Flexible biogas production for demand-driven energy supply--feeding strategies and types of substrates.

Purpose of this work was the evaluation of demand driven biogas production. In laboratory-scale experiments it could be demonstrated that with diurnal flexible feeding and specific combination of substrates with different degradation kinetics biogas can be produced highly flexible in CSTR systems. Corresponding to the feedings the diurnal variation leads to alternations of the methane, carbon dioxide and acid concentrations as well as the pH-value. The long-time process stability was not negatively affected by the dynamic feeding regime at high OLRs of up to 6 kg VS m(-3) d(-1). It is concluded that the flexible gas production can give the opportunity to minimize the necessary gas storage capacity which can save investments for non-required gas storage at site.