VITA - Volunteers in Technical Assistance

Understanding Pedal Power - 1/01/1986

Over the centuries, the treadle has been the most common method of using the legs to produce power. Treadles are still common in the low-power range, especially for sewing machines. Historically, two treadles were used for some tasks, but even then the maximum output would have been quite small, perhaps only 0-15 percent of what an individual using pedal operated cranks can produce under optimum conditions.

However, the combination of pedals and cranks, which today seems an obvious way to produce power, was not used for that purpose until quite recently. It was almost 50 years after Karl von Krais invented the steerable foot-propelled bicycle in 1817 that Pierre Michaud added pedals and cranks, and started the enormous wave of enthusiasm for bicycling that has lasted to the present.

The main use of pedal power today is still for bicycling, at least in the high-power range (75 watts and above of mechanical power). In the lower-power range there are a number of uses of pedal power--for agriculture, construction, water pumping, and electrical generation--that seem to be potentially advantageous, at least when electrical or internal-combustion engine power is unavailable or very expensive.

Six Simple Pumps - 1/01/1983

Complete instructions for building each pump are included in the manual, with detailed drawings to guide construction. Operating and maintenance directions are also given. Efficiency comparisons enable the user to choose the best design for a particular situation.

Readers who may be using this manual as part of an irrigation or water supply project are urged to contact VITA for needed technical assistance. The decision making guide in Appendix I will help frame questions and focus project considerations. VITA can also provide technical. and management assistance to those who may be interested in manufacturing the pumps.

Home Soap Making - 1/01/1983

Soap is an essential cleaning agent, helping people to keep themselves and their surroundings clean. When soap is mixed with water, it forms a lather that washes out dirt and grease far better than water alone.

Soap can be made on a small scale in the home or village cheaply and easily. The main ingredients are fats and lye, both of which can be made from materials found throughout the world. Making soap at home is practical when there is waste fat or oil and when there is no cheap source of soap.

Biogas Systems In India - 1/01/1983

This study is an assessment of the "appropriateness" of biogas technology in meeting some of the needs of India's rural population. Such an assessment is quite complicated, despite claims that a biogas system is a simple village-level technology. While there is evidence that biogas systems have great promise, they are subject to certain constraints. It is impossible to describe here all the factors that one might study to assess any technology. I only hope that the approach used in this study will help others.

3-Cubic Meter Biogas Plant - 1/01/1980

A biogas digester is the apparatus used to control anaerobic decomposition. In general, it consists of a sealed tank or pit that holds the organic material, and some means to collect the gases that are produced.

Many different shapes and styles of biogas plants have been experimented with: horizontal, vertical, cylindrical, cubic, and dome shaped. One design that has won much popularity, for reliable performance in many different countries is presented here. It is the Indian cylindrical pit design. In 1979 there were 50,000 such plants in use in India alone, 25,000 in Korea, and many more in Japan, the Philippines, Pakistan, Africa, and Latin America. There are two basic parts to the design: a tank that holds the slurry (a mixture of manure and water); and a gas cap or drum on the tank to capture the gas released from the slurry. To get these parts to do their jobs, of course, requires provision for mixing the slurry, piping off the gas, drying the effluent, etc.

In addition to the production of fuel and fertilizer, a digester becomes the receptacle for animal, human, and organic wastes. This removes from the environment possible breeding grounds for rodents, insects, and toxic bacteria, thereby producing a healthier environment in which to live.

Understanding Biogas Generation - 1/01/1984

Biogas generation is a process that takes place in an oxygen-free environment. It uses anaerobic bacteria--bacteria that live only in the absence of oxygen--to break down complex organic compounds in fairly well-defined stages. The process is called anaerobic digestion. It produces biogas, a gas composed of approximately 50 to 60 percent methane, 40 to 50 percent carbon dioxide, as well as water vapor and a small quantity of nitrogen, sulfur, and other trace compounds. Biogas is flammable, which is what makes it useful, but it has a relatively low heat content, approximately 6.1 Calories per liter (around 600 BTU per cubic foot). Compare this with pure methane, which has a heat value of 995 BTU per cubic foot, or natural gas with over 1,000. Nevertheless, biogas can be an important fuel source for many applications.

Comparing Simple Charcoal Production Technologies For The Caribbean - 1/01/1984

The objectives of the project were to:

1. substitute local renewable fuel for imported fuel, 2. use the forest resource wisely, and 3. create local industry and employment.

More specifically for the charcoal portion of the project, we wanted to find the best charcoal production techniques in terms of efficiency, economics, and acceptability. An efficient technique would produce the greatest quantity of good quality charcoal from the smallest amount of wood and labor input. But it would have to be economical as well. And regardless of efficiency or economics, to make an impact the technique would have to be acceptable to the charcoal producers.

Comparing Charcoal And Wood-Burning Cookstoves In The Caribbean - 1/01/1980

The objectives of the Montserrat Fuelwood/Charcoal/Cookstove Project were to:

1. Substitute local renewable cooking fuel from the forest for imported liquid fuels,
2. Use the forest resource wisely, and
3. Create local industry and employment.

Specifically for the cookstove portion of the project, all three objectives would be enhanced by identifying and testing techniques for efficiently using charcoal and wood fuel for cooking.

Making Charcoal: The Retort Method - 1/01/1980

The retort is one of the most efficient means of producing good quality charcoal. Wood is placed in a large steel cylinder (or "retort"). This has a tightly closed door, and some means to let tar and gases escape. The cylinder is heated from the outside. No air enters the barrel. When the wood in the cylinder has been heated to the right temperature, a chemical reaction (called carbonization) begins that gives off heat and by-products. Little additional outside heat is necessary.

Crafts And Village Industry: Pottery - Waste Oil Fired Kiln - 1/01/1988

Ceramic kilns that burn waste oil from automobiles and other industries have been operating in Tanzania, Haiti, and several other developing countries for several years. These kilns offer the advantages of good operational control that is easily achieved with fuel oil, but lower fuel cost because waste oil is used.