At present, there is no energy storage technology that can meet all the needs of the new energy grid. Due to different working principles and application scenarios, the advantages and limitations of each energy storage technology are not the same. The evaluation standards for energy storage technology in the industry are still vague, so it is necessary to sort out them and put forward a common scoring standard that meets the objective and practical needs.
1. Safety evaluation standards of energy storage technology
During the whole life cycle, the battery energy management system is in good condition and does not pose a threat to human beings under normal operating conditions or when accidental events occur. Safety is the first and basic element of energy storage technology evaluation. Energy storage applications are different from battery applications in mobile communication, electronic products, automobiles and other fields. The main difference lies in its large scale, large and concentrated number of batteries, complex control, and huge investment. Once safety problems occur, huge losses will be caused. Safety is a systematic engineering. The causes of accidents not only include thermal runaway of energy storage battery body, but also involve battery management system and other aspects. It is necessary to systematically study and establish energy storage safety evaluation system. Therefore, safety must be taken as the primary indicator to evaluate battery energy storage. On the one hand, the industry should strengthen the formulation of safety standards, and on the other hand, more secure energy storage ontology and security control system should be developed.
2. Evaluation standard of energy storage technology performance
The basic performance of energy storage equipment that can meet the needs of users, such as capacity, power, response time, cycle times, life, charging and discharging efficiency and other factors. At present, energy storage management system has many application scenarios, covering all aspects of power system generation, transmission, distribution and use. Due to different roles, the demand for energy storage equipment is also different. For example, from the power generation side, energy storage application scenarios include energy time shift, capacity unit, load tracking, system frequency modulation, standby capacity, renewable energy grid connection, and so on. The energy time shift and capacity unit plays the role of peak cutting and valley filling, and has low requirements on charge and discharge power, time, annual operating frequency and response speed. The load tracking, system frequency modulation and reserve capacity are typical power applications. In order to solve the problem of slow power generation from traditional energy sources, the energy storage management system needs fast response speed and high annual operation frequency. Renewable energy generation includes both power-based applications and energy-based applications. For photovoltaic, due to its discontinuity, excess power in the day needs to be stored and released at night, which belongs to the time-shift of renewable energy. For wind power, due to its large fluctuation, it needs to be smooth, so it is mainly applied in power type.
3. Evaluation criteria for environmental friendliness of energy storage technology
Low environmental load throughout the life cycle. For energy storage technology, on the one hand, it is necessary to reduce the damage to the environment during the construction and use of energy storage system, and on the other hand, it is necessary to do a good job in the recycling of materials in the energy storage system. Energy storage is a resource-intensive industry, the carrier of energy storage is chemical, especially for battery energy storage, it involves a variety of elements. However, the amount of each element in the Earth’s crust varies. In battery energy storage technology, these precious metals are recyclable. Therefore, improving the recovery rate of cobalt in power batteries and simplifying the technological process are also the focus of current research.
The evaluation indexes of energy storage technology are interrelated, and the cost restricts the large-scale application of energy storage to a large extent, while the cost reduction mainly relies on key technology breakthroughs (reliability of energy storage body, rational optimization of performance configuration) and large-scale production. While the cost reduction and technological breakthrough, the safety should be ensured. Therefore, it is necessary to comprehensively evaluate the specific characteristics of various energy storage technologies and select appropriate technologies according to their application fields.