The large number of renewable energy sources, such as wind and photovoltaic (PV) access, poses a significant challenge to the operation of the grid. The grid must continually adjust its output to maintain the grid power balance, and replacing the grid power output by adding a battery energy storage system (BESS) is a perfect solution. Based on this, this paper first analyzes the cost components and benefits of adding BESS to the smart grid and then focuses on the cost pressures of BESS; it compares the characteristics of four standard energy storage technologies and analyzes their costs in detail. It is challenging to gain benefits from BESS consisting of lead–acid batteries or vanadium redox flow batteries, while BESS consisting of lithium-ion batteries can gain a meager number of benefits. The best-performing one is BESS, consisting of sodium-ion batteries, which can bring considerable benefits to the system and can finally analyze the feasibility of sodium-ion batteries applied to wind–PV-containing power grids. Lithium-ion batteries are widely used because of their excellent performance, and sodium-ion batteries have a similar version to lithium-ion batteries and are more suitable for grid energy storage due to their lower price and more abundant raw materials.

In recent years, the proliferation of renewable energy power generation systems has allowed humanity to cope with global climate change and energy crises [1]. Still, due to the stochastic and intermittent characteristics of renewable energy, if the power generated by the above renewable energy sources is directly connected to the grid, it will significantly impact the grid [2–4]. In this situation, the development of efficient and convenient grid energy storage technology to meet the clean energy needs of human beings has become a worldwide research hotspot [5]. Battery energy storage system (BESS) is suitable for grid systems containing renewable energy sources [6]. After long-term safety and reliability testing, BESS is essential in improving smart grid reliability, smoothing renewable energy fluctuations and emergency power supply [7]. For smart grids, BESS is crucial in different application scenarios, such as peak shaving, frequency regulation and reactive power compensation [8].

Lithium-ion and lead–acid batteries dominate existing battery energy storage technologies [9]. While lithium-ion batteries have performed well in traditional markets such as electric vehicles and portable electronic devices, there still needs to be resistance to deploying lithium-ion batteries in large-scale grid storage due to their high cost and low safety issues [10]. Lead–acid battery technology is very mature and safe. Still, lead–acid batteries have a meager lifetime. They are challenging to cope with harsh operating conditions such as high-current charging and discharging, making them unsuitable for renewable energy applications such as wind–photovoltaic (PV) [11]. The more advanced vanadium redox flow battery has received much attention because of its long cycle life and high safety, but its high cost is still a big obstacle [12].

Factors affecting the scale application of energy storage technology in the power grid mainly include the scale of the energy storage system, technology level, safety and economy. Lithium-ion batteries remain the first choice for grid energy storage because they are high-performance batteries, even at their higher cost. However, the high price of BESS has become a key factor limiting its more comprehensive application. The search for a low-cost, long-life BESS is a goal researchers have pursued for a long time. Sodium-ion batteries have almost similar performance to lithium-ion batteries [13], but unlike lithium-ion batteries, which use expensive elements such as lithium, cobalt and nickel, sodium-ion batteries are sodium-rich, low cost and environmentally friendly [14] and can achieve slightly lower energy densities than lithium-ion batteries but have the advantage of being cheaper as well as safer, making them quite competitive for future renewable energy grid storage [15, 16]. Commercialized sodium-ion batteries are expected to become an alternative to lithium-ion batteries in renewable energy storage applications [17].

In this paper, we analyze the impact of BESS applied to wind–PV-containing grids, then evaluate four commonly used battery energy storage technologies, and finally, based on sodium-ion batteries, we explore its future development in renewable energy and grid energy storage.

Figure 1 shows the cost of BESS, which consists of construction cost, operations & maintenance (O&M) cost, charging cost and battery replacement cost.

Construction cost

The cost of BESS.

The construction cost mainly includes project initiation, design, equipment purchase, land purchase, project construction, etc. The charges in this phase are collectively referred to as one-time input costs. Usually, the land for the construction of a wind–PV-storage-containing smart grid is included in the project. It does not need to be calculated additionally, and the acquisition cost of BESS is the main one, so the price of BESS mainly determines the construction cost. It primarily contains batteries, integrated devices, battery management systems, power conversion systems (PCS) and auxiliary facilities.

O&M cost

O&M costs are incurred in equal annual amounts and consist primarily of system and labor costs. System costs are related to the type of storage battery; for example, lithium-ion batteries have higher O&M costs than lead–acid batteries.

Charging cost

The cost of charging is primarily the cost of obtaining energy from the battery. For wind–PV-storage systems, there are two ways for the battery to acquire power: one is to absorb the wind–PV overflow, which is costless because it is original energy to be discarded, and the other is for the BESS to acquire power from the grid to improve the reliability of grid operation, which is costly.

Battery replacement cost

Considering that the battery performance gradually decreases with the number of uses, when the battery performance is challenging to meet the requirements, the battery needs to be replaced to improve the utilization efficiency of the BESS investment and shorten the payback period. In the BESS, PCS and auxiliary equipment have a long life span of more than 20 years and are not considered to be replaced, so only the cost of battery replacement needs to be considered, which is related to the type of battery.

Figure 2 shows the benefits of BESS, which mainly include renewable energy consumption, grid peak shaving, system frequency regulation and reactive power regulation.

Renewable energy consumption

The benefits of BESS.

The critical parameters of four battery energy storage technologies.

The critical parameters of four battery energy storage technologies.

Due to wind–PV characteristics, it is impossible to achieve power balance with the load, so energy abandonment will inevitably occur, but adding BESS can additionally absorb this energy. At the same time, the purpose of using wind–PV is to maximize the use of renewable energy, and it is very appropriate to consider BESS.

Grid peak shaving

People’s daily routine significantly affects the peak power of the grid, and high peak power means that a higher capacity grid is needed to support it. As a flexible energy storage method, BESS can store the energy gained from wind–PV that should have been discarded, as well as the energy absorbed from the grid, and provide energy to the grid near the peak power of the grid, which will significantly reduce the load pressure on the grid. At the same time, BESS can gain economic benefits from providing energy to the grid, which mainly depends on the electricity price of the grid at the peak.

System frequency regulation

During power system operation, automatic generation control mainly realizes the control of grid frequency by real-time adjustment of the active output of the frequency regulation power supply in the grid. BESS can control power output quickly and accurately, which meets the demand for grid frequency regulation, and there are economic benefits to BESS’s participation in grid frequency regulation.

Reactive power regulation

Generators or other reactive power sources in the grid inject or absorb reactive power into the system to maintain nodal voltages in the grid within permissible limits and provide sufficient reactive support to prevent system voltage collapse after power system failures. It is a perfect idea to utilize BESS to compensate reactive power and get economic compensation accordingly, as it is simple and easy to implement.

Overall, adding BESS has excellent benefits for the smart grid, and the only thing that needs to be focused on at this point is cost, as the high price of BESS cannot be ignored.

Table 1 shows the critical parameters of four battery energy storage technologies. Lead–acid battery has the advantages of low cost, mature technology, safety and a perfect industrial chain. Still, it has the disadvantages of slow charging speed, low energy density, short life and recycling difficulties. The above shortcomings make it not suitable for large-scale renewable energy storage power stations but instead ideal for uninterruptible power supply and other occasions. The lithium-ion battery is widely used because of its high performance. Still, the safety of lithium-ion batteries must be addressed, and the scarcity of raw materials makes it difficult for lithium-ion battery prices to appear to decline substantially. The industrialization of the vanadium redox flow battery is well established, and it has virtually no capacity degradation, which significantly extends its cycle life; however, it is costly, and future development of materials with excellent properties will be needed to reduce its cost. Finally, sodium-ion batteries have almost similar performance to lithium-ion batteries; however, the raw materials for sodium-ion batteries are very cheap, making it possible to keep the cost of sodium-ion batteries low, making them very suitable for renewable energy applications.

Figure 3 shows the LCOE for four different energy storage technologies.

The LCOE for four different energy storage technologies.

Technology A is the lead–acid battery; Technology B is the lithium-ion battery; Technology C is the vanadium redox flow battery; and Technology D is the sodium-ion battery. Lead–acid batteries have the highest LCOE, mainly because their cycle life is too low, which makes it necessary to replace the batteries frequently when using them as an energy storage method, significantly increasing the system cost. The initial investment cost of a vanadium redox flow battery is very high, mainly because of its high battery cost. Still, its LCOE is not high because of its very long cycle life and nearly zero capacity degradation. Its advantages need to be used for a long time to be able to show. Still, using the vanadium redox flow battery as a renewable energy storage method in a short period, its capital cost pressure is very high. The LCOEs of both lithium-ion batteries and sodium-ion batteries have outstanding performance, thanks to their excellent performance, but sodium-ion batteries have superior performance than lithium-ion batteries because sodium-ion batteries have a lower cost, the use of sodium-ion batteries for renewable energy storage power plants, the initial investment cost is only about half of that of lithium-ion batteries. With the maturity of the technology, sodium-ion batteries will be even lower in charge because it is not like raw materials limit lithium-ion battery cost.

In terms of BESS economics, as shown in Figure 3, the LCOEs of lead–acid battery and vanadium redox flow battery are close to RMB 1/kWh, which means that BESS needs to sell electricity at a price higher than RMB 1/kWh to be economically viable, while lithium-ion batteries are about RMB 0.6/kWh, in China, if only consider domestic use, these three technologies are not financially viable, because the price of electricity for domestic service in China is only about RMB 0.56/kWh. However, the cost of electricity price for industrial use in China is higher than that for domestic use, about RMB 1/kWh, which means that if lead–acid batteries and vanadium redox flow batteries absorb the energy from renewable energy sources such as wind–PV and get a 0-cost price for electricity, and then sell this energy to the industry at a price of RMB 1/kWh, which is only enough to maintain its cost; however, the advantages of BESS for renewable energy consumption and relieving power tension in the grid still exist.

However, lithium-ion batteries can make a small economic gain because their LCOE is about RMB 0.6/kWh, and it is feasible to obtain renewable energy at no cost and sell it to industrial applications. However, the sodium-ion battery has a much lower LCOE, and unlike the other three technologies, it can be economically beneficial even for domestic applications, and for industrial applications, it can be financially helpful in a relatively good way.

Figure 4 shows the initial investment cost of building a 1 MWh BESS with four different technologies. Technology A is the lead–acid battery; Technology B is the lithium-ion battery; Technology C is the vanadium redox flow battery; and Technology D is the sodium-ion battery. Lead–acid batteries have the best performance; however, the cycle life of lead–acid batteries is shallow, and the batteries need to be replaced in about 2–3 years, which makes the replacement cost of lead–acid batteries in the later stages very high. Vanadium redox flow batteries have the most increased initial investment cost; even though it has almost no replacement cost in the latter stages and have nearly no capacity degradation, the high initial investment cost prevents them from being used in further applications. Unlike lead–acid batteries, sodium-ion batteries have a slightly higher initial investment cost. Still, it has no battery replacement cost at a later stage, making it more suitable for application than lead–acid batteries.

Initial investment costs for four technologies.

In the above analysis, it is usually difficult to get satisfactory economic benefits from BESS in China, mainly because of the high cost of BESS and the low price of electricity; however, lithium-ion batteries and sodium-ion batteries are worth choosing, and through our evaluation, they can get a slight economic return, and at the same time, BESS can also bring renewable energy consumption, grid peak shaving, system frequency regulation and reactive power regulation benefits.

Sodium-ion batteries are superior to lithium-ion batteries in terms of cost. Although they are slightly inferior to lithium-ion batteries in terms of performance, they do not affect their future application prospects. However, the sodium-ion battery has yet to be widely used because its technical maturity is not as good as lithium-ion batteries; after all, sodium-ion batteries are derived from the high cost of lithium-ion batteries as a substitute. With the development of technology and lithium-ion battery production lines that can be well applied to sodium-ion batteries, sodium-ion batteries will be components to replace lithium-ion batteries in grid energy storage.

Sodium-ion batteries are more suitable for renewable energy BESS than lithium-ion batteries for the following reasons:

Cheap raw materials for sodium-ion batteries

Regarding cost, the electrode raw materials of lithium-ion and sodium-ion batteries can be synthesized from Li2CO3 and Na2CO3, respectively. Therefore, the price fluctuations of raw materials will significantly impact the cost of the battery. Figures 5 and  6 show the price fluctuations of Li2CO3 and Na2CO3 from 2015 to 2022, respectively. Although the price of Li2CO3 has fallen back to approximately RMB 20 000/t in 2023, the cost of Li2CO3 is still very high compared to Na2CO3, and the price of Li2CO3 is very volatile. The higher price level of Li2CO3 is primarily related to the geographic limitations of lithium resources. The growth in demand for lithium-ion batteries in recent years has led to a marked increase in price, unlike Na2CO3, which has a very flat fee due to the wide distribution of the element sodium on the planet. Mature technology in the alkali mining industry allows the price of Na2CO3 to remain relatively stable. In renewable energy, grid storage, cost and product price stability are critical for suppliers and customers. Sodium-ion batteries are a better choice for renewable energy and grid storage than lithium-ion batteries in terms of profitability and long-term utility projections.

The price fluctuations of Li2CO3 from 2015 to 2022.

The price fluctuations of Na2CO3 from 2015 to 2022.

Even if the future prices of lithium-ion battery raw material fall, sodium-ion batteries also have an outstanding prospect because sodium-ion battery raw materials are abundant and lithium-ion battery raw materials are scarce.

Sodium-ion batteries are safer than lithium-ion batteries

In the case of wind–PV grids, the safety hazards of batteries will cause severe life damage and expensive property losses, and the safety accidents of battery fires and explosions will be catastrophic. Therefore, BESS should pay more attention to the safety of the battery system. No fire occurred in all the safety tests for sodium-ion batteries, which is a better safety performance. The internal resistance of sodium-ion batteries is slightly higher than that of lithium-ion batteries, resulting in less instantaneous heat generation and lower temperature rise in safety tests such as short-circuit, which is one of the reasons for the better safety performance. Reports on sodium-ion batteries show that they are safer than conventional lithium-ion batteries due to the excellent thermal stability of their electrode materials.

Therefore, compared with lithium-ion batteries, the energy density of sodium-ion batteries is slightly lower, and the application of sodium-ion batteries to wind–PV energy storage will increase the cost of installation equipment and land. However, sodium-ion batteries do not have to worry about overdischarge in the charging and discharging cycle; the depth of discharge can reach 100%, and the actual usable capacity is nearly equal to the nominal capacity. In addition, due to the wide temperature adaptability of sodium-ion batteries, the auxiliary energy consumption during the charging and discharging process is further reduced. Throughout the product life cycle, sodium-ion battery energy storage can also reduce manufacturing, transportation and battery pack replacement costs through innovative design of the battery structure and process, thereby reducing the LCOE of the entire energy storage plant.

This paper evaluates the impact of adding BESS to a wind–PV-containing smart grid, and the following conclusions are obtained:

Adding BESS has many benefits for grid operation, but the cost of adding BESS needs to be focused on.

In BESS, it is challenging to gain benefits from using lead–acid batteries, mainly because their cycle life is too short. The high battery replacement cost hinders its development. It takes a very long time to gain benefits from using vanadium redox flow batteries because capacity degradation is almost nonexistent. Still, the high initial investment must be addressed. Lithium-ion batteries can yield meager gains, while sodium-ion batteries can yield more desirable economics than lithium-ion batteries due to their low cost.

The similarity between sodium-ion batteries and lithium-ion batteries, as well as the abundance of raw materials for sodium-ion batteries, makes sodium-ion batteries promising for a wide range of future applications.

Di Yang (Project administration [equal], Resources [equal]), Yuntong Lv (Investigation [equal], Methodology [equal], Writing—original draft [equal]), Ming Ji (Data curation [equal], Writing—review & editing [equal]), and Fangchu Zhao (Writing—original draft [equal], Writing—review & editing [equal])

Data will be available from the corresponding author via email upon reasonable request.

Hossain   MS, Madlool   NA, Rahim   NA  et al.   

Google Scholar

WorldCat

Amamra   SA, Meghriche   K, Cherifi   A  et al.   

Google Scholar

WorldCat

Phuangpornpitak   N, Tia   S.

Google Scholar

WorldCat

Kebede   AA, Kalogiannis   T, Van Mierlo   J  et al.   

Google Scholar

WorldCat

Castillo   A, Gayme   DF.

Google Scholar

WorldCat

Saez-de-Ibarra   A, Martinez-Laserna   E, Stroe   DI  et al.   

Google Scholar

WorldCat

Subburaj   AS, Pushpakaran   BN, Bayne   SB.

Google Scholar

WorldCat

Keck   F, Lenzen   M, Vassallo   A  et al.   

Google Scholar

WorldCat

Nair   NKC, Garimella   N.

Google Scholar

WorldCat

Diouf   B, Pode   R.

Google Scholar

WorldCat

Yanamandra   K, Pinisetty   D, Daoud   A  et al.   

Google Scholar

WorldCat

Cunha   Á, Martins   J, Rodrigues   N  et al.   

Google Scholar

WorldCat

Hwang   JY, Myung   ST, Sun   YK.

Google Scholar

WorldCat

Vaalma   C, Buchholz   D, Weil   M  et al.   

Google Scholar

WorldCat

Nayak   PK, Yang   L, Brehm   W  et al.   

Google Scholar

WorldCat

Abraham   KM.

Google Scholar

WorldCat

Deng   J, Luo   WB, Chou   SL  et al.   

Google Scholar

WorldCat