Evaluation of performability index of biogas plants using graph theory and matrix method

The production and use of biogas benefits both the participating farmers and the wider community in terms of providing clean environment and affordable energy in accordance with the requirements specified in the sustainable development goal 7 (SGD 7). Uninterrupted and safe production of quality gas by employing simple digesters is the sustainable solution to achieve SDG 7, which could be met by considering performability in design and evaluation of the plant. The performability of a biogas production unit is a function of factors such as sustainability, safety, maintainability, reliability and quality. The evaluation of performability index is highly desirable for monitoring the performance of the plant, thus ensuring dependable and sustainable operation over its whole life cycle. Although these factors help to evaluate the performability index, yet their interdependencies that influence the performability intangibly cannot be neglected. The performability evaluation without considering the interdependencies among these factors will yield wrong performability value. It is therefore important to consider the performability factors along with their interdependencies while evaluating the index, which is the measure of performance of the biogas production plants. Graph theory in conjunction with matrix method, which has been extensively used to derive such indices considering interdependencies, is employed to address this issue. The index is useful not only in design stage for developing an efficient biogas plant but also in operation to assess and improve its performability.