<prompt> Translate the following text to EnglishMakadirio haya ni ya kihafidhina, kwa kuzingatia kwamba mifumo ya hivi karibuni ya FGD inafanya kazi katika viwango vya karibu na stechiometric, na nyongeza hutumiwa kwa kawaida kufikia uondoaji wa juu wa SO2, haswa ili kuboresha utendaji wa vifaa vya kisasa.  <response>: These estimates are conservatively high given that recent FGD systems are operating at near stoichiometric levels8 and additives are commonly used to achieve higher SO2 removal, particularly to enhance the performance of existing retrofits. 