Repurposing coal plants to solar ones profitable: Experts

Repurposing the state’s ageing coal plants with the solar photovoltaic plants with battery storage and a synchronous condenser would provide significant financial benefits rather than operating plants or decommissioning them, finds a new study.

“For Tamil Nadu, a state with significant coal capacity struggling due to age, low capacity utilisation levels, reduced profitability and growing environmental concerns, it would be advisable to explore means to wean away from coal. One such approach includes repurposing coal plants for various productive end uses ranging like solar generation,” said the Report Financial Benefits of Repurposing Tamil Nadu’s Old Coal Plants by Dr Gireesh Shrimali and Dr Abhinav Jindal.

The report analysed Tuticorin I, II and III (1050 MW), Mettur I and II (840 MW), North Chennai I (630 MW), and Neyveli II Stage I and II (1470 MW) thermal power plants to enumerate the financial benefits that such coal plant repurposing would bring. “Total decommissioning costs for the four plants assessed were approximately Rs 1,300 crore, while the benefits from repurposing for solar PV with battery storage would be Rs 2,400 crore and if the old power plant turbogenerator is also repurposed to serve as a synchronous condenser, the benefits are even more significant at nearly Rs 4,000 crore,” it added.

Ashish Fernandes, CEO, of Climate Risk Horizons said that Tamil Nadu has a large fleet of coal power plants but not has been utilised fully.

“Even during the pre-COVID, the plant load factor is less than 60 per cent. The state has about 3,000 MW of ageing coal plants which are over 30 years old. These plants have to be retired soon or retrofitted. “Instead we are suggesting shutting down of these power plants in the coming years, they could be repurposed with cheaper solar power plants,” he said.

For power utilities like Tangedco, which owns old thermal power plants, he said that repurposing coal plants offers many advantages. “Repurposing reduces decommissioning costs because it allows partial re-use of existing assets such as the degraded land as well as the generators, substations and grid connections. Second, it reduces the cost of commissioning solar PV plants at the same site with much cheaper generation costs,” he said. Repurposing coal plant equipment allows for retaining a part of the reactive power service for voltage control originally provided by the coal plant, he said.

Fernandes said that given variable costs ranging from Rs 3.3 to Rs 4.4 per unit, these coal plants are no longer cost-competitive compared to new renewable energy. The utilisation of pre-existing land and grid connections facilities would result in a significantly reduced cost for the power generated for standalone solar and solar with battery storage. This would bring the levelised cost of solar energy down to Rs 1.42 per unit and Rs 2.33 per unit,” he said, adding that the quantum of energy generated through solar would not match thermal power generation, but would provide financial benefits to the utility.