A Comparative Review of the Lubrication of Bearings in Wind Turbines and Spacecraft to Address Wind Turbine Bearing Failures

Wind turbines have improved in terms of reliability over the past ten years, but they still experience crucial and expensive tribological issues that shorten their intended lifespans. Most turbines require significant repairs or complete replacements of the tribo components in the 5- to 7-year range. The pricey gearboxes have high repair rates, which greatly raises the operating costs for wind turbines and the cost of wind energy. Currently, various bearings in the turbine are lubricated by automatic lubrication systems with the necessary oil filters to ensure cleanliness. The commonly used lubrication methods for wind turbine bearings are centralized lubrication, oil-air lubrication, oil mist lubrication, and oil bath lubrication. There are similarities between wind turbines and spacecraft-moving mechanical systems. Most spacecraft are designed to work for decades in a remote environment without periodic maintenance. Spacecraft use efficient lubrication systems for their moving mechanical systems to provide the required lubricant to the bearings for the required life. Depending on the lubrication requirements, proven active and passive lubrication systems are employed in spacecraft. This paper reviews the lubrication issues of the wind turbine in comparison with the spacecraft and proposes a few lubrication systems that are successfully performing in spacecraft, intending to improve the reliability of wind turbine tribo-systems.