Penstock material selection in small hydropower plants using MADM methods

Small hydropower (SHP) is a promising source of renewable and clean energy. Selection of proper material for different components of SHP projects in general and penstock in particular is one of the most challenging tasks as civil work components contribute substantially in the overall cost of the project. There is no systematic and efficient approach found in the literature for selecting best material and consequently engineers take number of criteria for such selection. In the recent time, the verities of material are increasing very fast with various properties, which make material selection process complicated. In the present study, an effort has been made to apply Multiple Attribute Decision Making (MADM) methods for solving the material selection problem for penstock in SHP installations. Analytic hierarchy process (AHP), technique for order preference by similarity to ideal solution (TOPSIS) and Modified TOPSIS methods are used to select the best material. Four alternative materials such as polyvinyl chloride (PVC), high-density polyethylene (HDPE), glass reinforced polymer (GRP) and mild steel (MS) and five assessment attributes/criteria such as yield strength, life, thickness, cost of material and maintenance cost have been considered in the analysis. Two case studies have also been analyzed and included in the study. It has been found that TOPSIS and Modified TOPSIS methods are best suited for penstock material selection and mild steel is the suitable material as compared to other materials.