ing ), ▁some ▁with ▁FA ▁( F an ▁Ass istance ) ▁a . ▁Top - lit ▁upd raft ▁( known ▁as ▁T L UD s ) ▁w / ▁migr ating ▁py ro ly t ic ▁zone ▁( batch ) ▁b . ▁Up d raft s ▁and ▁dow nd raft s ▁w / ▁station ary ▁gas ification ▁zones ▁( continu ous ) ▁c . ▁Other ▁draft s , ▁including ▁cross ▁and ▁opposite / opp osing ▁draft s ▁ 6 . ▁" F an - jet " ▁with ▁very ▁strong ▁air ▁curr ents ▁into ▁the ▁fuel ▁( 3 ▁known ▁examples ): ▁a . ▁Phili ps - FA ▁b . ▁Lu cia - FA ▁c . ▁Tur b oc oc ina ▁ 7 . ▁Non - bi om ass . ▁Sto ves ▁not ▁using ▁raw ▁dry ▁bi om ass ▁fu els : ▁Char co al ; ▁alco hol ; ▁ref ined ▁foss ils ; ▁coal ; ▁bi og as ; ▁electric ; ▁solar . ▁ ▁Multi - mode ▁capable ▁st ov es ▁can ▁be ▁used ▁only ▁in ▁one ▁way ▁at ▁any ▁one ▁time . ▁ ▁Bar riers ▁to ▁cook st ove ▁ad option ▁ ▁There ▁are ▁currently ▁more ▁than ▁ 1 6 0 ▁operating ▁cook st ove ▁implementation ▁programs ▁in ▁the ▁world . ▁A ▁few ▁thousand ▁of ▁the ▁cook st ove ▁implementation ▁program ▁dist ribute   ▁st ov es ▁in ▁specific ▁areas . ▁This ▁is ▁due ▁to ▁high ▁cost ▁of ▁alternative ▁st ov es , ▁cook st ove ▁mal function , ▁and ▁the ▁lack ▁of ▁understanding