved stoves can help control the external costs to both the environment and human society. Fuel savings may not be the driving factor in the adaptation of improved stoves. Improved stove work because they make cooking quicker, safer, and cleaner. Improved stoves protect children from the dangers of burns from the open fire, reduce respiratory diseases, and burn clean and free of soot.
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