Saturday, May 24, 2008

Biogas Harvest, Sorta

Today the boys and I tried to harvest some more biogas from the backyard biodigester. It's a 55 gallon plastic drum that I filled with biodegradable materials ranging from old spinach, to oak tree leaves, to stale potato chips, to rotten fruit. Then I poured in enough water so that it was about 15 gallons. The next step is to seal it so that the bacteria inside are deprived of any oxygen (which kills them) and let it sit for a few weeks in the Texas heat.

Theoretically, metsophylic bacteria, present in our own digestive tracts, will grow in an oxygen free environment. There are actually two types of bacteria, one consumes the output of the other. The end result is, digestible biomaterials get eaten and biogas is produced. Biogas is about 2/3 methane (CH4) and about 1/3 carbon dioxide (CO2). There are also small amounts of N2, H2, CO, O2 and a bit of hydrogen sulfide (HS4). The hydrogen sulfide is the stinky part.

We were able get a few liters of biogas out of the system today! Unfortunately, we were unable to light it. Our only verification that it was indeed biogas was the smell. Oh yeah, it was biogas. Gag.

I think my haphazard harvesting method is flawed, but I only realized this after we filmed the clip above. I used a different method later, and though I got more gas, I was still unable to light it. I am going to have to arrange some kind of Bunsen Burner gizmo for future testing.

1 comment:

Lisa Bradbury said...

Hey PT, today I got my Tevo's and I'm ready to head to the airport! Glad to hear all is well in La Ceiba for now.