( ( The ( released energy ) ) ( ( is ( what ( powered ( the ( ( thunderstorms and ) tornadoes ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ released) (NN energy)) (VP (VBZ is) (SBAR (WHNP (WP what)) (S (VP (VBN powered) (NP (DT the) (NNS thunderstorms) (CC and) (NNS tornadoes)))))) (. .)))
The released energy is what powered the thunderstorms and tornadoes.
(ROOT (S (NP (NP (DT The) (NN rate)) (SBAR (IN that) (S (NP (NN energy)) (VP (VBZ is) (VP (VBN released)))))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (NN power))))) (. .)))