Economical analysis of the indian model methane digestor

Abstract

The methane digestor has been considered as an alternative energy source aiming to rural energy self-sufficiency. The Pantanal region offers favorable conditions for biogas production because of cattle manure abundance, and temperature suitable for the most efficient methane-producing bacteria. From analysis of biodigestors between 3.3 and 70 m³ total volume, it is concluded that maximum efficiency size relates to digestors above 70 m³. For units at the 3.3 to 53 m³ range an elasticity mean cost/daily production coefficient of -0.33 and a function coefficient of 1.49 were estimated, indicating receipts in increasing scale, the scale factor being 0.59 + 0.36. Budgets were specified for three production capacities (2.4, 6.2 and 13.2 m² biogas. Day^-1), investments being estimated from 9,302 (smallest unit) to 3,400 cruzeiros (largest unit) per m³ of gas, considering 11.7 years usefulness. For the three analyzed models, labour return rates, increasing with size, were estimated as 5, 17 and 31 cruzeiros when replacing diesel oil, and 6, 19 and 34 cruzeiros when substituting kerosene. The best alternative was for gasoline, while the replacement of petroleum gas showed the lowest profitability.