TN to repurpose four coal plants for clean energy, grid stability

The Tamil Nadu government will soon increase its renewable focus as its coal-based thermal plants get phased out one-by-one as they turn 25 years old.

According to a study, four coal-based thermal power plants of 3,990 MW capacity and repurposing them for clean energy and grid stability can benefit the state by Rs 4,000 crore. It can also stabilise the state’s electricity system.

Climate Risk Horizons has quantified the costs and benefits of retiring 3,990 MW of old coal plants, including Tuticorin I, II and III of 1,050 MW, Mettur I and II of 840 MW, North Chennai Stage-I of 630 MW and NLC-II Stage-I of 1,470 MW.

The four coal power have high per-unit running costs and are dependent on lengthy coal supply chains, prone to disruption, as seen by the recent power crisis caused by low coal stocks.

Oxford Sustainable Finance Group study suggests that the financial benefits of repurposing these coal plants would be 2-3 times the costs of decommissioning and most cases, more than cover the cost of new capital expenditure (capex) required for solar, batteries and synchronous condensers.

Total decommissioning costs for the four plants were about Rs 1,300 crore, and the benefit of repurposing solar PV with battery storage would be Rs 2,400 crore.

Utilising the pre-existing land and grid connection facilities would significantly reduce the cost of the power generated. It would lower the Levelised Cost of Energy to Rs 1.42 and Rs 2.33 per unit for solar PV and PV with battery storage, respectively.

Repurposing the thermal power plants and their associated ash ponds for solar and battery storage would yield 348 MW of solar and 36 MW of four-hour battery storage capacities.

Reducing the state's dependence on expensive and obsolete coal plants is essential for the energy and financial security of the state. With increasing air and water pollution from coal plants and the severe climate change impacts that Tamil Nadu is currently facing, the state requires long-term solutions.

CEO of Climate Risk Horizons, Ashish Fernandes, said that Tamil Nadu has the opportunity to improve its financial and environmental health and also decarbonise its electricity sector.

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