ion . ▁By ▁replacing ▁some ▁or ▁all ▁of ▁the ▁calci um ▁carbon ate ▁entering ▁the ▁plant ▁with ▁waste ▁calci um ▁ox ide , ▁the ▁CO 2 ▁ ▁caused ▁from ▁calc ination ▁can ▁be ▁avoided , ▁as ▁well ▁as ▁some ▁of ▁the ▁CO 2 ▁ ▁from ▁foss il ▁fuel ▁comb ust ion . ▁ ▁This ▁calci um ▁ox ide ▁could ▁be ▁s our ced ▁from ▁other ▁point ▁sources ▁of ▁CO 2 ▁ ▁such ▁as ▁power ▁stations , ▁but ▁most ▁effort ▁has ▁been ▁foc uss ed ▁on ▁integr ating ▁calci um ▁looping ▁with ▁Port land ▁c ement ▁manufact ure . ▁By ▁replacing ▁the ▁calc iner ▁in ▁the ▁c ement ▁plant ▁with ▁a ▁calci um ▁looping ▁plant , ▁it ▁should ▁be ▁possible ▁to ▁capture ▁ 9 0 % ▁or ▁more ▁of ▁the ▁CO 2 ▁ ▁relatively ▁in exp ens ively . ▁There ▁are ▁alternative ▁set - ups ▁such ▁as ▁placing ▁the ▁calci um ▁looping ▁plant ▁in ▁the ▁pre he ater ▁section ▁so ▁as ▁to ▁make ▁the ▁plant ▁as ▁efficient ▁as ▁possible . ▁ ▁Some ▁work ▁has ▁been ▁undert aken ▁into ▁whether ▁calci um ▁looping ▁affect s ▁the ▁quality ▁of ▁the ▁Port land ▁c ement ▁produced , ▁but ▁results ▁so ▁far ▁seem ▁to ▁suggest ▁that ▁the ▁production ▁of ▁strength - g iving ▁phases ▁such ▁as ▁al ite ▁are ▁similar ▁for ▁calci um ▁loop ed ▁and ▁non - cal ci um ▁loop ed ▁c ement . ▁ ▁Econom ic ▁imp lications ▁ ▁Cal ci um ▁looping ▁has ▁several ▁economic ▁advantages . ▁ ▁Cost ▁per ▁metric ▁ton ▁for ▁CO