CHENNAI: The State received average rainfall during the South West Monsoon season this year, but poor storage at the reservoirs in and around Nilgiris has brought down the total hydropower generation by 32 per cent in April-September period.

As the region does not get heavy rain during the North East Monsoon, the officials said the utility would be forced to buy power to meet summer demand.

The storage in the 47 hydel reservoirs in TN stood at 718 million units (MU) on October 1, which is only 30 per cent of its total storage of 2,439 MU. According to Tangedco officials, the generation in April-September has come down by 32 per cent to 2,113 MU in 2023-24 from 3,113 MW in 2022-23.

“The sharp fall was due to less rainfall received in the Nilgiris district during the SW monsoon. The hydel stations in the Nilgiris districts account for two-thirds of the State’s total hydel storage, “ the official said.

Of the total hydel storage of 2,439 MU, the Nilgiris Group comprising Pykara and Kundah reservoirs have a combined storage of 1,523 MU. However, the present storage there stands at 491 MU as against last year’s 1,337 MU. “The reservoirs in those districts will not get rain from the North East Monsoon as well,” the official said.

Other factors such as the ongoing works on the 4X100 MW Kadamparai Power House for leakage in the pressure shaft and fall in Cauvery water release by Karnataka also impacted power generation, the official added.

Last year, Mettur Dam and Mettur Tunnel Power House recorded the highest ever generation due to release of surplus water by Karnataka.

Hydro stations are mainly used during the morning and evening peak hours, as they offer the cheapest energy. “Due to less availability, we will be forced to procure power during the peak hours to meet hydel shortfall during the summer,” the official said.