The experimental study on biogas power generation enhanced by using waste heat to preheat inlet gases

A 30 kW generator at the Taiwan Sugar Swine Farm in Taichung was used to collect data intended for long-term electricity generation. This three-part experimental study utilized a biogas with a 73% methane concentration. First, the effect of the biogas supply rate on generator performance at different excess air ratios is investigated. Second, the results from this study are compared with results obtained from work performed on a biogas with a 60% methane concentration. Finally, for a 73% methane concentration biogas, the effect on generator performance of preheating the inlet gas to different temperatures is investigated by applying a waste-heat recovery system.Power generation increases with increasing biogas methane concentration, except when λ (excess air ratio) < ∼0.85. However, thermal efficiency increases with increasing methane concentration only when λ > ∼0.95, although on the relatively rich side (λ < 0.95), there is no benefit. The improved generator performance obtained by preheating the inlet gas is apparent when the excess air ratio is relatively high, such as when λ > 1.3.

► The effect of biogas supply rate on generator performance at different excess air ratios is investigated.
► The cases with 60% and 73% methane concentrations are compared.
► Preheating the inlet gas by a waste-heat recovery system to different temperatures is investigated.