Stochastic optimal sizing of integrated cryogenic energy storage and air liquefaction unit in microgrid

This paper investigates the optimal sizing of cryogenic energy storage (CES) in a microgrid (MG). Nowadays, energy storage units have been considered as a viable solution to solving the peak load problems and output power fluctuation of renewable energy resources. At this paper, the CES technology has been presented as large-scale energy storage. In the CES process, the cryogenic liquid (nitrogen and oxygen) is used for storing the energy of electricity. The CES recovers electricity by expanding the cryogen liquid in peak periods. In this respect, the optimal sizing problem of adding CES to an existing air liquefaction unit (ALU) in an MG system is investigated in order to minimize storage unit investment cost as well as the MG operation cost. The problem is modeled as a two-stage stochastic optimization problem and is solved by general algebraic modeling system, in which the pool price market, MG load and wind speed are considered as stochastic parameters.