A thermo-economic analysis and comparison of pumped-thermal and liquid-air electricity storage systems

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Title: A thermo-economic analysis and comparison of pumped-thermal and liquid-air electricity storage systems
Authors: Georgiou, S
Shah, N
Markides, C
Item Type: Journal Article
Abstract: E ff icient and affordable electricity storage system s have a significant potential to support the growth and increasing penetration of intermittent renewable - energy generation into the grid from an energy system planning and management perspective , while difference s in the demand and price of peak and off - peak electricity can make its storage of economic interest. Technical (e.g., roundtrip efficiency, energy and power capacity ) as well as economic (e.g., capital, operating and maintenance costs ) indicators are anticipated to have a significan t combined impact on the competitiveness of any electricity storage technology or system under consideration and, ultimately, will crucially determine their uptake and implementation . In this paper , we present thermo - economic models of two recently proposed medium - to large - scale electricity storage systems, namely ‘Pumped - Thermal Electricity Storage’ (PTES) and ‘Liquid - Air Ene rgy Storage’ (LAES) , focusing on system efficiency and costs . The LAES thermodynamic model is validated against data from a n operational pilot plant in the UK; no such equivalent PTES plant exists , although one is currently under construct ion . As common with most new ly proposed technologies, the absence of cost data results to the economic analysis and comparison being a significant challenge. Therefore, a costing effort for the two electricity storage systems that includes multiple costing approaches based on the module costing technique is presented , with the overriding aim of conducting a preliminary economic feasibi lity assessment and comparison of the two systems. Based on the results , it appears that PTES has the potential to achieve higher roundtrip efficiencies , although this remains to be demonstrated. LAES performance is found to be significantly enhanced throu gh the integration and utilisation of waste heat ( and cold ) streams. In terms of economics on the other hand , and at the system size intended for commercial application, LAES (12 MW, 50 MWh) is es timated in this work to have a lower capital cost and a lower levelised cost of storage than PTES ( 2 MW, 11.5 MWh ) , although it is noted that the prediction of the economic proposition of PTES technology is particularly uncertain if customised components are employ ed . However, when considering the required s ell - to - buy ratios , PTES appears (by a small margin) economically more competitive above an electricity buy price of ~ 0.15 $ /kWh , primarily due to its higher roundtrip efficiency. When considering the two systems at the same capacity, the costs are similar with a slight edge to PTES. Finally, it is of interest that t he most expensive components in both systems are the compression and expansion devices , which suggests that there is a need to develop affordable high - performance devices for such systems .
Issue Date: 15-Sep-2018
Date of Acceptance: 29-Apr-2018
URI: http://hdl.handle.net/10044/1/59333
DOI: https://doi.org/10.1016/j.apenergy.2018.04.128
ISSN: 0306-2619
Publisher: Elsevier
Start Page: 1119
End Page: 1133
Journal / Book Title: Applied Energy
Volume: 226
Copyright Statement: © 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).
Sponsor/Funder: Natural Environment Research Council
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: NE/L002515/1
EP/J006041/1
EP/P004709/1
Keywords: Science & Technology
Technology
Energy & Fuels
Engineering, Chemical
Engineering
Electricity storage
Liquid-air energy storage
Pumped-thermal electricity storage
Thermo-economic analysis
ENERGY-STORAGE
POWER-SYSTEM
PERFORMANCE OPTIMIZATION
HEAT
COST
Energy
09 Engineering
14 Economics
Publication Status: Published
Online Publication Date: 2018-06-26
Appears in Collections:Faculty of Engineering
Centre for Environmental Policy
Chemical Engineering
Faculty of Natural Sciences



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