The main 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 pre-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.
Even a cursory glance at the chart is sufficient to reach the obvious conclusion that the biomeiler has finished composting for the season. I attempted to restart the composting process by mechanically aerating the pile in the middle of the month, but it clearly had no effect. However, I am not at all disappointed with this outcome.
Since October, the biomeiler has functioned so effectively that we were able to make it through the coldest winter on record in Fairbanks, Alaska, using no electric heat in the coop. It is a result I am sharing proudly whenever the opportunity presents itself. Sadly, though, the news has a decidedly niche appeal and seems not to generate much excitement amongst the non-enthusiasts.
The fact that the biomeiler no longer generates heat is actually beneficial, because the outdoor air temperature has risen to the point that the coop now needs to be cooled. As I wrote in the last post, the biomeiler has conveniently switched operation mode from heating to cooling at precisely the time of year when the change would be most appreciated. Now, the outdoor air is being cooled as it is pulled through the pile and it enters the coop as a form of air conditioning.
Since the last post, the snow and ice have melted away from the perimeter of the biomeiler and the ground is drying. Soon, I will be able to set a ladder in place and climb onto the pile to carry out an investigation as to what changes have taken place while it was operating through the winter. Last year, the pile acted as a heat sink well into the warm part of the summer due to a large volume of ice which formed at the upper surface during the winter. This year, my strong suspicion is that there will be only a small amount of ice present.
A compost pile has a natural convection pattern that pulls air in from the sides and releases it out the top. The biomeiler should be no exception, but it seems likely that any moisture that rose to the top surface would be trapped by the Reflectix insulation and would freeze there. In the absence of mechanical aeration, I don’t expect that the natural convection could lift much moisture to the top surface after the surface became frozen over.
I will soon explore this hypothesis and report back with the findings. Stay tuned.
