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SUSTAINABLE ANAEROBIC DIGESTER/COOK STOVE DESIGN TO PROMOTE HEALTH, ENVIRONMENT, AND ECONOMIC PROSPERITY FOR INDIGENOUS PEOPLE OF ECUADOR

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http://cfpub.epa.gov/si/si_public_comments.cfm

Impact/Purpose:

The acquisition and use of biomass fuels for heating and cooking presents a ubiquitous problem for the majority of people on three continents. Inefficient cooking and heating practices (wood burns at 5–8% efficiency and cow dung at 60% of that of wood, which implies an open-fire efficiency of only 3–5% for dung) not only pollute the home but deplete biomass resources and require increasing amounts of time and energy for fuel acquisition. These factors challenge the sustainability of local and global environments as well as the health and economic prosperity of vast numbers of people in the developing world. Properly designed and used, an anaerobic digester (a process of converting organic wastes to methane) mitigates a wide spectrum of these environmental undesirables: it improves sanitation; it reduces greenhouse gas emissions; it reduces demand for wood and charcoal for cooking, it provides a sustainable source of high quality fertilizer for crop production, and helps preserve forested areas and natural vegetation. But for the developing world, biogas’s greatest benefit may be that it can help alleviate a very serious health problem: poor indoor air quality.

In response to these issues, we propose a holistic approach to design, develop, and implement an anaerobic digester with an integrated efficient burner system for three villages of indigenous Quechua people in the mountains of central Ecuador.

Description:

Phase I prototype digesters demonstrated the feasibility of biogas generation, using simple materials such as trash cans, oil drums, and polyethylene bags – a full scale digester, based on prototype biogas production volumes, range from 5000 to 9000 liters, depending on the design implemented (fixed drum or polybag). This digester volume is projected to meet the cooking needs of a typical Ecuadorian family of six, 2m3/day.

A plant growth room study was conducted from January through March 2009 to evaluate the effects of field application of the anaerobically digested manure. The study included a pasture grass mixture and potatoes. Pasture grass was planted at a rate of 3 seeds per pot in 15 cm diameter pots containing a 2500 g sand/ 150 g potting soil mixture. Potatoes were planted, one per pot, in 35 cm diameter pots containing a soil mixture of 11,330 grams sand and 880 grams potting soil. Soil mixtures were designed to simulate the low organic matter, nutrient-poor volcanic ash soils of Chimborazo, Ecuador. The study utilized a completely randomized experimental design with 12 pots, 3 biodigested manure application rates, and 4 replications of each biodigested manure application rate. Rates of applied anaerobically digested manure were equivalent to approximately 0, 1660, and 3320 kg /ha manure fresh weight application.

For both potatoes and grasses, plant heights were measured and recorded. The averages of the heights for each test group (control, low application, and high application) were recorded. The dry weights of plant material were also recorded to determine yield differences. There is a clear growth difference for potato applications, and there was also a 132% and 131% yield difference over control for low and high applications of digested sludge, respectively. The growth data for pasture grass showed no significant results, however yield data indicated a clear difference. There was a 51% difference between the control group and low application yields for pasture grasses, and an 80% difference between the control group and high application group yields. There is a community cost savings of $2.59 - $5.17 per acre ($6.40 - $12.78 per hectare).

URLs/Downloads:

Final Progress Report

Record Details:

Record Type:PROJECT( ABSTRACT )
Start Date:08/15/2008
Completion Date:08/14/2009
Record ID: 200984