There are many ways to store energy, including thermal storage, electrical storage, and hydrogen storage, among others. Among them, electrical storage can be further divided into electrochemical storage and mechanical storage. Currently, pumped hydro storage, which falls under mechanical storage, is the most mature and largest-scale energy storage technology, accounting for more than 90% of installed capacity.
However, the disadvantage of pumped hydro storage is also visible to the naked eye - it needs to be built in areas with abundant water sources and large elevation differences. Such areas are, of course, limited. Electrochemical storage, which has advantages such as flexible installation and a wide range of applications, has become the recognized energy storage technology with the most promising development prospects. Especially after the proposal of carbon neutrality and peak carbon emissions, electrochemical storage will have greater and faster development.
Because carbon neutrality requires the development of renewable energy sources such as photovoltaic and wind power to replace fossil energy. And these renewable energy sources are intermittent. The mismatch between the availability of intermittent energy sources and actual energy demand is a major obstacle to their utilization. To solve this problem, only electrical energy can be stored when photovoltaics and wind energy are abundant and release energy storage when needed. Therefore, carbon neutrality can be simply defined as renewable energy + energy storage.
In the field of electrochemical storage, lead-acid batteries were originally mainly used, and lithium-ion batteries began to emerge. Relevant data shows that lithium-ion batteries currently account for approximately 86% of the entire electrochemical storage. The main application scenarios of lithium batteries are also different for energy storage batteries and power batteries. Power batteries, as the power source for electric vehicles, require high energy density as far as possible on the premise of safety, so as to have longer endurance. Its charging and discharging speed requirements are also relatively fast. Energy storage batteries, on the other hand, do not have the requirement for mobility and do not require such high energy density. However, they have higher requirements for cost and service life. Low cost, long service life, high safety, and easy recycling are the overall development goals.
One-time investment cost and full-cycle electricity cost. The smaller the former, the shorter the investment recovery period, and the smaller the latter, the larger the profit. Backed by the booming power battery industry, lithium iron phosphate has a significant cost advantage. In addition, it also has high energy conversion efficiency, long service life, and safety characteristics, making it the best comprehensive performance and widely used in various aspects of power system generation, transmission, and distribution. Although ternary lithium batteries have a higher energy density than lithium iron phosphate batteries, they are more cautious in their application due to the fact that energy density is not the most core indicator for energy storage systems, and they have higher requirements for safety and price.
Other batteries have specific applications due to their performance characteristics. Lead-carbon batteries are generally suitable for applications with a discharge duration of 3 hours or more, mainly used in fields such as peak shaving, and standby power for commercial and industrial use. Vanadium redox flow batteries are generally suitable for applications with a discharge duration of 2.5 hours or more, mainly used in centralized renewable energy grid connection and large-scale load balancing.