The birth of electricity is traditionally traced back to the great Italian inventor, Alessandro Volta, whose name lives on in the word “volt.” Between 1799 and 1800, Volta worked on a prototype of the device that is now called a battery. It can therefore be said that batteries are at the origin of the history of electricity. And today they are still an essential part of the world's energy system in the form of “Battery Energy Storage Systems” (BESS). What are BESS? BESS are the power plants in which batteries, individually or more often when aggregated, are used to store the electricity produced by the generating plants and make it available at times of need. The fundamental components of a Battery Energy Storage System are the blocks formed by the batteries, but other elements are also present. They are namely: an inverter, which converts the direct current (DC) from the batteries to the alternating current (AC) from the Grid (and vice versa); a transformer, for adapting the system's voltage to that of the Grid; and finally, auxiliary systems (particularly for cooling and fire-fighting). How do storage plants work? The technology for BESS is based on the use of electrochemical storage, which can store the energy produced by renewable power plants. It’s a kind of power bank that can give back stored energy, by returning it on demand. BESS are one of the main energy storage system: sometimes they are also called electrochemical energy systems to distinguish them from others, such as gravitational energy systems (including pumped-storage hydroelectric power plants), mechanical energy systems (including compressed air or flywheel systems) and (Thermal Energy Storage, TES) systems As in all storage systems, in the case of BESS the electricity produced by a power plant, or any other generating plant (even a single photovoltaic panel), is stored and then released at the desired times and moments. BESS uses a specific technique for storage: since an electric current is a flow of electrical charges, a battery is charged by accumulating charges of particular materials (called electrolytes) at one of the two poles, from which they then flow to the other pole in the discharge phase. Types of battery Batteries are distinguished mainly by the chemical elements used: Lithium-ion batteries: this is the most widespread, efficient and increasingly cost-effective technology today; typically, they use lithium in combination with other materials, such as iron and phosphate used in LFP (Lithium Iron Sulfate) batteries. More advanced research also points to lithium-sulfur batteries; Alternatives to lithium include lead-acid and sodium-sulfur batteries, which are already in use, while others are being studied, such as aluminum-sulfur batteries; Another emerging technology comes in the form of flow batteries, in which the internal dynamics change: unlike conventional batteries, electrolytes are stored separately, then flow into a central cell where they are set to react in the charging and discharging phase. The most common example is vanadium, but research is also focusing on zinc-bromine and zinc-iron models. This is a promising solution, especially because of their longer lifespan; Solid-state batteries: while conventional and flow batteries normally use electrolytes in the liquid state, here they are in the solid state (e.g., ceramic or synthetic materials). Their performance is good, but the costs are still high. The benefits of battery storage Energy storage is one of the most prominent elements in the ongoing energy transition. Indeed, its role is increasingly crucial in light of the large-scale deployment of intermittent and unpredictable renewable sources. Thanks to storage systems, the electricity produced by wind and solar power plants can be stored and then released at the desired times: it can thus be delivered to customers at all hours, regardless of the time of day or weather conditions. In practice, storage is essential for enabling the penetration of new renewable sources into the energy system: it’s essential for reducing reliance on fossil fuels, and thus greenhouse gas emissions into the atmosphere. The other major benefit of storage systems concerns the transmission grid. The stored electricity makes it possible to cope with any imbalances between supply and demand in the market: this makes the Grid more stable and greatly reduces the risk of service disruptions or blackouts. Of all the storage systems, BESS has the advantage of affordability: thanks to the very rapid advances in technological innovation, especially in the field of materials science, and the spread of production for the automotive sector, battery prices are continuing to fall while their efficiency is constantly increasing. Furthermore, Battery Energy Storage Systems, thanks to their modular design, offer great flexibility and scalability: additional battery blocks can be easily added to a plant that’s already in operation in order to increase its capacity. What are the main applications? The most natural users of Battery Energy Storage Systems are electricity companies with wind and solar power plants. In this case, the BESS are typically large: they are either built near major nodes in the transmission grid, or else they are installed directly at power generation plants. There are many other possible applications, however, and they are increasingly widespread. Their growth is steady and is also linked to the prosumer (producer + consumer) phenomenon, i.e., self-producers of electricity: if, for example, private individuals have a solar panel on their home, a small BESS enables them to store the excess electricity produced during the day for use at night. It also provides them with a degree of autonomy, if there are blackouts, and the ability to disconnect from the Grid. BESS has similar benefits for industrial and commercial companies, but with greater variety. A company, especially an energy-intensive one, can regulate the amounts of electricity drawn from the Grid. For example, it can decrease the amounts at times when prices are higher, and it can avoid consumption peaks. A company can also decide in advance to reduce the amounts at times of peak demand. This not only provides greater energy security, but it can also contribute to Grid stability while ensuring a financial advantage through the Demand Response mechanism. BESS are also indispensable elements for microgrids, the small Grids that are used for producing and distributing energy locally (e.g., large factories, industrial districts, or residential complexes). BESS are also functional for smart Grids for electricity distribution because they enable them to draw on a reserve, in case of immediate need. Batteries for photovoltaic storage Some of the most natural users of BESS include photovoltaic systems, from individual prosumer panels to large solar farms run by power companies. For this reason, solar panel suppliers frequently offer commercial packages in which batteries for storage are already included. Lithium-ion batteries are used in the vast majority of cases: they are cost-effective compared with alternatives (such as lead-acid batteries) mainly because of a far better relationship between cost, efficiency, and lifespan. The size of the BESS depends, of course, on that of the photovoltaic system to which it is connected; usually one is chosen with a power rating that’s 50-100% higher than the theoretical maximum power that the PV system is capable of delivering. The economic and social impact of BESS Battery Energy Storage Systems have a very favorable impact on the energy market. This is because they work in such a way that they are able to provide grid services and energy at times of high demand at more competitive prices than traditional generation plants. Furthermore, they promote the flexibility of the electricity system and distributed generation, which is a characteristic of the new paradigm. The old unidirectional model, whereby a few large power plants deliver to passive users, is being transformed into a multidirectional Grid with many producers, who are active players in the market. This is a momentous change, not only from a technological but also from a social point of view. From an economic point of view, the most immediate beneficiaries of BESS are private users, who save on their electricity bills and enjoy greater security of electricity supply. This has significant benefits both for the comfort of individual citizens and, even more so, for the competitiveness of companies. Moreover, in the case of microgrids or energy communities, BESS has also become a tool for social cohesion. Last but not least, Battery Energy Storage Systems have an environmentally beneficial impact on humanity: by promoting the spread of clean energy sources, they help mitigate climate change and improve air quality. The role of BESS in the energy system is therefore increasingly crucial from a social and environmental sustainability perspective: to bring about a fair and safe energy transition, it is important that its presence is increasingly widespread. And continued improvements in cost and performance legitimately suggest that this will be the case.
