GOALI/EFRI-RESTOR Novel Compressed Air Approach for Off Shore Wind Energy Storage

The research is focused on developing a localized compressed air approach for storing excess energy from off-shore wind turbines to dramatically alleviate power supply and demand imbalances during the day. In the current approach, the energy prior to electricity conversion is stored, and an efficient compressor/expander that operates nearly isothermally is used directly for energy storage and extraction. This novel approach avoids losses associated with multiple conversions and allows the electrical generator and the transmission lines to be substantially down-sized. The key missing enabling technology for this approach is an efficient and power dense pneumatic (air) compressor/expander capable of very high pressure ratios. In this project this compressor/expander design combines a liquid piston concept and the active spraying of tiny water droplets to achieve its heat transfer requirements. To ensure high efficiency in the presence of high surface areas and flow velocities, a nanotextured surface will be employed to reduce the frictional drag on the liquid piston. Control methodology will be developed to optimize components? and overall system efficiencies. The research will make fundamental contributions to these individual fields such as: multiphase convective heat transfer in a coupled matrix media and with droplets and mist; dynamics of liquid/air free surface; nanotextured surfaces for drag reduction; a new generation of efficient wind turbine power generators that operate with sea / lake water; and optimal control of complex systems. In terms of the broader impacts, by allowing economical storage of excess energy, the research will significantly increase the energy available from off-shore wind turbines where currently available economical options for energy storage are not feasible. This will be a major step towards the US goal of deriving 20% energy from wind by 2030. Active participation by the industry partner enhances the pace of production and market adoption. The engineering system focus and interdisciplinary nature of the research will impact undergraduate and graduate engineering curriculum and will be employed in the education of a new generation of engineering researchers and practitioners with broad skill and interdisciplinary perspectives on problem solving. This project will benefit, in research, education and outreach, from close collaboration with the NSF Engineering Research Center for Compact and Efficient Fluid Power and the newly formed DOE funded Wind Turbine Research Consortium at the University of Minnesota.

The FY 2010 EFRI-RESTOR Topic that supports this project was sponsored by the US National Science Foundation (NSF) Directorates for Engineering (ENG), Mathematical and Physical Sciences (MPS) and Social, Behavioral and Economic Sciences (SBE), and Computer & Information Science and Engineering in collaboration with the US Department of Energy (DOE).