Energy storage systems

Guest Editorial: Situational awareness of integrated energy systems

Worldwide, several studies have investigated many proposals for the use of hybrid systems as alternative energy sources, operating together with energy storage technologies. Accordingly, there are large concerns about the use of appropriate methods to evaluate the application of renewable energy sources and storage energy systems. Thus, it is important to observe that the renewable hybrid systems are environmental friendly, having as consequence governmental incentives for their development in many countries, like Brazil. This paper presents a methodology taking as basis the theory developed by Saaty -- the Analytic Hierarchy Process (AHP method) - and multi-rulesbased decision and multi-sets considerations applied using fuzzy logic. By exploiting a multi-criteria decision making, this methodology evaluates the operation of storage energy systems such as: compressed air energy storage (CAES), pumped hydro storage (PHS), H2 storage, flywheel and super-capacitors. In addition, different scenarios are investigated concerning environment impacts and costs. For the purpose of the study, these five different energy storage technologies are evaluated objectifying to find the most appropriate storage energy system for different scenarios, always considering the desirable criteria, namely: efficiency, costs, technical maturity, environmental impacts, power application range and lifecycle.

Enhancement of renewable energy penetration through energy storage technologies in a CHP-based energy system for Chongming, China

The World's energy consumption has increased drastically over the past several decades, particularly driven by increasing population and economic activities as well as rising living standards with technological advancements. Since the industrial revolution, fossil fuels have been the major source of energy productions, which is today shown as the primary cause of the ongoing climate change and associated environmental challenges in threatening the existence of many living species and human life and comfort. According to the statistics provided by International Energy Agency (IEA),1 the global energy supply was 14 282 Mtoe in 2018 that is 115% higher than that of the value for 1973. Fossil fuels, such as natural gas, coal and oil are still playing a critical role and covering more than 80% of global energy demands. The concerns associated with global warming and depletion of energy sources have been directing the attention to renewable and environmentally-benign energy solutions. However, efficient, affordable, and nature-friendly energy storage systems are the key to using renewable energy sources effectively. In this study, a comprehensive literature search is conducted to study and bibliografically evalute Canada's energy storage research and development activities over the last five decades. The present study intends to present the cumulative picture on energy storage reseach and development efforts and assess how universities, research institutes and funding agencies have contributed to this particular field. The literature search compiles a total of fifty-year data on energy storage-related research and development activities conducted in Canada. The number of conducted studies associated with energy storage regarding research articles, books, research projects, dissertations, and patents is presented in the period from 1971 to 2021. Furthermore, the Canadian institutes are ranked based on their scholarly ouputs and publications to indicate the most productive ones in the field of energy storage based on the data presented in the literature sources. Energy storage is described as the capture of harvested energy for later use to maintain the balance fluctuations between energy demand and supply. As the world moves towards a low-carbon economy, energy storage systems are exepcted to even play a more critical role in extracting more energy from renewable resources.10 The intermittent characteristic of renewable resources, specifically solar and wind, is one of the major challenges ahead of a reliable and steady renewable energy supply. This can be avoided by storing excess energy to re-use when the renewable resources are not sufficient or unavailable. Energy storage systems can be categorized in different ways in regards to the form of converted and stored energy. Figure 1 presents an overview of energy storage system categories which are considered in this study. It is important to note that chemical energy storage allows to storage and transportation of large amounts of energy for long distances with minimal self-discharge rates, which is crucial for the distribution and effective use of renewable energy resources. Figure 2 presents the energy density of various chemical fuels and batteries. Despite possessing high energy density, environmental concerns associated with the production and consumption of fossil-based chemical fuels, e.g. diesel, gasoline or natural gas, should be adrressed. In regards to nature-friendly chemical energy storage, particularly power-to-gas chemical storage, hydrogen is attracting favorable attention nowadays. In this regard, hydrogen appears to be the lightest and most abundant chemical element in the universe, but is not available freely (by itself). However, it occurs naturally within a compound such as water (H2O); therefore, it is an intermediate energy form. Excess electricity from renewables can be utilized in hydrogen production processes, i.e. electrolysis of water, to store energy in chemical form. Power-to-hydrogen chemical energy storage is a unique and clean method, and it can be compatible with electrochemical storage since hydrogen possesses much greater energy content. One of the major challenges with hydrogen is the low calorific value per unit of volume (MJ/m3) due to its low density. This can be avoided by deploying alternative hydrogen carriers, such as ammonia. Liquefaction at atmospheric conditions, high hydrogen atom content and high energy density characteristics make ammonia a favorable medium for storage and transportation of energy. It is further to note that batteries and capacitors are devices allowing electrochemical storage of electricity. The potential energy is stored in chemical form in batteries, while capacitors are expected to store their potential energy in the form of an electric field.14 Batteries are thus most commonly used and matured options that propose high energy densities and voltages. Lithium-ion (Li-ion), sodium-sulphur (NaS), nickel-cadmium (NiCd), lead acid (Pb-acid), lead-carbon batteries, zebra batteries (Na-NiCl2) and flow batteries are the existing battery types used in various applications. Due to their high specific energy (per unit weight) and high specific energy (per unit volume), lithium batteries attract considerable attention in electrical energy storage. Capacitors can be classified as electrostatic capacitors, electrolytic capacitors, and electrochemical capacitors, among which electrochemical, so-called supercapacitors, promote the highest capacitance per unit of volume owing to a porous structure 15. As a mechanical energy storage method, pumped hydro accounts for more than 95% of the global installed energy storage capacity.15 The main advantage of mechanical energy storage is to readily deliver energy. The method is easy to adapt for conversion and storage of energy from various sourcessuch as water current, wave, or tidal. Pumped hydro, compressed air, and flywheel are the commonly practiced mechanical energy storage methods. Pumped hydro and compressed air are bound to specific geographical characteristics, which is the main restriction for the implementation of these energy storage methods. A flywheel stores the energy obtained from a rotor mass spinning at very high speeds as kinetic energy. The stored kinetic energy can be later used to produce electricity by altering the angular velocity of the flywheel through a decelerating torque and using an electric motor in reverse 16. Despite of being non-suitable for long-term energy storage, flywheels offer favorable advantages, that is, long-life spin, high energy densities and low maintenance costs, and fast charging.17 Thermal energy storage (TES) systems are effective systems to store heat in a reservoir for a period of time (defined or undefined) for later use, that is, space heating and cooling, electricity production, hot water. If the reservoir temperature is kept under the atmospheric temperature, the storage process is called cold thermal energy storage.18 Operating temperature range, capacity requirements, charging and discharging requirements are some of important parameters when choosing an appropriate TES system for a desired application. Since the major proportion of produced and consumed energy is heat around the world, TES systems carries a significant weight regarding the development of effective energy systems . Furthermore, energy losses from the systems commonly occur in the form of heat. Decreasing losses via further utilizing from waste energy is one of many way to mitigate environmental impacts, which can be accomplished by implementing TES systems in a cost effective manner. In the current study, an overview of Canada's energy storage related studies from 1971 to 2021 is presented. The scope of this study is to present the contributions of Canadian universities, research institutes and funders to energy storage research and development efforts over the last five decades. The keywords and methodology that are used for the literature search are depicted in Figure 3. The collected and compiled data for the corresponding fields are presented in figures, and results are discussed in the following sections. In this study, an online literature search is conducted on Canada's energy storage related studies over the last five decades. The current section presents collected and compiled data in charts. The findings of the conducted study are discussed in detail. The most productive institutes of Canada regarding conducting or sponsoring energy storage-related studies are presented. The documents associated with energy storage in all subject areas are presented in Figure 4. In this regard, the highest number of energy storage-related studies were conducted in the subject area of engineering in Canada from 1971 to 2021. The fields of energy and chemistry appear as the other two major subject areas in which high number of energy storage research was conducted. While compiling data, attention has been paid to any potential field conflicts concerning the multi attribution of interdisciplinary publications. Therefore, it should be noticed that chemistry may have an impact on the subject areas of biochemistry, genetics, and molecular biology. The same impact of engineering could be seen on the subject area of energy. The data collected and analysed for comparative evaluation reveals that the Canadian institutes have produced 37 386 energy storage-related academic research publications over the last 50-year period. In this regard, Figure 5A presents the breakdown of energy storage-related publications affiliated to Canada in the corresponding material types in accordance with the publication years. Figure 5A shows that studies in this field consistently increases every year. Consequently, the year 2020 appears as the most productive one in this regard as of April 2021. In the light of this trendline, predicting that the year 2021 will be more productive than 2020 would not be wrong. Figure 5B has been prepared as a heat map to show Canada's provinces where energy storage-related studies were conducted over the last 50 years. In this regard, Ontario appears as the most productive province of Canada in terms of scholarly publications. However, one has to keep in mind that Ontario has the highest number of contributing institutes/universities compared to the rest of the provinces in Canada. Figure 6 presents the breakdown of the number of energy storage-related books, book chapters, and editorials in accordance with publication years in Canada. The year 2018 was the most productive year of Canada by producing 200 documents in the corresponding classification. The other important point that should be pinned in the figure is the year 2005. Compared to the previous year, almost five times more energy storage-related books were published in 2005. Compared to 2019, the number of published books decreased almost by half in 2020. The impact of COVID-19 is recognized as one of numerous reasons behind this result. The number of energy storage-related dissertations completed in Canada over the last five decades is primarily searched through and collected from Library and Archives Canada. The search results are, in this regard, presented in Figure 7. It can be noted that the data presented in Figure 7 is based on the number of energy storage-related theses available in the library; and thus, the results are subject to change in accordance with instantaneous new data entry to the library. As of April 2021, there are 626 energy storage-related MSc and PhD theses/dissertations entered in the online system of Library and Archives Canada. The highest number of theses/dissertations was recorded in the year of 2013 with a value of 62. Based on data collected from the website of Canadian Intellectual Property Office, the number of energy storage-related patents of Canada is 11 719 for the last 50 years. The corresponding results are presented Figure 8. According to this, the year of 2018 appeared to be the Canada's most productive year in terms of patents registered under the title of energy storage. Canada is blessed with institutions that have been supporting energy storage-related research and developments by providing funds. Over the evaluated period of 50 years, the Natural Sciences and Engineering Research Council of Canada (NSERC) appears as the major funding agency for Canada's energy storage related research, development, partnership, strategic innovation and commercialization efforts and has supported more than 8500 projects in the field of energy storage. A total number of projects that have been funded by Canadian institutes have become 18021 from 1971 to 2021. It is most likely to observe a major increase in the number of projects by the impact of the recent hydrogen strategic plan of Canada. Being an excellent energy storage medium is one of many advantages of hydrogen. Therefore, there is a significant correlation in between hydrogen and energy storage research efforts. The subject matter report is already named as call-to-action for green hydrogen transition for the energy sector. In the report, the importance of dedicating more domestic resources to green hydrogen efforts to achieve the targets by 2050 is emphasized clearly (Figure 9). The development and implementation efforts of effective, affordable, and nature-friendly energy storage systems are recognized as a key requirement in achieving a green energy transition. In this regard, Canada intends to be the country leading and inspiring many others. Figure 10 shows the a number of Canadian institutes/universities that have produced more than 100 scholarly publications on energy storage under the subject area of energy. According to this, the total number of such scholarly publications has been 9125 over the past five decades. The results clearly show that there are two universities, such as University of Waterloo with 809 publications and Ontario Tech. University (formerly University of Ontario Institute of Technology) with 697 publications, leading in this particular area. University of Waterloo appears as the most productive Canadian university with a total number of 809 publications while Ontario Tech. University, which is one of the Canada's youngest universities, follows with a total number of 697 publications. The specific affiliations in the publications show that the researchers working in the productive environment of Clean Energy Research Laboratory (CERL) at Ontario Tech. have played a major role in this achievement. The data that support the findings of this study are available in Scopus, Library and Archives Canada and Canadian Intellectual Property Office with the reference number of [17], [18], and [19], respectively. These data were derived from the following resources available in the public domain: https://www.scopus.com/search/form.uri?display=basic&zone=header&origin, https://www.bac-lac.gc.ca/eng/services/theses/Pages/search.aspx, https://www.ic.gc.ca/opic-cipo/cpd/eng/search/basic.html?wt_src=cipo-patent-main.

Motivated by the future of clean energy sources and storage systems, the purpose of this research is to evaluate the ability to combine nuclear and solar photovoltaic generation systems as well as an energy storage system in order to meet the demand of an electric power system load. While nuclear power generation has been around for decades, renewable energy is becoming more popular as technologies begin to become more affordable. In addition, energy storage is still the most expensive component of this equation. A case study was conducted by using an example load pattern for various time periods in a year that is gathered from a North Carolina electric utility. A scalable nuclear power source (such as NuScale) was assumed to supply a constant and continuous power level. A range for solar farm size was selected, and the solar output was calculated by gathering the solar irradiance data from Oak Ridge National Laboratories. The energy storage system capacity for a select nuclear and solar farm size was later determined. These calculations were executed in a MATLAB environment. By comparing energy storage system capacities for a range of nuclear and solar farm sizes, one can determine that renewable resources alone, will not be able to provide enough flexibility to meet the demand of large-scale loads. Our calculations specifically showed that solar PV operation alone results in 9560 MWh energy storage capacity. However, an optimized solar PV and nuclear hybrid generation scheme reduced the energy capacity requirement significantly (by approximately a factor of 13). Utilities are using energy storage systems comprised of batteries like lithium-ion due to their ideal and decreasing price range. Optimizing the size of generation plants and reducing the battery capacity eases the economic impact of variable load demands.

Life-cycle assessment of gravity energy storage systems for large-scale application

The implementation of renewable energy systems (RESs) in the agricultural sector has significant potential to mitigate the negative effects of fossil fuel-based products on the global climate, reduce operational costs, and enhance crop production. However, the intermittent nature of RESs poses a major challenge to realizing these benefits. To address this, thermal energy storage (TES) and hybrid heat pump (HHP) systems are integrated with RESs to balance the mismatch between thermal energy production and demand. In pursuit of clean energy solutions in the agricultural sector, a 3942 m2 greenhouse in Yeoju-si, South Korea, is equipped with 231 solar thermal (ST) collectors, 117 photovoltaic thermal (PVT) collectors, four HHPs, two ground-source heat pumps (GSHPs), a 28,500 m3 borehole TES (BTES) unit, a 1040 m3 tank TES (TTES) unit, and three short-term TES units with capacities of 150 m3, 30 m3, and 30 m3. This study evaluates the long-term performance of the integrated hybrid renewable energy and thermal energy storage systems (HRETESSs) in meeting the greenhouse’s heating and cooling demands. Results indicate that the annual system performance efficiencies range from 25.3% to 68.5% for ST collectors and 31.9% to 72.2% for PVT collectors. The coefficient of performance (COP) during the heating season is 3.3 for GSHPs, 2.5 for HHPs using BTES as a source, and 3.6 for HHPs using TTES as a source. During the cooling season, the COP ranges from 5.3 to 5.7 for GSHPs and 1.84 to 2.83 for ASHPs. Notably, the HRETESS supplied 3.4% of its total heating energy directly from solar energy, 89.3% indirectly via heat pump utilization, and 7.3% is provided by auxiliary heating. This study provides valuable insights into the integration of HRETESSs to maximize greenhouse energy efficiency and supports the development of sustainable agricultural energy solutions, contributing to reduced greenhouse gas emissions and operational costs.

Thermodynamic analysis of an integrated energy system based on compressed air energy storage (CAES) system and Kalina cycle

The microgrid represents a controllable electric entity that contains different loads into distributed energy resources. All typical microgrids use two or more sources by which electricity is generated, at least one of which is a renewable source. In this respect the main issues of the energy storage systems (ESS) are the enhancing of the stability of microgrid and power balance. Also the insertion of the energy storage systems is beneficial for both operation modes of microgrids, grid connected and islanded. This chapter begins with an overview of the current state of microgrids and ESS. The island operation mode of microgrids is based on the energy storage system. At the first level the control tasks during this mode of operation are to regulate the voltage and to maintain the frequency at the constant value. The power in each unit is shared among the storage units by secondary control of the energy storage system taking into account the energy level of each of them. Further, the authors present storage technologies of the electrical energy, i.e. converting it into mechanical, chemical, electrochemical, electromagnetic and thermal energy. The widespread mechanical energy storage technology is the pumped hydro (99% of the world total storage capacity) followed by the compressed air energy and flywheel. Afterwards, the fuel cell, biomass and fossil fuel compose the chemical storage domain. Batteries constitute the electrochemical storage technology. Electromagnetic and thermal energy storage technologies are represented by the super capacitors respectively the heat pumps. Both the features of the energy Storage technologies and the main properties will be presented. A comparison of the discharge time of the storage technologies by application is taken into account. The advantages and disadvantages of the storage technologies will be highlighted. The lack of the appropriate standards of interconnecting different kinds of energy sources and ESS to the microgrid is a disadvantage in technology developing. Thereby the IEC/ISO 62264 standards refers to wind turbine technology, while the IEEE 2000 standard refers to photovoltaic interconnection power systems. In order to reduce air pollution and mitigate climate change, in recent years the need to use renewable energy sources in microgrids has become important. In fact, technological development, public and political policies, availability of different renewable energy resources to be used in microgrids, are elements that create real perspectives in widespread development of renewable energies and their required ESS. The environmental impact and the costs of renewable energy resources have been estimated through the life cycle assessment (LCA) methodology, which determines whether the use of renewable sources and ESS is sustainable. A case study regarding a PV system with and without batteries used into a microgrid that supply a wastewater treatment plant situated in Romania will be presented. Life cycle assessment was used to quantify ecological sustainability and costs in both cases compared to a conventional supply of electricity from the grid. Conclusions and measures are drawn in order to increase the utilization of renewable sources and ESS in microgrids. Also the technically, economic and environmental benefits of inserting microgrids are discussed. The bibliographic references will be presented at the end of the chapter.

Energy security and energy storage technologies

A high peak demand causes the escalating cost of electricity costs for both the utility and end-users. This paper investigates the challenges raised by the high peak demand and the state-of-the-art technologies adopted to reduce the peak demand. The peak shaving technologies can be categorized into four groups. The first category is peaking power plants which include the open-cycle gas turbine (OCGT) power plants and hydroelectric power plants. The second category is the energy storage system (ESS) comprising of the pump hydro storage (PHS), compressed air energy storage (CAES), battery energy storage (BES), flywheel energy storage, thermal energy storage (TES) and hydrogen fuel cell. The third category is the hybrid renewable energy – storage system (HREES) that combines the renewable energy (RE) and energy storage system. The fourth category is the demand-side management (DSM. The advantages and shortfalls of these technologies are highlighted in this paper.

The fight against climate change requires harnessing novel technologies to decrease CO2 emissions. Renewable energy must be among the main strategies for complying with the COP-21 agreements. Energy storage technologies will play a crucial role in increasing the efficiency and availability of this kind of energy source. Moreover, energy storage technologies will help reduce the supply risk of the electric power system, by overcoming the uncertainty of renewable energy generation. Compressed air energy storage (CAES) enables large amounts of energy to be accumulated reliably. Although there are different structures in the subsurface that may be considered for this purpose, the development of CAES in a salt dome offers several technical and economic advantages. Furthermore, currently this kind of structure is the only one used for this purpose on an industrial scale. In order to reduce the inherent risk associated with the definition and selection of subsurface structures, this study proposes a multi-criteria algorithm based on the Analytic Hierarchy Process methodology. In this scenario, the algorithm focuses on the process to rank salt domes for CAES development. The study applies this methodology in the Basque–Cantabrian basin, where as many as eleven structures have been examined.

A comparative sustainability assessment of several grid energy storage technologies

Chapter 21 - Energy Storage Integration

A comprehensive performance comparison between compressed air energy storage and compressed carbon dioxide energy storage