By Mukesh Singh Parihar, Assistant General Manager and Sector Head – Wind, and Kuberaganapathi V.K., Manager, Tata Consulting Engineers Limited
With India moving closer to its goal of becoming carbon neutral by 2070, many industries across the country have set goals and implemented strategies to reduce their carbon impact. The Ministry of New and Renewable Energy (MNRE) has set an ambitious goal of achieving 50 per cent of the total installed power capacity from renewables by 2030. By this time India’s peak energy demand is predicted to reach 335 GW and electrical energy requirement of 2,280 BUs. Further, by 2030, onshore wind farms would account for close to 100 GW of the anticipated 777 GW total built power capacity in the country. However, any addition in offshore wind capacity would be possible only after 2030.
India has significant wind resource, and it can meet the power needs for industrial growth and public consumption through wind energy. Over 20 years back, wind farms belonging to the public and commercial sectors were constructed at sites with exceptionally high wind potential. These wind farms, which had a model capacity of 250-800 kW, were constructed between 1990 and 2000. The National Institute of Wind Energy (NIWE) estimates that wind farms with less than 2 MW of installed turbine capacity have a repowering potential of about 25 GW. Since each wind turbine has a design life of about 20 to 25 years, wind farms that were built in the early 21st century or even earlier are now ageing. Some of them have less than five years left in their operational lifespan due to issues pertaining to component efficiency and power output reductions. Wind farm owners are forced to replace all or part of the current turbines with new, high-efficiency turbines due to the constantly changing regulatory environment and the need for high capacity utilisation factors.
Repowering of old wind turbines has been successfully performed in countries such as the UK, the USA, Spain and Denmark, by replacing either outdated turbine parts or the complete wind turbines on farms located at high wind potential sites. Repowering of wind farms gained steam after the Government of India amended its policy in December 2023, seven years after it released its initial guidelines.
In this article, we focus on the two main variables that determine wind farm capacity: the hub height of a wind turbine generator (WTG) and the distance between wind turbines. In India, the wind potential doubles merely at a height difference of 20 metres. At 100 metres, the wind potential is around 302 GW, at 120 metres, it is 695 GW, and at 150 metres, it is 1,163 GW. Therefore, using a WTG with a hub height of 120 metres or more significantly increases wind farm efficiency.
Here, the repowering concept is investigated through the process of wind resource assessment (WRA) for former wind farm locations, which involves a review of the micro-siting and new layout development. This desktop analysis compares WTG spacing of 2D x 3D–2D across the primary wind flow and 3D along the flow–with the conventional turbine spacing of 5Dx7D. Here, “D” stands for the WTG rotor diameter. In a research study, the recent 3X-WTG models have been used in conjunction with a reduced WTG spacing and a hub height of 120 metres. For this study, three distinct wind farms have been chosen, using open source data for the current wind farm and technical characteristics for the new WTG model available in windPRO, the software used for WRA.
According to the study, the plant load factor (PLF) increases by two-three times and the energy generation increases by 500 per cent or more when the spacing between wind farms is relaxed from 5D x 7D to 2D x 3D during micro-siting using the larger capacity WTG with higher hub height, within the current wind farm boundaries. The wake effects are also within allowable limits.
According to this analysis, in order to fully exploit the available wind resources and make the best use of the available areas, obsolete wind farms must be repowered. Therefore, repowering can play a major role in both maintaining the sustainability of the environment and helping India meet its 2030 target for renewable energy.
Nguồn: https://renewablewatch.in/2024/02/01/lets-repower-rationale-for-reviving-old-wind-assets/