2009 Energy Prize First Runner Up

Wind turbines operate under a wide range of weather conditions which directly influence the temperature and loading on mechanical components. These natural variations have been shown to cause a large number of the reliability problems in modern wind turbines. Of these, nearly one-third occur in components that are heavily lubricated. This concept proposes a new type of lubricant called Gas-Expanded Lubricants (GELs) with properties that could be changed in response to prevailing weather conditions.

Conventional lubricants are petroleum-based mixtures with characteristics, such as viscosity, that tend to decreases with temperature. GELs are binary mixtures of lubricants and liquid carbon dioxide whose characteristics can be tuned dynamically by controlling the pressure or composition of carbon dioxide in the mixture. In this fashion, GELs can decouple temperature and viscosity as well as other important properties that protect wind turbine components. The synthetic lubricants envisioned for GEL applications could be derived from either petroleum or bio-based sources.

Preliminary experimental results confirm that CO2 pressure and composition are directly related to dynamic viscosity of the mixture. The experimental results hold over a range of shear rates, which is important in mechanical components. Modeling results demonstrate that GELs could reduce power losses through some bearings by as much as 20%. There are secondary benefits associated with heat dissipation that could assist in protecting mechanical devices. This technology could represent a transformative technology in wind turbines, subsequently improving the effectiveness of the nation’s wind power sector.

About the Finalist:

Andres Clarens is an assistant professor of civil and environmental engineering at the University of Virginia and the Director of the Virginia Environmentally Sustainable Technologies Laboratory. His research focuses of pollution prevention and green engineering with an emphasis on reducing greenhouse gas emissions from manufacturing, power and transportation systems. He has more than eight years of experience applying his formal training in surface chemistry to problems in metalworking, coal-fired power production and carbon sequestration. He has been particularly interested in the use of high-pressure mixtures of bio-based lubricants and gases as an alternative to petroleum and water mixtures in various applications.

In his spare time, Professor Clarens enjoys running, backpacking, fly-fishing and traveling. He holds a B.S. in Chemical Engineering from the University of Virginia and an M.S.E. and Ph.D. in environmental engineering from the University of Michigan. He has also served in the United States Peace Corps developing water drinking systems for rural villages on the Dominican/Haitian border.