Citation: Rajabdorri, M.; Sigrist, L.; Lobato, E. Liquid Air Energy Storage Model for Scheduling Purposes in Island Power Systems. Energies 2022, 15, 6958. https://doi.org/ 10.3390/en15196958 Academic Editors: Thomas Kienberger and Sonja Wogrin Received: 5 September 2022 Accepted: 20 September 2022 Published: 22 September 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). energies Article Liquid Air Energy Storage Model for Scheduling Purposes in Island Power Systems Mohammad Rajabdorri * , Lukas Sigrist and Enrique Lobato Instituto de Investigación Tecnológica (IIT), Universidad Pontificia Comillas, 28015 Madrid, Spain * Correspondence: mrajabdorri@comillas.edu Abstract: Moving towards clean energy generation seems essential. To do so, renewable energy penetration is growing in the power systems. Although energy sources such as wind and solar are clean, they are not available consistently. Using energy storage will help to tackle variability. Liquid air energy storage is gaining attention among different energy storage technologies, as it is a promising option for grid-scale energy storage. This paper presents a detailed mixed integer linear model of liquid air energy storage to be used in scheduling and planning problems. A comprehensive cycle diagram of different processes of liquid air energy storage is presented, and a model has been developed accordingly. Simulations of the proposed model are carried out for the power system of Tenerife island and compared with the basic models. Basic models overlook specific characteristics of liquid air energy storage systems, such as charging and discharging start energy. Results confirm that the use of simple models will lead to misleading conclusions and overestimate the economic benefits of liquid air energy storage. Keywords: LAES; energy storage; renewable generation; unit commitment problem 1. Introduction Generating electricity has been reliant on burning fuels for decades. Although thermal generation is cheap, it emits a considerable amount of greenhouse gasses, which have negative environmental impacts. To go towards cleaner ways of generating electricity, the share of renewable energy sources (RES) is increasing in the power systems in the recent decades. Contrary to the thermal generation that can provide as much as it is demanded, renewable sources only produce energy when they are available. The abundance of avail- able renewable energy might happen in low-demand hours, or there might be a lack of renewable production in high-demand hours. To use available RES more efficiently, it is wise to store energy when there is a surplus and inject it when required. Different types of energy storage systems (ESS) are used in the power system, including electrochemical and battery, thermochemical, flywheel, compressed air, liquid air, magnetic, etc. [1]. There is a wide range of benefits that can be expected from energy storage systems, including load balance when the demand changes, providing additional energy to end- users during overload situations, and storing the excess energy of RES to minimize CO 2 emission [2]. In [3], a demand management model for industrial parks considering the integrated demand response of combined heat and power (CHP) units and thermal storage is proposed to reduce the peak demand charge. Among different technologies, liquid air energy storage (LAES) seems promising for large-scale energy storage. Chemical energy storage systems, such as batteries, have the highest efficiency, but their short lifetime makes them expensive. In addition, they should be recycled when their life is over, which has negative environmental impacts. Large-scale mechanical storage systems such as pumped hydroelectric energy storage (PHES) and compressed air energy storage (CAES) have geographical limitations, as they need big vessels or underground caverns. These disadvantages of other technologies have led LAES Energies 2022, 15, 6958. https://doi.org/10.3390/en15196958 https://www.mdpi.com/journal/energies