  Citation: Menezes, M.V.P.; Vilasboas, I.F.; da Silva, J.A.M. Liquid Air Energy Storage System (LAES) Assisted by Cryogenic Air Rankine Cycle (ARC). Energies 2022, 15, 2730. https://doi.org/10.3390/en15082730 Academic Editors: Yongliang Xie and Shimao Wang Received: 23 February 2022 Accepted: 7 April 2022 Published: 8 April 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 System (LAES) Assisted by Cryogenic Air Rankine Cycle (ARC) Mylena Vieira Pinto Menezes 1, * , Icaro Figueiredo Vilasboas 1 and Julio Augusto Mendes da Silva 2 1 Industrial Engineering Program (PEI), Federal University of Bahia, Salvador 40210-630, Brazil; icaro.vilasboas@ufba.br 2 Department of Mechanical Engineering, Federal University of Bahia, Salvador 40210-630, Brazil; julio.silva@ufba.br * Correspondence: mylenavmenezes@gmail.com Abstract: Energy storage plays a signiﬁcant role in the rapid transition towards a higher share of renewable energy sources in the electricity generation sector. A liquid air energy storage system (LAES) is one of the most promising large-scale energy technologies presenting several advantages: high volumetric energy density, low storage losses, and an absence of geographical constraints. The disadvantages of LAES systems lay on the high investment cost, large-scale requirements, and low round-trip efﬁciency. This paper proposes a new conﬁguration using an air Rankine cycle (ARC) to reduce the exergy destruction during heat-exchanging in the liquefaction process while reducing liquefaction power consumption. The addition of the ARC increases the round-trip efﬁciency of the LAES from 54.1% to 57.1%. Furthermore, the energy consumption per kg of liquid air drops 5.3% in comparison to the base case LAES system. The effects of compression, storage, and pumping pressure on the system performance are investigated by parametric analysis. The results from exergy analysis show that the overall exergy destruction is decreased by 2% and a higher yield of liquid air can be achieved. The results reveal that the increase in the yield of liquid air is more important to the overall efﬁciency than the power that is generated by the Rankine itself. From an economic viewpoint, the proposed system has a better economic performance than the base case LAES system, decreasing the levelized cost of storage (LCOS) by almost 2%. The proposed conﬁguration may improve the performance and economic competitiveness of LAES systems. Keywords: cryogenics; cryogenic energy storage; liquid air energy storage; cryogenic Rankine cycle; round-trip efﬁciency; exergy analysis 1. Introduction Nowadays, there has been an intense adoption of renewable energy sources, especially solar photo-voltaic (PV) and wind power, aiming to achieve deep decarbonization in the en- ergy sector. According to estimates from the International Energy Agency (IEA), renewable energy sources represented 27% of the total electricity generation in 2019, almost half of this is from wind and solar PV. This scenario is forecast to increase up to 49% by 2030 [1]. Such rapid incorporation of renewable sources presents challenges to the electricity grid since these sources usually operate intermittently and cannot directly provide reliable and stable power supply. Energy storage systems can signiﬁcantly mitigate the unpredictable nature of these renewable energy sources, providing predictability and also availability to the electricity grid so that a better match between demand and generation can be obtained [2]. Different large-scale energy storage solutions are currently being explored to alleviate these issues, such as pumped hydroelectric energy storage (PHES) and compressed air energy storage (CAES) [3]. However, the application of these technologies is limited by their draw- backs. For instance, PHES and CAES systems can ensure large storage capacity, but further expansion of these technologies is limited by geographical restrictions [4]. In addition, Energies 2022, 15, 2730. https://doi.org/10.3390/en15082730 https://www.mdpi.com/journal/energies