Since it is the acetylene generated by carbide + water which does the work, a small acetylene cutting torch gas bottle might work. Maybe use a trash bag over the plant & fill it, acetylene is lighter than air. There could be a small explosion danger, but do the work away from spark or flame and should not be more dangerous than gasoline DO NOT USE OXYGEN IN CONJUNCTION WITH ACETYLENE! (makes a very nice boom when the trash bag explodes-been there done that) I have a small cylinder which I got refilled for soldering. You may know someone with such a rig you could borrow for a test.