You could probably use dried cactus, lots of dried cactus.
Most scrap yards have them and Ag fuel centers as well as truck stops usually have oil barrels in bulk. You have to cut the tops off for burn barrels that can get a bit unnerving but relatively safe.I'm still working on getting a 55 gallon burn barrel.
With all due respect sir, carbon turns to gas at something like 5000+ degrees F yet the autoignition temp is something like 1200 degrees(F). If carbon must turn to gas to combust you couldn't produce a temp high enough to get it to burn with ordinary measures.We went out to make a batch of charcoal. Soon things got carried away when a semi heated discussion on why and how things burn ensued. My point was that a sold must transform into a liquid then into a gas and then may ignite. I furthered that the gas could be trapped and used. Upon disagreement to my theory I illustrated my point by stopping the burn of the charcoal prematurely and sealing the container. We left the area by some 700 yards. The estimate is that the 55gl. steel drum made it about thirty feet from the compression of the gas being generated. Not much charcoal left.