Wind energy accounts for a major share of renewable energy capacity in India. The current installed capacity is over 25 GW, which is the fourth largest in the world after China, the US and Germany. Most of the wind turbines installed till 2000 are of below 500 kW capacity. It is estimated that over 3,000 MW of capacity installations comprise wind turbines of 500 kW or below. These turbines are located at premium locations, which have huge wind power potential. However, due to the smaller capacity of these turbines, the actual potential of these sites has not been tapped effectively. In order to optimally utilise the country’s wind energy resources, repowering is required.
Repowering of wind turbines is a process wherein first-generation small-capacity wind turbines are replaced with advanced high-capacity wind turbines. It not just provides an opportunity to increase the installed capacity and electricity output, but is also an economically viable solution. This is possible because there is no need to acquire new land and hence no costs are associated with site-related activities. The typical wind turbine generators (WTGs) that can be repowered are those that have completed at least 12-14 years of their service life.
Modern wind turbines make better use of the available wind energy, thus improving the efficiency of the wind farm and lowering operating costs. These turbines operate more consistently and achieve a greater number of full load hours. In addition, the turbines rotate at much lower speeds, which reduces noise levels and draws low reactive power. The grid integration of modern wind turbines is similar to that of conventional power plants and is able to fulfil the grid code requirements.
Draft policy for repowering of wind power projects
In a bid to encourage the optimum use of the wind energy resources, the Ministry of New and Renewable Energy has come out with a draft policy for repowering wind power projects. Under the policy, WTGs with a capacity of 1 MW and below would be eligible for repowering. Further, the Indian Renewable Energy Development Agency (IREDA) will provide an additional interest rate rebate of 0.25 per cent for repowering projects. This will be over and above the interest rate rebate available for new wind projects being financed by IREDA. Benefits such as accelerated depreciation and generation-based incentives would also be available for such projects. The new policy is expected to immediately benefit about 3,000 MW of installed wind capacity in projects using turbines of 500 kW or less.
Challenges and the way forward
Several factors govern the decision to repower wind projects. One of them is stakeholder consultation. It is necessary to identify and engage concerned stakeholders such as owners of wind farms, original equipment manufacturers, project developers, financial institutions, regulatory bodies, nodal agencies, landowners, and operations and maintenance agencies to arrive at a workable business model. One of the major challenges facing repowering is multiple ownerships, which also acts as an impediment. Therefore, the engagement of key project proponents is a crucial factor. Another factor is single-window absence of it. Given that many approvals and permissions are required from the regulatory bodies, having a single-window clearance mechanism would avoid delays in obtaining approvals.
Another important factor influencing the decision is the revenue sharing mechanism. The power procurer (which could be a state utility or a third party) may not be interested in discontinuing the power purchase agreement before the stipulated time. Therefore, solutions need to be worked out for such challenges before repowering can be taken up.
There is also a need for grid augmentation. The existing wind turbines are connected at the 11 kV and 22 kV feeders. However, the repowered wind farms will have to be connected at a higher level (110/230 kV) since modern turbines are designed for higher grid integration, thereby minimising losses.
Although the country’s wind power capacity is the fourth largest in the world, the capacity utilisation factor of wind projects is abysmally low at below 30 per cent. Repowering will ensure better capacity utilisation of these projects at a lower cost. The government’s initiatives in this direction are likely to give a further impetus to this alternative. N