[Popular Science] The most comprehensive review: Current status and cost analysis of 6 energy storage technologies!

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[Popular Science] The most comprehensive review: Current status and cost analysis of 6 energy storage technologies! [Copy link]

Source: Jiangsu Energy Storage Industry Association

In the new power system, energy storage will become a crucial link. It is a necessary guarantee for the consumption of new energy and the security of the power grid. It will be widely used in the power generation side, the power grid side, and the power consumption side, and there is a vast demand space. In the domestic market, the policy of mandatory storage for wind and solar power has promoted the exponential growth of energy storage demand. Driven by the explosion of market demand and policy encouragement, mature pumped storage and lithium battery energy storage have shown explosive growth, and other new energy storage technologies have also entered the fast lane of development.

This article evaluates the development status, system cost, and application prospects of six types of energy storage: pumped storage, lithium-ion batteries, compressed air, sodium ion, all-vanadium liquid flow batteries, and lead-carbon batteries.

Among them, pumped storage is the most mature application; lithium-ion battery energy storage has been rapidly applied in recent years; compressed air and flow batteries will also usher in large-scale commercial applications.

1

Pumped Storage

Pumped storage has the advantages of superior technology, low cost, long life, large capacity and high efficiency. Since the operation mode of a pumped storage power station is to convert energy between electrical energy and water potential energy, its energy storage capacity mainly depends on the height difference between the upper and lower reservoirs and the reservoir capacity. Since the loss caused by water evaporation and leakage is almost negligible, the energy storage cycle of pumped storage can be extended indefinitely, which can meet various energy storage cycle requirements, and the system cycle efficiency can reach 70%-80%. At the same time, the dam of the pumped storage power station after construction can be used for about 100 years, and the estimated service life of motor equipment is about 40-60 years.

The installed capacity of each energy storage technology in my country in 2021

Cost estimation: the most economical energy storage method at present

In order to explore the economic feasibility of pumped-storage power stations, we calculated the energy storage cost per kilowatt-hour of pumped-storage power stations.

Key assumptions for pumped storage LCOS calculations

Considering that the initial investment cost of a pumped storage power station is closely related to the site selection of the project, the economic efficiency of the site selection of new projects in the later period will decrease, and the initial investment cost may increase. In addition, the actual number of cycles of the power station is assumed to be between 300 and 500 times. We estimate that without considering the charging cost, the LOCE range of a conventional pumped storage power station is 0.23-0.34 yuan/kWh.

Pumped Storage LCOS Sensitivity Analysis

Since the 14th Five-Year Plan, my country has accelerated the deployment of pumped storage project development and construction. The Medium- and Long-Term Development Plan for Pumped Storage (2021-2035) stipulates that by 2025, the total scale of pumped storage production will double compared with the 13th Five-Year Plan, reaching more than 62 million kilowatts (according to the calculation of 6 yuan/W, the investment must reach about 180 billion); by 2030, the total scale of pumped storage production will double again compared with the 14th Five-Year Plan, reaching about 120 million kilowatts. (According to the calculation of 6 yuan/W, the investment must reach about 540 billion); In addition, the list of planned energy storage projects announced in August 2021 includes 551 projects, totaling 679 million kilowatts.

my country's pumped storage installed capacity and planning (10,000 kilowatts)

Driven by policies, provinces and cities across the country have rapidly deployed pumped storage projects. Since January 2022, 20 provinces have announced lists of provincial key construction projects for 2022. According to statistics from the International Energy Network, as of now, among the key projects announced by various provinces in my country, the cumulative installed capacity of pumped storage has reached 104.3GW, with a cumulative investment of over 600 billion yuan.

Pumped storage installed capacity and investment by province

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2. Lithium-ion battery energy storage

In 2021, lithium-ion batteries accounted for 89.7% of my country's electrochemical energy storage installed capacity. It is currently the energy storage method with relatively mature technology and the fastest development momentum.

The lithium-ion energy storage industry chain consists of upstream equipment manufacturers, midstream integrators and downstream end users. The equipment includes batteries, EMS (energy management system), BMS (battery management system), PCS (converter); integrators include energy storage system integration and EPC; end users are composed of power generation side, grid side, user side and communication/data center.

Schematic diagram of the upstream and downstream of electrochemical energy storage

Energy storage batteries are the core part of electrochemical energy storage systems. The mainstream batteries on the market can be roughly divided into lithium-ion batteries, lead-carbon batteries, flow batteries and sodium-ion batteries according to different technical routes. Batteries with different technical routes have different response speeds and discharge efficiencies, and also have their own scope of application and advantages and disadvantages.

Comparison of batteries with different technical routes

According to GGII statistics, domestic energy storage battery shipments in 2021 were 48GWh, of which power energy storage battery shipments were 29GWh, a year-on-year increase of 339%; and according to global research institutions EVTank and Ivy Economic Research Institute, global energy storage battery shipments in 2021 were 66.3GWh, a year-on-year increase of 132.6%, with power system energy storage being the main incremental contribution.

my country's energy storage battery shipments and growth rate from 2017 to 2021

Lithium iron phosphate battery energy storage cost analysis

According to the different cathode materials, the current mainstream lithium-ion batteries are divided into two categories: ternary and lithium iron phosphate. The energy density of lithium iron phosphate batteries is lower than that of ternary materials, and the cost is also lower. The energy storage field does not require high energy density, and lithium iron phosphate batteries with low cost and long life are more popular.

As a core component of the entire energy storage system, the battery accounts for 50% of the cost of the entire energy storage system and is an important channel for subsequent cost reduction of the energy storage system. In 2021, the winning bid prices of lithium iron phosphate battery energy storage in my country were mostly concentrated at 1.2-1.7 yuan/Wh. According to Bloomberg New Energy Finance (BNEF), the global electrochemical energy storage EPC cost in 2022 will be approximately US$261/kWh (equivalent to RMB 1.66/Wh), and is expected to drop to US$203/kWh (equivalent to RMB 1.29/Wh) in 2025. Since 2021, a large number of EPC winning bids have been between 1.3-1.7 yuan/kWh.

EPC bidding status of some lithium iron phosphate battery energy storage power stations in 2021

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3. Compressed air energy storage

Domestic compressed air energy storage technology continues to improve, and research on compressed air energy storage (CAES), advanced adiabatic compressed air energy storage (AA-CAES), supercritical compressed air energy storage system (SC-CAES), liquid compressed air (LAES), etc. has been covered. Compressed air energy storage demonstration projects with capacity levels of 500kW, 1.5MW and 10MW have all been built.

Internationally, the commercial compressed air energy storage power station built in Germany's Hantford Sea in 1978 and in Alabama, USA in 1991 are commercial power stations. China has successively carried out the research and development and construction of compressed air, supercritical compressed air, and liquid compressed air energy storage projects. Among them, Zhangjiakou's first international 100MW advanced compressed air energy storage demonstration project was successfully connected to the grid at the end of 2021, and the overall research and development process and system performance are at the international leading level.

Some compressed air projects at home and abroad

Large-scale air compression energy storage projects approved in 2022

Compressed Air Energy Storage Cost Analysis

The improvement of system efficiency and the reduction of costs are the basis for the commercial development of compressed air energy storage. Judging from the projects that have been built and are under construction, the system efficiency of megawatt-level can reach 52.1%, the system efficiency of 10 megawatts can reach 60.2%, the system design efficiency of 100 megawatts and above can reach 70%, and the efficiency of advanced compressed air energy storage systems can approach 75%. As the system scale increases, the unit investment cost continues to decline. For every order of magnitude increase in the system scale, the unit cost can drop by about 30%.

Core assumptions for LCOS calculation of compressed air energy storage system

The changes in initial investment and utilization hours have a huge impact on the cost per kilowatt-hour. With technological advances, the initial investment still has room to decline. The utilization hours mainly depend on the utilization rate of the power station in actual operation. The higher the number of charge and discharge times per day, the lower the cost. In a 100MW/400MWh system, with an initial investment of 5-6 yuan/W and an annual cycle of 450-600 times, the cost per kilowatt-hour ranges from 0.252-0.413 yuan/kWh.

Compressed Air LCOS Sensitivity Analysis

Overall, after the energy efficiency of compressed air energy storage is improved, it is expected to become an important supplement to pumped storage in the field of large-scale energy storage power stations.

Characteristics of various types of energy storage

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4

Sodium ion energy storage

Sodium-ion batteries have excellent performance and are highly anticipated. The key factors that determine whether electrochemical energy storage can be widely used include safety, availability of material resources, high and low temperature performance, lifespan, investment cost, etc. According to the latest research progress of sodium-ion batteries, it has shown good performance in all these aspects. After large-scale application, the cost is expected to be lower than that of iron-lithium batteries. It can be widely used in large-scale electrochemical energy storage, low-speed electric vehicles and other fields, and is expected to complement and effectively replace lithium-ion batteries.

Performance comparison of lead-acid batteries, lithium-ion batteries and sodium-ion batteries

Relevant research shows that the material cost of sodium-ion batteries is about 370 yuan/kWh, considering the positive electrode materials, negative electrode materials and current collectors. Moreover, as the industrial chain matures, the material cost is expected to drop further. Combined with the cost of structural and electrical parts, the initial capacity investment is expected to be controlled at 500-700 yuan/kWh. In terms of performance, with continuous investment in research and development and technological iteration, the battery cycle life is expected to exceed 8,000 times.

Sodium-ion batteries have obvious material cost advantages

Since 2010, sodium-ion batteries have received extensive attention from domestic and foreign academic and industrial circles, and related research has ushered in explosive growth. Many companies at home and abroad are actively making arrangements for the industrialization of sodium-ion batteries, including the British company FARADION, the American company NatronEnergy, the French company Tiamat, the Japanese company Kishida Chemical, Toyota, Panasonic, Mitsubishi Chemical, and Chinese companies such as my country Science and Technology Sodium, CATL, and Sodium Innovation Energy. At present, the domestic work on the research and development, manufacturing, standard setting, and market application promotion of sodium-ion batteries is in full swing. Sodium-ion batteries are about to enter the commercial application stage, and related work has been at the forefront of the world.

Sodium ion cost analysis

Core assumptions for LCOS calculation of sodium-ion battery energy storage system

Considering that after commercialization, battery cost and performance will be greatly improved. Assuming the initial investment cost is 0.9-1.2 yuan/Wh, the life is 10 years, and the cycle life is 2000-6000 times, a sensitivity analysis of sodium-ion batteries is conducted. If the cost is below 1.1 yuan/Wh and the cycle life is more than 3000 times, the cost per kilowatt-hour will be between 0.270-0.662 yuan, which is better than iron-lithium batteries.

Sodium-ion battery LCOS sensitivity analysis (yuan/kWh)

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5. All-vanadium liquid flow battery energy storage

The electrical energy of vanadium batteries is stored in the form of chemical energy in sulfuric acid electrolyte of vanadium ions of different valence states. The electrolyte is pressed into the battery stack through an external pump. Under the action of mechanical power, it circulates in the closed loop of different storage tanks and half-cells. The proton exchange membrane is used as the separator of the battery pack. The electrolyte solution flows parallel to the electrode surface and an electrochemical reaction occurs. The current is collected and conducted through the double electrode plates, so that the chemical energy stored in the solution is converted into electrical energy. This reversible reaction process enables the vanadium battery to successfully complete charging, discharging and recharging.

Principle of all-vanadium liquid flow battery

All-vanadium liquid flow battery structure

Liquid flow batteries have the characteristics of long life, good safety, high output power, large energy storage capacity and easy expansion. The life span reaches 15-20 years. Compared with other energy storage technologies, it has the highest matching degree with wind farm hardware and is particularly suitable for wind power plant energy storage to meet its frequent charging and discharging, large capacity and long-term energy storage needs. Of course, the energy density of all-vanadium liquid flow batteries is low, and the volume and mass are much larger than other batteries, requiring a temperature environment of 5-40°.

Advantages of all-vanadium liquid flow energy storage technology

Since 2010, my country's megawatt-level all-vanadium liquid flow battery demonstration projects have been carried out one after another. Since 2019, my country's liquid flow battery energy storage demonstration projects have been accelerated. In February 2022, the first phase of the "200MW/800MWh Dalian Liquid Flow Battery Energy Storage Peaking Power Station National Demonstration Project" 100MW/400MWh all-vanadium liquid flow battery energy storage power station completed the main construction and entered the single module commissioning stage. It is expected to complete the grid-connected commissioning in June. It is the world's largest vanadium liquid flow energy storage project.

Vanadium liquid flow energy storage projects planned or constructed in my country in recent years

At present, the cost issue is still the biggest challenge facing the large-scale commercial application of vanadium batteries. Since it has not yet been commercialized on a large scale and is subject to equipment, production capacity and high initial investment, referring to the investment in Datang's 10MW/40MWh all-vanadium liquid flow battery energy storage system equipment bidding and Dalian liquid flow battery energy storage peak-shaving power station national demonstration project, it is estimated that the initial cost of vanadium batteries is about 3 times that of lithium batteries.

Core assumptions of LCOS calculation for all-vanadium liquid flow battery energy storage system

The changes in initial investment and utilization hours have a huge impact on the cost per kilowatt-hour. With technological advances, the initial investment still has room to decline. The utilization hours mainly depend on the utilization rate of the power station in actual operation. The higher the number of charge and discharge times per day, the lower the cost. In a 100MW/400MWh system, when the initial investment is 11-13 yuan/W and the annual cycle number reaches more than 600 times, the energy storage cost per kilowatt-hour ranges from 0.44-0.69 yuan/kWh.

All-vanadium liquid flow battery LCOS sensitivity analysis (yuan/kWh)

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6

Lead-carbon battery energy storage

Lead-carbon battery is a capacitor-type lead-acid battery, which is a technology evolved from traditional lead-acid battery. The positive active material of ordinary lead-acid battery is lead oxide (PbO2), and the negative active material is lead (Pb). If the negative active material Pb is completely replaced with activated carbon, the ordinary lead-acid battery becomes a hybrid capacitor; if activated carbon is mixed into the negative active material Pb, the ordinary lead-acid battery becomes a lead-carbon battery.

Lead-carbon battery structure diagram

Progress of Lead-Carbon Energy Storage

Axion, an American company, established a lead-carbon battery production line in 2006 and began selling lead-carbon batteries in batches in 2009. Major lead-acid battery manufacturers in my country have conducted research and development and production of lead-carbon batteries. For example, Sacred Sun and Japan's Furukawa signed a cooperation agreement in 2014, authorizing Sacred Sun to conduct localized production of lead-carbon batteries in Chinese factories; Narada has developed energy storage projects such as Lin'an 2MWh, Zhejiang Luxi Island 4MWh microgrid energy storage, and Zhuhai Wanshan Island 6MWh; in 2018, Chaowei Group's "Lead-carbon Battery 2V1000 for Power Energy Storage" project won the second prize of Zhejiang Science and Technology Progress; Tianneng Power said that its high-performance lead-carbon battery is a new type of battery with internationally leading technology level independently developed, and won the highest award in my country's industrial field approved by the State Council in December 2020-the China Industrial Award Project Award.

Lead-carbon battery cost analysis

Core assumptions for LCOS calculation of lead-carbon battery energy storage system

Sensitivity analysis of lead-carbon batteries found that when the annual cycle number reaches more than 500 times, the initial investment cost is 0.8-1 yuan/W, and the cost range of lead-carbon battery energy storage is 0.52-0.747 yuan/kWh.

Lead-carbon battery LCOS sensitivity analysis (yuan/kWh)

Through calculation and comparison, it is found that although the initial investment cost of lead-carbon batteries is low, the cost advantage per kilowatt-hour is not obvious because its discharge depth is lower than other energy storage forms. In addition, if the energy loss cost in actual use is considered, the economic efficiency of lead-carbon batteries will be at a certain disadvantage due to their lower energy efficiency than iron-lithium batteries. With the flourishing of new energy storage, lead-carbon batteries will also be expected to achieve energy efficiency improvement and cost reduction through technological progress.

fjdeepblue

Very good popular science article, the content is very detailed and comprehensive, I learned a lot.

xutong

Great, well done