This is something I hadn't considered. Thanks.
Yerba Mate and Guayusa, as far as ease of use and availability.
Guarana seeds (whole) are nice to throw into teas and tisanes as well.
Cocaine and caffeine?
What are the most energising plants?
Interesting, Mr. theFool. I'll have to consider that for the calcinations. Maybe I can set it up to take multiple fuel sources -- propane and charcoal