That is what I thought I was seeing in that picture too. Doesn't look real efficient. To make that work real well, you cover the top of the side bins with air tight glass, or clear plastic covers that can be lifted up to add compost, etc. That will make the material bake. Then put a smaller hole in the greenhouse connecting it to the the bottom of the bin, and let the heat and CO2 enter the greenhouse. Even better, would have like bins on both sides so heating is more uniform.
