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Energy storage is a necessary design consideration to address intermittent generation on islanded, renewable microgrids. Using renewable energy in excess of immediate demand, Liquid Air Energy Storage (LAES) can produce and cryogenically store liquefied air for recovery and power generation later. While LAES has been demonstrated for large-scale energy storage, current designs use heat exchangers, expansion turbines, and co-located industrial processes. This study explores the use of simpler, low-pressure equipment, which may be suitable for smaller-scale applications. A prototype using a Stirling cryocooler for liquefaction, a vacuum dewar for storage, and a Stirling engine for energy recovery was built, tested, and analyzed. This paper focuses on quantifying the liquid air production for the prototype. A series of experiments was ran to gather data on liquid yield as a function of time for different power settings, dewar sizes and dewar shapes. An empirical relationship, useful for modeling, simulation, and design, was developed. Future work will include design, simulation, and construction of a new prototype for a specific capability. This work is part of a larger effort to determine the feasibility of different energy storage methods for small, mobile applications as well as fixed infrastructure energy storage systems. |
