The 264 MW capacity Upper Tamor Hydropower Project is set to use a tunnel boring machine (TBM) for tunnel excavation. Pushpajyoti Dhungana, chairman of Tamor Energy Pvt. Ltd., stated that this is the first time such a machine is being used in a hydropower project in Nepal. Traditionally, tunnel excavation has been carried out using conventional methods.
TBM technology was previously implemented in the Bheri Babai Multi-Purpose Irrigation Project and the Sunkoshi Marin Diversion Project, where it significantly expedited tunnel excavation.
Chairman Dhungana further mentioned that preparations for initiating TBM usage have reached the final stage. In an interview with New Business Age, he explained that TBM technology had previously been used in irrigation projects, which were successfully completed ahead of schedule. He added, "We have completed the necessary arrangements, and within the next ten days, we plan to begin mobilizing the machine."
The initial estimated cost of constructing the Tamor Hydropower Project was Rs 55.12 billion; however, current projections suggest that it could be completed for Rs 51 billion. The project secured financial management in June, through a consortium led by Everest Bank pledging Rs 38.60 billion in loans.
Dhungana revealed that the project has already secured investment of Rs 25 billion and has initiated the process of receiving loans of Rs 29 billion pledged by banks.
The Upper Tamor Hydropower Project is a reservoir-based hydropower project to be built in Fungling, Taplejung. Unlike run-of-river type projects, this project will ensure full production for six hours during winter when the water levels in rivers recede. The project aims to reduce load-shedding and ensure stable power supply, even in winter.
Why Use TBM?
Traditionally, tunnel excavation involves drilling and the use of explosives, which can be time-consuming and less efficient. Ganesh Kaji, a hydropower expert, emphasized that TBM usage ensures a faster and more effective excavation process. Compared to conventional methods, TBM technology offers nearly double the efficiency in tunnel construction. While the initial investment cost is higher, TBM significantly reduces the overall construction time.
For example, the Melamchi Water Supply Project, a national pride project, took nearly nine years to excavate a 26-km tunnel using conventional methods. In contrast, the 12.2-km tunnel of the Bheri Babai Multipurpose Irrigation Project was completed in less than two years with TBM.
Despite its advantages, private-sector hydropower projects in Nepal have been slow to adopt TBM technology due to its high initial costs. However, as private developers increasingly undertake projects of over 100 MW capacity, the use of TBM is expected to become more widespread. Some project promoters, including members of the Independent Power Producers' Association, have begun showing interest in TBM technology, with certain investors already in discussions with Chinese companies for its procurement.
