Repowering Tamil Nadu’s aging wind farms to meet clean energy targets !

<p>Tamil Nadu has thousands of old turbines below one-megawatt (MW) capacity, functioning past their lifecycle, and, according to wind sector experts, they must be repowered to meet clean energy targets.<br>Fragmented ownership of land and turbines, lack of clear and mandatory repowering policies by the state, the need to improve evacuation structures and grid, and different tariff requirements are a few of the challenges that have slowed the progress in windfarm repowering in Tamil Nadu.<br>While some wind energy developers are ready to work on recycling the old turbines if repowering begins, guidelines for recycling are needed. Ecologists recommend choosing repowering sites carefully and studying the biodiversity impacts of installing larger turbines in biodiversity-rich areas, to get repowering right.<br>In an old wind farm in the wind-rich region of Kayathar in the Thoothukudi district of Tamil Nadu, there are 30 wind turbines, each with a 200-kilowatt (kW) capacity. Many of these turbines are nearing the end of their lifecycle of 20-25 years. Generally, the wind turbine generators (WTGs) at the end of service life exhibit high breakdown rates, require repairs, and are likely to suffer from a shortage of relevant replacement parts as the technology has improved significantly over the years.</p><p>What if these turbines could be removed and replaced with the latest technology WTGs that are taller and more efficient? The six megawatts (MW) wind power plant would then generate 16.2 MW, finds a 2021 study that conducted an economic investigation of repowering existing wind farms, with Kayathar as a case study.</p><p>This is just one old farm; if all the old wind farms in the southern Indian coastal state with rusty turbines and obsolete/low functioning components were to be removed and replaced with newer turbines, it would be a huge boost in terms of renewable targets. However, Tamil Nadu has thousands of turbines installed before the year 2000, with less than 550 kW capacity and the state faces many challenges in repowering.</p><p>What is repowering of wind farms?<br>Repowering of wind farms means replacing older turbines which have mostly completed their lifecycle of 20-25 years (or are nearing their end), with newer and larger turbines which have increased energy capacity and efficient designs; the first-generation turbines can be replaced with multi-megawatt turbines. The hub height of these turbines would be longer, and the blades would be larger with an optimised design.</p><p>Through the years, the technology has improved, and the wind farms located in Tamil Nadu, that were installed in the 1990s, are functioning below their capacity. The obsolete components in these turbines result in significant maintenance costs and time inefficiencies, and increased downtime, which lowers average energy production, says the study. Looking into the future of these old wind farms is crucial because not only have they completed their life cycle, but they also occupy the best wind sites of the state.</p><p>It was in 2016, that the Union Ministry of Renewable Energy (MNRE) released a policy for ‘repowering’ of the wind power projects in India. The policy stated that initially, the wind turbine generators of one-megawatt capacity and below would be eligible for repowering. Each state’s nodal agency or the organisation involved in the promotion of wind energy in the state was in-charge of implementing repowering plans. Six years later, Tamil Nadu, with the country’s oldest onshore windfarms, is yet to start repowering.</p><p>Tamil Nadu is home to about 25 percent (close to 9.86 gigawatts) of India’s total installed wind power capacity of 40.35 GW. Moreover, India aims to install 140 GW of wind power capacity by 2030. TANGEDCO, the Tamil Nadu electricity distribution company aims to install 24 GW of onshore wind by the year 2050 with ‘determined effort’. To meet this target and lead by example for other states, Tamil Nadu must take the right steps forward in repowering, according to wind energy experts.</p><p>A close-up image of a new wind turbine seen in private wind farm in Thoothukudi district, Tamil Nadu. Photo by Narayana Swamy Subbraman/Mongabay.<br>Improved energy capacity<br>“Repowering basically means that, old turbines will be uprooted and replaced with newer turbines. The old machines generate less energy and the new ones that come with an increased hub height and a larger rotor diameter, can harvest wind energy with increased electricity generation. In many cases, in the place of 20 turbines, around three to four turbines would be enough,” said K. Balaraman, Director General, National Institute of Wind Energy (NIWE), while explaining the benefits of repowering .</p><p>According to a 2018 study, supported by MNRE, in India more than 10 GW of old wind turbines with less than 1 MW capacity are installed in wind-abundant sites. Repowering these sites with modern turbines will quadruple the energy generation. However, there is no state-specific repowering policy in Tamil Nadu, although the MNRE’s repowering policy says that states would implement these plans.</p><p>What is the state government’s stance? In 2021, the Tamil Nadu Electricity Regulatory Commission (TNERC) issued a clarification on MNRE’s repowering policy replying to some frequently asked questions by different stakeholders. It said that “TANGEDCO and the State are benefited by way of optimum utilisation of natural resources and existing Transmission Infrastructure erected by way of realising additional generation,” recognising the benefit of repowering. However, the TNERC also said that “TANGEDCO does not intend to make the repowering procedure mandatory as has been understood by many of the stakeholders. It is an option left to the generator.”</p><p>Therefore, since repowering has not been made ‘mandatory’ it is being left to the choice of the wind turbine owners to decide whether old turbines need to be repowered.</p><p>Wind turbines in one of Asia's largest wind farms along the Tirunelveli-Kanyakumari state highway roads in Tamil Nadu. Old windfarms when repowered, produce a lot more energy, which will help India meet its renewable energy targets.</p>