That energy storage as a new industry, must do first to stand firm, in order to talk about walking up and running forward. Without the premise of safety adventurous or big dry fast, will bring endless harm to the industry.
In mid-June, South Korea's Ministry of Industry and Information Technology announced the results of 23 previous energy storage plant fire accident investigations, summarizing the following reasons: battery system defects, insufficient protection systems to deal with insulation testing, insufficient management and maintenance of energy storage plants after construction is completed, and poor integrated management systems between the converter (PCS) and the energy storage system (ESS).
The energy storage battery system has to meet four kinds of usage needs: energy transfer, peak and frequency regulation, smoothing out power, tracking the dispatching curve, etc. To how to both enhance the specification and not hinder the development is a problem to be discussed by the whole industry.
Compared with physical energy storage, the biggest problem of electrochemical energy storage is that the large-capacity battery system is prone to safety problems, even if the best battery of mature manufacturers, if the work of the poor power balance, it will cause safety accidents.
Decomposition that the cause of the battery fire from two sources: on the one hand, due to electrical wiring, inverters, battery management systems and other unreasonable design or failure, the failure of the part of the local long-term heat, arc or spark instant exothermic, will cause a short circuit in the line leading to electrical fire; on the other hand, with the increase in the number of battery cycles, overcharge and overdischarge, irreversible side reactions and other reasons lead to capacity decay, increased internal resistance On the other hand, with the increase in the number of cycles, overcharge and overdischarge, irreversible side reactions and other reasons lead to capacity decay, increased internal resistance, internal short circuit, abnormal gas production, lithium precipitation and other phenomena, when the local or overall temperature rises rapidly, heat accumulates in the internal, will lead to thermal runaway battery system.
At present, high nickel ternary and other high-energy batteries should not be the focus of development, the success of all-solid-state batteries there is uncertainty. At present, it seems that the lithium iron phosphate ion battery safety, long life, neither nickel nor cobalt and other metals, and today has mastered the micro-nano structure & mdash; carbon cladding technology, can become the main force, but to continuously improve the cost performance.
Theoretically speaking, lithium iron phosphate is not absolutely safe, but only relatively safe. Currently seen in energy storage power plant safety accidents, often in the absence of early warning or lagging situation, coupled with the existing fire protection measures are not for the fire configuration, and eventually evolved into serious accidents.
Therefore, energy storage safety issues in addition to enhanced battery management, but also take into account some passive security measures, such as sensors, fire protection systems, and even early intervention at the operation and maintenance level, just like photovoltaic power plants, energy storage systems should also bear in mind the seven points by design, three points by the principle of operation and maintenance and put into action, in order to ensure that the system is safe and controllable.
Some industry insiders have also proposed that the safety of energy storage systems on special use scenarios, to introduce appropriate norms and standards, such as on the installation of commercial and industrial user-side energy storage systems in the city in the basement, must pay great attention to safety issues, careful assessment. It is reported that the Australian StandardsAustraliaAS5139 standard in the consultation, had required lithium-ion batteries installed in a separate space / housing, household battery energy storage system can only be installed in a dedicated outdoor area.
Energy storage is still far from any advanced, economic, today's first to do a steady and stable, the entire energy storage system safety balance issues, from the cell, battery to bMS (battery management system), all the way to EMS (energy management system) through to do a good job.
What should be the choice of battery technology route? As costs fall, can battery storage replace pumped storage? These are the same questions that the industry is concerned about.
It cannot be said absolutely which energy storage method is the best, whether it is the physical nature of pumped storage, flywheel energy storage, or electrochemical battery, they have their own use scenarios, the scientific approach should be based on its characteristics, deployed in the right place, to better play its function.
Battery storage and pumped storage are not mutually exclusive, not a relationship between you and me, but can develop into a harmonious symbiotic relationship that complements each other, develops together and promotes each other. The reason is that battery storage can track the fluctuation of grid frequency and load in a very short period of time (100 milliseconds), the power climbing rate is very fast, and the power is almost completely synchronized with the frequency, but the durability is limited. The shortage of pumped storage is that the time from no load to full load takes 10 seconds, but it can supply from daily regulation to weekly regulation, supplying more reliable protection for the system's large stability and accident backup, and supplying irreplaceable uses for the grid above the subsequent replenishment.
From the scenario, battery storage currently important scenarios include: power side of the generation side of the scenic power station, thermal power plant AGC frequency regulation; grid side of the substation energy storage, virtual power plant, peaking, auxiliary services (frequency regulation, voltage regulation, black start, rotating backup); user side of the optical storage power station, home energy storage, backup power, etc..
From the battery type, the most important thing is the power characteristics and capacity characteristics of the battery. Therefore, according to the different requirements of different energy storage use scenarios about the battery power to capacity ratio, the energy storage battery is roughly divided into three types: capacity type (0.5C), energy type (1C) and power type (2C). The larger the ratio, the higher the power density of the battery is represented, but the capacity density will be lower and the price per unit of capacity will be higher.
Among the various types of current energy storage batteries, liquid flow batteries and lithium slurry batteries are typical capacity type batteries, while lithium ion batteries in lithium ion batteries, lithium ion titanate batteries and supercapacitors are a typical class of power type batteries. Other types of batteries can have some degree of property adjustment by changing battery materials and processes to suit different energy storage use scenarios.
Energy storage batteries do not have high requirements for energy density, but for different use scenarios, there will be certain requirements for their power density, such as the need for safety, long life, high energy conversion efficiency, and the number of cycles should generally be greater than 3500 times.
Comprehensive view, power peaking, off-grid photovoltaic energy storage or user-side peak-valley spread energy storage, generally want to storage battery continuous charging or continuous discharge for more than two hours, so suitable for charge/discharge multiplier 0.5C capacity type battery; about power frequency regulation or smooth renewable energy fluctuations in the energy storage scenario, the energy storage battery in seconds to minutes of rapid charging and discharging, so more suitable for charge/discharge multiplier 2C The power type battery; and in some scenarios to bear both frequency regulation and peak regulation, the energy type battery will be more suitable, of course, this scenario can also be used together with the power type and capacity type battery.
Disruptive innovation in the industry must be supported by a new generation of technology. It was precisely because of the emergence of a new generation of memory chips that broke through the mechanical addressing method that Steve Jobs launched the Apple phone. While energy-using devices are becoming thinner, lighter and smarter, batteries are still suffering in the hope of an upgrade.
In the face of a variety of energy storage technology routes, many experts said that although there are currently many battery technology routes, these existing technologies will not be the mainstream route in the future, the future will certainly appear disruptive technology.
Since 2018, many battery experts have publicly stated that in the future, the power lithium battery and energy storage battery technology routes will be separated, and special cells for energy storage will also make an appearance.
The existing lithium-ion battery for energy storage is the progressive development of micro and small batteries such as cell phone batteries, in addition to making the battery larger, it has not been separated from the core design idea of bonding and coating the film electrode structure of small batteries, which brings the problem of consistency design for large lithium-ion batteries for energy storage. In addition, the use of batteries based on the existing principles of safety hazards, after the solution is also more difficult.
Therefore, it is necessary to completely break away from the original small battery design ideas and develop disruptive large energy storage battery structure technologies, including ultra-thick paste electrode technology for capacity-based energy storage and ultra-high voltage structure technology for power-based energy storage, based on which innovative development of low-cost manufacturing technology, safe life-extending repair technology and green recycling technology to meet the needs of different energy storage use scenarios and support energy storage Industry to achieve breakthrough development. It is understood that the current slurry battery developed by Kyocera Japan, which can reduce the cost of raw materials by about 30% compared to the past, will start mass production as soon as 2020 and be used in residential and factory energy storage systems.
The next decade will see disruptive developments in electrochemical energy storage technology. With regard to energy storage companies, the following categories are worthy of attention: reliable technology, with an international perspective of energy storage products or processing equipment export suppliers; unique technical route, in terms of cost has clear competitive advantages of energy storage product suppliers; master the core use of technology, and insurance companies to cooperate in the supply of energy storage leasing services, energy storage operation and maintenance service providers; energy storage systems under the power grid companies.
In the future, the goal of electrochemical energy storage technology is low-cost, long life, high safety, easy to recover, pending disruptive innovation and breakthroughs in technology.
JUNLEE Energy, which has been committed to battery research and development, is a challenge and an opportunity. The R&D team of engineers will provide the world with more economical new energy batteries, and will improve lithium-ion battery technology to reduce the total cost.
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