TY - CPAPER AB - © 2017 IMEKO An efficient and affordable electricity storage system can assist the increasing penetration of intermittent renewable-energy generation, while the difference in the demand and price of peak and off-peak electricity can make its storage of financial interest. Technical indicators (e.g., roundtrip efficiency, energy and power density) along with economic indicators (e.g., capital, operating and maintenance costs) are expected to have a substantial combined impact on the competitiveness of any electricity storage technology or system under consideration. In this paper we will present thermodynamic models of two newly proposed medium- to large-scale electricity storage systems, namely ‘Liquid-Air Energy Storage’ (LAES) and ‘Pumped-Thermal Electricity Storage’ (PTES). The LAES model is validated against data from a pilot plant in operation in the UK; no such equivalent PTES plant exists. As with most new technologies, the lack of cost information makes the economic analysis and comparison a significant challenge. A costing effort for the two systems based on the module costing technique is also presented with the overriding aim of performing a preliminary economic feasibility assessment of the two systems. Based on initial results, PTES achieves higher roundtrip efficiencies, although the performance of LAES is found to be significantly enhanced through the utilisation of waste heat (and cold) streams. In terms of costs, LAES is estimated to have lower capital costs by roughly £600/kW. The most expensive components in both systems are the compression and expansion devices. AU - Georgiou,S AU - Dowell,NM AU - Shah,N AU - Markides,CN PY - 2017/// TI - Thermo-economic comparison of liquid-air and pumped-thermal electricity storage ER -