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Abstract Liquid air energy storage (LAES) is a novel proven technology that can increase flexibility of the power network, obtaining revenue through energy price arbitrage. To assess the economic potential of a variety of energy storage options, this study develops a cost research framework for LAES, which is also applicable to other energy storage technologies. For the calculation of Levelized Cost of Storage (LCOS), it is essential to evaluate the electricity purchasing cost and the total electricity generated. However, they are often estimated by simply assuming an average electricity price and an annual operating cycle in the previous studies. In this paper, a price arbitrage algorithm is developed, according to which decisions are made at each time step whether to charge, discharge or stand by. Thus, the electricity purchasing cost as well as the amount of electricity generated by the storage unit is determined and the LCOS of the energy storage system is calculated. Results show that the LCOS for a 25MW/125MWh LAES system is in the range 191-590 £/MWh, depending on different round-trip efficiencies and different costs set in three scenarios. If the round-trip efficiency is assumed to be 60%, the LCOS would in the range 191-294 £/MWh under the three scenarios. [ABSTRACT FROM AUTHOR]

Highlights • Individual energy systems have their own specific technical, and non-technical needs. • A framework is presented for assessing energy storage options against these needs. • It uses multi-attribute value theory and is tested in Cornwall, UK. • It promotes engagement with stakeholders which can inform decision makers. • It is less complex than alternatives and so can be used by non-expert actors. Abstract With the growing adoption of intermittent renewable energy generation the role for energy storage to provide a number of service needs is being increasingly recognised. However, 'energy storage' encompasses a family of technologies, each with its own set of performance, cost and physical characteristics, at different stages of development. At the same time, each energy system – however defined – has specific needs; and energy systems are themselves part of a wider socio-technical system which has aims beyond the confines of the energy 'trilemma'. As energy storage technologies develop, funding is becoming available to demonstrate their application in realistic environments. However, with multiple technical and non-technical factors to consider, it is challenging for many decision makers who often have limited expertise and resources to select which projects to support. In this paper we first describe a novel framework for assessing the wider benefits that could come from deploying energy storage using Multi-Attribute Value Theory (MAVT), a form of Multi-Criteria Decision Analysis. We then use the framework to assess six potential energy storage projects through a combination of technical analysis and stakeholder input in the county of Cornwall in the UK: a region that has good solar and wind resource with relatively low demand and constrained network infrastructure. The projects assessed were: power to gas, a distributed battery system, battery storage integrated with solar PV and demand from Cornwall Airport Newquay, liquid air energy storage, battery storage integrated with wave energy, and thermal energy storage at a new residential development. We conclude that MAVT can provide a straightforward and user-friendly approach, which can be easily used by decision makers for assessing energy storage projects across a range of criteria and promoting engagement with stakeholders. This approach also allows the subjectivity of decision-making, a potential limitation, to be explored through a sensitivity analysis. The use of MAVT can lead to important insights for the development of energy systems, which in this study included the importance of local priorities to decision-making. In this case, battery storage with PV and demand from Cornwall Airport Newquay was the top-ranking project, performing well across a range of attributes including the maturity of the technology, its ability to defer grid upgrades and economic viability. [ABSTRACT FROM AUTHOR]

Abstract The need to increase energy system flexibility, alongside the need to lower fossil fuel use in the food sector, and the importance of refrigeration infrastructure presents an opportunity for Liquid Air Energy Storage (LAES) integrated with refrigerated warehouses. To quantify this opportunity in Europe we analyse energy scenarios and existing refrigeration infrastructure for four countries with diverse energy systems (UK, Spain, Bulgaria and Germany). We find that with growing levels of electricity generation from variable renewable sources and numerous refrigerated warehouses, LAES has the potential to provide value in many areas of the EU through the 2020s. However, LAES is still pre-commercial, and with the proportion of electricity from variable renewable sources still low in many countries it is likely that LAES will not be deployed widely alongside refrigerated warehouses under current market conditions. Countries such as the UK and Spain, which have the greatest need for additional energy system flexibility and the most refrigerated warehouses are likely to gain the most value initially. [ABSTRACT FROM AUTHOR]

Abstract: In the UK dwelling type is a commonly used term to refer to the ‘building style’ of a residential property. The concept is used frequently in urban analysis, social science research and Government policy, and has been used as a measure of homogeneity in the construction of Output Areas (OAs) in the UK 2001 census. However, there are no formal definitions of dwelling types in the UK beyond a basic statutory definition of dwelling-house and flat. The British Government’s Office of National Statistics (ONS) also categorises dwellings into different types but provides no clear guidance to how these are defined. There is no source of dwelling type data for individual properties at a national scale beyond sample surveys. The main source of information is the 2001 census, which provides counts of ONS defined dwelling types for OAs. The objective of this research is to use OS Mastermap, a high resolution topographic database of Great Britain, to model and provide dwelling type information for individual residential addresses. The success of the modelling exercise is measured by comparing the modelled dwelling type information to data on dwelling type collected in the 2001 census, using Chi-square as a goodness of fit measure. Small area differences in the two measures are analysed in order to ascertain where OS Mastermap does not provide a very good estimate of dwelling type. The analysis highlights problems with the modelling process and discusses the potential of OS Mastermap as a source of dwelling related data and also possible small area errors in the 2001 census. [Copyright &y& Elsevier]

Energy storage has been identified as a priority technology for innovation. However, the rapidly developing family of storage technologies will find it difficult, under the current regulatory regimes, to compete with conventional generators for the provision of electricity system services, and this is likely to impede innovation. This paper analyses and categorizes 16 investment barriers hindering the near-term deployment of energy storage technologies in electricity markets, which are related to four regulatory and public attitudes barriers. The most important regulatory barrier is the current classification of storage as a generation asset, despite it being unable to provide a positive net flow of electricity, which is used to justify double network usage charges. The merit order design of balancing and ancillary markets hampers the ability of storage technologies to recoup their relatively high capital cost, while capacity markets penalize their limited discharge duration. Network companies are in the best position to realize the system value of storage, but their ownership may only be acceptable if system operation is made independent of network operation. Current initiatives to address these issues include flexible connection agreements and the development of enhanced frequency response and aggregate fast reserve services. However, to remove the identified barriers, a market structure that valued the flexibility offered by storage, viewing it as complementing rather than competing with network and generation assets, would be required. [ABSTRACT FROM AUTHOR]

Rooftop photovoltaic systems integrated with lithium-ion battery storage are a promising route for the decarbonisation of the UK’s power sector. From a consumer perspective, the financial benefits of lower utility costs and the potential of a financial return through providing grid services is a strong incentive to invest in PV-battery systems. Although battery storage is generally considered an effective means for reducing the energy mismatch between photovoltaic supply and building demand, it remains unclear when and under which conditions battery storage can be profitably operated within residential photovoltaic systems. This fact is particularly pertinent when battery degradation is considered within the decision framework. In this work, a commercially available coupled photovoltaic lithium-ion battery system is installed within a mid-sized UK family home. Photovoltaic energy generation and household electricity demand is recorded for more than one year. A comprehensive battery degradation model based on long-term ageing data collected from more than fifty long-term degradation experiments on commercial Lithium-ion batteries is developed. The comprehensive model accounts for all established modes of degradation including calendar ageing, capacity throughput, ambient temperature, state of charge, depth of discharge and current rate. The model is validated using cycling data and exhibited an average maximum transient error of 7.4% in capacity loss estimates and 7.3% in resistance rise estimates for over a year of cycling. The battery ageing model is used to estimate the cost of battery degradation associated with cycling the battery according to the power profile logged from the residential property. A detailed cost-benefit analysis using the data collected from the property and the battery degradation model shows that, in terms of utility savings and export revenue, the integration of a battery yields no added benefit. This result was, in-part, attributed to the relatively basic control strategy and efficiency of the system. Furthermore, when the cost of battery degradation is included, the homeowner is subject to a significant financial loss. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the influence of alternative population distribution models on GIS-based spatial accessibility analyses using the two-step Floating Catchment Analysis technique. Two population models were tested: the de facto standard of even-distribution within census tracts and a dasymetric-based approach. The latter builds on previous research through the use of a novel methodology that integrates raster map data with a recently built mailing information database in order to enhance the precision with which residential areas are identified. Analysis was conducted for a case study area (Cardiff, South Wales) in order to examine variations in accessibility to a number of public services in the city. The dasymetric model showed a general tendency to report lower accessibility scores, but detailed patterns depended on local factors and, to some extent, on modelling assumptions and methodological issues. A paired T-Test analysis demonstrated that significant differences in outcomes were dependant on the population model adopted. Accessibility-based measures are increasingly being incorporated into deprivation indicators and the paper concludes by suggesting that, if such analysis is to inform urban planning, local service provision and the spatial allocation of financial resources, greater attention needs to be given to the method of population representation utilised in such models. [Copyright &y& Elsevier]

This work assesses the economic feasibility of adopting decoupled energy storage technologies in the UK, using a methodology to optimize the size of individual components for charging, storing and discharging energy. Such technologies, including pumped hydro and compressed air energy storage, are likely to become more important in the future energy system. In this paper we consider liquid air energy storage as a case study - a technology that has the potential to provide multiple balancing and ancillary services to the electricity grid, as well as to obtain revenues through energy price arbitrage. Based on the UK’s half-hourly electricity spot price in 2015, the developed numeric model calculates the revenue streams of a liquid air energy storage system from providing reserve service and arbitrage every half hour. Results from the genetic algorithm give the optimal sizes for the liquefaction, storage and recovery units, to maximize the net present value and allow us to calculate other economic objectives. Our model results suggest that the profitability of a liquid air energy storage system can be improved by either introducing waste heat into the system or increasing system scale. The payback period could vary from 25.7 years to 5.6 years for a 200 MW system, with the use of waste heat ranging from 0 °C to 250 °C. [ABSTRACT FROM AUTHOR]

Background Independence from fossil fuels, energy diversification, decarbonisation and energy efficiency are key prerequisites to make a national, regional or continental economy competitive in the global marketplace. As Europe is about to generate 20% of its energy demand from Renewable Energy Sources (RES) by 2020, adequate RES integration and renewable energy storage throughout the entire food cold chain must properly be addressed. Scope and approach Refrigerated warehouses for chilled and frozen foods are large energy consumers and account for a significant portion of the global energy demand. Nevertheless, the opportunity for RES integration in the energy supply of large food storage facilities is often neglected. In situ power generation using RES permits capture of a large portion of virtually free energy, thereby reducing dramatically the running costs and carbon footprint, while enhancing the economic competitiveness. In that context, there exist promising engineering solutions to exploit various renewables in the food preservation sector, in combination with the emerging sustainability-enhancing technology of Cryogenic Energy Storage (CES). Key findings and conclusions Substantial research endeavours are driven by the noble objective to turn the Europe's Energy Union into the world's number one in renewable energies. Integrating RES, in synchrony with CES development and proper control, is capable of both strengthening the food refrigeration sector and improving dramatically the power grid balance and energy system sustainability. Hence, this article aims to familiarise stakeholders of the European and global food preservation industry with state-of-the-art knowledge, know-how, opportunities and professional achievements in the concerned field. [ABSTRACT FROM AUTHOR]

This paper reports an integrated system consisting of a diesel genset and a Compressed Air Energy Storage (CAES) unit for power supply to isolated end-users in remote areas. The integration is through three parts: direct-driven piston-compression, external air turbine-driven supercharging, and flue gas waste recovery for super-heating. The performance of the integrated system is compared to a single diesel unit and a dual-diesel unit with a capacity of electricity supply to a village of 100 households in the UK. It is found the fuel consumption of the integrated system is only 50% of the single-diesel unit and 77% of the dual-diesel unit. The addition of the CAES unit not only provides a shift to electrical energy demand, but also produces more electricity due to the recovery of waste heat. [ABSTRACT FROM AUTHOR]