( Also ( , ( they ( ( ( ( ( ( use heat ) , ) ( in ( ( the form ) ( of ( burning propane ) ) ) ) ) , ) ( to ( produce ( ( the cold ) ( inside ( the refrigerator ) ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB Also)) (, ,) (NP (PRP they)) (VP (VBP use) (NP (NN heat)) (, ,) (PP (IN in) (NP (NP (DT the) (NN form)) (PP (IN of) (NP (VBG burning) (NN propane))))) (, ,) (S (VP (TO to) (VP (VB produce) (NP (NP (DT the) (NN cold)) (PP (IN inside) (NP (DT the) (NN refrigerator)))))))) (. .)))
Also, they use heat, in the form of burning propane, to produce the cold inside the refrigerator.
(ROOT (S (NP (NNP Heat)) (VP (VBZ is) (VP (VBN produced) (SBAR (WHADVP (WRB when)) (S (NP (NN paper)) (VP (VBZ is) (VP (VBN burned))))))) (. .)))
Heat is produced when paper is burned.