(230d) Optimization of Liquid Air Energy Storage Systems in Future US Electricity Markets

Grid-scale energy storage demand is increasing due to the growing adoption of renewable energy sources, which are intermittent and necessitate reliable storage solutions to ensure a continuous and stable power supply [1]. Pumped hydro energy storage and compressed air energy storage currently supply over 96% of global grid-scale energy storage capacity; however, due to their location-constrained nature, they both face severely limited expansion opportunities [2]. Thus, alternative grid-scale energy storage solutions, such as liquid air energy storage (LAES), are sought to meet growing demand.

LAES is a clean and scalable long-duration energy storage technology capable of delivering multiple gigawatt-hours of energy storage. All LAES systems operate by following the same basic steps as outlined in Figure 1. First, air is taken from the atmosphere at off-peak times to charge the system. The influent air is cleaned and dried before it is compressed to high pressure and cooled to a liquid state in an air liquefaction unit. The liquid air is then stored at low temperature (∼ 90 K) and atmospheric pressure in insulated tanks. Small energy losses of around 0.1-0.2% of the storage tank’s total energy capacity per day enable long-duration storage for up to several weeks [3]. The system is discharged through the power recovery unit, within which liquid air is pumped from the storage tank to high pressure, evaporated, heated, and expanded to drive a generator to recover power. The round-trip efficiency of this process is enhanced through implementation of hot and cold thermal recovery systems throughout the process. Since the LAES process does not depend on the presence of any specific geography, and the components required to construct it (e.g., compressors, turbines, multi-stream heat exchangers, etc.) are readily available from existing industries, these systems can be constructed quickly in virtually any location where a small plot of land is available.

The inherent locatability of LAES systems unlocks nearly universal siting opportunities for grid-scale storage, which were previously unavailable with pumped hydro energy storage and compressed air energy storage. While the technical viability of LAES has been well established through several academic studies and industrial ventures reporting round-trip efficiencies above 60%, the economic viability of LAES has not yet been rigorously assessed across a broad range of electricity markets [2].

In this work, a mixed integer linear program was used to conduct a high-level economic analysis of LAES systems in eighteen US electricity markets under eight different decarbonization scenarios proposed by the National Renewable Energy Laboratory. By simultaneously optimizing the design and hourly operation of LAES systems to maximize their net present value over their projected lifespan, a yes/no indication of their economic viability can be obtained. The results of this analysis provide conservative estimates of the economic performance of LAES systems across the US and may serve as useful planning aids for LAES deployment. Levelized costs of storage are also calculated based on the optimal operating schedules obtained for all systems and compared to those of other long-duration energy storage technologies. Finally, sensitivity analyses are performed to elucidate how improved technical performance and economic incentives might affect the economic feasibility and, consequently, the adoption of LAES technology more broadly in the future.

References:

[1] Edenhofer, O., Pichs-Madruga, R., Sokona, Y., Seyboth, K., Kadner, S., Zwickel, T., Eickemeier, P., Hansen, G., Schlömer, S., von Stechow, C. & Matschoss, P. (Eds.). (2011). Renewable energy sources and climate change mitigation: Special report of the intergovernmental panel on climate change. Cambridge University Press.

[2] Vecchi, A., Li, Y., Ding, Y., Mancarella, P., & Sciacovelli, A. (2021). Liquid air energy storage (LAES): A review on technology state-of-the-art, integration pathways and future perspectives. Advances in Applied Energy, 3, 100047.

[3] Borri, E., Tafone, A., Romagnoli, A., & Comodi, G. (2021). A review on liquid air energy storage: History, state of the art and recent developments. Renewable and Sustainable Energy Reviews, 137, 110572.