Mr Switchgrass is an inverted downdraft gasifier design that burns/gasifiers chopped switchgrass or weeds with little to no smoke problems. A rule of thumb is that each section will burn for a solid ten minutes at full flame. I measured 66 lbs for one load and it ran for about 40 to 50 minutes.
This article explains the various methods that I have used to make paper fireballs. The most practical method is what I call the "rock & roll" method. The end product can be seen in the above picture 17.
This is an interesting ash/slag switchgrass fireball. The outside is hardened by becoming slagged. Not all swichgrass fireballs turned to slag. As a matter of fact I think most of my slag came from tests that over heated the gasifier. Simply need more testing.