cling ▁system ▁could ▁save ▁the ▁city ▁over ▁$ 2 0 ▁million . ▁Municipal ities ▁often ▁see ▁fis cal ▁benefits ▁from ▁implementing ▁rec y cling ▁programs , ▁largely ▁due ▁to ▁the ▁reduced ▁land fill ▁costs . ▁A ▁study ▁conducted ▁by ▁the ▁Techn ical ▁University ▁of ▁Den mark ▁according ▁to ▁the ▁Econom ist ▁found ▁that ▁in ▁ 8 3 ▁percent ▁of ▁cases , ▁rec y cling ▁is ▁the ▁most ▁efficient ▁method ▁to ▁dispose ▁of ▁household ▁waste . ▁However , ▁a ▁ 2 0 0 4 ▁assess ment ▁by ▁the ▁Dan ish ▁Environment al ▁Ass ess ment ▁Institute ▁concluded ▁that ▁inc iner ation ▁was ▁the ▁most ▁effective ▁method ▁for ▁dispos ing ▁of ▁drink ▁containers , ▁even ▁al umin ium ▁ones . ▁ ▁F is cal ▁efficiency ▁is ▁separate ▁from ▁economic ▁efficiency . ▁Econom ic ▁analysis ▁of ▁rec y cling ▁does ▁not ▁include ▁what ▁econom ists ▁call ▁external ities , ▁which ▁are ▁un pr iced ▁costs ▁and ▁benefits ▁that ▁acc r ue ▁to ▁individuals ▁outside ▁of ▁private ▁transactions . ▁Ex amples ▁include : ▁decre ased ▁air ▁poll ution ▁and ▁green house ▁g ases ▁from ▁inc iner ation , ▁reduced ▁ha z ard ous ▁waste ▁le aching ▁from ▁land fill s , ▁reduced ▁energy ▁consumption , ▁and ▁reduced ▁waste ▁and ▁resource ▁consumption , ▁which ▁leads ▁to ▁a ▁reduction ▁in ▁environment ally ▁dam aging ▁min ing ▁and ▁tim ber ▁activity . ▁About ▁ 4 , 0 0 0 ▁min er als ▁are ▁known , ▁of ▁which ▁only ▁a ▁few ▁hundred ▁are ▁relatively ▁common . ▁Kn own ▁res erves ▁of