LAUSR

The purpose of this study is to evaluate PERT-based critical paths of new service development (NSD) process for renewable energy investment projects. In this context, a novel three-stage model has been proposed. In the first stage, 10 different steps in NSD process are weighted by considering 2-tuple hesitant interval-valued Spherical fuzzy IVSF DEMATEL approach. In the second stage, 26 different critical paths for NSD process are identified. Moreover, the third stage includes the ranking the renewable energy alternatives by path scenarios with 2-tuple hesitant IVSF TOPSIS. The findings demonstrate that idea screening and the formation of cross-functional team are the most significant criteria for the NSD process of renewable energy investments. Additionally, while considering all activities of NSD process, it is concluded that solar energy is the most appropriate renewable energy alternative. This result is also similar for considering the longest path by activity number, the longest path by duration and the shortest path by activity number. However, it is also determined that geothermal energy is the most ideal type of renewable energy to invest in while considering the shortest path by duration. Therefore, it is obvious that investors should primarily give importance to generate new products for solar energy projects. In this way, it can be easier for them to provide efficiency in their investments. On the other hand, if there is time constraint or a positive result is expected from the project in a short time, geothermal energy is the most suitable renewable energy type to invest.