Analysis of six major energy storage method routes

Analysis of six major energy storage method routes

In the new power system, energy storage method will become a crucial link, is the necessary guarantee of new energy consumption and grid security, in the generation side, grid side, power side will be widely used, demand space is vast. In the China market, the wind-power mandatory distribution and storage policy promotes the exponential growth of energy storage demand.
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Under the dual promotion of market demand explosion and policy encouragement, mature pumped storage and lithium electric energy storage method show explosive growth, and other new energy storage methods have also entered the fast lane of development.

In this post, the development status, system cost and application prospect of six kinds of energy storage method, including pumped storage, lithium ion battery, compressed air energy storage method, sodium ion, vanadium fluid flow battery and lead carbon battery, are evaluated.

A variety of energy storage method routes have entered the fast track of development
According to different time requirements, the application scenarios of energy storage can be roughly divided into four categories: capacity type (≥4h), energy type (about 1-2H), power type (≤30min) and standby type (≥15min).

Capacitive energy storage scenarios include peak cutting and valley filling or off-grid energy storage, etc. There are many kinds of long-term energy storage methods, including pumped energy storage, compressed air, heat storage, cold storage, hydrogen storage, and various capacitive energy storage batteries (such as sodium sulfur battery, flow battery, lead carbon battery, lithium slurry battery, etc.).

From 2017 to 2020, the power grid responded to the decision of the Energy Bureau and the China Development and Reform Commission to reduce the wind and light curtailment rate, and made full use of the flexible resources of the power system to absorb new energy, so that the wind and light curtailment rate decreased to 2%. At the same time, the power grid pressure has become prominent, and some provinces began to require the power side to configure energy storage. In 2021, a number of blockbuster documents of the energy storage industry were published, and energy storage ushered in a historic development opportunity.

From the perspective of the whole power system, the application scenarios of energy storage can be divided into three major scenarios: generation side, transmission and distribution side, and electricity side. In addition, the applications also include auxiliary services, distributed generation and micro grid.

Energy storage technology is widely used in the electric power industry

From the technical principle, energy storage method can be divided into physical energy storage, electrochemical energy storage and electrical energy storage, thermal energy storage and chemical energy storage method.

pumped storage

Path analysis of energy storage technologies

Among all kinds of energy storage method, pumped storage is the most mature application. Heat storage method has also been in the large-scale application stage, and the majority of thermal power flexibility reform in China adopts heat storage technology; Lithium-ion battery energy storage method has been rapidly applied in the past two years; Compressed air and flow batteries have also been used commercially.

Analysis of six types of energy storage methods

1.Pumped storage

Pumped storage has the advantages of excellent technology, low cost, long life, large capacity and high efficiency.Due to the pumped storage power station running mode is the energy conversion between electricity and water potential energy, the energy storage capacity mainly depends on the difference in height between the upper and lower reservoir and reservoir capacity, loss due to evaporation of water leakage phenomenon almost negligible.

pumped storage to unlimited extension of storage period, can adapt to all kinds of energy storage cycle requirements, The cycle efficiency of the system can reach 70%-80%. At the same time, the dam body of the pumping and storage power station after construction can be used for about 100 years, and the expected service life of the motor equipment is about 40-60 years.

New type storage

Proportion of installed energy storage technologies in 2021

Cost calculation: At present, the most economical energy storage method is to explore the economy of pumped storage power station. We calculated the kilowatt-hour cost of stored energy of pumped storage power station.

Initial investment cost

The core assumptions for LCOS calculation of pumped storage power stations

Considering that the initial investment cost of a pumped storage power station is closely related to the project site selection, the site selection economy of a new project in the later stage decreases, and the initial investment cost may rise. In addition, the actual cycle number of the power station is assumed to be between 300 and 500 times.It is estimated that the LOCE range of conventional pumped storage power stations is 0.23-0.34 RMB /kWh without considering the charging cost.

Since the 14th Five-Year Plan, China has accelerated the deployment of pumped storage projects. By 2025, the total scale of pumped storage put into production will double compared with the “13th Five-Year Plan”, reaching more than 62 million kW (according to 6 RMB /W calculation, the investment must reach about 180 billion RMB);

By 2030, the total scale of pumped storage production will double again compared with the “14th Five-Year Plan”, reaching about 120 million kW.(based on the calculation of 6 RMB /W, the investment must reach about 540 billion RMB);In addition, the list of planned energy storage projects released in August 2021 totaled 551 projects, totaling 679 million kW.

data

China’s installed capacity and planning of Pumped storage (GW)

Driven by the policy, provinces and cities across the country have rapidly laid out pumped storage projects.Since January 2022, 20 provinces have announced the list of key provincial construction projects for 2022. According to the statistics, the cumulative installed capacity of pumped storage has reached 104.3GW and the cumulative investment has exceeded 600 billion RMB among the key projects announced by the provinces so far.

2.Lithium-ion battery energy storage method

In 2021, lithium-ion batteries accounted for 89.7% of the electrochemical energy storage installed in China, which is the most mature energy storage method with the most rapid development momentum, and common lithium-ion home energy storage battery is a powerwall battery.

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

Equipment manufacturer

Schematic diagram of upstream and downstream electrochemical energy storage

Energy storage battery is the core part of electrochemical energy storage method. At present, the mainstream batteries in the market can be roughly divided into lithium-ion batteries, lead-carbon batteries, fluid-flow batteries and sodium-ion batteries according to different technological routes.The response speed and discharge efficiency of batteries of different technology routes are not the same, but also have their own application scope and advantages and disadvantages.

According to statistics, in 2021, the China shipment of energy storage batteries is 48GWh, among which the shipment of electric energy storage batteries is 29GWh, a year-on-year growth of 339%; And according to report, the total global energy storage battery shipment in 2021 was 66.3GWh, a year-on-year growth of 132.6%, with power system energy storage as the main incremental contribution.

Energy storage lithium battery shipments in China

Energy storage battery shipments and growth rate in China from 2017 to 2021

Cost analysis of lithium iron phosphate battery energy storage method
According to the different cathode materials, the current mainstream lithium ion batteries have two types: ternary lithium battery and lithium iron phosphate.The energy density of lithium iron phosphate battery is lower than that of ternary material 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 the core component of the entire energy storage system, the cost of battery accounts for 50% of the entire energy storage system cost, which is an important channel for the subsequent cost reduction of energy storage system.In 2021, most of the bidding prices of lithium iron phosphate battery energy storage in China are concentrated in 1.2-1.7 RMB /Wh.

The global electrochemical energy storage EPC cost in 2022 is about 261 US dollars /kWh (equivalent to about 1.66 RMB /Wh), and is expected to fall to 203 US dollars /kWh (equivalent to about 1.29 RMB /Wh) in 2025. Since 2021, a large number of EPCs have been awarded at prices between 1.3-1.7 RMB /kWh.

3.Compressed air energy storage method

Compressed air energy storage method in China continues to progress. 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) and so on have been covered by research. Compressed air energy storage demonstration projects of 500kW capacity level, 1.5MW capacity level and 10MW capacity level have been completed.

The commercial compressed air energy storage power station in Hantford, Germany, built in 1978 and Alabama, USA, built in 1991 are commercial power stations. Research and development of compressed air, supercritical compressed air and liquid compressed air energy storage projects have been carried out in China.

Among them, Zhangjiakou International’s first 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.

Cost analysis of compressed air energy storage
The improvement of system efficiency and the decrease of cost are the basis for the commercial development of compressed air energy storage.At present, according to the completed and under construction projects, the system efficiency of megawatt level can reach 52.1%.

The system efficiency of 10 megawatt level can reach 60.2%, the system design efficiency of 100 megawatt level and above can reach 70%, and the efficiency of advanced compressed air energy storage system can approach 75%. With the increase of the system scale, the unit investment cost also continues to decrease, and the unit cost can decrease by about 30% when the system scale increases by an order of magnitude.

Initial investment cost

Core assumptions of LCOS calculation for Compressed air energy storage system

The change of initial investment and utilization hours has a great impact on the KWH cost, and with the technological progress, the initial investment still has room for decline.The utilization hours mainly depend on the utilization rate of the power station in actual operation. The higher the charging and discharging times per day, the lower the cost.In a 100MW/400MWh system, with an initial investment of 5-6 RMB /W and an annual cycle of 450-600 times, the kWh cost range is 0.252-0.413 RMB /kWh.

In conclusion, compressed air energy storage is expected to become an important supplement to pumped storage in the field of large-scale energy storage plants after energy efficiency is improved.

4.Sodium ion energy storage method

Sodium-ion batteries are expected to perform well.The key factors that determine whether electrochemical energy storage can be applied in large areas include safety, availability of material resources, high and low temperature performance, life, investment cost, etc.

According to the latest research progress of sodium ion battery, it has shown good performance in these aspects.After large-scale application, the cost of sodium ion battery is expected to be lower than that of iron lithium battery, and it can be widely used in large-scale electrochemical energy storage, low-speed electric vehicles and other fields. It is expected to form a complementary and effective replacement with lithium ion battery.

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

Related studies show that the material cost of sodium ion battery is about 370 RMB /kWh, and with the maturity of the industrial chain, the material cost is expected to further explore, combined with the cost of structural parts and electrical parts, the initial capacity investment is expected to be controlled at 500-700 RMB /kWh;In terms of performance, with the continuous investment in research and development and technological iteration, the battery cycle life is expected to exceed 8000 times.

Sodium-ion batteries
The material cost advantage of sodium-ion batteries is obvious

Since 2010, sodium ion battery has been widely concerned by China and other countries academia and industry, and its related research has ushered in an explosive growth. Many China and other countries enterprises are actively carrying out the relevant layout of sodium ion battery industrialization. Including FARADION, NatronEnergy, Tiamat, Kishida Chemical, Toyota, Panasonic, Mitsubishi Chemical, as well as China’s Hinabattery,CATL, natriumenergy and other companies.

At present, the China work in the research and development and manufacturing of sodium ion battery products, standard formulation and market application promotion is being carried out in an all-round way. Sodium ion battery is about to enter the stage of commercial application, and the related work has been in the forefront of the world.

Sodium ion cost analysis Sodium ion battery energy storage system LCOS calculation core assumptions

Considering the commercialization, the battery cost and performance will be greatly improved.Assuming that the initial investment cost is 0.9-1.2 RMB /Wh, the life span is 10 years, and the cycle life range is 2000-6000 times, the sensitivity analysis of sodium ion battery is done.If the cost is below 1.1 RMB /Wh and the cycle life is above 3000 times, the KWH cost will be between 0.270-0.662 RMB, which is better than lithium iron battery.

5.Full vanadium flow battery for energy storage

Vanadium battery electrical energy in the form of chemical energy stored in the different valence vanadium ion of sulfuric acid in the electrolyte, stacked electrolytic hydraulic into the battery through an external pump body, under the influence of mechanical power.

In the different storage tank and the half cell cycle in closed loop flow, using proton exchange membrane as battery diaphragm, electrolyte solution parallel through the electrode surface and electrochemical reaction, Collect and conduct the current through the double electrode plate, so that the chemical energy stored in the solution is converted into electric energy.This reversible reaction process allows the vanadium battery to be successfully charged, discharged and recharged.

Liquid flow battery has the characteristics of long life, good safety, large output power, large energy storage capacity and easy to expand, the life of 15-20 years, compared with other energy storage method, with the wind farm hardware has the highest degree of matching, especially suitable for wind power plant energy storage, to meet its frequent charge and discharge, large capacity, long time energy storage needs.Of course, the all-vanadium liquid flow battery has low energy density, much larger volume and mass than other batteries, and requires a temperature environment of 5-40°.

Full vanadium flow battery

Full vanadium liquid flow energy storage method advantages

Since 2010, China’s megawatt all-vanadium liquid flow battery demonstration projects have begun to be carried out successively. Since 2019, China’s liquid flow battery energy storage demonstration projects are accelerating the construction.

The first phase of “200MW/800MWh Dalian Liquid Flow Battery Energy Storage Peak Power Station National Demonstration Project” 100MW/400MWh all-vanadium liquid flow battery energy storage power station has completed the main engineering construction and entered the monomer module commissioning stage. It is expected to complete the grid commissioning in June, which is the largest vanadium liquid flow energy storage project in the world.

Vanadium liquid flow energy storage project planned or constructed in China in recent years

At present, the cost problem is still the biggest challenge for the large-scale commercial application of vanadium batteries.Due to the lack of commercial scale, and limited by equipment, capacity and high early investment, referring to Datang 10MW/40MWh all-vanadium flow battery energy storage system equipment bidding and Dalian flow battery energy storage peak power station national demonstration project investment situation, it is expected that the initial cost of vanadium battery is about 3 times that of lithium battery.

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

The change of initial investment and utilization hours has a great impact on KWH, but with the technological progress, the initial investment still has room for decline.The utilization hours mainly depend on the utilization rate of the power station in actual operation. The higher the charging and discharging times per day, the lower the cost.In a 100MW/400MWh system, when the initial investment is 11-13 RMB /W and the number of annual cycles reaches more than 600 times, the cost range of energy storage kWh is 0.44-0.69 RMB /kWh.
Sensitivity Analysis of LCOS for All-vanadium Flow Battery (RMB /kWh)

6.Lead-carbon battery energy storage method

Lead-carbon battery is a capacitive lead-acid battery, which is a technology evolved from the 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 all replaced by activated carbon, the ordinary lead-acid battery becomes a hybrid capacitor.If the activated carbon is mixed into the negative active material Pb, the ordinary lead-acid battery into lead carbon battery.

Progress of lead-carbon energy storage method
Axion, an American company, established a lead-carbon battery production line in 2006 and began to sell lead-carbon batteries in bulk in 2009.China’s leading acid battery factories have carried out the research and development and production of lead carbon batteries, for example, Shengyang shares and Japan Furuhe signed a cooperation agreement in 2014, authorized Shengyang shares in China factory lead carbon battery localized production;

Lead-carbon battery energy storage

Nandu Power has developed energy storage project segments such as Linan 2MWh, Zhejiang Luxidao 4MWh micro grid energy storage, Zhuhai Wanshan Island 6MWh;In 2018, the “lead carbon battery 2V1000 for Power storage” project of Sunway Group won the second prize of Science and Technology Progress of Zhejiang Province;Tianeng Power said that its high-performance lead carbon battery is a new type of battery independently developed with international leading technology level.

In December 2020, it won the highest award in China’s industrial field approved by The State Council — China Industry Award Project Award. The sensitivity analysis of lead carbon battery shows that the initial investment cost is 0.8-1 RMB /W and the cost range of lead carbon battery energy storage kilowatt-hour is 0.52-0.747 RMB /kWh when the annual cycle number reaches more than 500 times. Through calculation and comparison, it is found that although the initial investment cost of lead carbon battery is low, its discharge depth is lower than other energy storage method, so the cost advantage of KWH is not obvious.

In addition, if considering the energy loss cost in actual use, lead carbon batteries will be at a certain disadvantage due to their lower energy efficiency compared with lithium iron batteries. Under the condition of new energy storage, lead carbon batteries are also expected to achieve energy efficiency improvement and cost reduction through technological progress.

Which of the six energy storage method routes do you prefer?

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