All vanadium flow battery: a reliable technology for large-scale and long-term energy storage, tailored for photovoltaic+energy storage!

Step into the zero carbon wind and crack the wealth code. The "dual carbon" goal has become a widespread consensus, with photovoltaic as the representative of new energy ushering in a golden era of installed capacity expansion and market explosion. In the pattern of industry and commerce, household use, and centralized photovoltaic in 2022, the new installed capacity of distributed photovoltaic in industry and commerce exceeded 25GW, breaking the annual record for new additions, marking the beginning of another hot track for photovoltaic. The National Energy Administration has issued the "Twenty Five Key Requirements for Preventing Electric Power Production Accidents (2022 Edition)", further increasing the safety requirements in the energy storage field. Vanadium batteries with high safety characteristics have further attracted market attention.
The professional name of vanadium battery is all vanadium redox flow battery, which is an environmentally friendly and large capacity energy storage battery that can be deeply charged and discharged. It uses the different chemical potential energy of vanadium ions in different oxidation states to store energy, and has the advantages of high charging and discharging efficiency and high safety. The capacity can be increased with the increase of storage tanks, and the electrolyte can be recycled.
All vanadium flow batteries have better safety
The electrolyte of vanadium batteries is stored in specialized tanks, and under the action of a pump, the positive and negative ions of the electrolyte are transported to the positive and negative ions of the battery stack. This structural design allows the capacity of vanadium batteries to be adjustable, and the electrolyte stored separately will not react, resulting in very high safety.
Compared to lithium-ion batteries, all vanadium flow batteries have better safety. For lithium-ion batteries, once there is a short circuit or high operating temperature inside the battery, the electrolyte is prone to decomposition and gasification, which can lead to battery combustion or explosion, posing a major safety hazard. The electrolyte of all vanadium flow batteries is an acidic aqueous solution of vanadium ions, which operates at room temperature and pressure without the risk of thermal runaway and has inherent safety.
According to empirical results, under theoretical SOC, even if the positive and negative electrolytes are directly mixed and the temperature rises from 32 ℃ to 70 ℃, the all vanadium flow battery system will not generate risks such as combustion and ignition. Therefore, for energy storage scenarios with dense personnel, large scale, and high safety requirements, all vanadium flow batteries are a safer and more stable technology.
The conditions for the large-scale development of all vanadium flow batteries are relatively mature
As mentioned earlier, as new energy gradually becomes the mainstay of the power system, its volatility and intermittency will have an increasingly significant impact on the power grid. Currently, energy storage systems only need to smooth out fluctuations at the daily, minute/hour level, while future energy storage systems need to consider fluctuations in new energy output between days and even seasons. According to the definition of Sandia National Laboratory in the United States, long-term energy storage is an energy storage technology with a continuous discharge time of no less than 4 hours, mainly aimed at multi hour, cross day, and even cross season electricity transfer needs.
Long term energy storage will become an indispensable part of the future power system. According to a report jointly released by the Long Term Energy Storage Committee (LDES) and McKinsey at the end of 2021, it is expected that the global installed capacity of long-term energy storage will reach 4-8TWh by 2030, and 85-140TWh by 2040.
The focus of long-term energy storage is somewhat different from the current short-term energy storage, and all vanadium flow batteries have strong comparative advantages in the field of long-term energy storage. According to a report jointly released by the Long Term Energy Storage Committee (LDES) and McKinsey at the end of 2021, long-term energy storage should have typical characteristics such as power and capacity decoupling, no need to increase power when expanding storage capacity, low unit energy storage cost, short project construction cycle, no geographical limitations, and no reliance on scarce resources. Due to the long duration of supporting energy storage, long-term energy storage pays more attention to the investment cost per unit energy (per Wh) rather than the investment cost per unit power (per W) when considering investment costs.
Therefore, long-term energy storage has a relatively high acceptance of the investment cost of power units (fixed costs can be diluted with the increase of energy storage time), while energy units need to have lower marginal costs.
All vanadium flow battery is a type of battery that utilizes changes in the valence state of vanadium ions to store and release electrical energy. It has advantages such as good safety, large energy storage scale, long lifespan, high cost-effectiveness in life cycle, recyclable electrolyte, and environmental friendliness. As a product in the early stages of industrialization, few companies internationally can provide mature commercial products for all vanadium flow batteries. The global production enterprises of all vanadium flow batteries mainly include Sumitomo Electric Company of Japan, Dalian Rongke Energy Storage Technology Development Co., Ltd., UniEnergy Technologies of the United States, and Gildemeister of Austria.
With the continuous iteration and updating of battery technology and the continuous decrease of costs, * Energy Storage believes that all vanadium flow batteries have the conditions for commercial development. At present, all vanadium liquid flow batteries are mature liquid flow batteries. Considering the advantages of liquid flow batteries themselves, all vanadium liquid flow batteries are an ideal technology to meet the requirements of large-scale energy storage industrialization, and their technical performance and cost have also reached the level of scalable development.
At present, the conditions for the industrialization of vanadium flow batteries are becoming increasingly mature and are in a critical period of advancing from technological accumulation to industrialization. Although all vanadium flow batteries have technological advantages, their commercialization process is relatively slow. According to relevant data, all vanadium flow batteries account for approximately 40% of the total market demand for flow batteries, while flow batteries account for 10% of the installed scale of electrochemical energy storage. Therefore, it is speculated that all vanadium flow batteries account for approximately 4% of the installed scale of electrochemical energy storage.
There is still a long way to go before domestic vanadium batteries can fully replace lithium batteries. The national energy storage industry support policy is comprehensive and does not specifically target vanadium battery products. In the field of vanadium battery development, there are now many capital and enterprises wanting to enter the vanadium battery industry. Although there are several vanadium battery demonstration enterprises in China, there is not yet a core vanadium battery enterprise or technology leader in the country. Domestic vanadium battery enterprises are all continuing on their existing technologies, and there is no new research and development technology for vanadium batteries. At the same time, the cohesion of related vanadium battery enterprises is also insufficient.
Development prospects of all vanadium flow battery industry
With the development of energy storage driving the application penetration rate of vanadium batteries, vanadium is expected to become an energy metal after lithium cobalt nickel. According to the "Guiding Opinions on Accelerating the Development of New Energy Storage" issued by the National Development and Reform Commission and the National Energy Administration, the installed capacity of new energy storage will reach over 30GW by 2025, and there is still huge space compared to the current installed capacity. Due to its long lifespan and good safety, the penetration rate of vanadium batteries in the energy storage field will steadily increase. By 2025, the penetration rate of vanadium batteries in the energy storage field is expected to reach 15% -20%.
In recent years, the installed capacity of energy storage in China has grown rapidly, and significant progress has been made in vanadium battery related energy storage projects. The installed capacity of liquid flow batteries, represented by vanadium batteries, was 20MW in 2019 and 100MW in 2020. The installed capacity of vanadium batteries has grown rapidly. However, the current penetration rate of vanadium batteries in China is only about 1%, and the future development prospects are broad.
New energy storage is the main application scenario for all vanadium flow batteries
Due to the fact that the power grid has become a bottleneck in the development of wind power, with the explosive development of wind power, the contradiction between wind power and the power grid will become increasingly prominent. In order to reduce the impact on the power grid, significantly increase the utilization rate of wind farm electricity, and earn a huge peak valley price difference, wind farms will need to be equipped with dynamic energy storage batteries with a power equivalent to 10-50% of their power.
For wind turbine off grid power generation, a larger proportion of dynamic energy storage batteries are required; The photovoltaic industry is one of the rapidly developing emerging industries worldwide. Due to the limited power, capacity, and lifespan of lead-acid batteries, all vanadium flow batteries are also used in the energy storage process of photovoltaic power generation.
All vanadium flow batteries are simultaneously used in fields such as power grid peak shaving, emergency power generation devices, and electric vehicle power sources. New energy storage is the main application scenario of all vanadium flow batteries.
All vanadium flow batteries are mainly suitable for large-scale, long-term energy storage scenarios
With the increasing diversification of energy storage scenarios, the coexistence of multiple energy storage technologies will become a long-term development trend. At present, traditional thermal power installations still occupy the dominant position globally, with wind and photovoltaic power generation accounting for only about 10%. Therefore, energy storage mainly plays an auxiliary role in the power system to solve short-term and small-scale supply and demand imbalances. But in the long run, as new energy gradually becomes the mainstay of the power system, the application scenarios of energy storage will continue to expand, covering the power range from kW level user side scenarios to GW level power generation side and grid side scenarios, and the duration of energy storage will vary from second level, minute level, hour level to cross day and cross season scenarios. Considering the significant differences in energy storage requirements across different scenarios, it is unlikely that a single energy storage technology will "unify the world" in the future. Instead, multiple energy storage technologies will coexist to support the security and stability of the power system.
All vanadium flow batteries have broad development prospects in large-scale and long-term energy storage scenarios. As mentioned earlier, the main advantages of all vanadium flow batteries are safety, longevity, and flexibility. However, at the current technological level, there is still a certain gap in energy density, conversion efficiency, and initial investment compared to lithium batteries. Therefore, we believe that the application field of all vanadium flow batteries is mainly for large-scale, long-term energy storage scenarios. Compared to pumped storage, the site selection of all vanadium flow batteries is more flexible and the construction period is shorter; Compared to lithium battery energy storage, all vanadium flow batteries have significantly superior safety and can be deployed in densely populated urban scenarios. The unit investment cost significantly decreases with the prolongation of energy storage time.
The current domestic vanadium battery industry can be classified based on its establishment time, and veteran players such as Dalian Rongke, Beijing Puneng, and Shanghai Electric can be called pioneers; The emerging forces represented by Weilide and Fluid Energy Storage Company can be called New Forces. In the competition of technology and market, the new and old forces are stirring up the vanadium battery market, gradually converging from a calm lake into a surging river.
*According to energy statistics, the market penetration rate of all vanadium flow batteries is currently less than 1%. Vanadium batteries, which were considered the "star of hope" in energy storage batteries more than a decade ago, have high safety performance and low cost, and are expected to become the "successor" to lithium batteries.
At present, there are three main technological routes in the new energy battery race: lithium-ion batteries, sodium ion batteries, and hydrogen fuel cells. Vanadium batteries, on the other hand, are a magical existence that is free from the three realms.
Vanadium battery, also known as all vanadium redox flow battery, is a type of redox battery that uses vanadium as the active substance in a circulating liquid state. It is different from lithium/sodium/hydrogen batteries in that both positive and negative are liquids, with only the middle separator being a solid.
That is to say, unlike most solid-state batteries on the market, vanadium batteries are essentially liquid batteries.
Because unlike solid-state batteries, vanadium batteries have obvious advantages and disadvantages.
There are three advantages: firstly, high security. Both negative and positive vanadium batteries are vanadium electrolytes, which are not flammable. 2、 Longer lifespan. At present, the cycle life of commercial vanadium batteries can reach over 16000 cycles, far higher than 6000 cycles of lithium batteries; 3、 Easy to maintain and worry free. Old batteries can be restored to their original state as long as the separator is replaced and the electrolyte is repaired.
The structure of a full electrolyte also has defects, mainly in three aspects:
1、 Low conversion rate. Due to the need for pumps to maintain the flow of a large amount of liquid in vanadium batteries, resulting in significant energy loss. Currently, the energy conversion efficiency of vanadium batteries is 70-75%, which is lower than that of lithium batteries (90%).
2、 High cost. The high cost is a major drawback of all vanadium flow batteries, ranging from 3 to 3.2 yuan/Wh. The cost of hydrogen fuel cells is about 2-3 yuan/Wh, the average cost of lithium batteries is 1.2-1.5 yuan/Wh, and the cost of sodium ion batteries is expected to be 0.8-0.9 yuan/Wh.
3、 Large volume. Liquids themselves occupy more space than solids, and in addition, there are two external structures of the electrolyte, a transport pump and an electric stack, which can be combined to complete charging and discharging. Therefore, the bulk of vanadium batteries is particularly large.
*The most promising energy source is liquid flow batteries, and Shanxi Guorun Energy Storage and Dalian Chemical Institute are mainly focused on this field. There are many systems for liquid flow batteries, among which the all vanadium liquid flow battery has a high technological maturity. It utilizes the valence state changes of vanadium ions to achieve mutual conversion between electrical and chemical energy.
The main shortcomings of liquid flow batteries are efficiency and cost. Currently, the energy efficiency of demonstration systems is around 75%, but its major advantages are long lifespan and safety.
Because all vanadium liquid flow is a water-based battery, it is inherently safe and has no potential for explosion or ignition; In addition, its power and capacity are decoupled, and it can be flexibly designed independently. The scale can also be relatively large, ranging from 10 kilowatts to 100 megawatts, which is very suitable for long-term energy storage. As long as the volume of electrolyte in the electrolyte tank is increased, the capacity can be increased. The longer the energy storage time, the better the economy, because the power unit can remain unchanged. In addition, both response speed and cycling performance are the advantages of liquid flow batteries, making them very suitable for medium to long term, even ultra long term energy storage.
Why does all vanadium flow battery have a long lifespan? This is because the active substances of this type of battery are stored in the electrolyte, and electricity is only the place where electrochemical reactions occur. The electricity material itself does not participate in the reaction and does not undergo phase change. The number of cycles can reach more than 16000, and the lifespan can reach up to 25 years. Moreover, the electrolyte can be recycled indefinitely, which means that after 25 years of battery life, the electrolyte can still be recycled and reused. The recycling and reuse method is very simple, as long as the parity state is adjusted. This is because the electrolyte is stored in the state of vanadium ion water without any other chemical reactions, which is very simple compared to lithium battery recycling technology. Therefore, I believe that all vanadium flow batteries have good application prospects in the field of large-scale energy storage.
In terms of cost, when all vanadium flow batteries were relatively expensive in the past few years, they were 5000 to 6000/kWh, but now they can be reduced to less than 3000. In the future, with the progress of technology and further improvement of the industry chain, there is still room for decline. At present, the price of vanadium pentoxide is basically stable at around 120000 tons, and the electrolyte is around 1200-1300 yuan. Based on calculations, the cost of all vanadium flow batteries can reach over 2000 yuan. Considering its ultra-long lifespan, it still has advantages in life cycle economy.
In addition, China's vanadium reserves and production are both the world's largest, and there will be no issues of being stuck or requiring overseas exploration. We can achieve independent and controllable development. Moreover, in terms of demand, as vanadium can be permanently recycled, as long as the electrolyte is kept in operation for the first 20 years, it can be recycled in the later stage, with only the need to update the power unit. Therefore, from the perspective of the entire life cycle, its economy is not a problem.
Moreover, if innovation is made in the commercial operation model, and the electrolyte is sold for rent, the one-time investment cost of all vanadium can be reduced by more than half, which is only about 1000 yuan/kWh, which has a cost advantage. At present, the industry has begun to explore this model, which has great promoting significance for the future promotion of all vanadium.
Fluid flow batteries are tailored for energy storage
Liquid flow batteries have two core advantages: 1) safety: fundamentally avoiding deflagration; 2) durability: slow decay of active substances, with a working life of up to 15-20 years. In addition, energy storage systems are generally static facilities, with low requirements for weight and volume, and energy density is not a key indicator, making them particularly suitable as large-scale energy storage systems.