text: Apart from these advantages, there are several disadvantages needed to take into considerations.  The plant integrating Ca-Looping might require a high construction investment because of the high thermal power of the post-combustion calcium loop. The sorbent capacity decreases significantly with the number of cycles for every carbonation-calcination cycle so the calcium-looping unit will require a constant flow of limestone. In order to increase the long-term reactivity of the sorbent or to reactivate the sorbent, some methods are under investigation such as thermal pretreatment, chemical doping and the production of artificial sorbents. The method applying the concept of fluidized bed reactor, but there are some problems causing the uncertainty for the process. Attrition of the limestone can be a problem during repeated cycling.