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CLOSE THIS BOOKOne Hundred and One Technologies - From the South for the South (IDRC, 1992, 231 p.)
VIEW THE DOCUMENT42. Iguana farming for food and tropical forest preservation
VIEW THE DOCUMENT43. Industrial waste exchange system
VIEW THE DOCUMENT44. Recycled plastic sheets for greenhouses
VIEW THE DOCUMENT45. Electronic networking for african environmental ngos
VIEW THE DOCUMENT46. Costa rica’s new national account system for the environment

One Hundred and One Technologies - From the South for the South (IDRC, 1992, 231 p.)


42. Iguana farming for food and tropical forest preservation

The green iguana (Iguana iguana), indigenous throughout Central America, has been traditionally used as a source of food by Latin American farmers who refer to the tasty reptile as “chicken of the tree” (gallina de palo). Unfortunately, over hunting of their eggs and meat and the destruction of their tropical forest habitat has caused a sharp decrease in the iguana population. They are classified as endangered in some countries and are extinct in others.

Iguana image

The Fundacin Pro Iguana Verde (FPIV) in Costa Rica is implementing a program for the conservation of green iguanas by successfully breeding and raising them in captivity for reintroduction into natural areas. Iguana farming offers an alternative source of food for local consumption and can increase the income of farmers with secondary production activities using skins and other products, such as fat and eggs for medicinal purposes.

The green iguana is the only iguana that lives and feeds on trees. Iguana farming offers an economic alternative to cattle ranching while protecting the natural habitat of the iguana - the tropical forest. Iguana management is designed to be one component of other productive activities in Latin American farming systems. It provides incentives for reforestation, which in turn counteracts erosion, conserves water resources, and enhances soil fertility.

The key elements of iguana farming are reproduction in captivity, controlled incubation, and raising hatchlings in captivity. Once the hatchlings are 7 months old they are released into forested areas on farms, where they grow to harvestable size in two additional years. It is estimated that iguanas can yield as much protein per unit area as cattle. Essential components of iguana farming are the restoration and protection of the tropical forests for food and habitat.

To create the farms, enclosures are constructed with sheet-metal walls sunk 30 cm into the ground. Inside, the animals sleep in shelters made of bamboo and vegetation. Each shelter has an adjustable entrance slit through which young lizards can slither, but predators, which are usually larger, cannot. Most are set on stilts and food is served in the shade underneath. With this system, 20 to 60 young iguanas are kept in an area of 10 ma (0.5-0.17 m² per individual). In another “high density” design, 30 hatchlings are kept in cages 1 m² (only 0.05 m² per animal). The iguana farms also include an artificial nest consisting of a “tunnel” leading to a sand-filled egg-laying chamber. Both tunnel and chamber are made of predator-safe material and are easily accessible by the farmer.

Artificial nests increase the number of hatched eggs and their survival rate to 90%, versus 50% in the wild. Using food supplements (iguana chow) it is estimated that the population can be maintained at 6 to 10 times the level possible in a rainforest, or around 50 adult iguanas per hectare. Iguana chow is a mixture of broken rice meal, meat meal, bone meal, fish meal, papayas, mangos, bananas, avocados, and a variety of leaves and flowers. Smallholders can erect simple feeding stations and keep them stocked with table scraps or weedy vegetation. This makes for very low-cost production before the iguanas reach harvesting size.

Presently work is being carried out to study existing legislation, land use, natural resource management policies, and socioeconomic settings in target areas in Costa Rica, Panama, and Guatemala. The goal is to establish optimal conditions for sustainable production and marketing of the green iguana to benefit the small farmer.

Cost and availability

The main investment is the cost of the enclosures. The cost of raising the iguanas to usable size entirely in captivity is too high to be profitable. Releasing the iguanas at 6-10 months into forests, farmland with scattered trees, or into village backyards considerably reduces costs. The economic feasibility of iguana management will vary according to social and environmental circumstances.

FPIV will establish collaborative projects for the transfer of technology providing that environmentally beneficial conditions are met. A farming manual will be made available to collaborators .

Farmers living

Potential users

Farmers living close to tropical forest areas from Mexico to northern Brazil and Peru, including a number of Caribbean islands. Small patches of remnant forest encountered on farms and buffer zones surrounding protected parks provide adequate habitat.


Dr Dagmar I. Werner
Fundacin Pro Iguana Verde
Apartado 692-1007
San Jose, Costa Rica
Tel.: (506)40-6712
Fax: (506)35-2007

Resources and Publications

· Stoney, C. The day of the Iguana. VITA NEWS, October 1987, p. 3-8. (a short description of the Iguana Management Project in Panama, sponsored by the Smithsonian Tropical Research Institute).

· Microlivestock. Little-Known Small Animals with a Promising Economic Future. BOSTID and NRC, Chapter 33, p. 347-353. National Academic Press, Washington, DC, 1991.

· Werner, D.I., and Rey, D.I., El Manejo de la Iguana Verde; Tomo I: Biologa. Fundacin Pro Iguana Verde and Instituto de Investigaciones Tropicales Smithsonian, Panama. 42 pp.

43. Industrial waste exchange system

In the Philippines, pollution problems are compounded by the fact that most pollution control equipment and methods are too costly for the Philippine economy. Disposal of industrial wastes is becoming a major concern. As an alternative to costly and environmentally unsound disposal schemes, the Environmental Management Bureau of the Department of Environment and Natural Resources, with assistance from the Geotechnical Research Centre of McGill University in Canada, has developed an industrial waste recycling system, based on reusing the wastes in-house or transfering them to another industry. The idea is to use production residues that are in fact raw materials in the wrong place.

The project, called Industrial Waste Exchange - Philippines (IWEP), provides a contact point between industries that want to exchange materials. It is also an information centre providing lists of companies, as well as technical information and assistance on waste management. Project staff will also collect and analyze waste samples when a company is unable to do so in-house.

The system works through a directory of available and wanted materials, that is published twice a year. The entries are coded for confidentiality, and classified into the following categories: acids, alkalis, solvents, plastics and rubber, metals and metal sludges, wood and paper, other inorganic chemicals, other organic chemicals, oils and waxes, textiles and leather, and miscellaneous. Each material listed has a location code, a company code, and technical specifications such as its physical state, pH, colour, contaminants, etc.

Companies can fill out a listing form, free of charge, to be included in the directory. Although IWEP will put two companies in touch with each other, all agreements are negotiated directly between the generator and the potential user of the waste. In 1989, some 40 negotiations were underway in the Philippines.

Some examples of exchanges include:

· Using calcium carbide sludge as a neutralizing agent in wastewater treatment plants;
· Using pineapple pulp waste for cattle fattening;
· Using waste shrimp heads as an animal feed component;
· Using gypsum waste for wall boards and for cement production.

Two conferences on waste exchange were organized in 1988 and 1989, bringing together government and industry. The purpose was to explain the system, introduce new technologies in waste recycling, provide information on waste exchange and utilization, and encourage participation. The conferences were seen as essential elements in the success of the system.

The system has the potential to reduce environmental pollution, improve the economy through the recovery of usable resources, and reduce disposal costs as well as the costs of raw materials.

Potential users

Environmental ministries and organizations. Industries of all kinds can benefit from the system.

Industries of all kinds can benefit from the system


Industrial Waste Exchange - Philippines
Environmental Management Bureau
6th Floor, Philippines Heart Centre Building
East Avenue, Diliman, Quezon City
3008 Metro Manila, The Philippines
Tel.: 980421 loc. 2601/2632/2653; 975609/975698
Telex: 2507 NEPC PU; Cable: ENVIRON MANILA

Raymond Yong
Geotechnical Research Centre, McGill University
817 Sherbrooke St West
Montreal, Quebec, Canada H3A 2K6
Tel.: (514) 398-6672; Fax: (514) 398-7361;
Telex: 05-268510

44. Recycled plastic sheets for greenhouses

In the past two decades, the use of polyethylene (plastic) films for greenhouses and for mulch has increased dramatically in the Third World. Between 1967 and 1987 in Jordan, for example, the use of plastics for greenhouses doubled every 2 years, then doubled every 3 or 4 years. Jordan began producing its own plastic films, but this entails importing plastic pellets to make the sheets. As well, the sheets are now causing a major environmental problem regarding their disposal: lasting only 1-1.5 years, they are then either discarded in neighbouring land or burned. Discarded plastic has been responsible for the deaths of cattle who have ingested it while grazing.

Researchers in Jordan have now developed a process to recycle used plastic sheets in the production of comparable quality, less expensive films for mulch and greenhouses. The new process will lower costs for farmers, decrease pollution from plastics, and reduce imports. As well, it has the potential to increase employment, both in production plants and in the collection of the waste plastic.

The process used is called coextrusion, which allows for the combining of layers of different materials to create a stronger and more resistant plastic. The new recycled plastic film is made up of two layers: a highly stable upper layer made from virgin plastic, and a bottom layer made from recycled plastic. In Jordan, used plastic sheets are readily available for recycling, reducing the need for imported plastic. It is estimated that a reduction of 20 to 50% in material costs occurs when using recycled plastic. The new sheets contain up to 50% recycled plastic, and have properties similar or better than virgin plastic films.


Access to used greenhouse plastic films. The production plant requires a coextrusion machine, a fairly expensive item (US $240 000 to $400 000), 620 Kwh of electrical power, and 25 m of water to clean each tonne of used plastic. To save on water costs a closed system is recommended with a water recycling plant. The plant employs 10 people: two operators, two assistants and six labourers.

Potential users

There are plans to disseminate the technology to small and medium-sized plastic film producers in Jordan, Syria, Iraq, Turkey and Egypt. Currently the technology is being used in Jordan and Egypt, where it is being adapted to local materials and conditions. Researchers in Egypt are investigating as well the potential for using polyvinyl chloride (PVC) instead of polyethylene, which could reduce costs by as much as 45%.

Cost and availability

Raw materials (used films) cost about US $57 per tonne in Jordan. Total production costs for making regenerated plastic pellets from the used sheets is US $215 per tonne. Actual production of the two-layered recycled sheets runs from US $960 to $1150 per tonne for materials (depending on the thickness of the different layers), with production costs (covering salaries, water and electricity) at $500 per tonne. The coextrusion machine is the most expensive item, ranging from US $240 000 to $400 000.


Mr H. Khadra
Royal Scientific Society
PO Box 6945, Amman, Jordan
Tel.: 844802 or 844702; Telex: 21276 JO

Professor M.R. Kamal
McGill University
3480 University Street
Montreal, Quebec, Canada H3A 2A7
Tel.: (514) 392-5432; Telex: 05-268510

Professor A. Yehia
Polymer Department
National Research Centre
Tahrir Street, Dokki, Cairo, Egypt
Tel.: 701 211; Telex: 94022 NAREC UN

45. Electronic networking for african environmental ngos

Many obstacles exist in Africa which hamper the effective inter-communication of nongovernmental organizations (NGOs). This in turn prevents African NGOs from providing effective input as a group to international consultations such as the United Nations Conference on Environment and Development that was held in Brazil in 1992.

Electronic communications have the potential to strengthen NGO networking by increasing their capacity to exchange mail, discuss issues, and share information rapidly and at lower cost than through mail, fax, telex, and phone calls. The poor quality of voice telephone lines, the slow implementation of phone systems with packet switching, and fluctuations in the availability of electricity have all caused Africa to lag behind Asia and Latin America in electronic communication. As well, governments may not be supportive, seeing computers and modems as a security problem or as a source of revenue through high import duties and fees.

The Environment Liaison Centre International (ELCI), in Nairobi, has become a focal point of a networking project that will build on initiatives to develop a resilient, expandable, and directly interconnected NGO network in Africa. Through the use of microcomputers, modems, and common communications software, the network has, among other things, strengthened NGO capacity for information-sharing and advocacy work, and given NGOs access to new information, including documents and inputs of the preparatory meetings leading up to the UNCED Brazil 92 conference.

Participating institutions share responsibility for the risks and investments of the network. The aim is to develop self-sustaining networking nodes at the national level in several countries, which are linked to regional as well as international networks.

The African network was begun by creating or strengthening electronic links among organizations in Dakar, Harare, Nairobi, and Tunis, which can then be linked through the UK-based network GreenNet to NGOs around the world. In each of these cities, independent but interconnected low-cost DOS-based bulletin boards can be accessed by the NGO “end-users” participating in the network. These bulletin boards need only a small user base to be cost-effective, and they run on regular telephone voice lines.

Modems and software have been provided to some 40 users, along with training and online support. The network hopes to expand by building the capacity in end-users and operators to train new users. A short course and installation manual for the bulletin boards have been developed in English; French and Arabic versions are planned. Half-day workshops and users’ manuals have also been developed for the end-users of the network. Each user is expected to pay their telephone costs.


To participate in this or similar networks, an organization needs a microcomputer, a modem, a telephone line that works at least part of the time, and appropriate communications software. The small bulletin boards require an IBM-compatible computer with the DOS operating system, 40 to 100 Mbytes of hard disk space, and one telephone line, as well as the services of a part-time systems operator.

Potential users

African NGOs, particularly those involved in environmental work. The network could serve as a model for establishing other networks in Africa or elsewhere.


The Director, Environment Liaison Centre International PO Box 72461, Nairobi, Kenya Tel.: 254(2) 662015; Cable: ENVICENTRE Telex: 23240 ELC KE Fax: 254 (2) 562175 E-mail: FIDONET: 5:731/1 APC: GN:ELCIDWR

46. Costa rica’s new national account system for the environment

The current increase in environmental awareness is highlighting the deficiencies in the United Nations System of National Accounting (SNA), which overemphasizes consumption in national output and fails to account for the environment in income estimation. Conventional national income figures record only the consumption value of natural resources and do not account for losses of natural capital such as standing timber or fish stocks.

The ongoing destruction of forest, soils, and water - basic resources of the country’s economy is a loss in the productive value of the economy which is not reflected in national accounts. For instance, when a forest is cut down and sold, the country appears to grow richer, even though the depreciation of the natural capital - both in regard to the forest and the increased erosion of farmland - may create future losses several times greater than the present gain. The result is that, in the existing system, those responsible for economic policies make decisions based on inadequate information. It is therefore urgent that current national accounting procedures be revised.

Costa Rica’s agricultural product before and after natural resource depletion.

An IDRC-supported study by the Tropical Science Center of Costa Rica and the World Resources Institute of the United States, had as its main objectives to:

· Analyze a number of Costa Rica’s natural resources in physical terms and assign them an economic value;

· Treat natural resource assets consistently with other tangible capital so that resource depletion is treated as capital consumption.

The first step in the study was to develop physical resource accounts for each sector based on available data. These accounts were designed to record and identify the sources of either an increase in or depletion of the stock. The second step was to assign economic values to the resources using appropriate economic evaluation principles which allowed for the availability or unavailability of data. The physical accounts and economic values were then combined and aggregated to the national level. Finally, the completed natural resource accounts were used to adjust the conventional national income aggregates to arrive at a net, rather than a gross, national product. For example, the results of the study estimate that, when resource depletion is taken into account, the net national product in the fisheries sector between 1982 and 1987 was on average 51% of gross national product. In 1987, it was only 37%.

The Costa Rican natural resource accounting study represents a substantial advance over previous efforts. New techniques, such as remote sensing and satellite imaging, were used to estimate changes in forest cover, mangrove area, and other land uses. Both the data and analysis of the physical accounts were detailed and systematic. The economic analysis also represents a significant methodological advance, in that it used new bioeconomic models for fisheries accounts and assigned consumptive versus nonconsumptive use values for mangrove accounts.

The results confirmed that the national accounting system in Costa Rica is inadequate in its treatment of natural resources. The lack of knowledge within both the private and public sectors of the many secondary values of natural resources results in the wasteful destruction of important environmental assets. The methodology developed in this study can be used to confront economic development issues realistically.

These studies can be performed at the national or regional level, provided that basic information on economic parameters is available. As well, sectoral studies can be carried out to integrate environmental and economic policies.

Cost and availability

The developed methods to incorporate the depreciation and appreciation of natural resources in national accounts can be transferred and applied in other countries. Both the Tropical Science Center of Costa Rica and the World Resources Institute will provide technical support to interested groups. The collaboration of relevant government agencies is essential.

Potential users

Direct beneficiaries are planners, economists, and policy-makers in all sectors of government and industry. In addition, this demonstration, along with WRI’s earlier case study for Indonesia, will help build support among other governments in the region, international agencies, and other official bodies for a much-needed reform of the SNA.


Dr Ral Soldrzano Tropical Science Center Apartado 8-3870, San Jos, Costa Rica Tel.: (506) 25-26-49; Cable: SCIENCE

Resources and Publications

· Solrzano, R., de Camino, R., Woodward, R., Tosi, J., Watson, V., Vsquez, A., Villalobos, C., Jimnez, J., Repetto, R. and Cruz, W. 1991. Accounts Overdue: Natural Resource Depreciation in Costa Rica. Tropical Science Centre, San Jos, Costa Rica and World Resources Institute, Washington, DC, USA.

· Repetto, R., Magrath, W., Wells, M., Beer, C., and Rossini, F. 1989. Wasting Assets: National Resources in the National Income Accounts. World Resources Institute, Washington, DC.

· Wealth of Nature. The Economist, January 18th, 1992, 67 pp.