India is witnessing an increase in tunnelling activity in the hydropower sector. With an exploitable potential of about 250,000 MW, including pumped storage and small hydro, the sector offers huge scope for growth in the tunnelling segment. Of the total potential, around 75 per cent lies in hilly regions.
The total length of hydropower tunnel projects in India currently stands at over 2,400 km. This includes projects that are at various stages of development – awarded, bid out, completed, ongoing and planned. Some of the longest tunnels in India are in the hydropower sector.
Hydro tunnelling activity, especially in hilly regions, poses major challenges due to topo-graphic and geological complexities. Indian Infrastructure takes a look at the design and progress of the Kutehr hydroelectric project (HEP) being built in Himachal Pradesh, and the challenges that the segment faces…
Kutehr HEP
The Kutehr HEP is a 240 MW project in Chamba district of Himachal Pradesh. It is being implemented by JSW Energy Limited. Conceived in 2007, the project was put on hold as the then company could not enter into a long-term power purchase agreement (PPA) with the buyers. JSW Energy Limited has played a vital role in its revival. Recently, in March 2022, a PPA was signed with the Haryana Power Purchase Centre (HPPC) for the supply of 240 MW of hydropower. HPPC will purchase the power on behalf of Uttar Haryana Bijli Vitran Nigam and Dakshin Haryana Bijli Vitran Nigam. The PPA is valid for 35 years, with a further extension possible on mutually agreed terms, and has a levellised ceiling tariff of Rs 4.50 per kWh.
Challenges
There are several roadblocks in the successful and quality-assured delivery of hydropower tunnel projects. The challenges include a lack of state-of-the-art technologies due to low budget allocations and inadequate technical understanding, and more weightage being given to financial bids instead of technical bids for the award of contracts. Natural disasters and geological challenges such as shear rocks and high rock cover also pose hurdles in the implementation of tunnels. Natural disasters and geological disturbances such as high temperatures, shear zones and high rock cover pose hurdles in the implementation of tunnels. These lead to unexpected delays with rock failures and accidents in some cases as well. Investigations for these tunnels are also impacted by their huge length and high rock cover.
Such projects need a robust multi-hazard early warning system that can enable an action plan to mitigate any losses. Prediction through probe drilling, tunnel seismic prediction, monitoring and pre-grouting will also allow better preparedness against hazards. Some of these initiatives have been taken for the Salun Nala Aqueduct of the Kutehr HEP project by JSW Hydro Energy Limited. Despite the challenges in hydro tunnelling, the country has successfully constructed a number of tunnels and many others are in the pipeline.
With inputs from a presentation by Padmnabh Mishra, Deputy General Manager (Geotech), JSW Hydro Energy Limited, at a recent Indian Infrastructure conference