▁burn s ▁carbon ▁from ▁Board ▁of ▁Water ▁Supp ly ▁filters . ▁In ▁addition , ▁the ▁ash ▁waste ▁product ▁created ▁by ▁A ES ▁is ▁used ▁in ▁concrete ▁mix es . ▁In ▁negoti ations ▁between ▁Hawai ian ▁Electric ▁Company ▁( HE CO ) ▁and ▁A ES ▁in ▁ 2 0 1 4 , ▁it ▁was ▁asked ▁that ▁the ▁plant ▁be ▁converted ▁to ▁run ▁partly ▁on ▁bi om ass . ▁ ▁Environment al ▁impact ▁A ES ▁introdu ces ▁lim estone ▁early ▁into ▁the ▁coal - comb ust ion ▁process , ▁filtering ▁out ▁harm ful ▁sul fur ▁dio x ide ▁early . ▁Most ▁coal ▁plants ▁use ▁industrial ▁scr ub bers ▁to ▁remove ▁harm ful ▁poll ut ants ▁late ▁in ▁the ▁comb ust ion ▁process , ▁which ▁have ▁a ▁higher ▁cost , ▁but ▁are ▁much ▁more ▁efficient , ▁removing ▁as ▁much ▁as ▁ 9 8 % ▁of ▁SO 2 , ▁compared ▁to ▁the ▁ 7 5 % ▁removal ▁rate ▁at ▁A ES . ▁ ▁According ▁to ▁U . S . ▁Environment al ▁Prote ction ▁Agency ▁data , ▁the ▁A ES ▁plant ▁was ▁the ▁leading ▁source ▁of ▁to xic ▁poll ut ants ▁in ▁the ▁State ▁of ▁Hawai i , ▁producing ▁ ▁in ▁to xic ▁releases ▁in ▁ 2 0 1 3 . ▁This ▁represented ▁a ▁poll ut ant ▁increase ▁for ▁the ▁plant ▁of ▁more ▁than ▁ 1 0 0 % ▁from ▁ 2 0 1 2 . ▁ ▁Co al ▁tax ▁break ▁In ▁July ▁ 2 0 1 5 , ▁it ▁was ▁learned ▁that ▁the ▁state ▁approved ▁a ▁special