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[en] This document describes the main characteristics of various electric power storage methods and their application domains. The large-scale storages include the hydraulic systems, those using compressed air, the batteries or those implementing a thermal way. The small-scale storages are electrochemical as the accumulators, the super-capacitors, mechanical as the flywheel, magnetic or also by the hydrogen use. The first part presents the necessity of the electric power storage, the second part the places of these storage. The third part details the forms of storage. (A.L.B.)
[en] Salt caverns used for the underground storage of large volumes of natural gas are in high demand given the ever-increasing energy needs. The storage of renewable energy is also envisaged in these salt caverns for example, storage of compressed air and hydrogen mass storage. In both cases, salt caverns are more solicited than before because they are subject to rapid injection and withdrawal rates. These new operating modes raise new mechanical problems, illustrated in particular by sloughing, and falling of overhanging blocks at cavern wall. Indeed, to the purely mechanical stress related to changes in gas pressure variations, repeated dozens of degrees Celsius of temperature variation are superimposed; causes in particular during withdrawal, additional tensile stresses whom may lead to fractures at cavern wall; whose evolution could be dangerous. The mechanical behavior of rock salt is known: it is elasto-viscoplastic, nonlinear and highly thermo sensitive. The existing rock salt constitutive laws and failures and damages criteria have been used to analyze the behavior of caverns under the effects of these new loading. The study deals with the thermo mechanics of rocks and helps to analyze the effects of these new operations modes on the structural stability of salt caverns. The approach was to firstly design and validate a thermodynamic model of the behavior of gas in the cavern. This model was used to analyze blowout in gas salt cavern. Then, with the thermo mechanical coupling, to analyze the effects of rapid withdrawal, rapid injection and daily cycles on the structural stability of caverns. At the experimental level, we sought the optimal conditions to the occurrence and the development of cracks on a pastille and a block of rock salt. The creep behavior of rock salt specimens in triaxial extension also was analyzed. (author)
[en] The current boom in renewable energy, notably in wind or solar power, regularly gives rise to the question of the intermittence of supply from these sources. It's generally accepted that the network can take on board without major constraint a penetration rate of 20% for these renewables, specifically with regard to frequency modulation or tension. The reader will find in this article the main features that can be found in all forms of electricity storage, as well as a handful of technologies capable of rendering significant service to the network thanks to their sizeable capacities and power. (author)
[en] In the context of developing renewable energies, storing energy improves energy efficiency and promotes the insertion of intermittent renewable energies. It consists of accumulating energy for later use in a place that may be the same or different from the place of production. Converting electrical energy to high-pressure air seems a promising solution in the energy storage field: it is characterized by a high reliability, low environmental impact and a remarkable stored energy density (kWh/m3). Currently, many researchers are focusing on developing small scale of the compressed air energy storage system (CAES) coupled to a building applications based on the work done for multiple large scale CAES systems installed in the world. A global numerical model of trigeneration CAES system coupled to a building model and renewable energy modules was developed in order to analyze the CAES system behavior responding to electrical, building heating and cooling demands. Different energy scenarios (autonomous and connected to the grid modes), geographical locations and building typologies were proposed and analyzed. The CAES numerical model development is based on solving energy and heat transfer equations for each system component (compressor/expander, heat exchanger, high pressure air reservoir, thermal water storage tank). Adiabatic compressor and expander were firstly selected to investigate the trigeneration advanced adiabatic compressed air energy system (AA-CAES) coupled to the building and to grids with the different scenarios described above. Connected mode showed more benefits sides from using the CAES system coupled to the building and to grids with an electrical load management of 75.9 % (Nice location). In addition, the trigeneration AA-CAES system offered a compromise between the electrical round-trip efficiency (output/input), hot and cold coverage in function of building applications and the renewable energy modules size. Similar to adiabatic components, quasi-isothermal compressor and expander developed by LightSail Energy and Enairys Powertech were also analyzed by solving the energy and heat transfer equations for each phase of the compression and expansion processes. These analytical models allowed us to have a better understanding of these technologies operations and to have several orders of magnitudes of different physical parameters. The LightSail Energy technology showed more interests for hot/cold water production while compressing/expanding air than the Enairys Powertech technology which presented a nearly quasi-isothermal air compression/expansion process. I-CAES and AA-CAES were also compared from a financial point of view based on compressed air market analysis. Three different prototypes were studied: Two AA-CAES systems (ideal and virtual (some of which are based on commercial units found in the compressed air market)) and one I-CAES system (based on LightSail Energy CAES prototype). The compressed air market is concentrated on the small power units which make the small scale AA-CAES prototype building complicated specially for high storage pressure. Based on LCOE analysis, the LightSail Energy prototype presented the lowest cost of energy delivered (Euro/kWh) for a 20 years of operational period. (author)
[fr]Le developpement des energies renouvelables pose la question du stockage de l'energie electrique. L'utilisation du stockage par air comprime semble une solution prometteuse dans le domaine du stockage d'energie: elle se caracterise par une grande fiabilite, un faible impact environnemental et une remarquable densite energetique stockee (kWh/m3). Jusqu'a present, l'air comprime a ete utilise dans de nombreux domaines comme vecteur d'energie pour stocker differentes formes d'energies (transport routier, poste pneumatique, plongee sous-marine). Neanmoins, actuellement de nombreux chercheurs se concentrent sur le developpement de stockage d'energie par air comprime (CAES) a petite echelle couple a une application de batiment en se basant sur les travaux developpes pour les multiples systemes de CAES a grande echelle installes dans le monde. Un modele numerique global du systeme de stockage par air comprime a petite echelle, couple a un modele de batiment et a des modules d'energie renouvelable a ete developpe dans le but de modeliser differents compresseurs/detendeurs et structures d'installation developpes par plusieurs startups (LightSail Energy et Enairys Powertech) et chercheurs. Plusieurs scenarios energetiques (autonomes et connectes aux reseaux), localisations geographiques et typologies de batiments ont ete proposes et analyses. Le developpement du modele numerique CAES a ete base sur la resolution de l'equation de conservation de l'energie et des equations de transferts pour chaque composant du systeme (compresseur/detendeur, echangeur, reservoir d'air haute pression, reservoir de stockage d'eau chaude/froide). Les compresseurs et detendeurs adiabatiques ont d'abord ete selectionnes pour etudier le systeme de trigeneration de stockage d'energie par air comprime adiabatique avance (AACAES) couple au batiment et aux reseaux avec les differents scenarios decrits ci-dessus. Le mode connecte aux reseaux (electrique, chaud et froid) a montre l'importance d'utiliser le systeme CAES couple au batiment et aux reseaux avec un effacement electrique de 75,9 % (Nice). En outre, le systeme AA-CAES de trigeneration (electrique, chaud et froid) offre un compromis entre l'efficacite du systeme electrique, le taux de couverture du chaud et le taux de couverture du froid en fonction de l'application du batiment et de la taille des modules d'energie renouvelable. Les compresseurs et detendeurs quasi-isothermes developpes par LightSail Energy et Enairys Powertech ont ete modelises pour chaque phase de la compression et de la detente. Ces modeles analytiques ont permis une meilleure comprehension du fonctionnement principal de ces technologies et d'avoir l'ordre de grandeur de differents parametres physiques. La technologie LightSail Energy a montre plus d'interet par la production d'eau chaude/froide lors de la compression/detente de l'air que la technologie Enairys Powertech qui presente une compression/detente d'air d'avantage isotherme avec des rejets thermiques trop proches de la temperature ambiante pour etre recuperable. Les systemes I-CAES et AA-CAES sont compares d'un point de vue financier en se referant a une analyse du marche des systemes de production/utilisation de l'air comprime. Trois prototypes differents ont ete etudies: deux systemes AA-CAES (ideal et virtuel (bases sur des unites commerciales trouvees sur le marche de l'air comprime)) et un systeme I-CAES (base sur le prototype LightSail Energy CAES). Le marche de la turbine est concentre sur les petites plages de pression et pour cela le montage d'un prototype AA-CAES avec une pression de stockage importante est complique. A partir de l'analyse economique LCOE (levelized cost of energy), il apparait que le prototype LightSail Energy presente le cout d'energie livre le plus bas (Euros/kWh) pour une periode operationnelle de 20 ans. (auteur)
[en] To date, Pumped Hydro Storage (PHS) is practically the only technology used to store large quantities of electricity. There are however other ways to achieve the same goal. There are not yet well known, because the interest for large scale storage is quite new A complete family of storage technologies can be defined as 'Thermodynamic Storage Systems'. Their only common factor is that a gas is pumped and expanded in the process. If the gas is air taken from the atmosphere and discharged to it, the system is said 'an open system'. This is already developed in the form of Compressed Air Energy Storage (CAES). Different embodiments are possible, following the way the heat gene - rated during the compression stage is conserved. The compressed air is generally stored in underground caverns created in deep salt formations. 2 installations are presently operating and many projects are envisaged. if the gas circulates in closed loop within the plant, the system is said 'a closed system' In this case, the energy is stored as heat and/or cold at different temperature levels. A great variety of technologies can be imagined and are under development, using different gases (e.g. argon, CO2) and different temperature ranges. PHS and CAES require specific sites for water reservoirs or underground caverns. The dosed systems can be installed basically anywhere. (author)
[en] With the important development of off-shore wind energy (22 GW in 2019, 70 GW in 2030), wind farms always further from coasts, comes the issue of the way to manage the surplus or to regulate electric power production. This article briefly comments the assessment of an envisaged technology which has been developed by a German research institute: the use of concrete spheres, immersed and equipped with a pump/turbine to create a pumped storage power station. A model at a one third scale is about to be built
[en] It is universally apparent that environmental and energy transition must evolve in order to meet the needs of a growing world population while still heeding environmental constraints. This change over time will be based on a sustainable energy mix, and consequently the use of renewable energy sources is likely to intensify over the coming decades in respond to rising demand for electricity worldwide. The International Energy Agency (IEA) predicts that 40% of electricity will come from renewable sources by 2050. Some of these renewable forms of energy generate power on an irregular and intermittent basis, and energy storage offers one solution for deploying these intermittent energy sources more widely as part of an efficient smart grid. (authors)
[en] As they are intermittent, renewable energies raise the issue of energy storage. A first article evokes the existence of energy-transfer pumping stations in France (they are associated with dams) and outlines that energy storage requires important investments. It also evokes the different considered and currently tested energy storage technologies (compressed air, hydrogen, flywheels, methane, batteries, or phase-change materials) and outlines that each of them is associated to a specific application. A second article discusses the issue of a precise control of the coupling between energy production and storage. Some experiments are evoked. A last article addresses the development of positive-energy buildings which require energy storage solutions which are based on smart grids
[en] As the global electricity systems are shaped by decentralisation, digitalisation and decarbonization, the World Energy Council's Innovation Insights Briefs explore the new frontiers in energy transitions and the challenges of keeping pace with fast moving developments. We use leadership interviews to map the state of play and case studies across the whole energy landscape and build a broader and deeper picture of new developments within and beyond the new energy technology value chain and business ecosystem. The topic of this briefing is energy storage. We interviewed energy leaders from 17 countries, exploring recent progress in terms of technology, business models and enabling policies. We showcase these in 10 case studies. While the brief addresses energy storage as a whole, most insights are focused on electrical storage. Our research highlighted that today's mainstream storage technologies are unlikely to be sufficient to meet future flexibility requirements resulting from further decentralisation and decarbonization efforts. Furthermore, a restricted focus on lithium-ion batteries is putting the development of more cost-effective alternative technologies at risk. A detailed list of the interviews with innovators, energy users and producers can be found at the end of this brief. Annex 4 provides a list of acronyms and abreviations. With major decarbonizing efforts to remove thermal electric power generation and scale up renewable energies, the widespread adoption of energy storage continues to be described as the key game changer for electricity systems. Affordable storage systems are a critical missing link between intermittent renewable power and 24/7 reliability net-zero carbon scenario. Beyond solving this salient challenge, energy storage is being increasingly considered to meet other needs such as relieving congestion or smoothing out the variations in power that occur independently of renewable-energy generation. However, whilst there is plenty of visionary thinking, recent progress has focused on short-duration and battery-based energy storage for efficiency gains and ancillary services; there is limited progress in developing daily, weekly and even seasonal cost-effective solutions which are indispensable for a global reliance on intermittent renewable energy sources. The synthesis of thought leadership interviews and case studies with 37 companies and organizations from 17 countries helped derive the following key takeaways and also provide the impetus to the solution steps that we discuss in detail later in this brief: 1 - Shared road-maps: Energy storage is a well-researched flexibility solution. However, while the benefits of energy storage are clear to the energy community, there has been limited bridge-building with policy-makers and regulators to explore the behavioural and policy changes necessary to encourage implementation. 2 - Market design - Access and stacking: Market access and the ability to stack different services simultaneously will enable cost-effective deployment of energy storage, regardless of the technology. 3 - More than batteries: Energy storage is too often reduced to battery technologies. Future-proofing our energy systems means considering alternative solutions and ensuring technologies have equal market opportunities. Demonstration projects of such technologies are necessary to disprove bias towards specific technologies. 4 - Sector coupling: Energy storage presents a sector coupling opportunity between hard-to-abate sectors, such as mobility and industry and clean electricity. Different vectors of energy can be used, including heat, electricity and hydrogen. 5 - Investment: Relying on investments by adjacent sectors such as the automotive sector is not enough. The energy sector must adopt more aggressively technologies aligned with the end-goal: affordable clean energy for all.
[fr]L'adoption a grande echelle du stockage de l'energie est consideree comme un changement de paradigme majeur pour le systeme energetique. Le developpement d'une technologie de stockage accessible aux consommateurs constitue le chainon manquant pour rendre fiables les energies renouvelables variables. En depit de ce defi technique, le stockage de l'energie peut remplir un role au-dela des energies renouvelables, notamment dans le controle des congestions et les variations de puissance du reseau. Malgre ces perspectives encourageantes, les progres autour du stockage sont restes centres sur les services secondaires et les gains d'efficacite acquis par le stockage a court terme. En revanche, tres peu de progres a ete fait vers les solutions diurnes, hebdomadaires ou saisonnieres rentables, qui sont necessaires a la fiabilite des sources d'energies renouvelables. Conclusions principales: 1 - Feuille de route partagee: le stockage d'energie est une solution de flexibilite reconnue. Cependant, il existe tres peu de visions communes entre legislateurs et experts, bien que tous reconnaissent le potentiel du stockage. 2 - Structure du marche: obtenir un deploiement rentable du stockage se fera grace a un acces equitable au marche et un cumul de differents services, quelle que soit la technologie utilisee. 3 - Au-dela des batteries: le stockage energetique est trop souvent reduit aux batteries. Un systeme energetique a l'epreuve du temps doit s'appuyer sur des solutions diverses, encouragees par un acces equitable aux opportunites sur le marche. 4 - Couplage sectoriel: le stockage energetique represente une veritable opportunite de couplage entre les secteurs difficiles a decarboner et les energies renouvelables. Differents vecteurs d'energie peuvent etre utilises, y compris la chaleur, l'electricite et l'hydrogene. 5 - Investissements: il faut diversifier les investissements au-dela des secteurs adjacents, tel que le secteur automobile. Le secteur energetique doit adopter de maniere plus agressive les technologies alignees avec leur finalite: de l'energie propre pour tous.
[en] As a key factor to allow the continuous growth of renewable energies, energy storage technologies are now more than ever in the spotlight. In order to grasp the stakes, understand the technology diversity, learn relevant orders of magnitudes and comprehend the close intricacy of energy storage with energy and environmental issues, ENEA has published a detailed and well-documented publication on the subject