Woodruff School of Mechanical Engineering


Storing Wind Energy with Fluid Power


Dr. Perry Li


University of Minnesota


Monday, December 3, 2012 at 3:00:00 PM


Love Building, Room 210


Richard Salant


Wind, as an energy resource, is renewable, abundant, clean, and free. Yet, wind is un-predictable and when it is available and when there is demand do not often coincide. These characteristics make it difficult to integrate wind into the electric grid and cause the wind turbine installations to be under utilized (capacity factor <50%). If energy storage can be incorporated into wind installations, electrical output will become reliable (and more valuable), energy in excess of demand can be captured, and electrical components become more fully utilized. This talk will discuss an ongoing NSF funded interdisciplinary research on a scalable and potentially cost effective novel compressed air energy storage system for this application. In contrast to conventional compressed air energy storage approach, the proposed system does not require additional fuel but utilizes a near isothermal liquid piston air compressor/expander. The “open accumulator” system operates at near constant pressure and makes use of the energy density advantage of pneumatics and the power density advantage of hydraulics. A key challenge relates to the trade off between efficiency and power density of the air compressor/expander which are functions of heat transfer. Three approaches to enhance efficiency and power density are being investigated: 1) optimal control trajectories, 2) porous material and 3) water sprays. The design and efficacies of these approaches will be discussed.


Perry Li is Professor of Mechanical Engineering at the University of Minnesota and Deputy Director of the NSF Center for Compact and Efficient Fluid Power. He received his B.A./M.A. (in Electrical and Information Sciences) from Cambridge University in 1987, M.S. (in Biomedical Engineering) from Boston University in 1990, and PhD (in Mechanical Engineering) from University of California, Berkeley in 1995. Prior to joining the University of Minnesota, he was on the research staff at Xerox Corp. He received the Japan/ USA Flexible Automation Young Investigator Award in 2000. In 2011-2012, he was “High Level Overseas Expert” (Visiting Professor) at Zhejiang University, China. Dr. Li’s research interests are in control and mechatronic systems, robotics, fluid power and imaging systems. Beside wind energy storage project, his current research projects include: hydraulic hybrid vehicles, fluid powered human interactive robotics, hydraulic transformers, digital displacement pump/motors, hydraulic surgical robots, control of remotely operated underwater vehicles.


Refreshments will be served.