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Condom experiment #2

Last week my sister served us delicious slow roasted Jerusalem Artichokes which a few hours later put our biogas digester to shame.

Come to think of it beans have the same effect… that got me thinking – are there some veges that are better than others to use in the biogas digester?

If you recall my earlier condom experiment showed that cowdung was so much better than any kitchen wastes for biogas production.

So I borrowed 3 condoms (Trust) and used up my remaining stash of Durex)  and started grating Jerusalem artichokes, sweet potatoes, and mashing beans.

I repeated each with the same amounts of beans, Jerusalem artichokes and sweet potato mixed with some fresh cow dung. Finally I did one last condom as a control with just dung. I tied each with a dougle knot – don’t want any leakage.

I put the whole lot in a dark box and let it sit in the sun to warm up for 2 days. At night I put it in a cool box with a hot water bottle so it doesn’t get cold.

Here are the results after 48 hours

Sweet Potato, Sweet Potato+dung, Mashed beans, beans+dung, Jerusalem Artichoke, J. Artichoke+dung, Just dung

This may not be super science but it’s very very convincing. Dung and Beans Rock!

Some gas is being produced in all the condoms, but it’s astonishing how much more productive mashed beans with dung is. And that’s exactly what my stomach feels like after a meal of beans – pity they are so delicious. The Jerusalem artichokes are disappointing. So is the dung on it’s own which is very surprising.

But is this methane being produced or what? Next we need to test whether this really is methane – condom experiment #3 coming up…watch this space.

And if you want to see the latest on my amazing biogas system at home check out my latest post about a poop mobile on Afrigadget.

July 6, 2010 Posted by | biogas | , , , | 4 Comments

Does kitchen waste produce as much biogas as fresh cow dung?

I am hoping to have a very successful home biogas production system (which I wrote about here)  in about 2 weeks. But what should I feed into my system to make it really successful?

According to Dr. Anand Karve  on the ARTI website 2 kg of carbohydrate rich vegetable feedstock produces about 500 g of methane, and the reaction is completed with 24 hours. While the conventional biogas systems, using cattle dung, uses about 40 kg feedstock to produce the same quantity of methane, and requires about 40 days to complete the reaction. He won an award for this finding.

So should I switch from cow dung to kitchen wastes?  I’m not convinced – maybe Dr. Karve’s Indian cows are less flatulent and produce little biogas – I know that our Kenyan cows are super producers of gas.  But then how can I be sure?

A shitty experiment

To find out whether kitchen waste is better than cow dung, I am conducting an experiment that involved cow dung, plastic cups, condoms, water and kitchen wastes.

I added equal amounts of dung and water and mixed it and poured into a plastic cup, then covered it with a condom to enable me to see the gas forming.

The same amount of kitchen waste was similarly mixed with equal amounts of water and mixed poured into a cup and covered with a condom.

A third experiment involved a mix of dung and mashed kitchen waste, mixed with equal amounts of water, poured into a plastic cup  and covered with a condom. I conducted this experiment in my kitchen using clean disposable utensils and unused condoms (had to say that just in case you people think I’m really weird).


I’ll be posting the results in pictures here

Day 0 (May 25 9 pm)

The condoms are all empty and flaccid. Sad. There was a slight emergency when one of the condoms broke as I was putting it on the cup…  I had to get more condoms purchased at 9 pm. Pharmacist was amused.

Day 2 (May 27th 9 am)

Hmmm, some biogas already being produced and poop looks like it’s slightly more than poop and veg which is more than veg alone. So far I’m putting my money on cow poop.

Day 3 May 28 10.20 pm

Watch this space for coming days and potential explosion of cow poop in my kitchen.

May 29, 2010 Posted by | Uncategorized | , , , , , , , | 9 Comments