( Methanogens ( ( use ( ( ( ( hydrogen ( and ( hydrogen ( rich compounds ) ) ) ) and ) ( carbon dioxide ) ) ( to ( ( ( ( produce energy ) ( for themselves ) ) and ) ( ( release ( methane ( -LRB- ( ( natural gas ) -RRB- ) ) ) ) ( as ( a ( waste product ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Methanogens)) (VP (VBP use) (S (NP (NP (NN hydrogen) (CC and) (NN hydrogen) (JJ rich) (NN compounds)) (CC and) (NP (NN carbon) (NN dioxide))) (VP (TO to) (VP (VP (VB produce) (NP (NN energy)) (PP (IN for) (NP (PRP themselves)))) (CC and) (VP (VB release) (NP (NP (NN methane)) (PRN (-LRB- -LRB-) (NP (JJ natural) (NN gas)) (-RRB- -RRB-))) (PP (IN as) (NP (DT a) (NN waste) (NN product)))))))) (. .)))
Methanogens use hydrogen and hydrogen rich compounds and carbon dioxide to produce energy for themselves and release methane (natural gas) as a waste product.
(ROOT (S (NP (NNS Archaeans)) (VP (VBP produce) (NP (NN methane) (NN gas)) (PP (IN as) (NP (DT a) (NN waste) (NN product)))) (. .)))