COIMBATORE: Kadamparai Pumped Storage Hydro Power Plant, Tamil Nadu's only facility with reversible two-way turbines, is struggling to stay operational as it is beyond its design life, functioning at just 25% capacity.
Out of four units, only one is generating power at present, while the rest are down due to recurring faults. Facing production losses and escalating repair costs, Tamil Nadu Power Generation Corporation Ltd (TNPGCL) is now planning to outsource repairs and maintenance to private players.
Commissioned in 1987, Kadamparai was the state's first pumped storage unit and remains unique for its ability to operate in both generator and motor modes. When the grid needs power, water is released from the upper dam at Kadamparai to the Lower Aliyar Dam, driving the turbines to generate electricity.
During night, with wind and solar creating surplus power in the grid, the same turbines reverse into pump mode and act as motors and push water back from the lower dam to the upper dam, effectively storing energy for the next demand cycle.
The Kadamparai Dam has a storage capacity of 1,080 mcft, while the Lower Aliyar Dam holds 937 mcft. Using a minimum of 4 mcft from the upper dam, each unit can produce 100 MW (1 lakh units) per hour. With four units, the plant's installed capacity is 400 MW per hour.
The first unit was installed in 1987 by an England-based company. Based on that technology, BHEL set up the remaining three units in 1989 and 1990. But after nearly 37 years of service, the machinery has become prone to breakdowns.
"Actual lifetime of the power production units is a maximum of 25 years. But they have been running beyond their lifetime, leading to frequent repairs," a senior TNPGCL official said.
"If we repair a part, the other parts turn faulty within a few days and the units are forced to remain idle. This situation has been continuing for the last one year. Now, three units are in the same condition and power generation is under way in one unit. Repair works are under way at three units." the official said.
The official said the plant plays a critical role in grid stability. It has a system for quickly balancing supply and demand, and integrates renewable energy by storing excess solar and wind power that would otherwise be wasted. During peak loads or sudden outages, the plant can provide quick backup power.
Sources said the government must take steps to restore the plant, with modernisation and replacement of equipment. TNPGCL has decided to bring in private players for repairs and maintenance, but no one has come forward to undertake it.
"The bidding to conduct a study on R&M was called for a few times. Yet, no one is willing to take it up as the cost may rise due to the unavailability of spare parts. Pumped storage plants are crucial for a renewable-heavy grid.
With solar and wind generation peaking at odd hours, facilities like Kadamparai prevent curtailment of green power by absorbing surplus and releasing it when demand rises. The prolonged outage of three units has reduced that flexibility, putting more strain on thermal plants," the official added.
J Radhakrishnan, Chairman and MD of Tamil Nadu Power Distribution Corporation Limited (TNPDCL) told TNIE that the restoration process to run the three units is in progress. “If needed, we will initiate further steps based on a detailed study.”
