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College of Science & Engineering > Department of Mechanical Engineering

Compressed Air Approach for Wind Energy Storage 





We are  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. This will also make availability of wind energy more reliable, predictable and less disruptive to the electrical grid.

In our approach, energy is stored prior to electricity generation in high pressure compressed air vessel, and an efficient compressor/expander with enhanced heat transfer that operates nearly isothermally is used directly for energy storage and extraction. This  approach avoids losses associated with multiple conversions and allows the electrical generator and the transmission lines to be substantially down-sized. An open accumulator configuration is used to maintain system pressure so that efficiency and power density can be maintained regardless of how much compressed air is present in the accumulator. A hybrid hydraulic-pneumatic power transmission and storage approach to achieve high power density, high energy density and control functions.

This project is a multi-disciplinary collaboration between the University of Minnesota, the University of Virginia, and Lightsail Energy Inc.

*  A video introduction
* A one-page project overview is here.
* A two-page project overview is here
* An even longer project overview is here.



- Mohsen Saadat presented the paper, "Combined Optimal Design and Control of A Near-Isothermal Liquid Piston Air Compressor/Expander for a Compressed Air Energy Storage (CAES) System for Wind Turbines" at the 2015 ASME Dynamic Systems and Control Conference (DSCC) in Columbus, OH. The paper was selected as one of 3 finalists for the Best Energy Systems papers presented at the conference. Congratulations, Mohsen.


  • - Perry Li presented a departmental seminar on "Control for a Novel Compressed Air Energy Storage System for Wind Turbines" at the Department of Mechanical and Aerospace Engineering, Ohio State University (April 17, 2015)


  • - Perry Li presented a plenary talk on "Control for a Novel Compressed Air Energy Storage System for Wind Turbines" at the XVI Latin American Control Conference (16th CLCA) held in Cancun, Mexico (October 14-17, 2014)
- Perry Li presented the paper "Design, modeling and control of a lab- scale compressed air energy storage (CAES) testbed for wind turbines with simulated input and demand power variability" at the ASME Dynamic Systems and Control Conference held in San Antonio, TX (October 22-24, 2014). The lead author of the paper is F. Shirazi.

  • - Jacob Wieberdink (ME, UMN) successfully passed his M.S. defense. Congratulations, Jake. He will be working at Cummins in Indiana.

  • 2014.7
  • - Eric Loth attended the 2014 Offshore Energy and Storage (OSES) Symposium in Windsor, Canada and presented two talks: 1. Economic benefits of hydraulic-electric energy storage wind turbine; 2. Tower mass savings and energy storage capacity of hydraulic-electric hybrid wind turbines.


  • - Terry Simon presented the key-note speech "Thermal Analysis of a Compressor for Application to Compressed Air Energy Storage" at the 2nd International Workshop on Heat Transfer Advances for Energy Conversion and Pollution Control, Xi'An China.

Doctoral student Mohsen Saadat won 2nd prize ($2500) for the Dow Sustainability Innovation Student Challenge Award (SISCA).

- Bo Yan (ME, UMN) successfully passed his M.S. defense. Congratulations, Bo. He will be working at Cummins in Indiana.

  • - In conjunction with the Science Museum of Minnesota, a group of senior Mechanical Engineering students at the University of Minnesota successfully created and demonstrated an Open Accumulator Compressed Air Wind Energy Storage exhibit. Congratulations to Pieter Gagnon, Pul Hilsen, Joseph McFarland,  David Vetter, Eric Mevissen, and Eric Oftedahl. The exhibit was displayed at the Annual Senior Design Show and at the NSF Center for Compact and Fluid Power Site Visit (on 5/25/12). It is currently being upgraded and will be displayed in the Science Museum of Minnesota soon. Check out the YouTube video here.

- NSF EFRI Grantee conference 3.8.2012 was held in Arlington VA where we presented a poster.
- All hands workshop 3.9.2012 was held at the University of Virginia, Charlotteville, VA. Thirteen of the team attended. Here are some photos (Pict1, Picts2)

- We had a successful all-hands workshop on November, 11, 2011 at the University of Minnesota. About 20 investigators, researchers and students attended.
- Andrew Rice graduated with his M.S. Congratulations.

- Andrew Rice presented a paper entitled: Optimal Efficiency-Power Tradeoff for an Air Motor/Compressor with Volume Varying Heat Transfer Capability" at the Joint 2011 ASME DSCC and Bath Symposium on PTMC.

- Prof. J. Van de Ven and student Shawn Willheim joined the University of Minnesota. Welcome Jim and Shawn!

- Perry Li, Eric Loth, Moshen Saadat, Chao Zhang and Chri QIn attended the 2011 NSF-EFRI Grantee Meeting in Arlington, VA.

- NSF-EFRI Project kick off meeting at Lightsail Energy, Oakland, CA. The project PIs together with Andrew Rice (UMN) and Shawn Willheim (WPI) attended.

- Our team is one of the four awardees (out of 84 entries) for the NSF EFRI-RESTOR awards. See the press release.


The project is funded by the National Science Foundation's Emerging Frontier in Research and Innovation Program (NSF-EFRI #1038294) under the 2010 topic of Renewable Energy Storage (RESTOR); the University of Minnesota's Institute of Renewable Energy and the Environment (IREE Grant# RE-0027-11); and the NSF Center for Compact and Efficient Fluid Power (CCEFP).

   NSF                     IREE                     CCEFP   

  Contacts: Prof. Perry Y. Li
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