Nature provides for ready-made fuel from a number of livestock, even convienently drying it in the sun where it falls, but this can prove to be a less than appealing form for many people and is not a particularly efficient form for storage or handling. To increase available fuel and minimize space required for it, the general practice is to collect the manure and other biomass and form it into easily manageable blocks or bricks. Several approaches were tested.
Compression
Waste was taken from the manure pile, mixed with water sufficient for binding and compacted in a wooden lever press. It was presumed this would be the default method of forming but the process is sensitive to the moisture content of the mix and it is inherently slow, yielding only a single brick per cycle (a gang press could be employed to increase this), and as well is unnecessarily messy. A limited number of bricks were made this way and when dried were also prone to a sort of de-lamination making them difficult to handle. |
Frames
In the same fashion as adobe brick, the moistened and mixed biomass was tamped into a frame having three compartments, each creating a nominal 6” x 9” x 4” block. The frame being pulled from the blocks left them in place on whatever surface was chosen for drying (a palette was used for this). This process is simple, rapid, and each cycle results in as many blocks as the frame has compartments. Dry time in clear, ~75 degree F conditions was approximately three days. Many of these bricks were made and burned at varying points to refine the process. This became the preferred method of production. |
Cutting
Skipping over any kind of mixing altogether, we instead cut directly into the lower level of the manure pile where the waste had been naturally compressed and composted. From this layer blocks could easily be cut with a spade in a manner identical to peat. It was then sun-dried. This method is fast but because of the high moisture content the dry time is very long (>5 days). Due to weather and incomplete drying these bricks were unable to be fully tested. |
Three test burns were conducted using 8 lbs. of formed and dried biomass and 8 lbs. of seasoned firewood. The chart at left shows the temperature curve for each over an hour and half from the moment of lighting, as measured at the stove/flue junction. This indicates heat output of the biomass to be ~25% less than an equivalent weight of hardwood.