CEA (Central Electricity Authority) has recommended implementation of 170 MW Tato-I, 120 MW Pauk and 210 MW Heo hydro power project within same timeframe. These three hydro power projects are planned on Yarjep (Shi) river in Arunachal Pradesh. While considering the detailed project report (DPR) of Tato-I for concurrence, CEA stated that development of these projects in isolation may not be feasible and thus all three projects need to be implemented in same timeframe.
CEA feels that Tato-I HEP forms the third stage of a cascade development of three projects — Pauk, Heo and Tato-I — with generation dependent on releases made from Pauk HEP. Heo HEP and Tato-I HEP have no storage and reservoir of Pauk HEP would be used as active storage by them. Optimisation studies have been carried out by CEA for all the three projects in cascade.
According to Central Water Commission, main regulating storage is available at Pauk and generation at Tato-I would be possible only in case Heo is also constructed in time frame when Tato-I is commissioned. However, peaking would not be available due to non-availability of storage at the head of cascade.
All the three hydro power projects have been proposed to be developed by Velcan Energy through its subsidiaries. Apart from Tato-I project, the Company has also submitted DPR for Heo HEP to CEA in July 2013. CEA has indicated that appraisal of Tato-I and Heo projects would be carried out simultaneously.
Further CEA has mentioned in the power potential studies that environment releases were considered as 10 per cent of minimum available flow in 90 per cent dependable year as proposed by the developer. However, as per recent practice adopted by the environment ministry, environment ministry has recommended environment releases as 30 per cent during monsoon period, 20 per cent during lean period and 25 per cent during intervening period of 90 per cent dependable year for other projects in region. Therefore, developer would need to submit recommendations of environment ministry regarding environment releases for Heo HEP for the project to be concurred. In case, there is a change in quantum of environment releases by the environment ministry, developer need to review power potential studies accordingly and resubmit to CEA.