Rocket stove biomass charcoal: Difference between revisions

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• The dominant cooking method in many ‘developing’ countries is using wood or charcoal over an open fire. Cooking is often done indoors and by women. This situation has caused significant health issues among woman and children who breath in the smoke, with respiratory illnesses being a leading cause of death. Children also often burn themselves accidentally on the open fires. This method of cooking is inefficient in terms of how much fuel is used to how much food is cooked. The demand for wood fuel further exacerbates the already incredible stressed natural resources, leading to more and more deforestation and placing more and more burdens on women who need to search and collect the fuel. The need for fuel efficient cooking and water boiling systems in third world countries is in extreme demand. This project focuses specifically on Haiti, where only about 1-2% of the original forest cover remains, with more trees being cut down each year. The limited availability of wood means that finding gathering fuel consumes time and energy, causes more severe weather, increases vulnerability, reducing capacity,costs money and further stresses an already depleted resource. Through the use of agricultural waste from main export crops such as sugar cane, coffee, rice, and beans, charcoal can be produced and used as efficient high powered fuel for rocket stoves. Haitian's are in need of alternatives to using wood as fuel for general cooking. The efficient alternative fuel source lies in the biomass produced post-harvest of many main cash crops local to Haiti. After a simple and inexpensive method to form briquettes from the burned biomass charcoal, Haitian's will be able to continue supplying themselves with material to heat and cook without deteriorating natural resources.
• Mitch Girard and Hoon Peerless will be working in conjunction to research, design, test, and report on the use of biomass waste charcoal briquettes for rocket stoves in Engineering 305 at Humboldt State University, during Spring Semester 2010. We will be seeking knowledge of biomass material type, binding agents, and charcoal press mechanisms. Outside resources will likely include, faculty of HSU, recent HSU engineering graduates, Aprovecho Research Center, and affiliates that are currently located in Haiti working on appropriate technology for local populations. The goal of the project is to supply biomass energy knowledge to the Haitian community to motivate the decrease in use of wood for stove fuel, help increase indoor air quality through improved ventilation cooking systems, and reduce the dependence on three rock stoves.

Literature review

This is a review of the available literature pertinent to the Rocket stove biomass charcoal project.

Theory of Stove design

• The Main technical objectives of stove design are to: 

1. Maximize the efficiency of the fuel combustion process

1. Transfer heat from the source to the food at the required rate as efficiently as possible. [1]

Intro to Charcoal Stoves

• Even though traditional charcoal stoves are usually more efficient than traditional woodstoves, 60% to 80% of the energy is lost in the process of converting wood to charcoal. Because of lower transport, handling and storage costs per unit of energy, charcoal has many adavantages economically over wood. It burns cleaner producing less smoke and demands less tending to maintain a constant heat output. [1]
• design guidelines for charcoal stoves differ from those  for wood stoves due to:

1. the fuel contains more energy per unit of volume and can be packed tightly

1. most of the heat transfer is from the charcoal bed rather than from moving flames
2. the fuel only needs to be tended every half hour, or longer, rather than every 3-10 minutes with wood stoves
3. there is usually no or little smoke from a charcoal fire, so chimneys are not necessary [1]

• Charcoal stoves are lightweight, portable, have one fire per pot, and have no chimney. Design improvements to increase cooking performance center on changes to the stove body surrounding the firebox. [1]

Basic design components [1]

• Primary air entrance
• Grate
• Combustion chamber
• Pot Seat
• Pot Shields
• Stove Body 

===Stove Testing=== 

• Tests to reveal quantitative and qualitative information about concerning the performance of the stove and /or fuel will embrace the following:

1. The amount of fuel required to cook a given amount of food

1. The thermal efficiency (or Percentage Heat Utilized -PHU) for different rates of boiling water
2. The range of power output (also expressed as ’turn down ratio’
3. The ease of operation
4. Level of pollution
5. Maintenance requirements [1]

• These characteristics will be tested through several water boiling and cooking tests

Charcoal production

Agricultural Waste Materials

When measured in terms of their weight, energy content or nutrient value, agricultural wastes/residues are a vital component in the rural agricultural system. They are a major resource, although patterns of production and use differ widely among different countries and agricultural systems[3]

Possible agricultural waste materials to make charcoal with:

• sugarcane bagasse
• corn cob
• sawdust
• coffee husk
• coconut shell
• Bamboo
• groundnut shell
• rice husk

Access and Availability

• Availability of Agr.wastes depends on production as well as social and economic factors *Access is influenced by land ownership and status
• Seasonality of supply is an important [3]
• Consideration for some storage facilities must be given in order to allow a year-round operation/supply [4]

Environmental Concerns

• The two main concerns with charcoal production are deforestation and intensive cultivation of mono-cultures and environmental issues in connection with carbonization (I.e. smoke, heat and byproducts)[2]

Charcoal Briquetting

1. Four major steps:

1. Preparation of charcoal fines
2. Mixing the charcoal fines with a binder
3. Briquetting of the mixture
4. Drying of the briquettes [2]

Binders

• Binders are needed when the pressure produced by the compacting equipment is too low for ‘self-bonding’ or when materials are compacted that do not self-bondsuch as straw, rice, husk and charcoal. Commonly used binding agents include starches from corn, wheat, cassava (manioc), sugar cane molasses, tars, pitch, resins, glues, fibre, fish waste and certain plants like algae[2]
• The effect of adding a bonding agent is to enhance cohesion and reduce pressure requierments. Binders hold components by both mechanical and chemical adhesion, and occurs when the binder molecules adhere to specific points in the molecular structure of the adherent [4]
• Cassava, a tropical root crop often used as a binding agent, is quite robust nad can be grown in infertile soil. It also has unique properties such as its high viscosity and reisitance to freezing [4]

Data

Data to be gathered

• Compaction ratio
• Firmness of the Briquettes
• Utilized Heat [4]

===Project Objectives=== 

• Our objectives are to develop an efficient and production type of briquetting machine made from locally available materials; test different agr. waste materials; test the performance of the machine in terms of compaction ratio, evaluate the firmness of the briquettes, and calculate their heat value [4]

References

1. Books

1. Stewart,Bill. Improved Wood, Waste and Charcoal Burning Stoves. London: IT

      Publications, 1987. 

1. Barnard,Geoffrey and Lars Kristoferson. Agricultural Residues as Fuel in the Third World. Technical Report

      No.4. London: IIED, 1985. 

1. Kristoferson, L.A. and V. Bokalders. Renewable Energy Technologies. Oxford: Pergamon, 1986. 

2. Journal

1. Martin, Jorelyn, Razel Mae Pineda, Johnyver Manaay, Sugar Ray Handa and Arnulfo Ocreto. "Design

      and      development of charcoal briquetting machine." USM R&D 16 no. 2 (2008): 85-90.

Literature Used for Project

Books

• Barnes, Douglas F. 1994. What makes People Cook with Improved Biomass Stoves?

a comparative international review of stove programs. Washington D.C.: World Bank. This book shows fuel and stove combination's from all over the world and goes into detail over efficiency and effects.

• Foley, Gerald. 1986 Charcoal making in developing countries.

London: Earthscan, International Institute for Environment and Development. Though partially outdated, this book focuses mainly on the fuel type and the production process that the fuel undergoes.

• Stewart, Bill. 1987. Improved wood, waste, and charcoal burning stoves: a practitioners manual.

London: Intermediate Technology Publications. Mid 80's structural improvements to stove designs that allow for more efficient use of all fuel types, including biomass charcoal.

Journals

• Antal, Michael J., Eric Croiset, Xiangfeng Dai. High Yield Biomass Charcoal.

Energy Fuels 10(3). 652-658 Advances in the production aspect of high efficiency biomass charcoal, including reaction times decreases and quicker production.

• Bhattacharya, S.C., D.O. Albina, Aung Myint Khaing.

Effects of selected parameters on performance and emissions of biomass-fired cookstoves. Biomass and Bioenergy 23(5). 387-395 Moisture content, fuel size, pot size, and method of ignition are all compared with the use of three different stove types to determine efficiency.