Biogas units turn waste into clean energy. Home biogas digesters utilize methanogen bacteria, similar to those present in cow stomachs, breaking down organic waste, to create clean gas and bio-fertilizer. From a self-sufficiency perspective, a biogas unit is a big win!
After a lengthy investigation of available designs, EBG decided to install an HB4 unit from HomeBiogas, a company in Israel. Designed for tropical climates, several problems had to be solved. First, a greenhouse was needed to keep the unit warm in wintertime (the average day/night temperature must be at least 68F). As both ends of the unit must remain accessible, the greenhouse would be difficult to seal properly.
Second, to install the unit in early spring, a means of pre-heating the water that goes into the unit had to be designed.
Third, a source of cow or horse manure had to be located for activating of the unit. Once activated, organic kitchen and garden waste can be fed to the system.
Shown here, the unit sits on an insulated pad (3/4″ styrofoam sheets wrapped in vinyl tarp) within a 4″x4″ enclosure that provides a frame for attaching the greenhouse frame and wiggly wire channel (for anchoring the 12-mil cover). Styrofoam pool noodles are used to minimize friction between the cover and the frame. Not shown is the gas line that runs beneath the pavers from the biogas unit to the stove.
The water pre-heating problem was solved by circulating the water (of the unit) through a 400′ water hose (laid on the floor of the greenhouse). The pump can be seen on crates at the rear of the unit.
Shown here with the 12-mil cover installed (but not attached to the base frame), arched PVC bows were added to keep rain from pooling. The third problem, that of activating the unit with cow manure is underway. Stay tuned.