CEE April-June 2012

Wind REPOWERING WIND PLANTS Strong case for efficiency improvement Ramesh Kymal, Chairman and Managing Director, Gamesa Wind Turbines Private Umifed The Indian wind energy market is more than 25 years old and the cumulative installed capacity has reached 16 GW over this period. The market has received an impetus in the last decade due to the increasing need for power, supportive regulatory policies, large foreign direct investments and the entry of several international wind turbine manufacturers. Growth was limited during 1986-2000, but a significant number of wind electricity generators (WEGs) were installed at the best available wind locations during this period. These first-generation turbines are highly inefficient as compared to the current breed of turbines. With increasing power demand and a decrease in the number of high-wind sites, especially in states like Tamil Nadu, there is an urgent need for optimizing the available resources. Repowering, which involves the replacement of old turbines with the current best-in-class equipment, is a key solution in this context. Over 4,600 turbines rated below 500 kW and operational for more than 10 years are ideal for repowering. Currently, such turbines in India have an aggregate capacity of 1.6 GW, which is 9 per cent of the total installed wind capacity and located at sites with excellent wind parameters (wind power density of more than 300 watt per square metre at a height of 50 m). The market available for repowering is valued at about $3.8 billion. Old projects aggregating 500 MW-1 ,000 MW could be repowered with high levels of success. Benefits and challenges Repowering leads to better utilization of wind– rich sites through the installation of latest technology models and improves the capacity utilization factor to 25-30 per cent (almost two to three times the current plant load factor [PLF] of old turbines). Also, the total cost of repowering a site is 20 per cent lower than that for greenfield installation. Moreover, the process does not require any permits or approvals. The return on investment is considerably improved by repowering old wind sites - through an increase in energy production and the renewable energy certificate mechanism. In addition, repowering reduces the noise produced by turbine operations and facilitates grid integration as modern turbines comply with grid code standards as well as demonstrate improved performance in erratic grid conditions. However, repowering is a relatively new concept in India, and, therefore, faces implementation challenges. Most of the turbines were installed a decade ago under power purchase agreements that were signed for 20 to 25 years. There are no exit clauses to retract these agreements before their expiry. The ownership of wind farms has a complex structure - a multitude of owners leads to complications. Moreover, additional costs are associated with decommissioning , transportation and disposal of turbines, all of which have to be factored into the repowering process. While on the one hand repowering involves additional costs, on the other, there are no incentives available for undertaking it. Consumers are also hesitant about replacing their existing turbines with new equipment. In this situation, specific guidelines or mechanisms to make repowering more attractive are required. Repowering initiatives Super Sales India, a part of the Lakshmi Machine Works Group, joined hands with Gamesa to implement Project Avatar, the first repowering project in India. The existing wind farm at Kethanur village of Tamil Nadu consisted of 29 units of 300 kW turbines and two units of 500 kW turbines. Gamesa recommended that 11 of the 300 kW turbines could be replaced with four units of Gamesa G58-850 kW machines, which would improve the overall performance and output. The first phase of this project was undertaken in March 2011. In July 2011 , another repowering project was commissioned in Aralvoimozhi, where 11 turbines - 10 units of 250 kW and one of 225 kW - were replaced by three units of the Gamesa G52-850 kW turbine. With the installation of the large diameter turbine, power generation more tan doubled from 12.5 MUs to 30 MUs at an average PLF of 27 per cent. To incentivise repowering, the Indian Wind Turbine Manufacturers Association has recommended the following: • The cost of shifting old turbines and retrofitting can be set of against the income generated over five years • Exporting old turbines to developing nations • Providing generators additional tariffs over the current tariffs. 43