Saturday, March 30, 2013

March 28: Important Considerations for "3 Best Ideas"


IMPORTANT CONSIDERATIONS for "3 Best Ideas"

1. The Shape of the Community: Sabana Grande, Nicaragua
  • Approx. 5 collections of houses, 20-30 individuals in each
  • Collections of houses also tend to be near water wells (pozos), general stores (pulperias), and mills (molinos)


2. The Typical Nicaraguan Diet (from http://grupofenix.org/courses/course-handbook/)
  • gallo pinto, a mixture of red beans and rice fried in veg oil
  • corn tortillas
  • cabbage salad
  • locally made salty cheese
  • meat or chicken

3. The Types of Biogas Digesters
  1. The Indian biogas digester (expandable cylinder or dome. The dome is made of sheet metal-- it moves up and down. The base is made with bricks and cement.

  1. The Chinese model (permanent structure. Appears more shallow)

  1. Sri Lankan model (Seems more extensive, like it might require more equipment to build)

4. The Standard Design Plan for a Homestead with a Biogas Digester...


5. The Composition of the Raw Material and Implications for Digester Model
  • Plant solids do not flow through pipes. Plant solid as the raw material fits best with a 'single batch digester.' In these digesters, the tank is opened between each batch of plant material. The plant material is removed and can be used as fertilizer; fresh plant matter is added
  • "Most vegetable matter has a much higher carbon - nitrogen ratio than dung has, so some nitrogen producers (preferably organic) must generally be added to the vegetable matter, especially when batch digestion is used. Weight for weight, however, vegetable matter produces about eight times as much biogas as manure, so the quantity required is much smaller for the same biogas production. A mixture of dung and vegetable matter is hence ideal in most ways, with a majority of vegetable matter to provide the biogas and the valuable methane contained in it." (-http://www.habmigern2003.info/biogas/methane-digester.html)




Thursday, March 28, 2013

http://engineeringforhumanitymonica.blogspot.com/

Notes from Today


Biodigestors

Different inputs: Rotten veggies (organic plant matter), or human waste.

Lack of cow and pig manure available

Existing biodigestor with cow and pig manure

concerns: access to plants... shouldn’t endanger food security (regional research-- what kinds of waste there is. What kinds of waste are most effective.)

We would like the design to be an affordable alternative to cooking with firewood.”

“The initial installation of the system should cost no more than US$200 and should use materials locally available. Fuel to be added to the biodiogester should be on a par of what is spent weekly in firewood consumption (approximately US$3) so that this can be a viable alternative.”


Questions: