Today we improved the UBAB to version o.2.
First, we appended a smaller batch (25L instead of 50L) which will be quicker to heat passively with the sunlight. Heat is necessary to fire up the anaerobic bacterias.
Second, we changed the gas-holder by removing the tire bowel, cutting the 100L open at the top and inserting an upside-down, perforated, 50L drum to collect gas. This bell system will help measuring the gas production more easily (we realised we had now good way to measure the gas volume with a bowel).
The overall product is now cheaper this way (batch of 25L is 180NPR rather than 300NPR for 50L and the bell is 300NPR rather than 650NPR for the bowel), saving 1000NPR.