Modelling study, efficiency analysis and optimisation of large-scale adiabatic compressed air energy storage systems with low-temperature thermal storage

The key feature of Adiabatic Compressed Air Energy Storage (A-CAES) is the reuse of the heat generated from the air compression process at the stage of air expansion. This increases the complexity of the whole system since the heat exchange and thermal storage units must have the capacities and performance to match the air compression/expansion units. Thus it raises a strong demand in the whole system modelling and simulation tool for A-CAES system optimisation. The paper presents a new whole system mathematical model for A-CAES with simulation implementation and the model is developed with consideration of lowing capital cost of the system. The paper then focuses on the study of system efficiency improvement strategies via parametric analysis and system structure optimisation. The paper investigates how the system efficiency is affected by the system component performance and parameters. From the study, the key parameters are identified, which give dominant influences in improving the system efficiency. The study is extended onto optimal system configuration and the recommendations are made for achieving higher efficiency, which provides a useful guidance for A-CAES system design

A review of pumped hydro energy storage development in significant international electricity markets

The global effort to decarbonise electricity systems has led to widespread deployments of variable renewable energy generation technologies, which in turn has boosted research and development interest in bulk Electrical Energy Storage (EES). However despite large increases in research funding, many electricity markets with increasingly large proportions of variable renewable generation have seen little actual bulk EES deployment. While this can be partly attributed to the need for technological developments, it is also due to the challenge of fairly rewarding storage operators for the range of services that storage provides to the wider network, especially in markets that have undergone significant restructuring and liberalisation. Pumped Hydroelectric Energy Storage (PHES) is the overwhelmingly established bulk EES technology (with a global installed capacity around 130 GW) and has been an integral part of many markets since the 1960s. This review provides an historical overview of the development of PHES in several significant electrical markets and compares a number of mechanisms that can reward PHES in different international market frameworks. As well as providing up-to-date information about PHES, a primary motivation for this work is to provide an overview about the types of rewards available to bulk EES for the wider storage community including investors, technology developers and policy-makers. Observing that bulk EES projects seem to be unattractive investments for the private sector, the paper also includes a brief discussion in terms of public sector investment

Design of System Architecture and Thermal Management Components for an Underwater Energy Storage Facility

The electricity industry is currently experiencing a significant paradigm shift in managing electrical resources. With the onset of aging infrastructure and growing power demands, and the influx of intermittent renewable energy generation, grid system operators are looking towards energy storage as a solution for mitigating industry challenges. An emerging storage solution is underwater compressed air energy storage (UWCAES), where air compressors and turbo-expanders are used to convert electricity to and from compressed air stored in submerged accumulators. This work presents three papers that collectively focus on the design and optimization of an UWCAES system. In the first paper, the field performance of a distensible air accumulator is studied for application in UWCAES systems. It is followed by a paper that analyzed the energetic and exergetic performance of a theoretical UWCAES system. The final paper presents a multi-objective UWCAES optimization model utilizing a genetic algorithm to determine optimum system configurations

Compressed air energy storage: characteristics, basic principles, and geological considerations

With increasing global energy demand and increasing energy production from renewable resources, energy storage has been considered crucial in conducting energy management and ensuring the stability and reliability of the power network. By comparing different possible technologies for energy storage, Compressed Air Energy Storage (CAES) is recognized as one of the most effective and economical technologies to conduct long-term, large-scale energy storage. In terms of choosing underground formations for constructing CAES reservoirs, salt rock formations are the most suitable for building caverns to conduct long-term and large-scale energy storage. The existing CAES plants and those under planning have demonstrated the importance of CAES technology development. In both Canada and China, CAES plants are needed to conduct renewable energy storage and electricity management in particular areas. Although further research still needs to be conducted, it is feasible and economical to develop salt caverns for CAES in Canada and China.Cited as: Li, L., Liang, W., Lian, H., Yang, J., Dusseault, M. Compressed air energy storage: characteristics, basic principles, and geological considerations. Advances in Geo-Energy Research, 2018, 2(2): 135-147, doi: 10.26804/ager.2018.02.0

Optimal integrated energy systems design incorporating variable renewable energy sources

The effect of variability in renewable input sources on the optimal design and reliability of an integrated energy system designed for off-grid mining operation is investigated via a two-stage approach. Firstly, possible energy system designs are generated by solving a deterministic non-linear programming (NLP) optimization problem to minimize the capital cost for a number of input scenarios. Two measures of reliability, the loss of power supply probability (LPSP) and energy index of reliability (EIR), are then evaluated for each design based on the minimization of the external energy required to satisfy load demands under a variety of input conditions. Two case studies of mining operations located in regions with different degrees of variability are presented. The results show that the degree of variability has an impact on the design configuration, cost and performance, and highlights the limitations associated with deterministic decision making for high variability systems

Inter-seasonal compressed air energy storage using saline aquifers

Meeting inter-seasonal fluctuations in electricity production or demand in a system dominated by renewable energy requires the cheap, reliable and accessible storage of energy on a scale that is currently challenging to achieve. Commercially mature compressed-air energy storage could be applied to porous rocks in sedimentary basins worldwide, where legacy data from hydrocarbon exploration are available, and if geographically close to renewable energy sources. Here we present a modelling approach to predict the potential for compressed-air energy storage in porous rocks. By combining this with an extensive geological database, we provide a regional assessment of this potential for the United Kingdom. We find the potential storage capacity is equivalent to approximately 160% of the United Kingdom’s electricity consumption for January and February 2017 (77–96 TWh), with a roundtrip energy efficiency of 54–59%. This UK storage potential is achievable at costs in the range US$0.42–4.71 kWh−1