What are the variables in O&M for on and off-shore projects?
The variables involved in the O&M for wind power projects are the wind turbine technology, size and location of wind farm and the O&M philosophy adopted, which can be either reactive, preventive or condition based maintenance. O&M for off-shore wind projects have additional variables to contend with, such as distance of wind farm from shore, wave condition (that will limit the accessibility of the turbines), logistics at the harbor (for spare parts and major components) and transfer system for O&M staff from shore to the wind farm. Advanced Condition Based Monitoring is usually adopted for off-shore wind farms aiming to increase availability and reduce the O&M costs.

How does O&M fit in the value chain?
The cost of electricity from wind has two primary components: capital cost repayments (with interest) and O&M costs. O&M costs covers a range of costs including land, insurance, servicing and spare parts (predictive, preventive and corrective maintenance), electricity purchases (import power) from grid, statutory electrical inspections, taxes, management and administration costs, and forecasting and scheduling costs. The O&M costs can account for up to 25 per cent of the project´s total life time cost for maintenance, repair and overhaul work.

How have O&M technologies evolved in India?
Current O&M strategies can be considered to fall broadly in three categories, viz. reactive, scheduled preventive and condition based/predictive maintenance. In the early days of wind power, the approach typically taken with regards to asset maintenance was ¨to run to failure¨. This approach was the result of a poorly consolidated and integrated supply chain industry. However, this is not pursued by today´s standards, even towards the end of life of a turbine. Given the large capacity of the wind farms being installed presently in India, scheduled preventive maintenance strategy has been adopted by most wind farm owners. The reason for the popularity, despite the high cost in the early life of the asset, is the ability to permit work to be planned and aligned with periods of expected low wind season and result in minimal to no impact on yield. Some IPP´s are planning to move towards a predictive maintenance strategy that combines the bene?ts of both reactive maintenance and preventive maintenance. This strategy however involves a higher CAPEX for a lowered OPEX over the turbine lifetime.

Is software a part of the O&M cycle, considering new technologies?
Enormous amount of data is generated by today´s wind turbines and wind parks. SCADA systems (for smart grids) are commonplace, providing a treasure trove of data collected by sensors fitted to the turbine. Operational data such as error logs, turbine status and operating conditions such as wind speed and direction reflect the real-time condition of a wind turbine. Continuous Monitoring Systems are used to analyse the vast amounts of SCADA data in real time to deduce the performance of the wind farm and health of turbine components. The use of software will continue to increase with the introduction of mandatory scheduling and forecasting for wind farms being planned by Load Dispatch Centers of many states.

Cost is an important consideration, so how much has the expense changed over the years?
Operation and maintenance costs vary signifcantly between projects depending largely on the service contract price and the duration of the contract. The experience of the IPP´s show that the expenses have not changed significantly over the years. The trend towards larger wind farm capacities coupled with higher component reliabilities (for major components such as blades, gear box and generator) and availability of skilled manpower has helped to stabilise the expenses. In general, the O&M expense for off-shore projects is expected to be double when compared with on-shore projects.