More news from the Philippine biodigester
I have managed to test a few carbon based feedstocks as we last discussed.
1. lawn-mower grass cuttings from the greens of a nearby golf course
2. shredded sweet potatoes (yams) - from waste bin in vegetable market
3. shredded potatoes - from waste bin in vegetable market
4. sliced tomatoes - from waste bin in vegetable market
5. pressed coconut meat - from a native cake bakeshop
The sliced tomatoes and pressed coconut meat did not appear to produce biogas.d(When fed to a working biodigester, biogas output continued to decline as if no feedstock was added.)
Worse, the pressed coconut meat floats and may be floating inside the digester impeding digestion.
With the grass cuttings, gas production did not drop. In fact, there was a small noticeable increase for a few days.
The yams and potatoes, however, gave a surge in biogas production for a few days. Yams and potatoes (apparently, vegetables that cause one to fart) are good for biogas production.
In all instances, approximately 5 % feedstock by volume was added once and production was observed for two weeks.
I plan to repeat the tests and validate the results.
I have also been keeping track of the listserv forum. The composting of biomass wastes before using it as feedstock is a good idea specially for wastes that tend to float.
Returning from a vacation, we passed a little remote-community that had signs saying they were using biogas. We stopped, interviewed two users and examined their set-ups. Though they invested heavily when their digesters were built in 2001, they are very happy to have them now that LPG prices have almost tripled.
I was able to track down one of the technicians who happily reported that he has built 41 digesters ranging from 5 to 10 m3 since 2000 -- with funding assistance from UNDP.
It was great to find that community with home-type or family-type biodigesters. The find affirms that biogas WORKS!
My biodigester which only costs about 80 % today for what they paid for in 2001 continues to appear to be a great idea for the Philippines. The DOST tech I mentioned above agrees and plans to try my units in his next projects.
The 10 m3 HDPE units installed in our farm are now full of biogas. We are going to test burning the biogas when I go there tomorrow.
I also have a couple of relatives interested in 10 m3 units for their farms. This is getting interesting.