The chart accompanying today’s post shows the temperatures measured in the biomeiler at a height of 4’ above the ground. This height marks the boundary between the existing biomeiler and the recent extension. The data were collected by a thermocouple buried in the pile at that height at the very center of the inner core, another placed halfway between the inner and outer walls of the outer core, and a third similarly placed between the inner and outer walls of the mantle. The air temperature was measured on a thermometer in the open air.
As December commenced, the air temperatures rapidly declined. The great mass of the biomeiler initially allowed it to resist the change, but it began cooling by mid-month. Around Christmas, we received a significant snowfall and the temperature of the inner core rose to almost 180F. I believe that the additional thickness of snow on top of the biomeiler acted as insulation and allowed the inner core of the pile to retain heat that was previously escaping upward. The outer core has less composting taking place and, correspondingly, would have benefited less from the snow’s insulative effect.
The mantle temperatures continued to split the difference between the warmth of the cores and the chill of the outdoor air. In the last week of the month, at the 1’ and 2’ elevations, the mantle temperatures rose noticeably higher, reaching 80F by New Year’s Eve. Again, I attribute the increase in temperature to the snowfall. At the beginning of the month, the lower 2 feet of the pile had an air gap between its surface and the nearby snow on the ground. That gap was filled in and the snow reached as high as 2.5 feet around the pile after the Christmas addition. The snow did not protect the pile at the height of 4’ and the temperature did not improve as much there – which lends further support to my insulation hypothesis.
As I wrote in the post about November’s results, one of the major advantages of using a biomeiler as a heat source is that its large mass and the simplicity of the anaerobic respiration process make it a reliable, stable generator. Indeed, it has passed a significant test this month!
The coop was kept warm during our coldest month since 2005 simply by collecting waste heat from the mantle at the modest cost of running two duct fans.
Such a remarkable result of your perseverance in perfecting the biomeiler. You have exchanged your work and analytical effort for the great reduction in dependence upon costly electricity for heating that coop.
Congratulations on your success.
There may not be a whole lot of followers who would dedicate their time and effort to the cause. You have shown, however, that it can be a profitable endeavor, and the cost of maintaining your egg business is significantly reduced.
You are to be greatly admired!