Chemical analysis of a sample of biogas from a digester gives the following results: CO 2 : 44%; CH 4 : 56% (all percentages are by volume). What is the HHV of this particular sample of biogas? Is this above or below average? It is later discovered that this analysis was in error and that the correct assay for this sample is CO 2 : 44%; CH 4 : 51%; H 2 : 5%. What is the corrected HHV of the biogas? If the objective is to produce a gas with as much heating value per unit volume as possible, is hydrogen a good coproduct? Assume the HHV of pure CO 2 and pure CH 4 are 0 and 1,000 Btu/SCF, respectively.