Renovation and modernisation (R&M), and life extension (LE) are cost-effective alternatives to improve the generation capacity of thermal power plants (TPPs), especially when asset life is nearing its time. A large number of thermal units, including the 200 MW/210 MW units, are old and have outlived their useful life. The R&M of such units is essential for improving the overall performance as well as for helping the plants comply with environmental norms. R&M is an important part of asset management; it is low on cost and has a short gestation period. Meanwhile, LE pertains to older thermal power units and plays a pivotal role in extending their useful life by 15-20 years. R&M/LE activities include life extension, improved safety, reliability and compliance with environmental norms.
During 2022-23, Unit 13 (200 MW in capacity) of the Obra TPS, owned by UPRVUNL, underwent R&M/LE works under the Central Electricity Authority’s (CEA’s) R&M programme. During the five-year period 2017-22, a total capacity of 1,197 MW (see table) underwent R&M/LE works in the state and central sectors. Meanwhile, the flexibilisation of TPPs, done in order to balance the variability and intermittency of renewable power generation, forms a vital part of R&M/LE as well. Plant operators are looking at modifications required for low load operation/high ramping for flexible operation. Hence, plants are undertaking studies to create scope for flexibilisation post CEA recommendations and corresponding release of roadmaps, and are being guided by a special task force on flexibilisation with NTPC, the CEA, POSOCO and BHEL on board.
Flue gas desulphurisation (FGD) installations form another crucial part of R&M, which makes the renewed plants more environment friendly. As of March 2023, 9,280 MW (22 units) of thermal power capacity has completed FGD installation, of which 2,330 MW (7 units) of capacity belongs to the central sector and 6,950 MW (15 units) belongs to the private sector.
R&M challenges
While R&M/LE has been a priority programme for the government for over three decades and offers numerous benefits for ageing TPPs, many challenges continue to dampen the progress and discourage gencos from engaging in R&M programmes. Establishing techno-economic viability is a major challenge and needs a thorough cost-benefit analysis as well as expert advice to create a feasibility report.
The scope of work is not well-defined, which often results in a skewed risk-benefit analysis. R&M practices are impacted by poor O&M practices that threaten the sustainability of R&M projects.
Challenges in design, procurement, execution and final acceptance may surface due to the inherent complexities of the process. An R&M design that accounts for past experiences and technical specifications for meeting the parameters mentioned in the environmental norms is needed. The regulatory mechanism needs to accommodate sequential equipment supply and should focus on availability of additional items.
Contracts are not well-structured and the vendors and contractors face a tough time to get things moving due to challenges such as volatile prices, increasing working cost and complex government specifications. There is a shortage of skilled workforce which along with other factors ends up delaying the completion of R&M works. Due to these challenges, there is lack of incentive for utilities to undergo the tedious process of R&M.
Roadmap for utilities
As per the CEA and Central Electricity Regulatory Commission guidelines, the normal economic life of a TPP is 25 years. However, adopting R&M can help regain the performance of units. Planned interventions to identify, augment and replace plant components that affect safety, reliability and efficiency can effectively extend the life of an ageing plant and restore the original performance.
For instance, as per a Lok Sabha report, there are around 79 TPPs that have completed 25 years. Of these, 52 units are over 30 years old and four are over 50 years old. Most of these units have either undergone R&M/LE procedures or are still undergoing R&M.
NTPC has robust O&M practices that were devised over years resulting in minimum degradation of performance even after the design/useful life of a plant is over. The company engages in R&M activities from time to time by adopting modern technologies and replacing aged equipment to maintain the performance level of the plant. NTPC does not retire its assets until it is absolutely necessary as in the case of the Badarpur TPS.
As a result of these efforts, the old units established by NTPC are well maintained and still among the best performing units of the country. The oldest unit of the NTPC fleet is the 38-year-old Singrauli Unit 1. Commissioned in 1982, it recorded a PLF of 100.24 per cent, the highest in India. The company made significant investments in these units to ensure compliance with new emission norms.
NTPC has also acquired a number of stressed assets in the past decade and carried out R&M for performance improvement. The Patratu TPS in Jharkhand and Barauni TPS in Bihar are the key projects that have shown remarkable improvement.
Future outlook
In a recent letter issued in January 2023, the CEA advised gencos against retiring thermal power units, urging them to carry out R&M for life extension and improving the flexibility and reliability of thermal power units. This is in lieu of the expected demand scenario and availability of capacity in the future. While 15-16 GW of new thermal power capacity is expected to come online by December 2023, the government has urged gencos to commence residual life assessment and other pre-R&M related preparatory works in the meantime.
As per the CEA’s phased plan, around 149 old units with a total capacity of 38,360 MW have been earmarked for R&M/LE works. As per Phase I of the plan, all units over 30 years are proposed to undergo R&M/ LE works by December 2026. In Phase II, thermal units between 25 years and 30 years should undergo R&M by December 2028 while units between 20 years and 25 years should complete the process by December 2030.
Conclusion
With the government’s increasing focus on R&M/LE works and attention to supply chain, more and more vendors will find the market favourable especially for complementary projects such as FGD.
R&M is crucial to the current power sector situation when renewable energy integration is a bigger challenge facing the country. R&M/LE works will reduce capex, which can be redirected to renewable energy integration. R&M can provide the reliability which the transition to renewable energy lacks. With newer technologies, the process can become smoother and help in reaching the goal of net zero.