Marco Togniazzolo

Storage, as is known, has occupied a prominent position in energy supply system installations. More than just a component of the system, storage is the protagonist of the solution, as it not only enhances solutions but also makes installations viable in many cases. Flow reversal, curtailment, clipping, and hourly PLD are some factors that, in themselves, justify the use of batteries to store energy for use when and how needed, but the growing use of batteries goes far beyond these. Storage increases predictability in the electrical system and significantly reduces dependence on operating expensive and polluting thermal power plants, which are still used today during peak demand periods to ensure electricity is supplied to consumer centers. In addition to offering an almost immediate response to variations in consumption demands – something that thermal power plants cannot achieve – the use of batteries also reduces the costs of electricity production, reduces environmental impacts, improves grid stability, and brings necessary security to the electricity sector. It is logical then to think that, if the electrical system is dynamic and its needs are increasingly greater and more diverse, batteries must keep up with such movements. To a large extent, this reasoning is correct and it is clear that the development of increasingly efficient battery solutions, with greater energy density and even greater safety, is the great quest of cell, battery and system manufacturers. To analyze the trends and paths these components are taking, we will use data and facts obtained from visits to three international fairs held this year. The Energy Storage Systems fair in Beijing and SNEC in Shanghai, both in China, and Intersolar in Munich, Germany. If, at these three fairs, we didn't see any new products or launches that surprised us like in past years, we feel that the paths that companies are taking are those of improving equipment that already exists on the market and is already being used in facilities. Speaking of cells, for some years now we have seen that the search for greater storage capacity is the path that industries are pursuing. Cells with ever-increasing capacities to compose equally larger battery banks have been a recurring theme in recent years' trade shows. A few years ago, lithium cells that previously stored 50Ah or 75Ah have already given way to the 128Ah cells of 2 years ago, reaching the 280Ah cells of last year and which are already being replaced by 314Ah cells and even larger. This means that cells are storing more energy because the need for storage has increased worldwide. Lithium Iron Phosphate cells continue to be the majority on the market, but I have been closely following sodium ion cells advancing rapidly among other technologies. The increase in cell capacity does not necessarily mean that it is at the same rate as the increase in energy density, that is, a cell with twice the capacity of its predecessor does not have half its volume or weight. Density has not increased as much as the supply of capacity. Technology has its limits, and I understand that density increases have been smaller each year, which suggests that we are approaching the limit imposed by the chemistry used. One concern of the industry has been the extraction of heat from inside the cells, as every chemical reaction in lithium cells produces heat, some more than others, but all produce this increase in temperature that can compromise the performance and even the safety of the battery. To reduce this heat extraction problem, industries have improved in creating systems and solutions and this is where cell cooling with the use of liquids comes into play, which makes heat exchange much more efficient than exchange with air, even air conditioning. This solution is already widely used in cell modules and BESS systems from various brands. Another technology that is gaining momentum and becoming an ally of cell safety and efficiency is the use of solid electrolytes (solid state). The electrolyte is one of the internal components of the cells that enables the efficient exchange of electrons between the electrodes and, until now, it was mostly liquid or gel. By adopting the electrolyte in solid form, both charging or discharging efficiency and safety are increased several times. More than the exchange or emergence of various technologies, industries are investing in solutions that are already more mature. Do we have flow batteries? Yes, as well as sand batteries or other types, but the superiority of LFP and Na+ is clear. Putting more energy into cells (even at larger sizes) poses a serious problem. If something goes wrong, how do you handle so much energy? How can facilities be protected from such a large amount of energy? To help solve these problems, storage systems have relied on BMS (Battery Management System), the electronic circuits that control, monitor, and protect the operation of the cells, implemented with Artificial Intelligence (AI) resources to ensure that problems are detected earlier and that mitigation actions are faster and more accurate. AI has also contributed to the longer lifespan of these storage systems and better control over them, providing greater efficiency for the system as a whole. All these advances are being accompanied by a drastic drop in the prices of cells, and consequently of storage solutions. In one year the price has plummeted by something close to 25% and continues to fall, albeit with less force. In short, technology continues to advance and better solutions are being introduced and implemented every day. And Brazil, with its enormous potential for storage applications, still relies on what is being presented at fairs around the world. We still have access to new technologies and are being increasingly pressured by manufacturers and integrators to make the use of batteries more and more popular.

Marco Togniazzolo

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