Haiti Orphan Schoold electricity

Digester design and construction info

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Haiti Orphan Schoold electricity

Postby haitischool » Sun May 11, 2008 5:29 pm

I want to provide electricity for an Orphan School that currently only has tin roof lentos for cover from storms. The school is 250 orphans’ grades 1 to 8. I am designing the school to have 10 class rooms, an office, and dorms with beds for 100 children, a kitchen with washing machines and a couple regular refrigerators. I am in the conceptual phase writing the description and plan for the project so I can solicit donations from various groups. The village is in the center of Haiti not far from the Dominican Border. I am thinking of a solar panel system but I think the cost would be too high. A generator with batteries for storage may be a solution. With 250 children and a staff of 14 the toilets will get flushed a lot. Shower water can be separated to a grey water system if too much water into the Digester is a problem. There would be minimal food scraps as currently rice and beans are cooked in two cast iron kettles on a camp fire for 250 children (the only meal the children get all day). There is no food left over or thrown out. There is no power in the town. There is a road leading to the town but can take 8 hours to go 15 miles in the rainy season with a truck loaded with supplies. I would like to run a dual fuel generator (methane and Diesel or Gasoline). In any case gas and diesel is expensive and there is no money. Can the toilet water and kitchen sink be run into a septic tank with a leach fields and produce methane? Would there be enough methane to run a 25 to 50 KW generator. What ever size I can get donated. I think 25 KW would be big enough. To keep cold water from entering the system each flush, the water could be heated in a solar panel heater on the roof. The water entering the toilet would then at least be warm, unless the toilets set too long (during the night until the first flush). I could use a European style toilet where the tank water for the toilet is recirculated until it is flushed then the water would be a whatever temp the solar heater could reach.

I know nothing about a digester only what I have read for the last 6 hours. They didn't teach digester design when I went to engineering school. long long time ago.

Whew lots of data to share to get to the questions.

1. Given the school complex description above would a digester produce enough methane to run long enough to charge the batteries several times a day? I have no idea how big the generator needs to be or how much battery storage would be needed to power the school.
2. is a gasoline generator better in remote areas or is Diesel as a backup fuel source?
3. Would a Digester work with preheated flush water?
4. How much methane needs to be produced to run a generator?
5. Would the digester require an accumulator to run the generator?
6. Does the methane need to be compressed in an accumulator or will the generator provide enough suction to pull the gas? If so how do I do that?
7. Is there any thing special that is needed for the septic design to produce methane?
8. Will a simple pipe going into the top of the tank with a hose connecting to the generator?
9. I understand that methane off a septic system has sulfur and water in it. Does this have to be separated to prevent damaging the generator motor?
10. If the methane has to be separated how do I design it?
11. How close does the generator need to be to the pipe going in the septic tank?
12. How deep does the septic tank have to be?
13. For a remote area what material and how would the septic tank be designed?

Sorry for all the questions? if you want you can e-mail me at louhagler@msn.com

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Re: Haiti Orphan School electricity

Postby Bob » Tue Dec 23, 2008 12:23 pm

Hi Lou,

Here is a digester design from Francisco X. Aguilar that may be suitable for your application. It is simple, minimum cost, and suitable for tropical environment. Little more than a polyethylene bag in a pit in the ground.

Hope this helps...
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