Why the energy storage market is decentralized-comparison between new and old batteries

As one of the hottest field at present, the expected installed capacity of energy storage industry often exceeds ten million watts, attracting capital from all walks of life. In the broad prospect, the decentralized energy storage market is becoming the industry consensus.

In the mainstream technology route, the electrochemical energy storage market has attracted the most attention. Among them, the lithium ion battery industry is the most mature, but the flammability is still the biggest weakness. The relatively safe sodium battery and liquid flow battery are limited by the weak industrial foundation.

The energy storage market is broad but decentralized

According to statistics, the scale of China’s energy storage market reached 50 billion to 60 billion RMB in 2021, an increase of more than 120% over 2020. Under the influence of the “3060 target”, the high-speed development period of the energy storage industry has just begun.

By the end of 2025, China’s installed capacity of new energy storage will jump from the current millions of kilowatts to 30 million kilowatts, further increase to about 150 million kilowatts by 2030, and may increase to more than 1 billion kilowatts by 2050. It is worth noting that, although energy storage is a hot field for industry companies, the actual profit depends not only on their own strength, but also on the selected technical route.

Single technology is difficult to meet the requirements of various application scenarios of energy storage, and the decentralized energy storage market has basically become a consensus. The risk of new battery technology replacing old battery technology always exists.

The dispersion of the energy storage market mainly means that the electrochemical energy storage technology has limited space to replace the pumped storage, and different technical routes within the electrochemical energy storage have their own advantages and disadvantages, which further form a competitive relationship with each other.

Public data shows that traditional pumped storage accounts for about 90% of the total installed capacity of energy storage in China, while electrochemical storage accounts for only about 10%, including lithium battery, sodium battery and liquid flow battery.

In practical application, electrochemical energy storage is restricted by high cost, low capacity and other factors, so whether it can be popularized on a large scale is still questionable.

The insiders believe that there are many theoretical application scenarios of electrochemical energy storage, but it is difficult to implement them. Among the main energy storage technology routes, pumped storage has been more mature in the peak shaving field, but the role of electrochemical energy storage is still not obvious.

Due to the small capacity, such projects are in a demonstration state for a long time, and the gap between the two energy storage technologies in the application end is also large.

Liquid cooled energy storage system may gradually become the mainstream of the market

Liquid cooling technology is getting the attention of the industry, and has become the development trend of energy storage heat management technology. The liquid cooling energy storage system generally uses ethylene glycol aqueous solution as the coolant.

Combined with the use of large capacity electric cells, the electric cells are integrated and arranged on the liquid cooling plate to form a PACK unit. The battery heat is exchanged through the liquid cooling unit.

Compared with the previous air cooling system, its energy density has been greatly improved. The cell can achieve a temperature balance of about 3-5 ℃, effectively improve the battery consistency level, improve the battery energy utilization rate throughout the life cycle of energy storage, and reduce the risk of battery thermal runaway.

Liquid cooling technology itself is not a new technology. Due to its advantages of large heat carrying capacity, low flow resistance and high heat transfer efficiency, it has been widely used in SVG, data center, DC equipment, electric vehicles and other fields. Due to its excellent temperature management characteristics, new applications in the energy storage field have gradually become the mainstream choice of the market.

At present, the world’s mainstream energy storage integration manufacturers have introduced energy storage equipment based on liquid cooling and thermal management technology. Since the second half of last year, it has been widely used in many projects.

The integration mode of liquid cooling cabin mainly includes centralized battery cabin, split battery cabin (cabinet) and other integration modes. Centralized battery cabin is generally equipped with centralized liquid cooling units. The battery clusters are directly connected in parallel or connected to the centralized PCS through DC/DC converter.

Cabin type generally includes two types of single row door opening and double row door opening, single row door opening and double row door opening. The distributed liquid cooling unit is adopted for the split battery compartment (cabinet), which can generally adopt the compartment type or cabinet type structure.The functions and systems of each cabinet are relatively independent, and modular combination can be realized according to the project scale.

In addition to the centralized energy storage system wiring type, the distributed battery compartment (cabinet) can also adopt the mode that a single cabinet is converted into AC through the string type PCS, and the AC side of multiple PCSs is connected to the local transformer in parallel.

In terms of fire fighting mode, the liquid cooling energy storage system has also achieved technical innovation. Due to the high protection level of liquid cooled battery PACK, it can generally reach the protection level of IP67. The realization of cluster level fire protection requires extremely high requirements for the structure and sealing of the cabin.

However, PACK fire protection has great advantages in preventing the uncontrolled diffusion of electric core heat and extinguishing fire. In the liquid cooled PACK, detectors and fire extinguishing measures are set to achieve early prediction and accurate spraying. In terms of fire fighting media, perfluorohexanone has been gradually popularized and applied due to its better cooling performance.

In addition, some manufacturers also propose to use aerosol as a conventional fire fighting method. The liquid cooling system also has its advantages in fire protection and explosion protection design. Because it adopts a non walk-in structure, the battery cabinet can be isolated by using a fireproof partition to reduce mutual influence.

Energy storage technology has developed rapidly. Liquid cooling technology has great advantages in improving battery consistency and integrated energy density. The formulation of relevant regulations and specifications needs to adapt to the development direction of integrated technology.

In addition, the liquid cooling system cannot fully cover the contact surface between the electric core and the cold plate, and the temperature control of the electric core still cannot achieve the temperature balance. The industry needs to further study the temperature balance of the electric core.

Both new and old battery technologies have advantages and disadvantages

Although there are still various problems in the application and implementation of electrochemical energy storage at this stage, it is still the hottest technical route at present, driven by the wealth creation effect of the new energy industry. Improving the capacity and safety of lithium batteries are hot topics.

As the main technical route of electrochemical energy storage, lithium battery has obvious advantages and disadvantages. It is a kind of rechargeable batteries. Its advantages lie in that its operation is not restricted by the region, its power is high, and its industrial supporting facilities are relatively mature.

However, the expensive lithium resources have greatly weakened the competitiveness of lithium battery energy storage, and the flammability of lithium battery also makes large-scale application more difficult. In order to reduce costs, insiders pointed out that long-term sharing of energy storage may be the fundamental way.

If the lithium battery energy storage time is extended to 4 to 12 hours, the thermal management system will be greatly improved. The battery life is expected to be improved from the current 6000 to 7000 times to 12000 times, thereby significantly reducing the use cost.

However, it is worth noting that although the lithium battery is technically feasible to develop long-term energy storage, its characteristics determine that short-term energy storage for about 2 hours is better, and extending the time will inevitably increase the cost burden.

As for electrochemical energy storage, liquid flow battery is undoubtedly more advantageous in the field of long-term energy storage. Compared with lithium battery, all vanadium flow battery has the advantages of safety, environmental protection and full life cycle economy, and will be one of the preferred technologies for large-scale long-term energy storage in the future.

China is also experiencing a round of rapid development in the number and scale of all vanadium liquid flow battery energy storage power station projects under planning, and the scale of projects in hand by industrial companies has reached several GWh levels.

Although all vanadium redox flow battery has certain advantages, the technology is still facing low efficiency and other problems. It is pointed out that its energy efficiency is still less than 75%. For users, power loss of more than 20% is unbearable. In the face of disputes over new and old battery technologies, some practitioners pointed out that it will take a long time for new technologies to form a complete industrial chain.

Within a limited time, the industrial foundation of lithium battery energy storage is mature and more practical. As an emerging technology, sodium battery and lithium battery technology have certain universality.

Sodium battery also has the advantages of technical safety and sufficient raw materials, but its industrialization progress is slow. It has long been used as a supplement route for lithium battery, and is far inferior to lithium battery and liquid current battery in today’s energy storage industry.